(a) With reference to food storage rooms: (i) state, with reasons, the possible danger present in a room used for storing vegetables and fruit;(2) (ii) state the devices necessary to prevent a person from becoming trapped in a storage room.(3) (b) State FOUR methods of detecting a refrigeration gas leak.(4) (c) State the name of the international agreement which stipulates that the production and consumption of compounds that deplete ozone in the stratosphere is phased out.(1)
With reference to safe storage and handling of refrigerant: (a) state where the refrigerant gas bottles should be stored;(2) (b) state the weakest part of the storage bottle;(1) (c) explain how it can be determined if refrigerant has been leaking from gas bottles;(1) (d) state the TWO methods of recharging a refrigeration system, stating where the connection to the system should be made for EACH method;(4) (e) state how excessive refrigerant should be removed from the system without infringing MARPOL regulations.(2)
With reference to refrigeration plants, describe the effects of EACH of the following, stating remedial actions to be taken in EACH case: (a) undercharge of refrigerant;(3) (b) air in the system;(3) water or moisture in the system.(4)
With reference to refrigeration plant; (a) state THREE indications of a loss in refrigerant charge; (b) state THREE methods of detecting the location of the source of leakage; (c) describe a safe method of bringing the gas charge back to its normal working level.
With reference to refrigeration systems: (a) state the THREE basic principles of refrigeration;(3) (b) sketch a direct expansion free standing mechanical refrigeration system, labelling the MAIN components and indicating where EACH of the three principles stated in part (a) occurs.(7)
(a) Sketch a vapour compression refrigeration system, labelling the main components.(5) (b) Indicate the refrigerant conditions at the salient points on the sketch in part(a).(5)
(a) Sketch a thermostatically controlled expansion valve for a vapour compression refrigeration system, labelling all components. (b) Describe the operation of the valve sketched in part (a).
