Level 1 All Flashcards by J 2023

State the chemical abbreviations for propane and natural gas.

Propane: C3H8, Natural Gas: CH4

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State the ignition temperatures of propane and natural gas.

Propane: 920o to 1020oF, Natural Gas: 1100o to 1300oF

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List the specific gravities for natural gas, propane vapour, and liquid propane.

Natural Gas: 0.6, Propane vapour: 1.5, Propane liquid: 0.51

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What are the limits of flammability for natural gas and propane?

Natural Gas: 4 to 14%, Propane: 2.4 to 9.5%

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What are the maximum flame temperatures that can be achieved with propane and with natural gas when mixed with air?

CH4:3500oF, C3H8: 3600oF

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What are the boiling temperatures of propane and natural gas at sea level?

Propane: -44oF, Natural Gas: -258oF

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What are the flame speeds of natural gas and propane?

25”/sec., 32”/sec. (tube method)

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Define the term Btu.

British thermal unit. The amount of energy acquired or liberated when changing the temperature of 1 lb. of water 1oF

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What is the energy content of 1 cubic foot of propane and 1 cubic foot of natural gas?

C3H8:2500 Btu/ft3, CH4:1000 Btu/ft3

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List the products of complete combustion of natural gas and propane.

CO2 + H2O + N2

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What are the expansion ratios from liquid to vapour for natural gas and propane?

CH4: 1:600, C3H8: 1:270

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What are the percentages of nitrogen and oxygen found in air?

O2 = 20%, N2 = 80%

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What is the air/gas ratio required to achieve complete combustion of natural gas and propane?

CH4: 10:1, C3H8: 25:1

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What is the ratio of air to Btu content required to complete combustion of all hydrocarbon gases?

10ft3/1000Btu

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How many Btu equal one kilowatt?

3413 Btu/Kw

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Explain the term primary air, with reference to an atmospheric burner.

The air entrained and mixed prior to combustion

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What is the term used to describe the additional air supplied to the combustion chamber of a gas appliance to ensure complete combustion?

Excess Air

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What is the purpose of dilution air?

To reduce the velocity of the flue gasses

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A gas appliance is considered to be high input when it exceeds what input?

400,000 Btu/hr., aka. 400MBH

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What are the pressure limitations of a Class “B” license?

No pressure limitations however Safety Standards Act is limited to 700Kpa (100Psi)

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pipe sizing

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If the calorific value of a cubic meter of gas was 37,000 Btu.

What would the Btu content be per cu. ft?
What would the kW content be per cu. meter?
What would the kW content be per cu. ft?

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Calculate the correction factor required when converting gas at 40 degrees F. to standard gas temperature conditions.

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Calculate the correction factor required when converting gas under a pressure of
134.5 kPa absolute to standard gas pressure conditions.

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100 cubic meters of gas is pressurized at 50 psig. Calculate the new volume if the gas is released to atmosphere at sea level.

A gas at sea level is contained under a pressure of 60 psig at 50 degrees F. Calculate the new pressure if the temperature is increased to 90 degrees F. Answer in psig.

Calculate the flow rate in Btuh and kW Service pressure 60 psig Inlet pressure to meter 5 psig Manifold pressure 7” w.c Test dial 5 Cu. Ft. Time of 1 Revolution 1.5 Min. Calorific Value of gas 1000 Btu/Cu. Ft.

Calculate the input under the following conditions. Service pressure 50 psig House line pressure 10 psig Meter pressure 10 psig Test dial 5 Cu. Ft. 1 Revolution 30 seconds Ambient air temperature 700 F. Gas temperature 500 F. Local atmospheric pressure 14.73 psia. Calorific value of gas 1000 Btu/Cu. Ft.

Calculate the time for 1 revolution of a 2 Cu. Ft. test dial. Input 1,575,000 Btu/hr Local atmospheric pressure 14.25 psia Ambient air temperature 450 F. Gas temperature 500 F. Calorific value of gas 1050 Btu/Cu. Ft. Meter pressure 10 psig

Three appliances are firing at 75,000 Btu/hr each; the time for 1 revolution of a 2 Cu. Ft. Test dial is 32 seconds when all of the appliances are operating. Is the total input correct? (Meter pressure is 7” WC.) A 4th appliance is added, rated at 27 kW. The time for 1 revolution is now 24 seconds. Is the input correct? Is it over fired or under fired?

The clocked input of an appliance is 2,000,000 Btuh. The test dial is 5 Cu. Ft. The local atmospheric pressure is 13.9 psia and the gas temperature is 200 F. How many seconds will it take to complete 1 revolution of the test dial? Calorific value of gas 1000 BTU/CF Meter pressure is 20 psig

Calculate the input Meter pressure 34 kpa Local atmospheric pressure 97.3 kpa Gas temperature 3 degrees C. Test dial 0.5 Cubic Meters Time for one revolution 31 seconds Calorific value of gas 10.35 KW/Cu. M

When dealing with the combustion of hydrocarbon gases why is stoichiometric combustion of fuel and air not a viable option for most burners? This will produce an unacceptable luminous flame Burners are not capable of perfectly mixing air and fuel This type of combustion produces unacceptable flue gas components Stoichiometric combustion is unstable and unsuitable for heating applications

Burners are not capable of perfectly mixing air and fuel

Why is it important to add excess air to the combustion chamber? To provide cooling for the heat exchanger To ensure that perfect combustion occurs To provide an adequate amount of dilution air To ensure complete combustion occurs

To ensure complete combustion occurs

What is the ideal combustion ratio air-to-fuel ratio for natural gas? 20 ft3 to 1 ft3 25 ft3 to 1000 Btu 10 ft3 to 1000 Btu 2 ft3 to 100 Btu

10 ft3 to 1000 Btu

What is a colourless, odourless, tasteless, and potentially lethal by-product of incomplete combustion? Oxygen Carbon monoxide Nitrogen Aldehydes

Carbon monoxide

What is a colourless, acrid smelling toxic by-product of incomplete combustion? Oxygen Carbon monoxide Nitrogen Aldehydes

Aldehydes

What can be another cause of incomplete combustion other than insufficient air? Flame temperature dropping below 1,200°F Poor fuel to heat exchanger ratio Combustion chamber too large Too much humidity in the air

Flame temperature dropping below 1,200°F

At what point on the venting system should an analysis of the flue products be taken? downstream of the draft control device downstream of the flue collar upstream of the draft control device upstream of the fan assist burner

upstream of the draft control device

If a natural gas appliance and a propane appliance were firing at the same rate and under the same conditions, which would have the greater air requirements and which would have the greater percentage of CO2 in the flue products? Natural gas has higher air requirements and lower CO2 Propane has higher air requirements and higher CO2 Both have the same air requirements, but natural gas has higher CO2 Both have the same air requirements, but propane has higher CO2

Both have the same air requirements, but propane has higher CO2

How much excess air is added to the combustion process to achieve the ultimate percentage of CO2? 1/3 volume of combustion air 2/3 volume of combustion air 50% of combustion air none is required

none is required

What percentage of excess air will produce equal percentages of O2 and CO2 in the flue products? 25% 33% 50% 100%

