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Cylinder oil
Posted by: BillB (IP Logged)
Date: November 13, 2015 01:11AM

I have been using mobil steam cylinder oil but now its transparent Hard to see in the winker. Is synthetic oil better? Whats the best oil to use?

Re: Cylinder oil
Posted by: SSsssteamer (IP Logged)
Date: November 13, 2015 03:11AM

Bill, The guys in the UK have been putting carbon black into their steam cylinder to give it color so that they can see the once clear oil in their winkers. I have been blending my clear 600w and my dark 600w to stretch out my oil supplies. A year ago when I restocked, I was still able to buy the dark 600W steam cylinder oil. I had accidentally bought a 5 gallon bucket of the clear stuff.

Re: Cylinder oil
Posted by: BillB (IP Logged)
Date: November 14, 2015 12:06AM

I have been doing the same thing mixing them together.I'm about out. Ive been running higher super heat in one of my projects. So is Mobile Hecla SSO* better or is super 600w OK. Rolly has posted this. [www.southernsteamtrains.com] Bill



Edited 1 time(s). Last edit at 11/14/2015 12:12AM by BillB.

Re: Cylinder oil
Posted by: BillB (IP Logged)
Date: November 14, 2015 12:18AM

I Just found this [www.mobil.com]

Re: Cylinder oil
Posted by: Rolly (IP Logged)
Date: November 14, 2015 03:12PM

Bill one thing you have to remember, the flash point is in free air. You do not have oxygen in superheated steam.
The other thing is you donít gain any advantage running superheat higher then 200F over the saturated pressure your running.
Rolly

Re: Cylinder oil
Posted by: BillB (IP Logged)
Date: November 14, 2015 07:33PM

Going to the engine is 600f 600 pounds steam Mobil 600 w is on the low end of working only good for 500F.I never had a problem but I always use about 3 times more than needed. This chart says only good for 500F [www.mobil.com]

Re: Cylinder oil
Posted by: Rolly (IP Logged)
Date: November 14, 2015 09:02PM

600 PSI saturated is 486F + 200F is 686F I think you can go as high as 700F superheat with no problems
With my Derr boiler I was running 700 F at the engine using Mobile One 634 ISO 460
Rolly

Re: Cylinder oil
Posted by: Caleb Ramsby (IP Logged)
Date: November 14, 2015 09:30PM

Just to complicate things a bit.

The higher flash point oils have longer hydrocarbon chains and thus when they do break down, they are more prone to depositing carbon. Which is a substantial destructive force.

The lower flash point oils break down at a lower temperature, but are ironically less prone to depositing carbon.

There was a really great article on this that I read a few years back, but I havn't been able to find it as of late. It was authored by the head of the oil companies experimental division. Can't recall the specific oil company unfortunately.

Bill,

Have you observed any carbon deposits in your engines?

Rolly,

I seem to recall that you spoke of an engine where you installed a massive superheater that gave close to 900 F at the engine, using Mobil One 634 ISO 460 and when you inspected it, it was clean as a whistle. No significant wear or carbon deposits. Also, you mentioned that the owner didn't observe any increase in efficiency with the higher superheat, thus it was somewhat of a redundant experiment.

Caleb Ramsby

Re: Cylinder oil
Posted by: Ben (IP Logged)
Date: November 14, 2015 10:40PM

I remember a sales brochure,,,either Skinner engine,,OR oil co
advertising,,about 30 years ago,,ok-ok make that 50 yrs,,
Carbon was an issue,,
There was a formula,,swept area of piston in sq inches,,which
calculated the vol of oil needed / 1000rpm or hours,,
Is Hal Fuller on here??

Re: Cylinder oil
Posted by: Caleb Ramsby (IP Logged)
Date: November 14, 2015 11:47PM

Hey Ben,

"Kent's Mechanical Engineers' Handbook" Twelfth Edition, 1950 has this to say.

