Mechanical lubrication steam locos. Non return valve opening pressure

Mechanical lubrication steam locos. Non return valve opening pressure

This topic has 3 replies, 4 voices, and was last updated 19 July 2026 at 09:27 by Nigel Graham 2.

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18 July 2026 at 23:47 #856721
peter allen 1
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@peterallen1
Repairing a Club Simplex with lubrication problems . i checked the non return valve fitted to the steam pipe to cylinders for sealing in reverse direction and opening in flow direction using air pressure with the valve under water. Surprised to find 100 psi needed to get flow. Adjusted valve to give 10 to 15 psi opening pressure. Out of curiosity checked a new in line oil NRV from a well known supplier and found that it would not open at 120 psi, the limit of my air supply. Am I wrong to set the NRV at a much lower lift off pressure?

I
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19 July 2026 at 05:59 #856738
Speedy Builder5
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@speedybuilder5
Mine just has a ball with no spring behind it, the steam pressure keeps it shut until the pump is active.
19 July 2026 at 07:25 #856744
Paul Lousick
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@paullousick59116
The non return valve on the lubricator on my engine is not adjustable and only has a soft spring to just hold the ball in position.
19 July 2026 at 09:27 #856756
Nigel Graham 2
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@nigelgraham2
It seems very unusual for any non-return valve, ball or disc type, to contain a spring (apart from those in i.c. engines where precise, rapid closing is necessary).

Where they are used, it is only to help the valve seat.

I would suggest the one that would not open at 120psi is faulty, assuming more than a very few psi difference across it.
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