0.5

Analyzing the flue products after servicing a burner shows acceptable levels of CO2 and O2, but unacceptable levels of CO. What type of circumstances could cause this to happen? lack of combustion air lack of excess air excessive dirt on fan blades cracked heat exchanger

cracked heat exchanger

If a gas hot water tank was 100% efficient, what would the temperature of the flue products be? same as ambient 100°F above ambient temperature 100°F below ambient temperature minimum 127°F to maintain draft

same as ambient

A gas appliance is firing at 1000 Mbh on natural gas. Calculate the volume of CO2 produced each hour. 100 ft3 1,000 ft3 2,000 ft3 10,000 ft3

1,000 ft3

A gas appliance is firing at 3,000 Mbh on propane. Calculate the volume of CO2 produced each hour. 1,200 ft3 3,000 ft3 3,600 ft3 4,800 ft3

3,600 ft3

A gas appliance is firing at 5,000 Mbh on propane gas and condensing all water vapor to a liquid state. Calculate the volume of water produced each hour (expansion ratio vapor to liquid is 1700:1). 30 Imperial gallons 60 Imperial gallons 90 Imperial gallons 120 Imperial gallons

30 Imperial gallons

If a 2,350 Mbh forced draft burner was firing on natural gas with 23% excess air, what would be the expected percent of O2 when taking a combustion analysis? 2.3% 3.5% 4.1 % 5%

0.040999999999999995

If a 2,350 Mbh forced draft burner was firing on natural gas with 23% excess air, what would be the expected percent of CO2 when taking a combustion analysis? 8.85 % 9.2% 10.4 % 13%

0.0885

What is absolute zero equal to in: Degrees F? Degrees C?

Degrees F: -460 F, Degrees C: -273 F

Convert 30 degrees Fahrenheit to Celsius

30 – 32 / 1.8 = -1.1 C

Convert 30 degrees Celsius to Fahrenheit

30 X 1.8 + 32 = 86 F

Define sensible heat

Heat that can be measured

Define latent heat

Heat energy required or liberated during a change of state

State the number of BTU’s required to change 1 lb. of 32oF ice to 32oF water.

144 BTU

State the number of BTU’s required to change 1 lb. of 212oF water to 212oF steam

970.4 BTU

State the specific heat of water

State the specific heat of steam

0.48 (ice: 0.53)

What is the formula to find the efficiency of a gas fired appliance?

Output/Input

Why do air requirements differ for appliances with and without draft control? All units require air to be supplied at a ratio of 30:1 Units with draft control require more combustion air Units with no draft control require more excess air Units with draft control require dilution air

Units with draft control require dilution air

In theory, which gas appliance will require more air per hour to operate? 1000 Mbh appliance with a draft hood and atmospheric burner 500 kW appliance operating on 50% excess air and no draft control device 1000 Mbh power burner using 30% excess air and a barometric damper 2200 Mbh power burner using 25% excess air and no draft control

1000 Mbh appliance with a draft hood and atmospheric burner

An atmospheric gas appliance has an input of 350 Mbh and is equipped with a draft hood. It is to be installed in a building that complies with code clause 8.2.1. A or B. What size duct is required to provide air to this appliance? 6 inch 7 inch 8 inch 9 inch

8 inch

A furnace room complies with code clause 8.2.1. (a) or (b). It contains a 200 Mbh furnace without draft control and a 100 Mbh hot water heater with a draft hood. Size the combustion air duct based on a length of 30'. 6 inch 7 inch 8 inch 9 inch

7 Inch

A boiler room contains the following five pieces of equipment: one 2500 Mbh boiler with draft control two 350 Mbh hot water heaters with draft hoods two 650 Mbh duct heaters without draft control. Calculate the required free area of the combustion air duct. 43 in2 300 in2 321 in2 343 in2

343 in2

The following gas appliances are installed in a mechanical room: one 1200 Mbh steam boiler with a barometric damper one 350 Mbh hot water heater with draft hood two 500 Mbh direct fired make-up air units Select a grill for the combustion air opening in the boiler room wall that will meet the minimum requirements of the B149.1 gas code (grills rated at 60% free area). 10" ´ 12" 10" ´ 14" 15" ´ 20” 20" ´ 20"

15" ´ 20”

The air supply to a 30,000 Mbh boiler, using a force draft burner, is provided by mechanical means through a horizontal duct 42 feet in length. What is the quantity of air required to be supplied to the boiler? 1 ft3 for each 1,000 Btu/h 10 ft3 for each 1,000 Btu/h 15 ft3 for each 1,000 Btu/h 30 ft3 for each 1,000 Btu/h

30 ft3 for each 1,000 Btu/h

What is the main reason for performing combustion analysis on gas fired equipment?

To ensure the equipment is operating in a safe and efficient manner.

How often should your combustion analyser be calibrated to ensure accurate test readings?

Once per year.

Where should the sampling probe take a sample from on a gas fired appliance?

Upstream of any draft control device or just downstream of a stack economizer.

What is the correct way to allow combustion analysis samples to be taken with plastic S636 systems?

Installing an access tee with a ½” tapped bushing as close as possible to the flue collar of the appliance where either a plastic or brass plug can be inserted.

What is a Peltier cooler used for in a combustion analyzer?

To drive out moisture from the sample

The gas cells in a combustion analyser are of what type?

Electrochemical

What can shorten the life span of the toxic sensors in a combustion analyser?

High gas concentrations or insufficient purging

What is the chemical formula for the Perfect combustion of Natural Gas?

1CO2 + 2H2O = 8N2

What is the chemical formula for the Perfect combustion of Propane?

3C02 + 4H2O = 20N2

What is added to the combustion process to produce Complete combustion?

Excess Air

What is the expected percentage range of O2 produced by a forced draft burner with CH4 as the fuel?

3% - 6%

What are four characteristics of Carbon Monoxide?

Toxic, colourless, odourless and tasteless

What can cause too much draft in a venting system?

High stack temperatures

What percentage gain in efficiency is achieved by lowering stack temperature by 45⁰F?

Less than 1%

Calculate the net stack temperature if the ambient temperature is 72⁰F and the stack temperature is 420⁰F? Is this temperature within typically expected values?

348⁰F, Yes (330 - 500⁰F)

If the measure percent O2 reading is 4.1% and the measured NOx reading is 55 ppm, what would the NOx ppm be when corrected to standard?

58.58 ppm

If the measured CO reading is 38 ppm, and the measured %O2 reading is 4.2% what would the calculated air-free ppm reading be?

47.56 ppm

What is the power end of the Honeywell, Series 90 Modutrol used for?

It is used to drive linkages

What is the auxiliary end of the Honeywell, Series 90 Modutrol used for?

It is used to devices like auxiliary switches

In what orientation should motors with crankshafts be installed?

Horizontal

How is strain avoided on the motor and linkage of a fuel/air system?

The drive lever rotational start point is kept off of the shaft centerline

Fixed Stroke Actuators are available in what two opening ranges?

90⁰ or 160⁰

Adjustable stroke model actuators can be field adjusted between what range?

