Displacement lubricator and safety valves

[Brian JohnParticipant @brianjohn93961]

1. I have been absent from the hobby for a few years and I noticed that the displacement lubricators that I purchased from PM Research in the US have lost their ”rubber” rings on the valve/control wheel. They have rotted away. What can I use to replace them ?

2. In the past I used Mamod safety valves on my home-made boilers (tiddlers – very low pressure) but I have found that Mamod have gone broke. Is anybody making replacement safety valves to fit all the Mamod machines still out there ?

[JasonBModerator @jasonb]

Hello stranger

 

I think PMR just use small O rings stretched onto the brass central wheel so you should be able to measure the cross section and work out the diameter then order online from a bearing or seal supplier of Australian ebay.

[WearyParticipant @weary]

Mamod safety valves available on ebay and loadsa other places.

There is a Mamod Owners Group on facebook if that is your thing & they will give you plenty of leads.

Phil

[Brian JohnParticipant @brianjohn93961]

Nitrile rubber – oil resistant ? Or is there something else more suitable ?

[JasonBModerator @jasonb]

Go for Viton it resists oil better. Sometimes also sold under the name FKM

[Nigel Graham 2Participant @nigelgraham2]

1) The stockists of seals etc often have charts showing O-ring grades suitability by application.

2) If necessary, carefully and non-destructively analyse an existing Mamod valve from one your models, and copy that.

[Brian JohnParticipant @brianjohn93961]

Can these also be used as piston rings in steam engines ?

[JasonBModerator @jasonb]

Yes they are OK for iston rings in both steam and IC engines

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