SC LP GAS DEALER INSTALLER EXAM QUESTIONS AND 100% ACCURATE ANSWERS (NEWEST)

350 QUESTIONS AND ANSWERS


1. Q: What is LP gas? ANSWER LP (Liquefied Petroleum) gas is a mixture
of propane and butane gases that are compressed into liquid form for storage
and transport.
2. Q: What is the primary component of LP gas used in residential
applications? ANSWER Propane (C3H8) is the primary component, typically
making up 90-95% of residential LP gas.
3. Q: What is the specific gravity of propane vapor compared to air?
ANSWER Propane vapor is approximately 1.5 times heavier than air.
4. Q: At what temperature does propane boil at atmospheric pressure?
ANSWER Propane boils at -44°F (-42°C) at atmospheric pressure.
5. Q: What is the BTU content of one gallon of propane? ANSWER One
gallon of propane contains approximately 91,500 BTUs.
6. Q: What is the expansion ratio of liquid propane to vapor? ANSWER
One gallon of liquid propane expands to approximately 270 gallons of vapor.
7. Q: What is the flammable range of propane in air? ANSWER Propane's
flammable range is 2.1% to 9.5% by volume in air.
8. Q: What is the auto-ignition temperature of propane? ANSWER The
auto-ignition temperature of propane is approximately 920°F (493°C).
9. Q: What odorant is commonly added to LP gas? ANSWER Ethyl
mercaptan is the most common odorant added to LP gas for leak detection.
10. Q: What is the minimum odorant concentration required in LP gas?
ANSWER The minimum concentration is 1.0 pound of odorant per 10,000
gallons of LP gas.
11. Q: What color flame indicates proper combustion of LP gas? ANSWER
A blue flame with minimal yellow tips indicates proper combustion.

,12. Q: What does a yellow or orange flame indicate? ANSWER A yellow or
orange flame indicates incomplete combustion, often due to insufficient air
supply.
13. Q: What is the normal operating pressure for residential LP gas
appliances? ANSWER Most residential LP gas appliances operate at 11 inches
water column (WC) pressure.
14. Q: What is the standard test pressure for LP gas piping systems?
ANSWER The standard test pressure is typically 20 psig for residential systems.
15. Q: What is the maximum allowable working pressure (MAWP) for
most LP gas containers? ANSWER The MAWP for most standard LP gas
containers is 250 psig.
16. Q: At what pressure does the relief valve on a standard LP tank
activate? ANSWER Relief valves typically activate at 375 psig (150% of
MAWP).
17. Q: What is the standard service pressure for propane tanks? ANSWER
Standard service pressure ranges from 100-200 psig depending on ambient
temperature.
18. Q: What percentage of liquid capacity should an LP tank be filled to?
ANSWER LP tanks should be filled to no more than 80% of their water
capacity.
19. Q: Why is the 80% fill rule important? ANSWER The 80% rule allows
for thermal expansion of the liquid propane as temperature increases.
20. Q: What is the difference between water capacity and propane capacity
of a tank? ANSWER Water capacity is the total volume, while propane
capacity is 80% of water capacity to allow for expansion.
21. Q: What does WC stand for in gas pressure measurements? ANSWER
WC stands for Water Column, a measurement of pressure.
22. Q: How do you convert inches WC to psig? ANSWER Divide inches
WC by 27.7 to get psig (1 psig = 27.7 inches WC).
23. Q: What is a manometer used for? ANSWER A manometer is used to
measure gas pressure in inches of water column.
24. Q: What is the purpose of a regulator in an LP gas system? ANSWER
A regulator reduces high tank pressure to safe, usable pressure for appliances.

, 25. Q: What are the two stages in a two-stage regulator system? ANSWER
First stage reduces tank pressure to approximately 10 psig; second stage reduces
to 11 inches WC.
26. Q: What is the advantage of a two-stage regulation system? ANSWER
Two-stage systems provide more consistent pressure to appliances and better
performance.
27. Q: What is vapor withdrawal? ANSWER Vapor withdrawal is taking gas
from the vapor space above the liquid in the tank.
28. Q: What is liquid withdrawal? ANSWER Liquid withdrawal is taking
liquid propane from the bottom of the tank through a dip tube.
29. Q: When is liquid withdrawal typically used? ANSWER Liquid
withdrawal is used for high-demand applications or when vaporization
equipment is employed.
30. Q: What is a POL valve? ANSWER POL (Prest-O-Lite) valve is a type of
tank valve with left-hand threads commonly used on older tanks.
31. Q: What replaced POL valves on newer tanks? ANSWER ACME
fittings with right-hand threads and safety features replaced POL valves.
32. Q: What is an OPD valve? ANSWER Overfill Protection Device (OPD)
valve prevents tanks from being filled beyond 80% capacity.
33. Q: How can you identify an OPD valve? ANSWER OPD valves have a
triangular handwheel and internal float mechanism.
34. Q: What is the purpose of a tank gauge? ANSWER A tank gauge
indicates the approximate amount of propane remaining in the tank.
35. Q: What are the most common types of tank gauges? ANSWER Dial
gauges, digital gauges, and in-line gauges are the most common types.
36. Q: What does BLEVE stand for? ANSWER BLEVE stands for Boiling
Liquid Expanding Vapor Explosion.
37. Q: When can a BLEVE occur? ANSWER A BLEVE can occur when a
pressurized container is exposed to external heat source.
38. Q: What is rollover in LP gas terminology? ANSWER Rollover is the
rapid vaporization that occurs when warm propane contacts cold propane.