90⁰ - 160⁰

What controls the speed and the amount of rotation of the driven lever pivot point?

It is controlled by the starting position of both levers and the connection distance of the linkage to the lever pivot points

Placing the drive lever closer to the shaft centerline than the driven lever is placed will do what to the rotation of the driven lever?

It will be reduced

Placing the driven lever closer to the shaft centerline than the driver lever is placed will do what to the rotation of the driven lever?

It will be increased

How are precise changes made on the linkage for a fuel valve?

By adjusting the cam spring

The gas butterfly valve is used to control modulation and to stop gas flow? TRUE / FALSE

FALSE, It is not used to stop gas flow

How can high and low fire be adjusted on a gas butterfly valve?

By using the stop screws

Where would you find information for making initial set up adjustments to linkages?

From the equipment manufacturer

What must be done while making any adjustments to linkages?

Combustion analysis must be performed

How do we balance safety and efficiency when adjusting our linkages with the use of a combustion analyzer?

- Adding more oxygen reduces the chance of CO and increases safety - Reducing oxygen increases our efficiency but has the potential to increase CO thus being less safe. - Always prioritize safety

Describe the relationship between the % values of CO2 and O2 in the flue gas when you adjust the air shutter on a fan-assist burner during set-up?

The greater the amount of excess air, the higher the % of O2 and the lower the % of CO2

If three flue samples were taken, the first with 20% excess air, and the second with 32% excess air, and the third with 44% excess air which would contain the higher CO2 reading?

The sample with 20% excess air

Both have the same air requirements, but propane has higher CO2

When performing an analysis of the products of combustion using natural gas, what percentages of carbon dioxide and oxygen you would expect to find if the excess air is set at 30%?

8.3% CO2, 5% O2

A gas appliance is firing at 5,400 Mbh on propane gas and condensing all water vapor to a liquid state. Calculate the capacity of water produced each hour in US Gallons.

38 US Gallons

What is the formula for perfect (stoichiometric) combustion?

Fuel + O2 + N2 = CO2 + H2O + N2

What is the formula for complete combustion?

Fuel + O2 + N2 + Excess Air = CO2 + H2O + N2 + Excess Air

How does tertiary air control NOx emissions?

It slightly cools the flame

What can be done to control NOX emissions from a burner?

Inject steam around the flame

What can be used to control the combustion air for a burner system?

A Variable Frequency Drive or Electronically Commutated Motor

List three factors that can create CO in the products of combustion?

Running too much fuel, not enough combustion air or a failing draft inducer

What is the maximum air-free CO level allowed to be produced during combustion?

400 ppm

How many pounds of CO2 are produced per hour from a 54,784,000 BTUH fuel oil fired boiler?

8765 lbs

How many pounds of CO2 are produced per hour from a 7,312,000 BTUH natural gas fired boiler?

856 lbs

According to legislation, how much ppm sulfur content does heating oil need to be below?

500 ppm

What chemical compounds from combustion are collectively called SOX?

SO2 & SO3

What are two results when NO2 reacts with other pollutants?

Ozone and Acid Rain

What chemical compounds from combustion are collectively called NOX?

NO & NO2

What would be the calculated theoretical draft developed by a stack 55 feet in height with an average temperature of 310°F, and the ambient temperature is 70°F?

0.246” w.c.

A boiler is firing natural gas at 4,000 Mbh with 30% excess air. What would be the calculated the volume in cubic feet per minute of flue gases leaving the flue outlet if the temperature is 450°F, and the outside air temperature is 70°F?

1603 cfm

A natural gas boiler is firing at 3 million Btu/h with 40% excess air. The ambient air temperature is 66°F and the stack temperature is 410°F. What would be the calculated velocity of the flue gas if the boiler is equipped with a 16-inch diameter stack?

889 fpm

If a stack has a velocity of 1000 fpm, what would be the calculated draft produced?

0.06 w.c.

A boiler equipped with a power burner is firing at 11 million Btu/h with 35% excess air. The combustion air duct is sized to meet the Gas Code requirements. What would be the calculated velocity through the combustion air duct if the boiler is operating at full input, the ambient air temperature is 70°F, and the stack temperature is 460°F?

972 fpm

You are called on to commission an installation of a 4,750,000 Btu/h natural gas boiler. - Excess air set at 30% - Stack diameter 18 inch - Combustion chamber and heat exchanger pass volume 188 ft3 - Gross stack temperature 485 deg. F - Ambient temperature 76 deg. F Based on this information what is the expected draft in the stack?

0.0762” w.c.

What factors would achieve the highest draft in a chimney?

Tall chimney, hot combustion products, hot ambient (outside) air

A mechanical draft produced by a device upstream from the combustion zone of an appliance is a definition of what type of draft?

Forced draft

A mechanical draft produced by a device downstream from the combustion zone of an appliance is the definition of what type of draft?

Induced draft

What reading would the draft pressure gauge indicate when measuring in the combustion chamber of a gas fired appliance using a force draft burner?

Positive pressure

What reading would the draft pressure gauge indicate when measuring in the combustion chamber of a gas fired appliance using a fan-assisted burner?

Non-positive pressure (Negative over-fire pressure)

What does a balanced draft system incorporate?

A forced draft burner and an induced draft fan

What type of draft control does a gas-fired appliance incorporate when using a forced draft burner?

Internal damper

Why is the draft reduced when using flue gas recirculation to control NOx?

Lower flame temperatures

Why is the draft reduced when using a scrubber (air pre-heater)?

Heat is removed from the flue gases

Calculate Draft Loss Referring to the figure below, to maintain a draft of 0.08” w.c. at E what will the draft pressure need to be across the damper B? The draft at A should be 0.6’ w.c. and the draft losses through the appliance are as follows: - C = 0.12” w.c. - D = 0.11” w.c. - Elbow = 0.05” w.c. each

Across damper B = 0.19 “w.c. - calculation: 0.6 – (0.08 + 0.12 + 0.11 + 0.10) = 0.19

What is the primary concern with ICI hydronic system design?

Protection of the equipment

What are two major concerns for the boiler in an ICI hydronic system installation?

Thermal shock and condensing combustion products

What is the typical system design temperature difference for a non-condensing ICI boiler?

20°F

What is the standard system design temperatures for a non-condensing ICI hydronic boiler?

180°F supply, 160°F return

What type of boiler is best suited to handle the thermal shock?

Flex tube

What minimum return water temperature must be maintained to avoid condensing of combustion products?

140°F

On an ICI hydronic heating system, what is the best location to install an air separator?

Immediately after the boiler supply outlet.

Why is it recommended to install the boiler outlet, air separator and expansion tank on the suction side of the system circulator pump?

To decrease air entry into the system piping and prevent imposing system head on the boiler supply.

Where is it recommended the system feed water be connected?

Into the air vent piping on the air separator

What is the purpose of a hydraulic de-coupler?

To isolate the source pump(s) from the load pump(s)

Which type of boiler installation will a stack economizer be most effective?

High pressure water-tube steam boiler

What is the purpose of a steam trap?

To hold steam upstream while allowing condensate to pass.

