A blocked drain can be caused by a plugged pin trap, tray, pan, or bio-waste bag placed over the drain piping. Additionally, melted plastic materials habitually block pin traps that fill the drain piping entirely.

Here is when you know you have to troubleshoot a blocked drain on a PRIMUS steam sterilizer.

Why is the chamber pressure not dropping?

A blocked drain usually shows up as a sterilizer that is “stuck in exhaust” with the pressure in the chamber not dropping as expected.

How to remove pressure from the chamber?

To remove the pressure from the chamber and ultimately open the sterilizer door, take the following actions in the sequence listed:

  • Shut off the main power on the sterilizer control box.
  • Open the control box door and switch from OPER to CAL (Operation mode to Calibration mode).
  • Turn the main power back on.
  • Lift the chamber relief valve (PSV) slowly to release pressure in the chamber.

Once the pressure is at or approximately at 0 psi, use the Up Arrow to scroll to OUTPUT DIAGS on the touchpad and press Enter.

Use the Up Arrow to scroll to RETRACT_A_&_VAC. Pressing the Enter key will retract the gasket.

Watch out!
Extreme caution should be taken to make sure nobody is in the path of the steam release.

  • Slowly open the sterilizer door to allow any remaining residual steam to escape.
  • Remove the blockage from the drain and replace any parts that cannot be thoroughly cleaned.
  • Return the controller to OPER (Operation mode).
  • The sterilizer is now ready to return to normal operation.

Determine the root cause of the blockage

Ensure countermeasures are in place to make sure that mistakes don’t happen again.

These countermeasures could include:

  • Operator training
  • Restrictions on who in the facility can change sterilizer cycle parameters
  • Restrictions on materials that can be sterilized
  • Provide a matrix listing material versus allowed sterilization temperature mounted on or near the sterilizer

Some materials can be readily sterilized at 250°F/121°C without problems
but will melt at 270°F/132°C. Lack of knowledge about the respective melting
point of a material is often the root cause of a blocked drain.

A polypropylene plastic pan is favored over polyethylene and polystyrene
because it can withstand average sterilizing temperatures without melting.

PRIMUS Sterilizer

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.

Back to Blog