Losing the orifice during valve replacement is the most common root cause of sterilizer issues. Here’s what you can do if you lose an orifice during your valve replacement.


PRIMUS receives Customer Service Call Log (CSCL) reports of sterilizer problems caused by a missing chamber orifice.

Where is the chamber orifice located?

The chamber orifice is located in a nipple or union fitting immediately downstream of the steam-to-chamber valve.

When you change the steam-to-chamber valve, please make sure the orifice remains in the piping when the new valve is installed. It can cause a lot of problems if the orifice is missing.

There is also an orifice located downstream of the steam-to-jacket valve.

NOTE An orifice normally does not wear out.

What happens if I lose a chamber orifice?

A missing chamber orifice can cause the following problems:

Over Temperature Alarm

Lack of an orifice will cause steam to enter the chamber at a greater than desired rate and can cause an over-temperature alarm.

Gasket Pressure Alarm

Additionally, a defective or missing orifice will cause a pressure drop in the gasket line as the steam-to-chamber valve fires. This can, in turn, cause a gasket pressure alarm.

PRIMUS Spare Parts

The following orifices can be ordered from PRIMUS through our online parts store or contacting the PRIMUS Parts Department.

The size of the sterilizer will determine which orifice to order. In the PRIMUS parts system, an orifice is referred to as a “Restrictive, Nipple, Brass.” This is important when ordering on the PRIMUS website.

Part NumberOrifice Size
6005063/8″ (Cap, 3/8″ 45 Flare Bonnet) – Used on piping in
the steam to jacket valve of small sterilizers
Visit the Spire Integrated Solutions PRIMUS parts store here

How to order an orifice

NOTE Orifices are normally not maintained in inventory but are made upon order receipt.
If the proper size of orifice is not known please provide the respective Job Number to PRIMUS Parts and the correct size orifice will be provided.

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 dschall@spire-is.com.

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