✓ TradeExamPro

TradeExamPro › Plumbing & Gas › Gas fitting (natural gas and LP)

Properties practice questions

29 questions from the gas fitting (natural gas and lp) practice test.

Properties practice test

10 questions, graded as you go, with the reason for every answer. No sign-up.

What this covers

Sample questions

What is one British thermal unit (Btu)?

  1. The heat needed to raise 1 lb of water by 1 degree F
  2. The heat needed to raise 1 gal of water by 1 degree F
  3. The heat needed to boil away 1 lb of water at 212 F
  4. The heat given off by 1 cubic foot of any fuel gas
Show the answer

A. The heat needed to raise 1 lb of water by 1 degree F

One British thermal unit raises one pound of water one degree Fahrenheit. A gallon of water weighs about 8.33 lb, so heating a gallon one degree takes about 8.33 Btu, not 1.

Reference: Basic heat units; ASHRAE Fundamentals

Gas utilities often bill in therms. How much heat is one therm?

  1. 1,000 Btu
  2. 10,000 Btu
  3. 100,000 Btu
  4. 1,000,000 Btu
Show the answer

C. 100,000 Btu

A therm is 100,000 Btu, which is roughly the heat in 100 cubic feet of natural gas. 1,000 Btu is about one cubic foot, and 1,000,000 Btu is a dekatherm (10 therms).

Reference: Gas utility billing units

Roughly what range of propane-in-air mixtures will burn?

  1. About 5% to 15%
  2. About 12% to 25%
  3. About 20% to 40%
  4. About 2% to 10%
Show the answer

D. About 2% to 10%

Propane is flammable from a little over 2% up to about 10% gas in air. The 5% to 15% range belongs to natural gas; propane ignites at a leaner mixture, which is one more reason small leaks matter.

Reference: NFPA 58 Annex B (properties of LP gases)

Other topics