Responsible for keeping the pressure within the levels considered satisfactory for the proper functioning of a cold system. Pressure switches play an important role, especially in equipment installed in bars, bakeries, supermarkets and other businesses.
Today we are going to remember the concept, identification of defects and the replacement of this important device.
First, it is worth remembering that, in the basic refrigeration cycle. The proper functioning of everything depends on the correct division of pressure. The compressor’s main function is to move the refrigerant fluid throughout the refrigeration circuit. It increasing the pressure of this fluid so that the heat can be dissipated in the condenser. Fulfilling such a task requires the equipment to be at a temperature above the external temperature.
In the evaporator, the opposite occurs: the refrigerant fluid needs to be at a lower temperature. “The compressor sucks in. Compresses and discharges the refrigerant fluid, increasing its pressure. Meanwhile, the condenser exchanges heat in order to dissipate it. The expansion device makes a sudden drop in pressure”,teaches professor in the refrigeration area. He also recalls that the evaporator also exchanges heat in order to absorb it. The refrigerant fluid is responsible for transporting all this hot air.
Pressure switch in Action:
Electro mechanical device, the pressure switch turns off the compressor when pressures fall outside the ideal range. It is also responsible for preserving the safety of the set, by controlling capacity, defrosting, fluid collection (pump down) and, also, condensation.
High and low pressure switches, fixed (cartridge, “chives”, mini pressure switch) or adjustable (adjustable) type. These are used in refrigeration, especially commercial refrigeration. “Fixed pressure switches are manufactured with predetermined pressure values to turn the compressor on and off. It is, the operating pressures for disarming and resetting are already established in the device without the possibility of alterations”, adds the professor.
They come with setup regulation for trip and reset pressures. “But both work, basically, with the same mechanism, where the movement of the diaphragm varies according to the pressure, causing electrical contacts to be activated to turn off or activate the compressor and the fan”, he emphasizes. Here are some tips for home
Pressure Switch Maintenance:
Pressure switches are installed in the refrigeration system in the suction (low pressure) and discharge (high pressure) lines. To verify its operation, we can simulate an increase or decrease in pressure.
Using a multi meter on the continuity scale, the refrigerator can measure the contacts to verify the opening and closing of these components. Fixed pressure switches are hermetic devices. Therefore, once a defect is found, it must be replaced.
If it is threaded, its replacement is simpler, but in welded models, it requires collecting the coolant. The models with regulation, on the other hand, have parts such as springs, screws and contacts, but the manufacturers do not provide parts for this replacement.
It often also requires replacement of the fluid. In commercial refrigeration (counters, chambers, racks), depending on the compressor model.
This device can be installed on valves with register to facilitate replacement. For Commercial HVAC Services Click here
And it’s worth remembering: we can’t forget about oil pressure switches applied to compressors that have forced lubrication in their mechanical parts, where keeping the pressure under control also makes all the difference.
So, did you refresh your knowledge about pressure switches?
This component of the cold circuits really deserves the most attention.