What factors should I take into consideration while buying a head pressure control for refrigeration, food storage rooms, and agriculture purposes?
This is a pretty broad question as is, what refrigerant are you running, what is your box design temperature and TD? What do you have for a condenser? Air sourced or fluid? Does your system have a receiver?
Depending on product in the box, you would be running somewhere between 32-38 degrees F. All TX valves are sized based on 90 degree F liquid, so depending on your refrigerant you would select a headmaster/ LAC or ORO valve to maintain that saturation pressure to your evaporator. This is all assuming you have a receiver on your system. If there is no receiver, your option would be fan cycling heat pressure control.