Gas & FuelQuestion 67 of 110
A propane branch must deliver a 75,000 BTU/hr appliance at a longest length of 40 ft. Propane is 2,500 BTU/ft^3. The 40 ft table lists 1/2 in = 45 cfh and 3/4 in = 95 cfh. What is the required cfh and minimum pipe size?
a.18 cfh, 1/2 in
b.24 cfh, 1/2 in
c.30 cfh, 1/2 in
d.30 cfh, 3/4 in
Explanation
cfh = 75,000 / 2,500 = 30 cfh, which is within the 45 cfh capacity of 1/2 in pipe at 40 ft, so 1/2 in is adequate. Because propane carries 2.5 times the energy per cubic foot of natural gas, the required cfh and pipe size are smaller for the same BTU load. Always convert BTU to cfh using the correct heating value for the fuel.
Law Reference: IFGC §402.4Practice all 110 questions free — no signup required.
Related questions on this topic
- Corrugated stainless steel tubing (CSST) must be electrically bonded to reduce the risk of arcing from a lightning-induced surge. Where is the bonding clamp attached?
- A newly installed natural-gas piping system is pressure tested before being placed in service. A common test is 3 psi (or 1.5 times working pressure, whichever is greater) held for a set duration. For low-pressure residential piping, what is a typical minimum test pressure and duration?
- During a gas pressure test, appliances and their regulators must be protected. What is the correct way to include or exclude appliances during a 10 psi test?
- A hospital adds a nitrogen line for surgical tools alongside oxygen and medical air. What single feature most prevents a fatal mix-up of these medical/industrial gases at the outlet?
- A gas piping system must include a sediment trap (drip leg) ahead of certain appliances. What is the purpose and typical location of the drip leg?
- Each gas appliance must have an accessible manual shutoff. Where must the appliance shutoff valve be located?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against Master Plumber Licensing Exam (UPC/IPC-based) · How we review