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Displacement lubricator

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Dennis Rayner20/11/2011 21:28:14
124 forum posts
8 photos
I am about to install a displacement lubricator on my 7¼" Elidir. It will use a steam supply from the manifold to a tank under the footplate. Then via a single sight feed to the front of the loco into the steam chest WITHOUT a non-return valve. It seems too simple. Have I forgotten something?
mgj20/11/2011 23:35:32
1017 forum posts
14 photos
I am told (and am installing on mine) that its a good idea to put an NRV in the steam line between manifold shut off valve and oil tank. What can happen if one is not fitted is that, on cooling down, if you fail to open open some other valve like the blower, the vacuum will suck oil back into the manifold and possibly from there into the boiler, which is a bit less than favourite.
Its also wise to fit a separate oil shut off valve. The needle valve can then be left set for the oil feed control, and when one is stopped, you just shut the globe valve, which doesn't disturb the steam setting, and prevents filling hte steam chest with oil. I am told.
You have some sort of condensing coil somewhere between steam feed valve (manifold) and oil tank? I have 12" of pipe zigzagged on a black painted plate on the side of the cab, but possibly with a 7 1/2" model there is enough pipe to ensure condensation anyway. Whatever, you need to be sure you are feeding water under pressure, and not steam into the oil tank.

Edited By mgj on 20/11/2011 23:36:21

Dennis Rayner22/11/2011 09:19:29
124 forum posts
8 photos
Thanks for that - I wasn't aware of the need to ensure condensation so I will maximise the pipe run. As I am putting a shut-off valve on the manifold controlling the steam supply to the oil tank, presumably closing this prevents the risk of syphoning back? Also , when in steam, would this valve not enable me to stop lubrication without altering the needle valve? Sorry to ask questions to which the answers may be obvious but this method of lubrication is completely new to me.
DMB22/11/2011 16:13:07
1312 forum posts
1 photos
The preserved "Dukedog" GWR 4-4-0 lives just up the road from me - @ the Bluebell Rly. That loco has the usual GWR displacement lube mechanically connected to the regulator. There is a huge condensing coil for it in the cab, tucked up under the roof.
We are talking here about 200lb + so big condenser. No doubt if you go to your nearest preserved railway that has a GWR loco, you will observe the same fittings.
There was at least one set of articles way back in Model Engineer on this subject - hazard a guess @ 1970`s??
mgj22/11/2011 18:13:55
1017 forum posts
14 photos
Dennis - agreed, your manifold valve should also serve as an oil cutoff, but its not so positive as a cutoff in the oil line.
2 points - if you have a leak you have no means of stopping a flood (how far do you take insurance?). Also steam pressure decays, so when you shut off steam, you will still get some oil shoved along until pressures equalise.
How much and will it matter? Probably on my litlte 5" gauge Metre Maid with its baby 3/32 lines, not hardly. On a bigger engine with more volume in the lines, you might well cop for a faceful after a halt. I don't know is the short answer, so someone more knowledgeable than I must advise.
I have valves in both lines, steam and oil, and an NRV in the oil line - I believe that is normal practise., and it is what other very experienced club members have advised, so I pass it on on that basis.
Glycerin for the sight glass, if you don't have it already, comes from cooking accessories/spices etc in any supermarket. Its used for special icing - so baking type stalls.
Paul Winstone08/09/2012 11:18:36
3 forum posts

I am considering fitting displacement lubricator to a Maxitrak Pearl. I was recommended a means of flushing the glass with steam if it all goes wrong for some reason. Any advice or experience from running ?

Paul Winstone08/09/2012 13:02:27
3 forum posts

I am planning on installing a displacement lubricator on a Maxitrak Pearl.

I was recommended to have a means of flushing the glass with steam if it gets mucky - any comments or advice on which way to flush?

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