Most of the laws we refer to in air conditioning and refrigeration are pretty obvious and practical. Dalton's law of partial pressures is no exception. John Dalton observed that the air pressure was equal to the added pressures of each gas that make up air. That means that the pressure and density of air can […]

Pump down solenoid valves are commonplace for any refrigeration technician. They are energized with the compressor still running, shutting off flow in the liquid line so that the refrigerant is pumped into the condenser and receiver. The compressor will then shut off once a low-pressure switch opens the circuit when the pressure falls below a […]

Educators love lockout relays, and we also love pretending you will still see them out in the field all the time. Sometimes, I have to look myself in the mirror in the morning and sadly repeat, “Lockout relays are dead.” I have to say it several times before the reality sinks in. Before I get […]