Some locomotives fed their appliances from a separate turret coupled to the superheater header, these locomotives were equipped with front end throttles and superheated steam was available even with the throttle in the closed position.

Thanx! Learn something every day.

Bob,

I took a long, hard look at our compressors today. The figure that came up with an ambient air temperature of 100-120* F was a maximum of 350* F on the high pressure side of the compressor. After looking at this, I feel that there is enough separation between the steam and air sides of the compressor that it would be a nominal difference in temperature.

So now, we boil this down to what oil will not swell up our gaskets and meet the temperature demands. I still have this question for everyone... Has anyone tried what is being used in a modern air brake system? The logic is that it has to be compatible with the gaskets. I have seen one outfit that is using Chevron ISO 68 in its compressor crank cases. It is designed for steam driven applications as well. Let me see if I can dig up a link to it on line...

Something to keep in mind about the ISO 68 stuff, it is being used in a crankcase environment with a pressurized lubrication system. Also, the heads on these compressors are liquid cooled.

This info was taken from this website...

http://www.chevron.com/products/prodserv/nafl/paperandforest/content/prodspecs.shtm

Clem,
"Chevron GST Oils provide long oil service life and reduced turbine down time. They are recommended for use in all turbines including gas, steam and hydroelectric models."
This is an oil for turbines of one flavor or another, these oils are for bearings or rotating shafts and are used with pressured recirculating systems.

I'd be interested to hear what the folks at Strasburg, TVRM, Tweetsie, and other frequent running shops use in the systems on their steam locomotives.
I have seen ATF used with fair results on saturated steam below 170psi, but I see that is about 368deg F and ATF does not do well above 350deg F.

-Sully

keep some o-rings and gaskets, cut them up into small pieces and soak them in jars filled with the various fluids in question. This will tell compatability in a "real world" way if you do not know their material makeup. Using an old hotplate and pan, good temp pyro, and superheating the oils (slowly, and well above anticipated operating temp) in question will yield a "real world" idea as to what you can expect out of any fluids. It will also show you what you will be eventually cleaning out of the system. Pay particular attention to fumes and tar created. Parker O rings has a free seals bible that explains chemical compatibility. There are many places to get the MSDS for the chem in question, read it carefully. Some synthetic and florinated oils release DEADLY fumes upon reaching a specific temp

Parker seal bible
http://www.parker.com/ead/cm2.asp?cmid=3903&

DR

I wonder if synthetic ATF would do much better?

Actually Mr. Odom, it was mobil 1 synthetic atf that I used.

Hi Jason,

You seem to be having good results with it. I just wonder if what Sully said about ATF not holding up well above 350 deg. F applies to synthetic ATF, or just conventional. I'd expect the synthetic variety to stand a lot more heat than the conventional product.

Hugh

Please don't take my word as rule or recommendation - upon reading the post I looked up the properties of ATF because I have used it. I found several technical pages and brands that said the fluid begins to break down in vehicle applications after 275deg to 360deg. Unfortunately, I couldn't find a manufacturers recommended temperature guide for any brand ATF, though I do beleive Mobil 1 is a top notch product.

it appears that Mobil 1 ATF has changed its original formula
(according to other forum searches)
Its flash point is 421F so you don't have to worry about flames
Thats awful close as far as possibly doing something weird (starts to tar of fume)
I'd heat some and see what it does
Anyone know what seal material is used in brake assy's?

dr

Are we speaking about brake cylinders, brake valves or air compressors?
If it is other than air compressors then over heating the oil at other locations does not apply. However if the oil is overheated prior to reaching these assemblies and the lubricating qualities are diminished then it does apply, somewhat.

Starting at the source of the air oil then would be the air compressor. The mentioned oils, I thought, were being discussed to see if they held up in the heat of a steam operated air compressor. Then my question is will the heat from the steam end transfer to the air side and if so how much will transfer? What then is the heat at the air compressor air squeezing side? I doubt that it is over 300F if all the check valves are functioning properly. The air oil then is to lubricate the cylinder walls and perhaps a little at the air checks. carboned checks and improperly set checks will warm the air significantly.

So if the air is being overheated at the checks then the oil is being overheated as well. Then we have air oil that is overheated and most likely the lubricating ability has diminished. Then what little that reaches the brake stand is probably fouling up the rotarys as well as the slide valves in the distributing valve. What about the brake valves on the cars? I don't think there is much to be worried about there, they are all pre-lubed when they were rebuilt.

Where then are we worried about heat. It has to be at the air compressor. can anybody tell me at what temperature the air side is on a correctly functioning cross compound?

It depends on the ambient air temperature going in. We figured high for an ambient air temperature for what will be doing. With an ambient of 100*F, the temp. figured at around 300*F at the outlet. Part of the estimate was attempting to figure in some heat soak from the right of way.