Several PRIMUS Customer Service Call Log (CSCL) entries continue to be made each year for field door gasket issues.

Below is a comprehensive troubleshooting guide describing the potential root cause of this problem.


On a PSS500 control system, a door gasket error will appear as “GASKET ERROR” on the touchpad screen. It will appear as “DOOR GASKET ERROR” on the printout. A door gasket error will always generate an audible alarm (buzzer) to alert operating technicians of the potential problem.

Steam to Gasket Bleed Valve

If the gasket bleed valve (needle valve) is open too far, a door gasket error can result. The bleed valve is set at the factory at ¼ turn open and this setting should be maintained in the field.

Additionally, if the internals of the bleed valve are significantly worn, a door gasket error can result in the same manner as if the valve was opened too far.

In some instances, if the valve packing gland becomes loose, the valve can open greater than ¼ turn due to normal sterilizer vibrations. This can be prevented by periodically checking the packing gland and tightening it, if necessary.

Worn or Damage Gasket

If the gasket becomes excessively worn or damaged, steam or air can leak into the chamber or to the outside of the door.

Particulate carryover in the steam or air supply can also prevent a complete gasket seal. If this situation is suspected, clean the gasket and the head ring groove. Determine the root cause(s) of excessive carryover and implement required corrective actions.

Low Steam or Air Pressure

The air pressure should be set at 30 psi for air-to-gasket steam sterilizers and 35–40 psi for steam-to-gasket sterilizers.

Defective Gasket Pressure Switch

If the sterilizer will not start upon pressing the Start button and gives a gasket alarm shortly thereafter, the root cause problem is likely the pressure switch. If the switch is simply worn out, 95%+ of the time it will fail in the “open” position.

Adjustable Gasket Pressure Switch (Older Models)

If an errant adjustment to the switch is made in the field, it can be set too high and the switch will never see the required pressure to “make” the switch, and a gasket alarm will occur.

Gasket Charge Valve

Verify that the gasket charge valve is functioning properly. If the valve is not opening fully or not opening at all, a gasket alarm will result because insufficient steam/air pressure is getting to the gasket.

Gasket Retract Valve

Check that the gasket retract valve is neither leaking nor stuck open. If the valve is leaking or stuck in an open position, a gasket alarm can result because insufficient steam/air pressure is getting to the gasket.

Cold Gasket Groove

If the jacket trap is clogged or defective, the jacket can fill with water. In this case, the gasket groove will remain cold. This causes excessive condensate to form, resulting in insufficient steam pressure to the gasket.

Have a question or having difficulties? Talk to Dave Schall, our PRIMUS sterilizer expert who is here to assist you anytime at 877.679.7800 extension 1212 or email at

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