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[DBS88]

A steam whistle can be a fun addition and even add a touch of realism to a model, have you ever seen a better stem whistle than this? It would be a fun project to replicate


https://youtu.be/BVZcJ87nVz0?si=cSVOKqGxqdUxsNjX

[1967Brutus]

oh the horror of wasting steam...

[KBIO]

Hello !
I took some time to go back to the principle of the condensation lubricator. [/size]The operating principle of the displacement lubricator, which is the best known in the world of model making, consists of a reservoir topped with a filler cap. When steam passes through the pipe to feed the engine, a quantity of steam enters the lubricator through a calibrated orifice. This immediately condenses on contact with the cold walls. As water is heavier than oil, it sinks to the bottom of the reservoir, displacing the oil upwards and then entering the steam pipe through the same steam inlet orifice.The temperature of the steam is far from being high enough to cause the oil to evaporate, which would cause it to lose its lubricating properties anyway. There is not even a Venturi effect through  the oil orifice. Just Utube effect by gravity .I would remind you that we use +/- 400 grade oil to lubricate our machines and the evaporating temp must be  well above 250°CThis condensation lubricator, as its name suggests (otherwise it would be called an “evaporation lubricator”), is not insulated, and it is even recommended to cool it down , as explained in the diagram I showed earlier.
Looking at the shape of our condensers , it is impossible to have any evaporation . The exchange surface is far too small in any case.
The purpose of this condenser is to reduce friction by placing a film of oil between two surfaces. And it is not as uniform as with a pressure lubricator.


There is a formula for calculating the amount of oil needed for proper lubrication of Stuart machines. But for those who don't like calculations, a table is available based on cylinder displacement. If it can help !

For engine displacement <= 3 cc E = 0,3 mm
For engine displacement > 3 cc and <= 5 cc E =0,4 mm
 For engine displacement > 5 cc and <= 8 cc E =0,5 mm
For engine displacement > 8 cc and <= 12 cc E = 0,6 mm
 For engine displacement > 12 cc and <= 15 cc E = 0,7 mm
For engine displacement > 15 cc and < or = 23 cc E =0,8
mm [/color]

[Mege66]

Very useful information KBIO. I think this should have been posted in the „Graupner Glasgow Refurbish“ thread.

[KBIO]

Thanks Mege !
I bet that an Admin will pass by and correct it !
 

[derekwarner]

KBIO........possibly a glitch    in your previous posting values implying that for the condensing lubricator to function, steam must be @ 250 degrees C +


Steam @ 250 degrees C ~~39 Bar, whereas many of our model steam engines are rated to 2 Bar only which is ~~134 degrees C


Displacement lubricators function at these lower pressure/temperatures


Derek

[KBIO]

Sorry !
I was meaning that , to start to evaporate 400 gr oil , a temperature above 250 °C would be necessary. In fact I do not know the real temp to evaporate the oil depending on its grade .
I couldn't find real information on that . If someone could help and tell us what the evaporating temp for different grade oil, I would appreciate. I just know that motor oil 20/40 start to evaporate @ 150 °C
This is to explain that , with our plants working between 2 & 4 b (15 to 60 psi) , the temp =+/- 120/140 °C is not enough to evaporate the 400 gr oil.
It would be interesting to have more infos and advices.
Cheers.


ps: Sorry to spoil this post on the whistle  [size=78%]. I hope that the Admin will rap me on the knuckles and displace our comments.[/size]

[1967Brutus]

Sorry !
I was meaning that , to start to evaporate 400 gr oil , a temperature above 250 °C would be necessary. In fact I do not know the real temp to evaporate the oil depending on its grade .
I couldn't find real information on that . If someone could help and tell us what the evaporating temp for different grade oil, I would appreciate. I just know that motor oil 20/40 start to evaporate @ 150 °C
This is to explain that , with our plants working between 2 & 4 b (15 to 60 psi) , the temp =+/- 120/140 °C is not enough to evaporate the 400 gr oil.
It would be interesting to have more infos and advices.
Cheers.


ps: Sorry to spoil this post on the whistle  [size=78%]. I hope that the Admin will rap me on the knuckles and displace our comments.[/size]

The reason you won't find any info on that, is that it basically is totally irrelevant: "Steam oil" is exclusively used in reciprocating steam engines, and you won't find many engines running over 15 bar.
Wet steam at that pressure is a touch over 200 deg C and virtually no lubricating oil, even normal engine oils for cars etc, have any significant evaporation at those temperatures. Synthetics can decompose above 180 deg C but synthetic oils do not have a place in our engines anyway. At least, NOT INSIDE it. Rods and bearings, but not slidevalves, pistons and cylinders.
Of course, superheated steam can be significantly hotter than that, but in reciprocating engines, superheated steam is not all that important, that is more a turbine thing.
Turbines do not require oil to be supplied with the steam. Turbines have no "rubbing parts".

Steam oils are made up with the heaviest of base stock, blended with animal oils like Tallow to give it that tenacity to stick to metal surfaces despite the presence of steam and condensate.

But don't get fooled by our commonly used low temperatures, this does NOT make the use of common engine oil OK. Engine oil cannot handle water, and will lose affinity with metal under the presence of steam. Only dedicated steam oil will provide proper lubrication. The oils as supplied by Wilesco, is not steam oil, it is basically sewing machine oil in a different label, not really suitable for displacement or pressure lubricators. I guess for low runtime applications it will do the job though.