What device controls the water level in a steam boiler?

Low water cut-off

What is the sparge tube used for?

Preheating feed water

What is done to remove dissolved oxygen from boiler feed water?

Heat the feed water

What is the major concern with steam systems?

Water chemistry

What is installed to remove dissolved gasses by mechanical means from the boiler feed water?

Deaerator

What is the main advantage of installing a deaerator?

Reduces feed water chemical treatment costs

What is the advantage of a thermal fluid heating system?

High fluid temperatures without high pressure

To protect against a low water condition how many fuel cutoff devices are required on an automatically fired steam boiler?

Why would a thermal fluid system be used instead of a water boiler?

Thermal fluid systems are used when higher temperatures are required than can be generated by water and without the added expense of a steam system

In relation to steam system what is the pressure of a thermal fluid system?

They have a lower pressure than steam systems

How high a temperature could thermal fluid operate at?

750°F

Why can we not use typical hydronic circulators in a thermal fluid system?

They are not rated for the high temperatures

What must be done when initially firing a thermal fluid system to remove the air?

Slowly raising the temperature of the fluid so the air can be vented off and the moisture driven out.

List some of the uses for thermal fluid systems?

Baths, kettles, rolls, reactors, steam/hot water generators, storage tanks, pressure moulds, fryers, ovens

Referring to Figure 1, What is this is the ASME symbol for?

Power boiler safety valve

Referring to Figure 2, What is this is the ASME symbol for?

Heating boiler relief valve

Referring to Figure 3, What is this is the ASME symbol for?

Unfired pressure vessel safety valve

Referring to Figure 4, What is this is the ASME symbol for?

Unfired pressure vessel rupture disc

Who can repair and set pressure relief devices?

Organizations authorized by the regulatory authority

What three things must be done to a safety valve to show it has been reserviced by an authorized service organization?

a. Affix a dated service nameplate to the reclosing pressure relief device b. Use a uniquely embossed seal to seal all adjustable parts c. Ensure the manufacturer’s nameplate remains on the relief device

What is the recommended time interval for a pressure relief device to be tested?

12 months

What is the recommended time interval for a pressure relief device to be serviced?

3 to 5 years

What type of opening characteristics does a Safety Valve have?

Pop opening from pressure

What type of opening characteristics does a Relief Valve have?

Gradual opening from pressure

Where is the Rupture Disk commonly installed on a boiler?

Upstream in series with a relief valve

The set point on a safety valve can be greater than the Maximum Operating Working Pressure (MAWP) of the vessel or piping. TRUE / FALSE

Referring to Figure 5, What type of vessel would you find this mechanical safety valve on?

High pressure steam boiler

Referring to Figure 6, What type of vessel would you find this mechanical safety valve on?

Unfired steam vessel

A 150 Psig 8,000 MBH boiler has a safety valve with a relief capacity of 8,350 lbs/hr. Can this safety valve safely relieve the boiler?

8000000/970 = 8274Lbs YES

What is the minimum relief capacity of a safety valve (in lbs/h) installed on a 150 Psig, 4,600 MBH steam boiler with an efficiency of 82%?

4600X33475/970 3888 lbs/h

What is the minimum relief capacity of a safety valve (in lbs/h) installed on a 150 Psig, 400 Horse Power steam boiler with an efficiency of 79%?

400bhpX33475btu/970btu/lb 13,801-4 lbs/h

A 150 Psig, 500 HP, 82% efficient steam boiler has two safety valves, one with a relief capacity of 6,576 lbs/hr and the other at 6,303 lbs/hr. Do the combined relief valves have enough capacity to relieve this boiler safely?

NO 500bhpX33475btu/970 btu per lbs = 17255 6576+6303=12879

A safety relief valve inlet can be smaller than the boiler outlet it serves. TRUE / FLASE

True

The piping connected to the outlet of a relief valve can be reduced by what size?

The size cannot be reduced

On a steam system, the safety valve must be installed in what orientation?

Vertically

All attached discharge piping for a steam safety valve must be supported___________.

Independently supported

What is best practice when the relief discharge piping from a safety valve is installed vertically to outdoors?

Install a drip pan elbow to allow moisture to drain away form the valve

How many inches should the center-to-center distance from the drip pan elbow to the safety valve not exceed?

24 inches

Referring to Figure 7, the slash in the discharge pipe should be cut at what angle?

45 degrees

Referring to Figure 8, if the safety valve is 3 Inches in size, what must the bet he minimum size of the drain-open to waste pipe be?

3/8 inch

What is the set relief pressure for a propane tank installed on a premise?

250 psi

What is the set relief pressure for a propane tank installed on a vehicle?

312 psi

What is the set relief pressure for a propane cylinder?

375 psi

Where is the primary relief valve installed for a vehicle’s LNG tank?

To the top fill line

Where is the secondary relief valve installed for a vehicle’s LNG tank?

To the vapour withdrawal line

What is the primary relief valve discharge setting set to for a vehicle’s LNG tank?

Set at the MAWP of the tank

What is the secondary relief valve discharge setting set to for a vehicle’s LNG tank?

1.5 times the MAWP of the tank

Referring to the figure below, what must be done to the discharge of this relief valve?

Nothing

Which code regulates the installation and testing of safety relief valves?

ASME Boiler and Pressure Vessel code

What is the maximum servicing interval for a pressure relief device installed on a 50 psig steam boiler?

Every five years

How often should a lift test be performed for a pressure relief device installed on a 50 psig steam boiler?

Annually

What is the maximum servicing interval for a pressure relief device installed on a 12 psig steam boiler?

Every five years

How often should a lift test be performed for a pressure relief device installed on a 12 psig steam boiler?

Annually

How often should a lift test be performed for a pressure relief device installed on a 150 psig hot water heating boiler?

Every two years

What fluid should a pressure relief device that has been serviced and installed on a steam boiler be tested on?

Steam

What fluid should a pressure relief device that has been serviced and installed on a hot water heating boiler be tested on?

a. Air b. Steam c. Water

When performing a lift test for a safety valve installed on a low-pressure steam boiler, at what percent must the pressure be under the device disk prior to lifting the test lever?

