Steamfitter - Pipefitter Flashcards
What does hydrostatic mean?
Water that is not moving
(Not only limited to water. Also includes any liquid / that is not moving)
What does Hydraulic tests require at high and low points?
High points = vents
Low points = drains
What does a pump do?
Discharge fluids (against pressure)
True or false: Compressors are also pumps
True, they discharge gases (against pressure)
What type is the majority of pumps used?
Positive displacement
What is the integral component of a pump?
Drive mechanism
Charts and recorders can come in what type?
Permanent ink record
Gauges can be what to ensure accurate testing?
Calibrated.
Gauges are usually what type?
Bourdon tube type
Gauges are usually what type?
Bourdon tube type
Why is a Larger-diameter fill line necessary?
To speed up the fill time for piping assembly
Hoses used for pressure testing should be rated what?
for a pressure equal or greater than the max pump output pressure
What temp are standard hoses rated for?
-20 F / 150 F
(-29 C - 65C)
Universal couplings are also known as what?
Chicago, crow’s foot or claw coupling
What is this?
A JIC type connection
What does Whipcheck mean?
Is a restraint that prevents hose ends from lashing around should the ends become disconnected.
What is the input pressure to output pressure ratio?
100:1
What is the psig that small pneumatic diaphragm pumps use?
30 psig supply air pressure
What is the determinate of which motor is suited for the job?
Local environment
What does TEXP stand for?
Totally Enclosed Explosion -Proof
True or False: you do not have to remove the moisture from air compressors.
False: Moisture in the test air should be removed at or ahead of the PRV
(The PRV is the connection point of system -→ compressor)
Pressurized gas is usually supplied how?
As a dry gas at high pressures via pressure-regulating valve assembly
What is CGA - 540?
Is the threaded connection that is ONLY on Oxygen tanks
(Type of gas determines the CGA thread type)
How many gauges and valves are mounted at the pressure pump?
pg 12 intro to pressure testing
1 - pressure gauge mounted at pressure pump
2 - valves to control fluid inlet and outlet
Oil-filed gauges can be used where?
on lines where vibration is not too severe
What can be used if a system has too much vibration or pressure?
A snubber
What does Quality assurance mean?
different codes are used for different processes
ASME B31 codes are used for what?
Fabrication + install of pressure piping
Codes differentiate between what?
Functions of inspection + those of examination / testing
True or False: Each job is different in documentation required for proof of satisfactory examination + testing
True. It’s all true.
The owner may require the contractor to provide what?
Additional documentation the owner feels is warranted for the system
Codes set a what?
min acceptable standards.
A preliminary pneumatic test may be allowed to locate what?
Major leaks
(using air pressure no greater than 25 psig)
True or False: compressed gases are much more hazardous than pressurized liquids
True
Two Pipe Direct Return systems are what?
Prone to short circuit.
First fed, first returned, water from the heat distribution units is returned to the boiler by the shortest feasible path…
Closed Loop defined, go!
protects circulation medium against exposure to atmospheric pressure
Latent Heat, go!
*Heat added to change state*
Heat + water = steam (970 Btu/lb)
Heat + ice = water (144 btu / lb)
EDR
Equivalent Direct Radiation
Another form of output rating
R - Value
A single materials ability to resist heat transfer
Stack effect
The impulse of a heated gas to rise in a vertical passage as in a chimney, small enclosure or stairwell
Critical Temperature
the temp. at which material begins to permanently deform or change its physical properties dt external stimuli or stress.
Series Loop
A piping system where the HTUs are part of the piping main
HTU = heat transfer unit
Heat energy adds….
Sensible heat to the water which = increase in the temp. of the water
The Boiler categories are largely based on what?
Temp and Pressure
What is the max temp and max pressure of Low - Temp Hot Water Boilers
Max 250 F
Max 160 psig
What is the max pressure of Cast Iron Boilers?
30 psig
What temp does high-temp hot water boilers start at?
250 F
Gross ratings can come in what type of ratings?
BTU and EDR
What does BTU stand for?
British Thermal Units
What does EDR mean?
Equivalent Direct Radiation
BTU means what?
Amount of heat required to raise the temp of 1 Lb of water by 1 F
What does EDR mean?
Is a measure of thermal radiation expressed in sq ft of steam radiation surface
Emitting 248 BTU / Hr/ Sq
(amount of heat given off by one sq foot of cast iron radiation)
How do you tell the difference bn a water boiler and steam boiler?
Steam boiler has: sight glass
Steam boilers: work off pressure
Steam boilers: do not have cushion tanks
Heat energy adds what to the water?
Sensible heat: it is the energy required to change the temperature of a substance with no phase change.
How do you convert EDR to BTU?
Water: btu = EDR x 150 BTU/Hr
Steam: BTU = EDR x 240 BTU/ Hr
How do you convert BTU to EDR?
Water: EDR = BTU / 150 btu/hr
Steam: EDR = btu / 240 btu /hr
(240 steam is hotter)
Input represents what?
