Non-condensing Stanley cars built before 1915 allowed the steam cylinder oil used to lubricate the pistons sliding in the cylinders to be exhausted with the spent steam.  With the introduction of condensing cars at the start of the 1915 production year the steam cylinder oil in the steam found its way back to the water tank along with the condensate.  With the water being returned to the boiler several times to be converted to steam the water tank and boiler collected oil deposits.  This eventually caused an problem with the boilers as the oil deposits allowed uneven heating to occur on the bottom flue sheet of the boiler and resulted in the flue tubes leaking.  Stanley solved the problem by changing to a very light steam cylinder oil (actually a mixture of steam cylinder oil and kerosene) and by changing the boiler design to steel flue tubes welded to the bottom flue sheet of the boiler.

Owners of Stanley condensing cars in the 21st century have to deal with a heightened concern related to environmental preservation.  Additionally the replacement boilers offered by a few individuals commercially are of the non-condensing design (copper instead of steel flue tubes are not welded to the bottom flue sheet) which means oil needs to be kept out of the boiler if at all possible.  Thus many Stanley condensing cars have been modified with the addition of a steam cylinder oil separator.

Various designs of oil separators have been custom retrofitted to remove the steam cylinder oil from the exhaust steam leaving the Stanley engine.  The principal behind the oil separator is for the steam to pass through a fine wire mesh where the steam can collect on the mesh.  As it collects on the wire mesh gravity allows it to flow to the bottom of the separator where it can be removed and properly discarded.



The steam cylinder oil separator I designed for my Model 735 Stanley was required to meet three primary criteria.  First and foremost it had to remove the vast majority of the oil from the steam (my goal was 80% or more).  The replacement boiler for my Model 735 would be the Stanley condensing car design where the steel flues would be welded to the bottom flue sheet thus the boiler design will tolerate steam cylinder oil.

The second requirement was that the separator had to be small and installed on the car without any modification to the car itself.  Some steam oil separators I had examined required frame modifications or other similar changes to the car.  At least one unit was over 3 feet long and of sizeable diameter and to me looked like it didn't belong.  For me, keeping the car as original appearing as possible is a prime concern.  In fact my intention was that the steam oil separator could be removed from the car and there would not be any indication that it ever had one installed to start with.

The final criteria was that it be easily serviceable.  I wanted to be able to drain the oil from it easily as well as be able to disassemble it quickly for periodic inspection and cleaning.  In addition to my three primary criteria the unit needed to be light weight, not costly to make, could not restrict the exhaust steam flow from the engine (that would mean a reduction in engine efficiency), had to look like it belonged on the car, and of course had to handle steam and water temperatures and pressures present in the exhaust from the engine (after passing through the feed water heater).

As the photograph indicates (bottom of the photograph) the heart of the separator is the stainless steel filter cartridge from Rosedale Products (part number 10-100-C-T-S-DOE)  The filter cartridge that I chose is ten inches in length with Teflon gaskets on either end.  It is a 100 micron non-pleated filter and includes a support layer of screen underneath to keep the filter element from collapsing.  It is housed in a four inch diameter aluminum tube and the filter and aluminum tube are captured between a pair of aluminum end plates which are tied together with four hexagonal retaining rods.  O-rings on the aluminum end plates insure sealing of the cartridge and aluminum tube to the end plates to prevent leaking.  On the side of the aluminum tube is an inlet port for the exhaust steam coming from the feed water heater while the steam leaving the separator flows up the center of the filter and out the upper end plate.  I've further increased the filter area by loosely stuffing the center of the filter cartridge with stainless steel wool.  Inside the aluminum cylinder, between the filter and the inlet port is a baffle that helps distribute the steam around the filter instead of letting it impinge directly onto the filter as it enters the separator.  In the lower end plate is a port for draining the steam cylinder oil off.  The steam oil separator is held in place by its 1-1/4" copper piping.  Removal of the unit for cleaning involves loosening the two 1-1/4" pipe unions on the copper pipe attached to the separator and lifting it out.  Loosening the retaining rods allows the unit to "fall apart" (this needs to be done over a tub as steam cylinder oil is everywhere).

The separator works fine and meets my expectations.  While it definitely doesn't capture 100 percent of the oil in the exhaust steam it does capture a significant amount (I'd estimate at least 90% to perhaps 96%).  The water in the water supply tank will become cloudy after a long day of driving (and multiple refillings) but it does not have floating globules of steam cylinder oil as found with condensing cars not steam cylinder oil separator equipped.  I have found that the separator will collect water due to condensation if I park the car and don't open the oil drain.  It's become part of the ritual when stopping the car for a period of time to open the separator drain valve (the only non-Stanley valve on the car; a ball valve to insure unrestricted passage through the valve) and allow the oil and water to collect in a small pail.  In cleaning the unit after 250 miles of operation there was significant steam cylinder oil on all internal surfaces of the unit but no steam cylinder oil to speak of on the piping between the separator and condenser or that could be observed in the condenser.

It is also worth mentioning that some steam car owners add "oil sorbents" to their water tanks to soak up excess oil.  Often used in machine shops to soak up cutting oils from lathes and milling machines, they are also known as "shop oil pigs" or "oil soaks".  They are the diameter of a sock and are available in various lengths.  Some Stanley owners, when cleaning their water supply tanks, insert several oil sorbent socks into the tank through an extra drain port installed in the bottom of the tank for collecting oil finding it way past the separator and into the tank (the existing drain can not be used as it has the power water pump suction line and suction line screen blocking most of the drain opening).  The socks are water repellent but they do collect and hold any oil that finds its way back to the tank.  When the tank is cleaned once or twice during an operating season the oil-soaked socks are removed and replaced with clean ones.  The use of oil sorbents with a condensing steamer that does not include a steam cylinder oil separator is only recommended if the sorbents are going to be changed with every couple of water fillings (they will become saturated with steam cylinder oil quite quickly).

Click here for a section of the Rosedale Products catalog detailing filters ~

Rosedale Stainless Steel Filter Cartridges (PDF file)

Click here for my drawing of the steam cylinder oil housing ~

Steam Cylinder Oil Separator Design (PDF file)

Click here for the Restoration section of this website that discusses the Steam Cylinder Oil Separator ~ Steam Cylinder Oil Separator Restoration