At least 75% of the Device set pressure

When dealing with the combustion of hydro carbon gases, why is stoichiometric combustion of fuel and air not a viable option for most burners? 1) This will produce an unacceptable luminous flame 2) Burners are not capable of perfectly mixing air and fuel 3) This type of combustion produces unacceptable flue gas components 4) Stoichiometric combustion is unstable and unsuitable for heating applications

2) Burners are not capable of perfectly mixing air and fuel

It is important to add excess air to the combustion chamber to: 1) Provide cooling for the heat exchanger 2) To ensure perfect combustion occurs 3) To provide an adequate amount of dilution air 4) To ensure complete combustion occurs

4) To ensure complete combustion occurs

Which of the air to fuel ratios shown below is for natural gas? 1) 20 ft3 to 1 ft3 2) 20 ft3 to 100 Btu’s 3) 10 ft3 to 1000 Btu’s 4) 2 ft3 to 100 Btu’s

3) 10 ft3 to 1000 Btu’s

Why do air requirements differ for appliances with and without draft control? 1) All units require air to be supplied at a ratio of 30:1 2) Units with draft control require more combustion air 3) Units with no draft control require more excess air 4) Units with draft control require dilution air

4) Units with draft control require dilution air

In theory, which gas appliance will require more air per hour to operate? 1) 1000 MBH appliance with a draft hood and atmospheric burner 2) 500 kW appliance operating on 50% excess air and no draft control device 3) 1000 MBH power burner using 30% excess air and a barometric damper 4) 2200 MBH power burner using 25% excess air and no draft control

1) 1000 MBH appliance with a draft hood and atmospheric burner

At what point on the venting system should an analysis of the flue products be taken? 1) Downstream of the draft control device 2) Downstream of the flue collar 3) Upstream of the draft control device 4) Upstream of the fan assist burner

3) Upstream of the draft control device

If a natural gas appliance and a propane appliance were firing at the same rate and under the same conditions, which would have the greater air requirements and which would have the greater % of CO2 in the flue products? 1) Natural gas has higher air requirements and lower CO2 2) Propane has higher air requirements and higher CO2 3) Both have the same air requirements but natural gas has a higher CO2 4) Both have the same air requirements but propane has a higher CO2

4) Both have the same air requirements but propane has a higher CO2

How much excess air is added to the combustion process in order to achieve the ultimate percentage of CO2? 1) 1/3 the volume of combustion air 2) 2/3 the volume of combustion air 3) 50% of combustion air 4) None is required

4) None is required

What percentage of excess air will produce equal percentages of O2 and CO2 in the flue products? 1) 25% 2) 33% 3) 50% 4) 100%

3) 50%

Analyzing the flue products after servicing a burner shows acceptable levels of CO2 and O2 but unacceptable levels of CO. What type of circumstances could cause this to happen? 1) Lack of combustion air 2) Lack of excess air 3) Excessive dirt on fan blades 4) Poor mixing ability of burner system

4) Poor mixing ability of burner system

If a gas hot water tank was 100% efficient, what would the temperature of the flue products be? 1) Same as ambient 2) 100°F above ambient temperature 3) 100°F below ambient temperature 4) Minimum 127°F to maintain draft

1) Same as ambient

A gas appliance is firing at 1000 Mbh on natural gas. Calculate the volume of CO2 produced each hour. 1) 100 CFH 2) 1000 CFH 3) 2000 CFH 4) 10000CFH

2) 1000 CFH

A gas appliance is firing at 3000 Mbh on propane. Calculate the volume of CO2 produced each hour. 1) 1200 CFH 2) 3000 CFH 3) 3600 CFH 4) 4800 CFH

3) 3600 CFH

A gas appliance is firing at 5000 Mbh on propane gas and condensing all water vapour to a liquid state. Calculate the volume of water produced each hour (note: the expansion ratio for water from liquid to vapour is 1700:1). 1) 30 imperial gallons 2) 60 imperial gallons 3) 90 imperial gallons 4) 120 imperial gallons

1) 30 imperial gallons

The theoretical perfect combustion of natural gas requires an air/gas ratio of: 1) 10:1 2) 15:1 3) 25:1 4) 30:1

1) 10:1

The complete combustion of propane in air (include 50% excess air) requires an air/gas ratio of: 1) 10:1 2) 15:1 3) 25:1 4) 37:1

4) 37:1

A furnace operating at the rated input on propane is converted to natural gas. The total air requirements for the furnace will: 1) Increase by 5% 2) Increase by 10% 3) Decrease by 15% 4) Remain the same

4) Remain the same

The ultimate percentage of CO2 in the flue products of natural gas is: 1) 8% 2) 12% 3) 15% 4) 20%

2) 12%

Some flue gas analyzers can test for combustibles. Which of the following could not be detected? 1) Carbon 2) Hydrogen 3) Carbon monoxide 4) Carbon dioxide

4) Carbon dioxide

The difference between the flue stack temperature and the room temperature is called the: 1) Net stack temperature 2) Ambient temperature 3) Gross stack temperature 4) Critical temperature

1) Net stack temperature

A fan assist burner operating at its rated input is producing flue gas with 8.6% CO2. In order to increase the CO2 level you must: 1) Increase the air supply 2) Decrease the air supply 3) Increase the fuel supply 4) Decrease the fuel supply

2) Decrease the air supply

A fan assist burner operating at its rated input is producing flue gas with 10% oxygen content. The efficiency of the appliance could be increased by: 1) Increasing the air supply 2) Decreasing the air supply 3) Decreasing the CO2 content 4) Decreasing the fuel supply

2) Decreasing the air supply

What is the voltage limitation on the secondary side of a control power transformer for a safety control circuit of a gas fired appliance?

120 V

What is the primary purpose of the design of an isolation transformer?

To physically and electrically separate primary and secondary windings from each other.

What type of transformer is used for power conditioning?

Isolation transformer

What is protected by fusing the secondary side of a control power transformer?

The transformers secondary winding

Referring to the figure below, what type of transformer is represented?

Control power transformer

Referring to the figure below, what primary and secondary voltage is the transformer configured for?

Primary 480 V / secondary 120 V

What information is required from the loads energized to size a control power transformer?

Total inrush VA

What is the minimum ignition transformer secondary voltage required for direct spark ignition of main burner gas?

6000 V

What is the minimum ignition transformer secondary voltage required for ignition of an oil burner?

10,000V

For control point instrumentation, what does RTD stand for?

Resistance temperature detector

What type of RTD is mostly used in the industrial sector?

Coiled element RTD

The known electrical resistance at a specific temperature of the metal that makes up an RTD allows the RTD to be accurate within its temperature limits.

True

What metal is most commonly used in an RTD in industrial applications?

Platinum

How does an RTD work?

The resistance increases as the temperature of the sensor increases

Which is the most common RTD wiring configuration that gives a good combination of accuracy and convenience?

3-wire

A 4-wire RTD gives the best accuracy even though most industrial controllers/measurement devices cannot make a true four wire measurement.

True

What is the characteristic of a 3-wire RTD configuration?

It allows the measurement to factor out the resistance of the leads

What type of circuit is used in an RTD to measure the resistance?

Wheatstone bridge

How does a thermocouple interpret changes in temperature?

Change in Voltage

A ____________ has wider operation ranges than an RTD.

Thermocouples

RTDs are more sensitive than thermocouples thus they react faster.

False

Which statement is true when comparing thermocouples to RTDs?

Thermocouples react faster than RTDs, but RTDs are more accurate

What can limit the maximum range of a thermocouple?

Its diameter

How does a pressure transducer work?

It converts pressure into an electrical signal

What produces the electrical signal in a pressure transducer?

Strain gauge

What types of electrical output is available for a pressure transducer?

Millivolt, 0-10 Voltage, 4-20 mA

How many platinum RTDs does a thermal mass flow meter use?

In a thermal mass flow meter, what task does each RTD perform?

One RTD measures the fluid temperature and the second maintains a constant temperature differential above the process fluid

What three things is an automatic O2 trim system designed to compensate for?