The amount of heat in the fuel burned by the burner
Ex: Oil has a heating value of 140 000 btu / hr, input = 140 000 Btuh
Gross output represents what?
The total heat output of the boiler (available as steam or hot water)
How do you find the Efficiency %?
(It’s a formula)
% Efficiency = Gross Output in Btuh / Inout in Btuh x 100
Cast iron boilers are classified as?
High-mas boilers
Fire tube boilers mean what?
Fire in the tube + water around
Water tube boilers mean what?
Water in the tube + fire around
What type of material is the only type approved to heat domestic water?
Copper tube
What is the benefit of stainless steel boilers?
Is corrosion resistant
Top choice for condensing boilers
How does the operation of a cast iron sectional boiler work?
Sections are joined together (vertical or horizontal-pancake)
Water flows freely between sections
Burner turned on -→ Products of combustion heat up + circulate bn sections + transfer heat to cast iron sections.
Products of combustion rise up + exit via draft hood
Fire tube boilers are considered to be what type of boiler?
High-mass boiler (the shell contains a considerable amount of water)
What happens if flue gas doesn’t reach the temp it needs for the stack effect?
Gas can spill out of draft hood or cool to dew point = corrosive condensate to drain back toward boiler => damaging vent system and or boiler
Low water cut-off is required on / when?
On a high mass boilers over 400 MBH
ASME code requires low mass coil type boilers over what to include what?
Over 400 MBH to include a flow switch
Flow switch: prevents boiler from firing when there is no flow through the heat exchanger.
What temp is the limit or high limit control on boilers?
121 C (250 F)
Low mass boiler or water tube boiler w/ heat input greater than 400 MBH needs what?
Have a flow sensing device
Gauges will normally operate where?
in the middle
What is the most common gauge?
Bourdon tube
Gauges on boilers are to be calibrated how often?
at least once per year
How are gauges calibrated?
(pg 23)
By comparing it to an inspector gauge or using a dead weight tester
A combination gauge includes what?
pressure, feet of head and temp.
Cushion / expansion tanks are on what type of boiler only?
Water boilers only
The circulator aka pump is used in a what?
closed loop system.
Does not have to lift the water but provide enough energy to circulate water through system.
Flow control valves are installed on systems to prevent what?
gravity circulation from occurring with piping system.
Safety Limit Control
Is a safety device that limits the temp of the water contained in the boiler
What are Thermal Wells about?
It is threaded into the boiler heat exchanger + the sensing bulb rests inside.
How do Flow Sensors (flow switch) work?
The paddle end is inserted into the piping -→ velocity of water causes paddle to move it closed when there is sufficient flow.
If flow stops or decrease -→ the paddle returns to normal position + breaks the circuit to the gas valve.
What does a Safety Limit Control do?
Is a safety device that limits the temp of the water contained in the boiler
What works hand in hand with low water -cut off
An Automatic Water Feeder
(float drops -→ signals AWF -→ allows water into boiler until level returns to normal operating level)
Steam boiler pressure gauges must what?
The graduations on the gauge = double operating pressure
Min of at least 1 ½ times the working pressure.
(Operating pressure = max)
(Working pressure = what system actually works at)
What indicates a Low - pressure steam boiler?
Has up to 15 psia (as per ASME section IV)
What is the definition of a Series Loop (Baseboard system)?
It’s a single pipe system in which each heat transmission unit is part of the main
What is the main disadvantage of a Series Loop Baseboard System?
The first convector receives the hottest water
What is a disadvantage of a Two-pipe direct return system?
Prone to short circuit
(dt first unit is the first to receive water and the first to return water)
What is a good type of valve for isolation valves?
Gate and BALL valves
What do balancing valves do?
They are installed in systems to balance the heat requirements of different zones.
(Balancing valve with a globe valve style)
(They allow water to flow into unequal length circuits)
Installing balancing valves on each circuit alleviates what?
Unequal friction caused by unequal circuit lengths
What side of the circuit is preferred for balancing valves?
on the return branch (in order to dial in the design flow rate)
Dead - heads are what and can cause what?
Pumps with no flow going through the circulator
Can cause overheating of the pump / damage to the seals
Zone valves connects to a thermostat to control what?
Heat emission (aka heat release)
What is the easier for air to be released from water?
(involves temp + pressure)
Higher the temperature + Lower the pressure
Temp and pressure are the 2 factors when considering air elimination
What is the measurement unit on pumps?
Gallons per min (gpm)
Where is the point of no pressure change?
(pg 25)
In the expansion tank
Should the circulator be placed on the upstream or downstream side of the diaphragm tank?
The down-steam side
The circulator can maintain the positive pressure on the suction side.
What is K value?
It is the conductance of heat of Uniform material
Btu/ Ft2 / 1 degrees F
What is U value?
Is the conductance of heat of combination of various materials
(Btu/ Ft2 / 1 degree F)
What is R value?
Resistance to heat transfer
(Btu / ft2 / 1 degree F)
What is the formula for heat loss?
U = 1/R*
* = sum of all R values
If there is no * then it is uniform
