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REFRIGERATORS
Refrigerators are commonly used for preservationof foodstuffs,chemicals, biological materials, and for producing ice .They have a liquid called refrigerant in a metal tube which is capable of being converted into vapor and back to liquid by a device known as compressor pump. The refrigerator has an evaporator at low pressure and a condenser at high pressure.
While the refrigerant is in the evaporator, it boils at a temperature lower than that in the refrigeration cabinet from which it draws warm air leaving the cabinet cool. When the refrigerant is pumped into the condenser, it evaporates at a temperature higher than that of the air outside the refrigerator and therefore the warm air collected from the refrigeration cabinet escapes to the atmosphere. The vapor condenses and becomes liquid to circulate again.
The whole refrigeration process involves the continuous drawing of warm air from the refrigeration cabinet and letting it escapes to the atmosphere. The required temperature is controlled by a thermostat, which can be switched to achieve temperatures as low as – 15 oc
Refrigerators generally require little maintenance so long as they are located in a clean atmosphere. They should be fitted with indicator light Flammable substances must not be placed in open containers inside the refrigerators because explosive concentration of vapor mixtures can be formed from very small amounts of solvents which may ignite sparks from thermostats or micro switches. The inside should be kept clean and dry.
- Avoid placing hot things in a refrigerator. Let them cool first.
- Avoid packing things tightly into the refrigerator because they interfere with free air circulation.
- Defrost the deep freezer region to prevent building up of mountains of ice which often breaks the delicate part of the refrigerator.
- Keep the doors of the refrigerators closed except when putting or removing materials from it. Frequent or prolonged opening of the refrigerator doors interferes with internal temperatures.
- Repair and servicing should be done regularly and by experts only.