Fuel characteristics, temperature, barometric pressure

What sensor is the critical component used to reduce emissions in a modern biomass boiler?

O2 sensor

To give better control and more consistent/accurate positioning for a modulating burner, in what system are servo motors used?

In a parallel positioning system

What is the standard voltage used for industrial control circuitry?

120 volts

Why are separate ignition transformers used for industrial burner systems?

To generate a big and hot enough spark to ensure the fuel ignites quickly and efficiently

Are limit circuits wired in parallel or series?

In series

List four specific conditions that a limit in a circuit control can control for?

Temperature, Pressure, Liquid Level and Liquid Flow

What are the two types of reset for limit switches?

Manual or Automatic

Referring to Figure 1, what type of limit is represented?

A High pressure limit switch

What does an operating control do and what are the two most common limits associated with them?

An operating control turns the burner system on and off based on temperature or pressure.

Referring to Figure 2, what is this the symbol for in a limit circuit?

Pressure switch

Referring to Figure 3, what is this the symbol for in a limit circuit?

Temperature switch

Referring to Figure 4, what is this the symbol for in a limit circuit?

Float switch

Referring to Figure 5, what is this the symbol for in a limit circuit?

Flow switch

What is one purpose of a permissive circuit?

To ensure two incompatible events don’t occur at the same time.

Define an interlock:

An interlock is a feature that makes the state of two mechanisms or functions mutually dependent (one can’t work without the other)

A DFMAH shall be ______ in such a way as to prevent its operation unless the exhaust system is functioning.

Interlocked

What must be proved when using automatically operated louvres for the inlet and discharge of a DFMA?

They must be proved fully open.

What is the purpose of a purge interlock?

To prove that the purge air flow rate is at maximum during the purge

An airflow switch is an example of what type of interlock.

Running interlock

The low fire start interlock permits the ignition of the pilot of main flame at an input of:

40% or less of the rated maximum input

What will the size of the wire be from the mag starter to motor if 230 volts is used?

6 AWG

What will the size of the mag starter be if 460 volts is used?

NEMA 2

What size overloads are required for the motor starter if 460 volts is used?

31.25 Amps 25 amps 1.15 service equals 125% of 25 amps less than 1.15= 115% rule 28 -208?

What will be the rated size of the disconnect time-delay fuses if 230 volts is used?

87.5 Amps

For a PID controller, what does the proportional do?

It produces an output value that is proportional to the current error value

For a PID controller, what does the derivative do?

It sums the error over time

For a PID controller, what does the proportional gain do?

It determines the ratio of output response to the error signal

For a PID controller, what does the integral do?

It acts as a brake or dampener on the control effort

A VFD or variable frequency drive is also know by what other names?

Variable speed drives, adjustable drives, adjustable frequency drives, frequency converts

What are some of the reasons why we would want to adjust motor speeds?

Save energy (improve efficiency), Match the speed to process requirements, match the torque to process requirements, lower noise levels, reduce mechanical stress, and improve working environment.

What are some applications where a gas fitter may see a VFD used?

DFMA, pumps, fans, compressors

What process takes AC power and turns it into DC power in a VFD?

The converter phase, also known as rectification. AC-DC --DC-- DC-AC converter DC BUS Inverter

What smooths out the DC power in a VFD?

The DC bus phase AC-DC --DC-- DC-AC converter DC BUS Inverter

What is the phase called were the DC power is turned back into AC power called?

The inverter phase AC-DC --DC-- DC-AC converter DC BUS Inverter

Why do we go through the process of changing AC power to DC power and then back to AC power?

This is done so that we can control the frequency (hertz) and voltage and in this way better control the motor.

What electrical component is used to rectify the AC power and convert it into DC power?

Diodes

How is the DC power smoothed out during the DC bus phase?

Through the use of capacitors which add energy to the DC waveform when voltage drops

What is used to change the DC power back to AC power?

IGBT (insulated gate bipolar transistors)

For what two reasons is an overcurrent protection device required in the AC supply to the VFD?

- To provide thermal protection for the VFD cables between the location of the overcurrent protective device and the VFD - To limit the energy available at the location of a short circuit

What four conditions can present issues for VFDs?

- No Flow conditions - High speed response - Full load conditions - Equipment speed limitations

What is main difference between the motors of a VFD and an ECM?

The ECM is a DC motor whereas the VFD is an AC motor.

What type of current and how many phase is an ECM?

The power produced is 3 phase DC output

What is the most common use of EC motors in the gas fitting world?

Fans: air-handlers, ventilation fans, furnace fans

How does an ECM achieve commutation?

Electronically, with onboard electronics

Where are the permanent magnets located in an ECM?

In the rotor

What, commonly, can cause a power surge?

A Lightning Strike, High power draws, Tripped breakers

What is the definition of insufficient voltage?

The decrease of electrical power to 90% of normal for 1 minute or more

What is the most common cause of insufficient voltage?

An overloaded system

What is a short circuit?

A low resistance connection between two conductors supplying electrical power to any circuit

What could cause a short circuit?

Damaged insulation, a loose wire, faulty appliance wiring

What device is used to break the circuit when it detects and electric arc in the circuit?

An Arc Fault Circuit Interrupter (AFCI)

What could be a reason for a fuse to blow?

An overloaded circuit, a short circuit, a ground fault, an arc fault

What could be a consequence of corrosion on our electrical connection?

- Loss of material leading to loss of function - Introduction of additional resistance leading to added heat and eventual failure

Which type of wire is the least resistant to corrosion?

Aluminum

What is the consequence of switching the neutral wire instead of the hot wire on an appliance disconnect switch?

The appliance will always be live, even when the switch is open. Leading to a risk of electrical shock for the technician

To protect against a low water condition how many fuel cutoff devices are required on an automatically fired steam boiler?

Beside shutting off the burner, what is another function of a low water cut-off device on a steam boiler?

Energize feed pump

What is done to change the operating level of an external float style LWCO device

Change the installation piping

What is the purpose of a steam trap?

It prevents steam from entering the condensate return piping

At what point does the thermostatic steam trap open?

When the condensate temperature drops below saturated steam temperature

What does the thermodynamic steam trap operate on the basis of?

Bernoulli’s principle

The thermodynamic steam trap will work on lower pressure systems. TRUE / FALSE

What is an arc flash?

The light and heat created from an arc fault explosion

What is an arc blast?

The pressure wave created after an arc fault

What is the major cause of an arc flash?

Voltage transients

Referring to the figure below, what is arc flash boundary 1 referred to as?

Arc flash protection boundary

Referring to the figure below, what is arc flash boundary 2 referred to as?

Arc flash limited approach boundary

Referring to the figure below, what is arc flash boundary 3 referred to as?

Arc flash restricted boundary

Referring to the figure below, what is arc flash boundary 4 referred to as?

Arc flash prohibited boundary

What is defined as an arc flash protection boundary?

The calculated safe working distance from electrical equipment which would not expose the employee to the hazards associated with an electrical arc flash.

What is defined as an arc flash limited approach boundary?

The minimum permitted distance that unqualified and unprotected personnel may approach a live component.

