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Author Topic: positive displacement lubricator for overheated steam.  (Read 471 times)

KBIO

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positive displacement lubricator for overheated steam.
« on: March 21, 2021, 04:33:26 pm »

Hello!
Most of us know how to lubricate the engines with two types of « greaser/oiler » ;
One is a ratchet type with definite volume of oil delivered and the other one on he classical condensate one. This one is sometime not easy to set properly for a good lubrication. Or it gets empty too fast or it does not deliver oil. Most of the time though , it does the job , more or less ! As long as the oiler is not bigger than the engine as I saw some !.
For my part, I sometime work with HP steam (not flash steam) and , as we all know, the higher the pressure is the higher the temps is. I over heat too. And come a point where the condensate greaser has no efficiency.
Lazy like a lizard in the sun, I did not want to machine down a ratchet greaser so I thought of another method.
Easy to build and easy to control. It’s incredible how I get more ideas coming up when I am sipping a Pastis on a rocking chair in my garden . Try it, you’ll see ! Maybe you need 2 or 3 but it works !;-))
The scheme below shows the principle. A big cylinder with a large piston , pushing a small piston in a narrow cylinder.
The big cylinder is connected up stream on the steam line and the small cylinder downstream.
The surface of the big piston is the double of the small one.
Obviously the steam pressure on the line  is the same up & down stream. But if I open a needle valve up stream on the big piston,  the pressure will be twice more than on the small one and will push it , displacing the oil in the line down stream !
As this is a glass through which , we can check the displacement, we can adjust the flow with the needle valve  and see what we are doing.
The only problem I have (but it is solved) , it is to get the pistons back in initial position and the oiler full. To do so I install a Tee down stream. A plug on the side and a globe  valve in the line. I take the plug off and close the valve. I fill a syringe up with oil and I squeeze the oil through the plug.
Cheap & easy !
Let me know what you think and if we can improve it.
I know that my explanations are fastidious , but I am confident that people of your calibre will get the scoop.
Thaks for your attention .
Regards.

derekwarner

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Re: positive displacement lubricator for overheated steam.
« Reply #1 on: March 21, 2021, 09:09:00 pm »

I for one must admit to being a little confused KBIO  :D ......from the Drawing, we see that the common piston rod 'connected to the piston' on the steam side would be  fully outwards when the oil cavity is full, then moving inwards as the oil is displaced <*< ....this does not appear to be the case as shown in the model

Or have I too much Pastis on my rocking chair on the balcony?

Derek
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Derek Warner

Honorary Secretary [Retired]
Illawarra Live Steamers Co-op
Australia
www.ils.org.au

KBIO

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Re: positive displacement lubricator for overheated steam.
« Reply #2 on: March 21, 2021, 10:11:34 pm »

Hello.
No,no, you can have another Pastis. This is my turn ! :-)

The piston rod has been removed on the model. It was there , originally to work as a syringe to fill up with oil by pulling it out. At the begining , I thought that I would need but I decided to inject the oil with a seringe , instead of using the oiler as one. That eliminates this piston coming out and taking some space.
I may have another drawing that I shall present tomorrow. It wil be clearer. ok2
The main thing is to understand that the oil is pushed in the steam line as the piston steam surface is bigger than the oil side one.
Regards.



KBIO

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Re: positive displacement lubricator for overheated steam.
« Reply #3 on: March 22, 2021, 07:47:51 am »

Good morning !
I found some drawing to help to understand the different versions that I thought of !
The first drawing shows one with a  piston rod to help sucking the oil in and another  version without but by pushing the oil in with a serynge.
The last drawing is what I have as a model. not exactly the same but everyone can modify as he likes. Note the vent port between the two pistons.


For the understanding.
PO = Pressure applied on oil side.
Ps = Pressure applied on Steam side
Ss = Suf Steam side.
So = Surface oil side.
PO = Ps x (Ss/So)


Let's take a piston
-  10 mm dia on Steam Side >>> surface = . 785 cm2
-    8 mm dia on Oil side.      >>> surface = . 496 cm2


Working steam pressure = 3 b
so
PO = 3 x (.785/.496) = 4.7 b applying a force of 1.5 kg on the piston pushing the oil in the steam line.
                                                              (friction forces NA)


A bit soon for a Pastis but I can wait ! :-)
Have a good day ! ok2






DBS88

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Re: positive displacement lubricator for overheated steam.
« Reply #4 on: March 27, 2021, 10:08:38 am »

Well done this looks to be a useful alternative for an oiler, what is the capacity of the oiler? and how long is it? I do fully appreciate that this is a prototype. My only suggestion so that it could be more widely used would be to make it more compact, it appears to be quite long? Is there a way the cylinders could be side by side, this would half the length, not sure how the pistons could be linked and the mechanism sealed? Perhaps I will pour a single malt and reflect further on the problem.
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KBIO

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Re: positive displacement lubricator for overheated steam.
« Reply #5 on: March 27, 2021, 06:26:04 pm »

Hello!
I agree that this prototype is a bit ugly & long = 15 cm.
I did with the glass that I had available in my drawers.
It is easy to make a short version by enlarging the surface of the pistons and reducing the course then. 1 or 2 cc of oil will be plenty enough to lubricate a 5cc engine for > 40 min.
It is up to each one to design its own oiler , keeping in mind that the goal is to inject just some traces of oil .
The idea for oiling an engine is to reduce the frictions , not to lubricate it , as for a thermic engine for example , so a slightly oil wet wall is enough to make the job. A hot & dry steam should not wipe the oil away. At contrario , too much oil will help forming condensate and make mayonaise in the sliding sleeves.
Sliding sleeves are good for that!
According to what I read and to what I have learnt during a visit to  Stuart (Guernesey) , a standard Stuart oiler is given to oil a D10 for 45 min to 1 H. Every one will apreciate according to its own experience.
How to measure the right quantity oil injection ? I have no idea ! I just make sure that some oil is going in.
 But for those who are a bit picky and to make sure that the oil has a positive effect , it is necessary to run the engine with and without oil , measuring the torque . A brake of Prony is easy to build.
Steam is a long and quiet river with some falls here and there!
Have a "double malt" , this is my round  !
Regards.
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