The Midmark M11 Door Gasket: a How-To

For a service technician like me, it's a story as old as time. A customer got an error code on their M11. They researched the error online and went through an exhaustive list of troubleshooting steps. They eventually gave up and called a service technician, only to be told that all they needed was a new door gasket.

How can you spot a bad door gasket early and avoid this headache? The first, best solution is to keep up with your scheduled maintenance and replace your gasket regularly. But let's assume we're past that. You don't know when this gasket was last replaced. What do you do now?

First, open the M11 door and examine the gasket. Make sure no part of the gasket has popped out of the circular channel in which it sits. Look closely - this can be easy to miss! If the edge of the gasket has slipped out, simply push it back into place.

Second, check that your dam gasket is installed correctly. That's the half-moon shaped gasket that sits at the bottom of the door. The edges of the dam gasket should be tucked into the center groove of the door gasket. Office staff will occasionally install this with the edges overlapping the front of the door gasket, which is incorrect and will cause a leak.

Next, hold the top of the door gasket (12 o’ clock position) between your fingers. Try to move the gasket around. Does it have room to wiggle back and forth? Is the top sagging down out of the channel? If so, the gasket is worn out. A good gasket should fit snuggly in the channel. IMPORTANT: It's best to check the fit when the gasket is at room temperature. Rubber expands when hot.

Even if the gasket passes the “snugness test,” it could still be worn/damaged in some way that is causing error codes. To rule this out completely, run a normal cycle and monitor the front of the sterilizer. Is steam visibly escaping from the door area? If so, your gasket needs replacement. ZERO steam should be coming from the sterilizer during operation (until the door opens at the end). Install a new gasket and see if the steam leak is resolved.

Don't have a gasket on hand? Not to worry. Did you know that when you buy any autoclave gasket from Duray Autoclave Service, we will deliver and install it for FREE? (This offer is valid for our customers in the South or East Twin Cities suburbs).

Still have questions about your M11 door gasket? Give us a call or look through these commonly-asked questions.

Why do some M11 door gaskets have a metal ring inside and some don't?

OEM gaskets (manufactured by Midmark) come with a metal ring inside. Aftermarket gaskets do not. Do NOT put one of the Midmark rings inside an aftermarket gasket. Aftermarket gaskets are meant to be used without the ring. Each new Midmark gasket comes with a new ring, so there is no need to save/reuse the previous one.

Is it OK to use an aftermarket gasket?

Absolutely. Using an aftermarket gasket will not negatively affect your autoclave in any way.

Is there any difference between OEM and aftermarket gaskets?

There is, yes. Aftermarket gaskets definitely do have a shorter life, and we have found this to be true for every aftermarket gasket we've tried, across all autoclave models. However, the price discount can be significant, so it may still be worth it to buy aftermarket. Feel free to try them. Just remember to keep an eye on the shorter lifespan. You may need to adjust your replacement schedule.