What is defined as an arc flash prohibited boundary?

The boundary where no electrical worker is permitted unless proper procedures, PPE, training, energized work permits, and risk assessment are all in place.

What is defined as an arc flash restricted approach boundary?

The minimum permitted distance where personnel need to have been trained in shock protection techniques, be wearing the correct PPE, and have a written and approved plan for any work in the zone.

Referring to the DFMA Wiring Diagram, the DFMA supply fan isn’t running and you take the following readings with your multimeter: - 120 Volts across terminals 1 and 2 - 0 Volts across terminals 1 and 12 - 120 Volts across terminals 12 and 13 What is the conclusion that you come as to why the DFMA supply fan is not running?

The inlet damper limit switch is open. Possible causes: the damper is not fully opening; the damper motor is not working; the damper linkages are disconnected; or the damper limit switch is not working.

Referring to the DFMA Wiring Diagram, the DFMA burner is not firing. You take the following readings with your multimeter: - 120 Volts across terminals 1 and 2 - 0 Volts across terminals 13 and 16 - 120 Volts across terminals 16 and 18 - 0 volts across terminals 19 and 20 - 0 volts at #7 terminal on the Fireye flame relay What is the conclusion that you come as to why the burner is not firing?

The burner start contact is open. Could be a faulty relay (not energizing) or the start button has not been pressed.

Referring to the DFMA Wiring Diagram, the DFMA burner is not firing. You take the following readings with your multimeter: - 120 Volts across terminals 1 and 2 - 0 Volts across terminals 13 and 16 - 0 Volts across terminals 16 and 18 - 120 volts across terminals 20 and 21 - 120 volts from terminals 20 to 2 - 0 volts from terminals 21 to 2 What is the conclusion that you come as to why the burner is not firing?

High airflow switch is open. Causes could be: fan speed too high (sheaves not set correctly - too much velocity across the profile plates), improperly adjusted profile plates (too much velocity), failed switch, sensing tubing disconnected.

Referring to the DFMA wiring Diagram, the DFMA burner is not firing. You take the following readings with your multimeter: - 120 Volts across terminals 1 and 2 - 120 Volts across terminals 18 and 22 - 0 volts across terminals 20 and 21 - 120 volts from terminals 20 to 2 - 120 volts from terminals 21 to 2 - 0 volts at #7 terminal on the Fireye flame relay What is the conclusion that you come as to why the burner is not firing?

Low airflow switch is open. Possible causes: the inlet supply filters are plugged, faulty air switch, a service door is open, fan speed too low (sheaves not set correctly - too little velocity), sensing tubing disconnected.

Referring to the DFMA wiring Diagram, the DFMA outlet temperature is too low. You take the following readings with your multimeter: - 120 Volts across terminals 1 and 2 - 0 Volts across terminals 18 and 22 - 120 volts at #7 terminal on the Fireye flame relay - 120 volts across terminal 30 to 2 - 24 volts across terminals 34 and 35 - 0 volts across terminals 36 and 37 What is the conclusion that you come as to why the burner is not firing?

Burner modulation 0-10 Volt system has no voltage. This means the burner is stuck in low fire and can't modulate/ramp up to high fire.

Referring to the figure below, the loop current is measured at 29 mA. What are the possible causes of the excess load on the loop?

Miswiring, ground loop, a problem with the transmitter

Referring to the figure below, what is the minimum power supply required for the 4-20 mA loop?

25 Volts

If two points in a 4-20 mA loop are grounded it can create an alternate pathway for the loop current to flow through. TRUE / FALSE

True

Referring to the figure below, what should the resistance value be of the shunt resister given the following information? - Source volts: 26 - Source current: 125 - Loop current: 20 mA max

125-20 = 105 26÷105= .2476 x 100 is 247.6 ohms 248 Ohms

In computer networking, what Does LAN stand for?

Local Area Network

In Computer networking, what does WAN stand for?

Wide Area Network

In computer networking, what is a LAN?

A group of computer devices connected with each other in a small place such as a home, school, campus, hospital, or a factory

In computer networking, what is a WAN?

A long-distance network that covers a country, continent, or the whole world

In computer networking, what is a MAN?

A larger networking area connecting Local Area Networks to a larger network of computers

In computer networking, what is the purpose of a firewall?

stops attacks from WAN to LAN

Even though it is old technology, what type of serial interface connection is still commonly used with industrial machines?

RS232

What type of ethernet connector is used in corrosive environments or when washdowns are needed?

M8 or M12 connectors

What four factors affect the flow of gas through a piping system?

Type of gas, diameter of pipe, length of pipe, pressure drop

What factor determines which of the two formulas are used to develop the code tables?

System Pressure

Pipe sizing tables in the B149.1 used to size low pressure piping systems make an allowance for a reasonable number of fittings. How is this accomplished?

By adding a hidden 20% to the displayed code zone lengths (as noted in the formula in the code book)

Plastic pipe is approved for use in a liquid propane system. TRUE / FALSE

FALSE (B149.1.20, 6.2.16)

In what two ways can the volume of gas required for an appliance be determined?

The appliance rating plate, or the appliance manufacturer when the rating is not shown on the appliance (B149.1.20, 6.4.2)

What shall not be done if piping or tubing is located in an area where a corrosive chemical is used?

It must not be concealed (B149.1.20, 6.7.3)

In British Columbia, piping of NPS 2 ½” and over shall have welded pipe joints. TRUE / FALSE

FALSE. BC Gas Safety Regulations - 2.3 Clause 6.9.2 of CSA B149.1-20 is repealed and the following substituted: 6.9.2 Piping of NPS 2-1/2 to 4 shall be either press-connect fittings certified to CSA 6.32(ANSI LC-4) or welded pipe joints. Piping greater than NPS 4 shall be welded pipe joints.

If a gas piping system requires welding, who can perform this welding?

Welding of gas piping systems shall be performed in accordance with a procedure and by an operator registered under the applicable provincial or territorial legislation. (B149.1.20, 6.9.3).

When can piping or tubing enter a building below grade?

Only when permitted by the Authority Having Jurisdiction (good luck) (B149.1.20, 6.15.8)

What are the three ways that piping or tubing can be identified by in a care, detention occupancy, commercial, industrial or assembly building?

The entire piping or tubing system shall be painted yellow, The piping or tubing system shall be provided with yellow banding that has a minimum width of 1” and is marked at intervals not exceeding 20’, or the piping or tubing system shall be labelled “GAS” or “PROPANE” utilizing yellow label s or markings. (B149.1.20, 7.17.1)

Can a quick disconnect device be used instead of a manual shut off valve?

NO (B149.1.20, 6.18.7)

In order to increase regulator accuracy, the pitot tube senses pressure at what point?

Lowest outlet pressure point

Which regulator will have the least amount of droop under flow conditions?

A pilot operated regulator

Critical flow in a regulator occurs when the velocity of the gas reaches what threshold?

Sonic Velocity

What does a double-ported balance regulator use to sense downstream pressure?

A downstream sense line

Where is the sense line connected on a proportional regulator?

