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Support => exam support and downloads => Plumbing, Gas fitting and Drainlaying Apprentice Support => Drainlaying Exam November 2007 => Topic started by: LisaS on April 20, 2009, 02:55:54 PM

Title: Question 7
Post by: LisaS on April 20, 2009, 02:55:54 PM: QUESTION 7
(a) Trade waste must be cooled before discharging to a drain or sewer. In relation to this
statement answer the following questions.
(i) A cooling tank must be a specific size. State the factor that determines this size.
(ii) Draw a side elevation of a typical cooling pit. [Cooling tank in ground].
(4 marks)

(b) A petrol trap is one type of special purpose interceptor trap. State what hazard the
interceptor trap prevents and how it prevents it.

(2 marks)
(c) State when a sewage pump is required on a foul water drainage system.

(1 mark)
(d) State where the non-return valve on the outlet of a sewage pump system should be
installed in relation to the isolating valve.

(1 mark)
Total 8 marks
Title: Re: Question 7
Post by: Plumber on April 27, 2009, 07:45:35 PM: Question 7
1) The tank must be large enough to hold the hot water discharge until cooled below 50 deg. C, before it is displaced by incoming water.
2) check jpeg

b) The trap separates and holds any oil or petrol present in wastes before it discharges to the sewer. The trap works on the principle that oil and petrol, being lighter than water, will float on the surface when the flow is reduced.
Title: Re: Question 7
Post by: mrchop on May 23, 2010, 04:59:12 PM: c) State when a sewage pump is required on a foul water drainage system.
when you can not gravitate it to the conection
(1 mark)
(d) State where the non-return valve on the outlet of a sewage pump system should be
installed in relation to the isolating valve.

(1 mark) depending on the location of pump

on the downstream side of the valve
Total 8 marks