Practice Proper Autoclave Maintenance: Door Opening and Closing

One of the most important aspects of autoclave maintenance is the door.

It’s designed to open quickly, be safe and reliable.

But if the proper precautions aren’t followed, damage to the autoclave and whatever is around it – including people – can occur.

This can slow production and cause lags that will cost you revenue in the long run.

Avoid injury by understanding the design and operation of the mechanism and any special characteristics of how it operates.

It’s important to remember that the door mechanism is very heavy and must be moved with care and caution. Gradual and gentle movements will keep the door from hitting other components and causing damage.

Here’s what you need to know about the proper way to open and close your autoclave’s door.

Door interlocks

What is a door safety interlock on an autoclave?

This mechanism prevents the operator from inadvertently opening the door while the autoclave is under pressure. It can also disable the process inside the vessel.

Each autoclave door is equipped with a door safety interlock.

It has two main purposes:

  1. To prevent the operator from unintentionally opening the door while the vessel is under pressure.
  2. To disable the process inside the autoclave.

A door safety interlock mechanism is well-tested before it’s used in autoclave construction.

Warning: Under no circumstances should you modify, alter or circumvent this important safety device.

Typical door safety interlock

How it works

A pressure-operated spring pins the operating handle in the locked position anytime there is pressure in the vessel.

When the door safety interlock handle is used, the vessel pressure indicator valve is activated.

This valve is to be a visual, audible indicator to alert the operator if there’s any pressure remaining in the vessel when the door safety interlock handle is opened.

Warning: If the vessel pressure indicator valve shows that ANY pressure is left in the vessel, do NOT open the door. There is still dangerous pressure in the autoclave.

Opening the door

WARNING! Not all doors are designed and/or operated in the same manner. These procedures are for informational purposes only! Use the procedures provided with your autoclave for proper operation and safety!

  1. Check to make sure there are no people or equipment in the door’s path.
  2. Confirm that there’s no pressure or vacuum in the vessel and that all the processes inside the autoclave have been stopped properly.
  3. Swing the door safety interlock handle to the “open’ position. If the handle doesn’t disengage, double-check to make sure there’s no pressure in the vessel.
  4. Turn the hydraulic power unit to the “ON” position.
  5. Push the hydraulic valve lever (or toggle switch) marked “LOCK RING LOCK/UNLOCK” and hold until the locking ring stops rotating. Release the lever, and it will return to the center position (which is neutral). The locking ring’s rotation distance is usually  6” to 7”. Visually confirm complete rotation by making sure the entire door lug is centered within the locking ring cutout.
  6. If your autoclave has a door-swing cylinder, push the toggle switch (hydraulic valve lever) marked “DOOR OPEN/CLOSE” and keep it held down while the door swings open. As the door gets close to the fully open position, slowly release the lever, and allow it to go back to the neutral (center position). On hand-opened doors, the operator has to make sure the door doesn’t open too quickly. It could result in damage to the door components.

Warning: Never let the door to come to a sudden stop when it’s traveling at full speed. The weight of the door could damage the hydraulic system if allowed to stop abruptly.

Don’t keep pushing the door further once it’s in the open position. This may damage the door’s hinge.

  1. You can safely turn the hydraulic power unit “OFF” at this time.

Closing the door

For your safety and the safety of those around you, it’s important for you to follow the correct procedures for closing the autoclave’s door, as well.

  1. Make sure there are no people or equipment in the door’s path.
  2. Turn “ON” the hydraulic power unit.
  3. If your autoclave has a door-swing cylinder, push the hydraulic valve lever (or toggle switch) marked “DOOR OPEN/CLOSE” and keep it depressed while the door closes. As the door nears being fully closed, slowly release the lever and allow it to return to the neutral, center position.

Warning: Don’t let the door head slam closed. Damage may result.

Don’t continue to push the door closed once it’s in the fully-closed position. This may damage the door’s hinge. The locking ring’s job is to secure the door and fully seal it.

  1. On autoclaves that don’t have a door-swing cylinder, swing the door head by hand until the door head’s face is flush against the door locking ring’s matching face. Keep the door head in this position.
  2. Pull the toggle switch (hydraulic valve lever) marked “LOCK RING LOCK/UNLOCK” and hold it until the locking ring lugs are entirely engaged with the door lugs, and the locking block clears the door safety interlock handle. Let the lever go and it will go back to the center (neutral) position.
  3. Visually confirm that the door lugs are totally engaged by observing their position within the locking ring cutout. It must be +/- ½” of full-wedge engagement.
  4. Swing the safety interlock handle to the “closed’ position.
  5. Turn “OFF’ the hydraulic power unit.

Autoclave maintenance and safety

You want to get the most out of your pressure vessel.

When you follow the correct autoclave maintenance and safety guidelines, you won’t have to worry about production lags and lost revenue.

Knowing how to properly open and close your autoclave’s door will prevent injury and protect your investment.

Author: Jeffrey Lippincott

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