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[frog32]

Hi
While doing my Boiler steam testing duties yesterday a club member asked me to take a look at a Richmond engine that he was having a problem with.
When running there appears to be a lot of water and steam bypassing one of the pistons; my first thought is that the O ring seal on the piston has failed? 
This is not an engine I know much about, so can someone please tell me if this particular engine has O rings fitted on the pistons.
Roger
Cheddar Steam Club.

[Bunkerbarge]

It certainly does.  It might have gone hard with age and be passing or actually split.

The usual challenge with this engine is passing at the control valve face.  This is as a result of a brass valve disc running against an aluminium valve body.  It starts scuffing quite quickly and passing.  The only way I resolved this was to have a very competent friend machine me a brass valve body.

When you say "when running" how do you know it is passing in one of the cylinders?

[frog32]

Thanks for the photo, it will give him a better understanding on how to disassemble the cylinders.


The fault was more noticeable on startup with a cold engine where you could visibly see the very wet steam running down the connecting rod.


The control valve face seemed ok but time will tell if problems occur.


I don’t suppose you would know the dimensions of the O ring and if it is Viton? Thank you.


Regards
Roger

[Bunkerbarge]

There is always the slug of condensate to go through on start up, which would usually just be carried over and collected in the separator, especially if he has a long pipe between his boiler and engine.  There is also the possibility that the piston rod gland might need attention.  There is another small 'O' ring behind the nut on the rod so this can also go hard and fail or, as sometimes happens, the nut simply slackens off and just needs tightening up again.  The trouble with an 'O' ring gland is that you can't tighten it otherwise you put too much pressure on the 'O' ring, so there is always a possibility of it slackening off.  It just needs a little gentle compression.


I'm afraid I don't know the dimensions of the piston 'O' ring, which I am sure will be Viton.  If it turns out to be that he will have to remove it and measure it up.  I'd check out the piston rod gland first though.

[rhavrane]

Bonjour,

The manufacturers of steam engines that I know recommend using Viton O'Rings of the diameter of the cylinder because larger, they generate friction and premature wear.

Having several machines without segmentation, and just fine grooves which retain the oil coming from the lubricator, this recommendation seems justified to me.

That would possibly mean that oil is needed (obvious even if water is self lubricant in our models at low pressure) without overheated steam which dries it.

For fun, what I call leaks    : https://youtu.be/ac-WakuhGRM

[Geoff]

I recently replaced the "O" rings in my Cheddar Puffin engine and used viton but on operating it swelled up and seized the engine. A friend told me to use silicon "O" rings which I did and it fixed the problem completely. Again I had too much steam and condensate passing and this was due to the old "O" rings becoming hard so its a very worthwhile service.


Cheers


Geoff

[Mege66]

Hi Bunkerbarge

I, too, have such a Richmond engine since a few weeks. It runs quite smoothly on oiled air and shall soon be installed in a recently aquired Hemmens Lady Jane steam launch which came with boiler but no engine.
After 30 years of little to no usage I am sure the rings are hard and need to be replaced (kind of preventive maintenance).I have not yet tried to remove the piston as it looks as if the lower cylinder cover with the gland nut is a press fit

How did you open the cylinder? Is there a 'trick' how to remove it?

Thanks and happy steaming

[Bunkerbarge]

Without getting into the complexities of comparing the two different type of 'O' ring seal, i.e. Nitrile Rubber as opposed to Viton, I would suggest that you read through this:


https://electricsolenoidvalves.com/blog/nbr-vs-viton-seals/#:~:text=Depending%20on%20the%20construction%20and%20grade%20of%20the,with%20Viton%20seals%20in%20situations%20with%20high%20temperatures.


The bottom line is that Viton is much better suited to our engine piston rings because it is generally more resistant to chemicals, i.e. steam oil, has much more resistance to temperature and is slightly harder wearing.


I suggest Geoff that there was something wrong with your Viton 'O' rings as they should not increase in size.  Nitrile should work OK but they will not last as long, mainly as a result of not being as temperature resistant, note the difference in the article.


As regards removing the cylinder covers, both ends are simply press fit onto the cylinder.  To remove your only real option is to try to force a blade into the joint and try to prise it apart.  Once you have a little gap you should be able to get a very small screw driver in and twist it.  The spigot is fairly deep, see the picture above, so do a little on opposite sides to remove it square.  Once removed and cleaned up you might well find it is not quite as tight to replace so a spot of bearing lock might be required.  Yes, this will make removing it next time all the more difficult however I originally simply pushed mine back on and once the top cover blew off an engine while the boat was in the middle of the pond.  That's why I use Viton rings as I don't want to be taking it apart any more often than I have to.

[andycheese]

Good morning
I have not logged on for a long time and seen your message.
May I suggest stripping the engine down and use a very fine emery paper, some oil and a piece of glass. In circular motions, gently 'reface' the flats on the piston assembly. I did mine and I hardly have any steam / water escape.
Another problem I have with this engine is the pump. When I first got the model, the engine would not rotate smoothly. The pump piston was getting stuck at the top of the stroke. The pump has now been removed until I get around to have a good look at the reason why it sticks.
My Lady Jane is still under renovation after 2 years on and off, but is looking good.

