The PRIMUS Pri-Matic® control system provides different alarms representing the various conditions that can cause the sterilizer to deviate from its normal operating conditions.

Alarm conditions will display a red alarm banner screen on top of the HMI current screen and will sound an audible alarm. Alarms are always annotated on the printout.

The red alarm banner screen will have a text message area that will identify the type of alarm, the date and time. The screen will have three buttons available to the user: CLOSE ALARMS, SILENCE ALARM, and END CYCLE (refer to Figure 1 E-stop Alarm Banner Screen on page 6).

If an alarm condition has occurred at any point during a cycle, the printout will end with the warning message: “Cycle May Be Compromised.” This does NOT mean the cycle is automatically unacceptable, but it indicates that the operator must look at the tape and decide whether or not to accept the cycle as valid.

Alarm Priority

The following table (Table 1 Alarm Priority) presents the alarm priority as they are presented to the user.

If during a specific alarm, a higher priority alarm occurs, the lower priority alarm will be replaced by the higher priority alarm and the user is required to service that higher priority alarm before the lower alarm is re-presented (if it is still active).

Table 1 Alarm Priority

Alarm PriorityAlarm
1Emergency Stop
2Loss of Power
3Rupture Disk
4Sensor Failure
5Max Chamber Pressure
6Door Gaskey
7Door Switch
12Under Temperature
13Over Temperature

Not all alarms are available at every phase of the sterilizer’s operation. The following table (Table 2 Alarms Enabled During Normal Operations) identifies which alarms are enabled during the different phases of a sterilizer cycle.

Table 2 Alarms Enabled During Normal Operations

Over Temp
Gasket ChargeXXX
Exhaust & DryXXXXXX
Cycle CompleteXXXXXX
Sterilize FilterXXX
Vacuum & HoldXXXXX
Vacuum TestXXXXX

When an alarm occurs, all processing stops, and outputs are de-energized except for the Under Temperature alarm.

Clearing an Alarm

Once an alarm occurs, the user will have to take some action to clear the alarm. Most alarms will halt the cycle and prevent the sterilizer from continuing until the condition causing the alarm is resolved.

The three buttons on the red alarm banner screen provide the mechanism for the operator to take action. The CLOSE ALARMS button returns to the screen active before the alarm was raised. The SILENCE ALARM button turns off the audible alarm notification. The END CYCLE button advances the cycle to EXHAUST & DRY or AIR-IN or STERILIZE FILTER COMPLETE for the STERILIZE, VACUUM LEAK TEST, or STERILIZE FILTER cycle, respectively.

Alarm Operation

The following table (Table 3 Alarm Operation) provides the operational information specific to each type of alarm. When an alarm occurs, all processing stops, and outputs are de-energized except for the Under Temperature alarm. A subsequent Sterilizer Reset can then be performed.

Table 3 Alarm Operation

Emergency StopEmergency Stop is disabled by deactivating the E-stop button.
Loss of PowerWhen loss of electrical power occurs, use interaction is required when power is restored.
Rupture DiskRupture Disk alarm requires maintenance personal. The repair must be made before the alarm can be cleared.
Sensor FailureDisabling sensor alarms with the Maintenance Key will not automatically provide the correct temperature/pressure reading. A false chamber pressure reading due to a pressure sensor failure alarm will lockout door gasket retraction. Subsequent Sterilizer Reset can be performed after disabling this alarm. In order to retract the
door gasket, the pressure sensor must reflect within + 1.0 PSI of atmospheric pressure.
Max Chamber PressureThis alarm should be set in the Cycle Parameters to occur below the Rupture Disk
Door GasketTouching the END CYCLE button will abort the cycle.
Door SwitchTouching the END CYCLE button will abort the cycle.
Water-in-DrainSubsequent Sterilizer Reset can be performed after disabling this alarm with the Maintenance Key.
Under TemperatureThis alarm will not suspend processing.
Over TemperatureOver Temperature will suspend all processing.

Once closed, the red alarm banner screen cannot be re-opened by the operator. If a new alarm comes in, depending on its priority, the red alarm banner screen may or may not re-appear. If several alarms have occurred, each red alarm banner screen will have to be closed. Because the red alarm banner screen always appears in the same place, it is possible to have more than one red alarm banner screen, but the second and subsequent screens will not be visible until the highest priority alarm condition is dealt with first.


Even if the red alarm banner is closed accidentally before being able to use the other buttons, there are END CYCLE and SILENCE ALARM buttons available on many of the HMI screens which the operator can use in lieu of the buttons on the alarm banner screen.

The E-stop

The Emergency stop (E-stop) is not strictly considered to be an alarm but is included in this section because of the tie to alarm priorities. The E-stop is unique in that it is available throughout all phases of sterilizer operation.

Activating the E-stop will remove electrical power from the PRIMUS Pri-Matic® PLC output module and provide the PRIMUS Pri-Matic® PLC with a discrete input which will cause the E-stop alarm banner to be displayed. Since the E-stop removes all outputs including the buzzer, the buzzer will not sound. The door gasket(s) will remain charged during the E-stop and/or loss of power.

The Figure 1 E-stop Alarm Banner Screen illustrates the E-stop alarm banner. Because all power is removed, the SILENCE ALARM and END CYCLE buttons will have no function in this instance and are grayed out.

Figure 1 E-stop Alarm Banner Screen

If the user closes the alarm using the CLOSE ALARMS button, the red alarm banner screen will close and the previous screen will be displayed. The sterilizer will remain stopped until the E-stop is deactivated.

Questions and Comments

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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