Midmark M7 Shutting Down Too Soon








Has This Happened To You?

Your Midmark M7 Autoclave heats up somewhere over 200 degrees F and suddenly the heat & pressure drops - and the autoclave shuts itself down.

Sometimes it will restart & sometimes it won't, without a significant cool down period.

This is a very common problem with the M7. What is happening is the vent valve is most likely failing, allowing water to return to the reservoir during the cycle. When this happens, the safety switches are activated when the unit runs dry and shut down is automatic.

You should be able to hear this happening by an exceptional amount of gurgling noises coming from the water reservoir during the cycle.

Depending on the extent of the problem, when you open the door, you may find a mostly dry chamber, even though the autoclave shut itself down prior to the vent cycle.

This strongly indicates a faulty vent valve.

Other times, you may be met with a wall of water when you open the door. The vent valve is in very bad shape if this is happening, because it is allowing the water to go in both directions.

Though the problem is a bad one, the remedy is a pretty simple, and very inexpensive one.

As a temporary fix, you can try removing the vent valve and cleaning the port, the stem and the o-rings to remove any debris. This may allow your M7 Autoclave to function until you get the repair kit in.

While you have the valve stem out, take a look at the 2 o-rings encircling the stem and note whether they are the same size or if 1 o-ring is smaller than the other.

There are 2 repair kits available:


If one of the o-rings is smaller than the other, you will need the valve repair kit for the OEM Part #RCS098-842

If the o-rings on the valve stem are the same size, then you will need the vent valve repair kit for the RPI replacement valve assembly Part #RCS097-841


This is a very simple repair to complete and no special tools are required.

Complete installation instructions are included plus we will be more than happy to help you if you encounter any difficulty

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