Mechanical lubrication steam locos. Non return valve opening pressure

[peter allen 1Participant @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

[Speedy Builder5Participant @speedybuilder5]

Mine just has a ball with no spring behind it, the steam pressure keeps it shut until the pump is active.

[Paul LousickParticipant @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.

[Nigel Graham 2Participant @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.

[noel shelleyParticipant @noelshelley55608]

The mounting  of a NRV with no spring may well need to use gravity to help keep it shut. A stainless spring will make sure that the ball is kept on it’s seat in any position and shut. The small pressure required to open it will be of no consequence.

The tiny volume of oil delivered if air has got into the system may result in a no spring valve causing the ball to shuttle back and forth.

Having just checked the Steam fittings twin pump unit and it’s inline NRVs I find that it has no spring in the inline NRVs ! The pump has an NRV in it’s base so how will back flow cause the inline NRV to close ? There shouldn’t be any ? The info says they should be fitted BUT Will they work ?  Noel.

[Nigel Graham 2Participant @nigelgraham2]

I wonder if the high viscosity of steam-oil has any influence here?

[Brian Baker 2Participant @brianbaker2]

Greetings Peter, I would definitely fit a light spring in any oil non return valve.  Without doubt the viscosity of oil compared with water may cause the ball to float as already mentioned.  The spring should do no more than return the ball to its seat, from which the ball will only move a very tiny am, amount since the volumes we are dealing with are tiny, compared with a water pump. The spring is best in a counterbore to keep it straight.  These pumps will deliver in excess of 150 psi when working properly and can be tested with a gauge, with care to avoid over pressurising the gauge, it goes up quickly!

Regards

Brian B

[noel shelleyParticipant @noelshelley55608]

Brians idea of pressure testing is interesting for the curious but his caution should be heeded ! DO NOT use your nice boiler pressure gauge. I was testing a vessel on a hot day using a 0 – 600 psi gauge, left it reading 200 ish, returned to it a while later to find it reading 400 psi due to expansion.  Noel.

[Brian Baker 2Participant @brianbaker2]

Greetings Noel, good to hear from you.  I would contend that the only way to be sure the pump and check valve are working properly is to use a pressure gauge, since that is what the pump must do, deliver oil at such a pressure to overcome the steam pressure in the cylinders or their feed system.

regards

Brian B

[noel shelleyParticipant @noelshelley55608]

Hello Brian, Depending on the pump, at least in part, the only way one might observe the operation of the pump would be to fit a T piece between the pump NRV and the inline NRV and see the pulses as the pump pushes oil through to the steam pipe or valve chest. The pressure generated will vary widely inline with the regulator opening and load on the engine. For those who had an engine seize up due to an oil pump failure this might prove an interesting modification. This could get complicated where 1 pump is feeding both cylinders and need 2 Ts and 2 pressure gauges.

This last issue was a known problem on my beloved 9F with only 1 oil pump. The answer was to fit a second oil pump.

I believe the 9F was one of few locos to be fitted with valve chest pressure gauges.  Noel.

[Brian Baker 2Participant @brianbaker2]

Interesting Noel, I think that what ever pressure is in the valve chest, the lub pump must be able to overcome it in order to ensure a reliable oil supply.

I also think that each cylinder should have a separate oil pump check valve as you describe for you 9F.

I agree a steam chest pressure gauge is very interesting to observe.

Regards

Brian B

[duncan webster 1Participant @duncanwebster1]

Try as I might I couldn’t get a single pump to deliver equally to 2 cylinders on one of my locos, so I fitted two pumps in one tank to my second loco. Tank has a divider so you can see that both sides are going down. Eventual plan on first loco is to fit 2 sight feeds with 2 control valves, then I can see the oil going in

[peter allen 1Participant @peterallen1]

Thank you all for your answers. I had wondered if there was something unique about oil systems that I did not know about.  New inline NRV sent back as faulty. Club Simplex back serviceable.

[noel shelleyParticipant @noelshelley55608]

Glad the loco is back in service.

With any sort of ball valve, first check the ball IS stainless. If it doesn’t seem to seat well get a spare ball ideally, must be the right size, and a brass/bronze punch. Stand the valve Etc on a solid surface. Place the ball on the seat and give it ONE sharp tap to the punch with a small hammer (3/4 Lb ). This should create a good seat. Now put the original ball back and test. Good luck.  Noel.

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