"The consumption of cylinder oil ranges from 0.1 pints to 4 pints per million square feet of surface area swept over by the piston (perimeter of piston times distance traveled), with an average of 0.8 pints per million square feet. In engines using steam of 700 to 800 F, an excess of oil forms carbon, which produces wear."

Caleb Ramsby

Re: Cylinder oil
Posted by: Rolly (IP Logged)
Date: November 16, 2015 03:52PM

Caleb
Iím not very good at explaining things all the time.
In a steam engine the pressure pushes the piston down the cylinder till the valve closes. Itís a pressure engine to this point. Then there is anywhere between 12 to 15 present of piston travel before the valve opens to exhaust. Depending on the valve design.
Steam expanses in volume as it cools. You have to go by the steam tables for the rate of expansion at the different temperatures, this is the real reason you superheat. After you play with numbers long enough you will come to the conclusion you gain nothing going over 200F over saturated temperature for superheat.
In a compound or triple you look for 25 to 30 percent expansion if you can get it. Not many do.
Yes I started off running 1000 psi at 1000F with my Derr boiler in my 1920. It didnít seem necessary and I dropped back to 600psi at 700 F using Mobil one 634 gear oil ISO 460. You cannot see it in the winker. Brent C used a die in oil in his car with the same stuff to see it in the winker.
Rolly

Re: Cylinder oil
Posted by: Caleb Ramsby (IP Logged)
Date: November 16, 2015 08:30PM

Hey Rolly,

I wasn't very descriptive either.

Yep, superheat has some severe practical limitations. The SES experiments with the poppet inlet valves and uniflow exhaust belt, which separates the "heat zones" also showed a significant limitation as to an effective superheat temperature.

The steam tables do indeed show a significant diminishing return with the increase in superheat temperature.

More importantly though is adapting the temperature to what the particular engine needs to keep the steam from condensing on the cylinder walls through the cycle. Which has to do with a million factors.

The SES data is interesting, they show the variance of cylinder wall temperature in regards to the cutoff percentage. The cylinder walls and head get much cooler with a shorter cutoff, thus diminishing the practical real world efficiency in relation to cutoff.

SES found that any temp above roughly 700 F or so and volumetric expansions greater then 8 or so had a detrimental effect on overall efficiency.

Caleb Ramsby

Re: Cylinder oil
Posted by: Caleb Ramsby (IP Logged)
Date: November 16, 2015 10:16PM

To expand a bit and get back to the oil issue.

As Stumpf found with his experiments and development of the uniflow type, it is the metal temperature more so then the steam temperature that influences the break down of the cylinder oil.

With a compound, the high pressure cylinder typically has a long cutoff, thus it's average cylinder temperature is much higher then a simple of similar initial temperature. This is why using a lower initial temperature and a reheat between stages has been popular for compounds.

Stumpf employed direct oiling with injection holes near the center of the cylinder bore for his poppet valved engines and more or less at the piston valves for the piston valved versions that he made.

The Stanley engines, being integral cast, with the exhaust channel cooling a significant portion of the casting and the valve and valve seat being exposed to the exhaust steam. The metal temperature allows for a much higher superheat without degrading the oil.

This especially influences the practical effectiveness of high superheats, seeing as the superheated steam is exposed to low temperature metal and the higher temperature differential zaps a ton of heat energy from the fresh superheated steam.

With uniflows, this is still a significant factor, even with high compression and short cutoff. The thermal properties and extra heat energy required for the highly superheated steam doesn't produce a superior overall thermal efficiency.

At best it lowers the weight of steam per horsepower hour, which would reduce the load on the condenser, but not the fuel for a given horsepower output.

Doble was able to achieve some serious reductions in steam lbs per hp hr with the use of high pressure and significant superheat, on the DYNO, but when he tested the setups on the road, they didn't translate into a real world decrease in fuel consumption.

Mostly due to the real world issues of low loading, cold starting and what not.

Caleb Ramsby



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