Compressed Air Systems
With reference to compressed air systems used for starting air and control purposes:
(a) state the pressure used for starting air;(1)
(b) explain why the pressure stated in part (a) is necessary;(3)
(c) state the pressure used for control air;(1)
(d) explain why the pressure stated in part (c) is different to that stated in part (a);(3)
(e) explain why the pressure stated in part (c) is greater than that necessary to operate the control equipment.(2)
1.Quiz. Study Notes
With reference to reciprocating air compressors:
(a) state the meaning of the term bump clearance;(2)
(b) explain the effects on operation if the bump clearance is:
(i) too large;(2)
(ii) too small.(2)
(c) explain why the air temperature must be limited in the HP stage, stating how this is achieved;(2)
(d) explain how an aftercooler helps remove moisture from the air.(2)
2.Quiz. Study Notes
With reference to a fully automatic, water cooled starting air compressor:
(a) state the alarms that should be fitted;(4)
(b) explain how damage from overpressure is prevented in EACH of the following:
(i) intercoolers;(3)
(ii) water jackets.(3)
3.Quiz. Study Notes
(a) Explain the circumstances under which EACH of the following devices fitted to an air compressor may operate;
(1) fusible plug;(4)
(ii) bursting disc.(4)
(b) State where EACH device in part (a) may be fitted.(2)
4.Quiz. Study Notes
With reference to compressed air systems, explain the purpose of EACH of the following:
(a) fusible plug on compressor discharge;(4)
(b) fusible plug on air receiver;(3)
(c) bursting disc on water cooled air compressor.(3)
5.Quiz. Study Notes
Explain why EACH of the following may have fusible plugs fitted.
(a) air compressor,(5)
(b) air receiver.(5)
6.Quiz. Study Notes
(a) Sketch a relief valve suitable for use on the air side of a compressor.(7)
(b) Explain how the valve sketched in part (a) is reset after overhaul.
(3)
7.Quiz. Study Notes
With reference to air compressors, explain EACH of the following:
(a) why an air filter is important;(4)
(b) why the compressor should not be allowed to run with a dirty air filter.(6)
8.Quiz. Study Notes
With reference to air receivers;
(a) list FOUR fittings on an air receiver;(4)
(b) describe the operation of TWO safety devices.(6)
9.Quiz. Study Notes
With reference to main air receivers:
(a) list FOUR safety features, stating the purpose of EACH:(8)
(b) state the pressure at which the relief valve should lift.(2)
10.Quiz. Study Notes
Sketch a system that is capable of supplying compressed air suitable for use in pneumatic control equipment.(10)
11.Quiz. Study Notes
Explain the hazards of unauthorised repairs to compressed air lines.
(10)
12.Quiz. Study Notes
(a) State THREE requirements for compressed air to be utilised for control instrumentation.(3)(b) Using the Worksheet Q3, identify ALL the components shown for a system suitable for the production of compressed air for control instrumentation.(7)
13.Quiz. Study Notes
(a) Sketch a starting air reservoir, labelling ALL mountings.(8)
(b) State TWO coatings that can be used to protect the interior surface of a large air reservoir against corrosion.(2)
14.Quiz. Study Notes