GAS RS & TQ Flashcards
how far can a pool heater be from the property line?
18”
how far must a direct vent be from a regulator vent?
3’
how many supports does a horizontal propane tank need
Max pressure in a family dwelling?
2psig
max propane pressure in a commercial building
20Psig
What type of material for a gasket
neoprene
Joining method for tubing underground?
Brazed, flare or mechanical
approved compressio
what is the max distance of Metal flex conn for decorative appliance?
2’
standard vent termination for gas above roof?
2’
What type of pipe is not allowed on gas:
cast iron
buried plastic pipe needs what:
tracer wire
min bury depth of gas line?
15” unless its a comm drive way then its 24”
Higher flammability of propane:
9.6%
when does the high limit operate?
an temp rise
min. service clearance?
min clearance of b vent?
min clearance c vent?
SER = 24”
B = 1”
C= 6”
How does the relief vent of a propane cylinder have to be connected?
in contact with vapour space and lose cap fitting
Know distances for vaporizer
plastic piping is allowed on liquid propane systems?
T or F
F
How far should a rooftop unit be from the edge?
6’
What is the minimum length of a dirt pocket:
3” but matches the diameter of piping
what must piping have in a corrosive environment?
a coating
if piping is less then 1/2” what must it be made of?
Schedule 80 pipe
what is the smallest pipe diameter that can be concealed?
1/2”
what is regulator freeze up caused by?
high demand
If snare flame at a regulator vent limiting orifice:
pin hole in
diaphragm?
incomplete combustion creates what harmful products
aldehydes
why do you drill a orifice two dms size smaller?
because can drill
steady enough to have a prefect hole
what type of current is use on a rectification signal?
DC
Primary air
provides a percentage of the combustion air, but more
importantly it controls the amount of fuel that can be burned
efficiently.
Secondary air
increases combustion efficiency by causing the fuel to
completely burn. Atmospheric burners require secondary air, but power
burners do not; however, air leaking in at the access or cleanout doors
will allow some secondary air to enter the combustion chamber.
Excess air
40% of theoretical air
s supplied to the combustion zone, is air in excess of the
air which is theoretically needed for combustion. It is added to ensure
each molecule is surrounded by air. Tuning the burner will improve the
mixing of the fuel and air, thereby reducing the amount of excess air
required. If the excess air is dramatically increased beyond what is
actually needed, the result will be lowered flue gas temperatures,
leading to lower combustion efficiency.
Dilution air
does not directly promote the combustion process but is
used to control the stack effect and to reduce the probability that the
moisture formed by the combustion of the fuel will condense in the
venting system. This will influence the amount of combustion air taken
in.
Theoretical air
Input BTU/ Calorific Value = CFH Natural Gas
CFH Gas X Ratio (10, 24, 31) = Theoretical Air
Excess air
40%
The amount of air to completely burn twenty cubic feet of propane gas
25 Calorific Value X 20 CU ft = 500 Cu Ft
how are Cylinders holding less then 300lbs. of propane filled?
by weight
he first indication of poor combustion would be a?
yellow flame
A thermocouple must be inserted ____ to _____ into the pilot flame
3/8” to 1/2”
The highest combustion efficiency in an appliance is obtained with:
ow stack
temperature and high CO2
he most common pilot burner found in gas appliances is a:
target type
The purpose of a draft hood is to
Allow the entry of dilution air, maintain a zero
overfire draft, dry the flue gases
Ultimate C02 for natural gas is
12%
Ultimate C02 for propane is
14%
to correct a lazy flame you must
increase the primary air supply
Hot water boiler service clearance (in front)
48” infront
Counter flow furnace being installed on a combustible floor must have
a factory
supplied base tee
domestic gas fired clothes dryer is not allowed to be installed where?
Bathroom
Appliance draft hood can be installed and connected to:
B vent, BW vent, a chimney
how are bw vent and b vent different
in shape
How many gallons of propane will a cylinder with WC (Water Capacity) of 595
hold at maximum filling density
595 X .42 (Specific Density)/5.1 Lbs = 49
Gallons
The minimum distance that 1000 USWG tank can be located from a concrete wall
is
10’
propane tank must be supported by no more the ______ supports
2
Propane cylinders stored at a construction site must be stored ________ in a secure
area
outside
he minimum clearance from combustibles for a single wall connector is _________ inches
6 inches
Flame sensing range
1-10 microamps
he recommended spark gap on an IPI pilot assembly is a _______ inch gap
1/8 inch
A type BH vent would have a stack temp rating of about ______ deg F
125 deg F
When a transformer in a system repeatly burns out what might be the issue
wrong VA rating on the transformer
VA rating
VA Rating is Voltage X Amperage=VA (Watts)
open circuit test ranges
Thermocouple using an open circuit test must be 17-32 mV
Thermopile using an open circuit test must be 500-750 mV
HWT clearances
Residential Hot water tank min 2” from combustible materials
Other Hot water tanks min 6” Clearance
Service clearance of 24“
Direct vented requires 3’ from burner side
Unit heaters clearances
8’ from floor unless protected
4’ from floor protected
Clearance from combustibles is 18 “
furnace clearances
Above 1”
Sides and rear 6”
Front is 24”
Boiler clearances
Top, sides, rear 18”
Front 48”
Natural Gas “Stats”
chemical formula: CH4
CV: 1000
C.A.R.: 10:1
Spcific Grav g/L: 0.6/0.424
Flame range: 5-15%
Propane Gas “Stats”
chemical formula: C3H8
CV.: 2500
C.A.R.: 24:1
Specific Grav G/L: 1.5/.51
Flame range: 2.3-9.5%
Fluctuating flame is caused by:
plugged vent on regulator
a noisy lifting flame is caused by:
too much air (adjust primary air shutter)
what are the three types of orifices?
plug cap and adjustable
Safe shut off means
pilot stays lit
100% shut off means
all the gas is off
OHMS law formula
E/IR
e voltage
i amperage
R resistance
vent termination from a mechanical air intake is _____ feet
10
How is the flame sensing current measured?
between spark and ground