To the top of the diaphragm

When zero governor regulators are used for burners that are to be operated under positive or negative combustion chamber conditions, how can the combustion chamber pressure be counterbalanced?Connecting a pressure reference line from the combustion chamber to the top diaphragm chamber of the zero governor

Connecting a pressure reference line from the combustion chamber to the top diaphragm chamber of the zero governor

What type of regulator is pictured below?

Double-ported balanced regulator

In the above image what is the purpose of connecting the sense line?

To sense outlet pressure

In the above image at what point is the sense line connected to the main supply piping?

Downstream to the top of the piping

What type of regulator is pictured below?

Atmospheric regulator

What type of regulator is pictured below?

Pilot operated regulator

What would happen if the regulator shown below was installed backwards?

It will pass no flow

What would happen if the above regulator was installed upside down?

It would provide lower downstream pressure

When selecting a regulator for a gas piping system, what regulator inlet pressure should you assume there to be when the system is under no flow?

Static pressure (system setting)

For a direct-operated regulator, what amount of droop can be expected?

10-20%, but by code should be no more than 10%

When you need extreme accuracy in high-pressure gas system applications, what type of regulator is best suited for this application?

Pilot-operated

If two or more available regulator springs have published pressure ranges that include the desired pressure setting, for more accuracy you would select the spring with the lower pressure range. TRUE / FALSE

What factors make it beneficial to select a regulator orifice size in the smallest diameter that will handle the desired flow?

Avoids instability and premature wear, Allows for smaller relief valves, Reduces lockup pressure

What is used to determine the required flow of relief valves for a gas system?

The wide-open flow rates of the upstream regulator

What is the maximum droop allowed from a regulator in a gas piping system?

0.1

Why do air requirements differ for appliances with and without draft control?

Units with draft control require dilution air

An atmospheric gas appliance has an input of 390 Mbh and is equipped with a draft hood. It is to be installed in a building that complies with code clause 8.2.1. A or B. What size duct is required to provide air to this appliance?

A furnace room complies with code clause 8.2.1. (a) or (b). It contains a 260 Mbh furnace without draft control and a 120 Mbh hot water heater with a draft hood. Size the combustion air duct based on a length of 21'

A boiler room contains the following five pieces of equipment: - one 3500 Mbh boiler with draft control - two 450 Mbh hot water heaters with draft hoods - two 750 Mbh duct heaters without draft control. Calculate the required free area of the combustion air duct.

436 in2

The following gas appliances are installed in a mechanical room: - one 1400 Mbh steam boiler with a barometric damper - one 550 Mbh hot water heater with draft hood - two 600 Mbh direct fired make-up air units Select a square grill for the combustion air opening in the boiler room wall that will meet the minimum requirements of the B149.1 gas code (grills rated at 67% free area).

18" x 18" (314.507 in2)

The air supply to a 20,000 Mbh boiler, using a force draft burner, is provided by mechanical means through a horizontal duct 42 feet in length. What is the quantity of air required to be supplied to the boiler?

600,000 ft3 (30 ft3 for every 1,000 btu/h)

A 2,752 Mbh forced draft natural gas boiler is operating in a mechanical room, excess air set at 40%. What is the required free area for the combustion air duct?

92 in2

A structure is equipped with a boiler rated at 5,300 MBH and a hot water tank rated at 400,000 Btu/h. Both pieces of equipment are equipped with draft controls and the air supply is ducted from outdoors. What is the size of the free ventilation air opening?

47.9 in2

A structure is equipped with a boiler rated at 750 kW and a barometric draft control. What is the free area of the combustion air supply opening in mm?

162,750 mm2

A structure has a mechanical room into which air must be ducted from outdoors. It contains the following appliances: - One boiler rated at 3,000 MBH, equipped with a barometric damper - Two duct heaters without draft controls rated at 950,000 Btu/h each - Two hot water tanks rated at 250,000 Btu/h each. Both tanks are equipped with draft hoods What is the free area of the combustion air supply opening?

385 in2

A structure is equipped with appliances rated at 1,900 MBH. None of the appliances is equipped with draft control devices and the air supply is ducted from outdoors. What is the free area of the ventilation air opening?

10 in2

A structure has a mechanical room into which air must be ducted from outdoors. It contains the following appliances: - One boiler with no draft control rated at 500 kW - One boiler with draft control rated at 4,000 MBH - One duct heater with no draft control rated at 125 kW - One hot water heater with a draft hood rated at 800,000 Btu/h What is the free area of the combustion air supply opening?

485.37 in2

A mechanical room is equipped with gas appliances with a total input of 3,200 Mbh. All appliances are equipped with draft control devices. The louvre specified for the combustion air opening has a free area of 70%. What is the size of the opening required to fit the louvre?

428.58 in2

What is the minimum opening size on a screen used on a combustion air-supply opening?

1/4"

On a combustion air louvre with dampers the dampers must be controlled in what way?

Automatically

What interlock is required for an automatically adjustable combustion air louvre?

Normally Open contact interlocked with burner control

What two fan styles are commonly used for mechanical air supply systems?

Axial and Centrifugal

When air is provided by mechanical means what type of switch must be used?

The code does not specify the type. Air proving switch (sail or differential)

What three factors would lead you to want to pre heat combustion air?

Prevent the freezing of pipes, prevent thermal shock of the boiler, maintain appliance efficiency

What do ICI Appliance manufacturers do for high altitude installations? (above 4500 feet)

Increase blower motor horse power

What is the relationship between static pressure and air flow?

As static pressure goes up air flow goes down

What three factors have the greatest affect the static pressure in ducting?

Cross sectional area, length, number of fittings

What is the static pressure ranges of the following combustion supply-air ducting systems? a. Low Pressure: b. Medium Pressure: c. High Pressure:

a. less that 3" w.c. b. 3" to 6" w.c. c. 6" to 10" w.c.

When is an overpressure protection device required by code?

When the inlet pressure to a main pressure regulator exceeds the pressure rating of any downstream component or accessory

What method of overpressure protection will interrupt flow of gas in the event of an over pressurization?

Automatic shut-off system

Which type of over pressure protection system must be manually reset after it has been activated?

Automatic shut-off

Referring to the figure below, if the main diaphragm ruptures, what is the likely result?

The relief valve will provide reduced flow rates

Referring to the figure below, this is an example of which type of over-pressure protection?

Pressure relief

Referring to the figure below, what method of overpressure protection is represented?

Upstream monitor system

Referring to the figure below, how can we easily change which regulator is the worker and which is the monitor?

Switch the set points on the regulators

A separate line relief valve shall be installed where in relationship to the regulator?

As close as possible downstream from the regulator

What is the purpose of tertiary air in the combustion process?

To add air to control emissions and flame shape

What type of heat transfer does an infrared burner utilize?

Direct radiation

What type of heat transfer does a low temperature indirect heating burner use?

It uses a fan to transport the heated air to the work

What type of heat transfer does a direct-fired burner use?

It uses a mix of radiation and hot gas convection

What type of heat transfer does a high temperature indirect-heated burner utilize?

Tubes or enclosed walls are heated and radiate heat to the work