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Support => exam support and downloads => Plumbing, Gas fitting and Drainlaying Apprentice Support => Gas Exam 2005 => Topic started by: LisaS on September 29, 2009, 02:50:17 PM

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Title: Question 3
Post by: LisaS on September 29, 2009, 02:50:17 PM

QUESTION 3
(a) Explain how the efficiency of a gas appliance is calculated.
(2 marks)

(b) An appliance has a input rate of 2m3/hr and is 70% efficient. Calculate its heat output,
given that the gas has a heating value of 40MJ/m3.
(2 marks)

(c) State what is meant by working pressure.
(2 marks)

(d) State the purpose of flash tubes on a cooker hob.
(2 marks)

(e) State the flammability limits for natural gas.
(2 marks)

(f) (i) State where the gas disperses to when a Liquefied Petroleum Gas (LPG)
leak occurs.
(ii) State where the gas disperses to when a natural gas leak occurs.
(2 marks)

(g) (i) Define the term vitiation.
(ii) State THREE effects of vitiation in relation to a gas appliance.
1
2
3
(4 marks)
Total 16 marks