Refrigerant Gas Pressure for AC

[Varadha]

Recently we had a troubleshooting session on our Split type Air conditioner and the mechanic refilled the refrigerant gas to 70 psi pressure. He had been working in a medical college cum hospital and having specialized in AC and refrigeration, he said that mortuaries are being refrigerated to 4*C and they require a R-22 pressure of around 20 psi. And I am struck with this:

If at home, the cooling is insufficient, we increase the pressure to around 70 psi. But why is it that we have to maintain the pressure of refrigerant at around 20 psi for centralized AC in mortuaries? In the former case, gas pressure is directly proportional to cooling effect apparently and it is converse in the latter case. How is it evident?

 

[Navin A S]

The reason why the refrigerant pressure in a mortuary needs to be maintained at a much lower level than a home AC system is because of the difference in temperature requirements. In a home AC system, the temperature needs to be kept cool enough for people to be comfortable. Whereas in a mortuary, the temperature needs to be kept very cold, usually around 4*C, in order to preserve the bodies and prevent the spread of any bacteria or other contaminants. Therefore, a higher pressure of refrigerant would cause the temperature to drop too low and could damage the bodies or other equipment in the room.