Environmental Test Chambers:
Start-Up and Preventive Maintenance

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Preventive Maintenance: How often?

Twice per year, or more frequent if your chamber is heavily used.

Here is a comprehensive start-up and preventive-maintenance checklist:

Electrical System

  • main disconnect: check for tight connections and corrosion
  • phasing: current and voltage should not be lagging or leading each other
  • line and control voltage: connections and terminations
  • contact points, timer settings, fuses, and grounding
  • general condition of boxes, labels
  • compressor head fans and crankcase heaters
  • heater frames and elements

    Verify Resistance (Ohms) per Specifications

    • compressor three-phase and single-phase elements
    • heaters and steam generator elements

Verify Current (Amps) per Specifications

  • high-stage, low-stage, and trim compressors
  • heaters, circulators, steam generator, condenser fan motor, and blower motor


  • readings correct?
  • check configuration, temperature
  • limit switches (such as on main door)
  • sensors (various, including humidity, RTD, etc.)
  • chart recorder -- print quality, mechanical operation


  • low- and high-stage refrigerant charge
  • low- and high-stage pressure switch settings
  • low- and high-stage oil level
  • capacity controls
  • low- and high-stage frost
  • low- and high-stage discharge temperature
  • fan-cycling operation
  • condenser and evaporator coils
  • inlet and outlet water temperature
  • inlet and outlet water pressure
  • water regulator
  • leak check
  • solenoids
  • cap tubes
  • oil separators
  • labels
  • valves
  • condition of foam insulation
  • compressor oils: acid test


  • humidity sensor (calibration test)
  • boiler and boiler hose condition
  • water level in wick tank
  • boiler leak check
  • tightness of fittings
  • thermostat
  • demineralization cartridge
  • atomizer fittings
  • condition of nozzles
  • pressure regulator: water and air
  • dry air purge
  • misc. leaks
  • solenoids
  • desiccant tower transfer
  • moisture indicator
  • air drier
  • pulleys, wheels and belts

General Items

  • physical condition of chamber, including insulation
  • condition of mineralacs, tie straps
  • labels (worn, faded or otherwise illegible)
  • panels and knobs (smooth operation?)
  • drip pan (in place, corrosion?)
  • door and door latch (smooth operation?)
  • interior light bulbs
  • bearings -- need greasing?
  • belts
  • fan blades and blower wheels
  • gauges (various analog and digital): check for water inside; zero-condition check; calibrate as necessary

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Updated: Tuesday, 2008-08-19 17:44 PST