[andycheese]

Has anyone had any problem with excessive heat from the bottom of the Wharfedale vertical boiler in the Lady Jane.
I have mounted the boiler on an aluminium plate with heat resistant cloth and event some 6mm asbestolux material. Even with all that, the plywood base gets so hot, it burns.
Any suggestions?

[DBS88]

Hi it will be worth checking to see if the flame is burning beneath the ceramic insert due to a crack or fault with the way the insert is sealed into the burner pan. The flame may be burning orange or making a roaring noise. The flame should comprise of small light blue cones sat just above the ceramic, the ceramic itself will glow orange

[andycheese]

Thank you for your response.
I did seal the burner some time ago with fire cement. Before I fire it up again, I will check the burn colour.
Regards
Andy

[DBS88]

Here is my recent experience, the ceramic burner to my Hemmens Horizontal boiler started to make an unusual roaring noise so removed the burner and found a crack across it, when lit, the gas would burn underneath it and made the holder very hot indeed, so much so it blued the chrome and destroyed the ceramic material, it just crumbled to dust. I purchased new ceramic material cut a round piece and sealed in into the holder with fire cement, once set I tested it and all seems to be ok now.

[andycheese]

Good morning
Very interesting!!!!
I have to say I do get a 'Roar' but this no evidence of any cracks in the ceramic.
Mine is a vertical boiler and is slightly different to yours.
I do have a nut and washer in the centre of the ceramic, so that may represent a 'crack'.
Have to do something, as the base does get extremely hot, even mounted on an aluminium base to act as a heatsink.
Need to invest in a new ceramic burner for starters.
Thank you for your help
Andy

[Circlip]

A 'Pad' of 3mm thick ceramic paper (Toy train boiler cladding) under the burner should isolate the burner.


  Regards  Ian.

[andycheese]

Thanks Ian.
I have been doing a lot of research about gas burners since DBS88 sent me some details and photos.
As previously mentioned, had a serious overheating problem on the base of the burner/boiler. Now learnt how important it is, to get the correct 'blue' colour. Having 'bench tested' my burner, it glows red hot, which is no good. Unfortunately on the Hemmens Wharfedale burner, the jet is fixed and cannot be adjusted to correct the mixture. May have to either buy a new burner, adjustment tube and jet, or machine one.
Difficult to source the ceramic burner material, when I found a jewellery soldering plate on Ebay.
Hopefully I can sort the over heating problem and get Lady Jane sailing.
Regards Andy

[DBS88]

About 18 months ago (it took me a while to find the photos) I refurbished my Hemmens Vertical Boiler and Engine Steam Plant which I think is similar to yours. The pan is not getting excessively hot like yours, however, the flame is not perfect, but it is effective in heating the boiler, so may change the ceramic at a later date to get a more consistent burn. Have attached photos so you can com[are the flame and burning with you own set up

[andycheese]

Good morning
Thanks again for the photos.
Mine is the same, except I see you have 2 gas inlets.
Yes I have all the colours!!!!
What I need to do is invest in a gas control unit to hopefully control the pressure?
I did read that the use of disposable camping gas cartridges have a better stable pressure? Give it try.
Andy 

[KBIO]

Hello !
Nice Hemmens plant you show here DBS88. I haven't see a double burner on a vertical steam plant yet ! But why not ??
be careful when buying "ceramic" for the burners. Most of the ceramics sold are for jewelers or electronic works. They melt when exposed to a flame.
The good type is the one as shown in Hemmens plant with big cavities. They are more expensive but work a lot better & safer . The others are good to lead to problems or questions concerning the heat . Thy are ceramic although they look like!
 

[andycheese]

Thank you KB10
Not found anywhere to buy the correct material. Thought the jewellery material was it.
May end up buying a new complete burner with the adjustable jet assembly.
I have spent a great deal of time rebuilding the boat, so don't want to spoilt it.
Regards Andy

[DocMartin]

Thank you KB10
Not found anywhere to buy the correct material. Thought the jewellery material was it.

See the link below for a short treatise on making a ceramic burner:

https://www.homemodelenginemachinist.com/threads/making-a-ceramic-burner.24993/

If you go to post #9 there is a description of the ceramic material used.  It can apparently be sourced at www.pollymodelengineering.co.uk
Page 12 of their Model Engineers Supplies Catalogue lists for sale the ceramic plaque material used in their burners

[andycheese]

Good morning Doc Martin
WOW!!! What a catalogue. The company is only 45 minutes away from where I live.
Whilst at present I am rebuilding a Lady Jane Hemmens boat, I also build Roundhouse locos. I can see me spending a lot of money at Poly Model Engineering.
Much appreciate your help.
Regards
Andy