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28 questions from the boiler operator and stationary engineer practice test.
10 questions, graded as you go, with the reason for every answer. No sign-up.
A boiler is rated at 150 boiler horsepower. What is its rated heat output in Btu per hour? (1 BHP = 33,475 Btu/hr)
Answer in Btu/hr.
5021250 Btu/hr
Output = BHP × 33,475 = 150 × 33,475 = 5,021,250 Btu/hr.
Reference: Boiler horsepower: 33,475 Btu/hr
How many Btu are needed to heat 500 gallons of water from 60°F to 180°F? Use 8.34 lb per gallon and a specific heat of 1 Btu/lb·°F.
Answer in Btu.
500400 Btu
Weight = 500 gal × 8.34 lb/gal = 4,170 lb. Temperature rise = 180 − 60 = 120°F. Heat = 4,170 lb × 1 Btu/lb·°F × 120°F = 500,400 Btu.
Reference: Sensible heat: Q = W × c × ΔT; water 8.34 lb/gal
A safety valve disc is exposed to boiler pressure over a circular area 3 in. in diameter. What is the total upward force on the disc at 100 psi? Use area = 0.7854 × D².
Answer in lb.
706.9 lb
Area = 0.7854 × 3² = 0.7854 × 9 = 7.069 in². Force = pressure × area = 100 psi × 7.069 in² = 706.9 lb.
Reference: Force = pressure × area