PILOT FUEL VALVE
   

the pilot fuel valve is located behind the burner access door at the front left side of the car

As one of the simpler systems on a Stanley steam car, there are three valves associated with the pilot fuel system~

  • Pilot Fuel Tank Pressurization (air) Valve

  • Firing-up Valve

  • Pilot Fuel Valve

The function of the pilot fuel valve is equally simple in that it controls the fuel flow to the pilot burner.  After the pilot vaporizer tube is sufficiently warmed with a torch so that the pilot fuel will vaporize on its way to the pilot burner, the pilot fuel valve is opened to admit fuel while an ignition source is held above the pilot so that it lights.

 

STANLEY VALVE CONSTRUCTION AND MAINTENANCE

Stanley valves are very simple in their construction.  They consist of a cast brass body, valve stem, handle, and a machined brass packing nut.  The drawings at the left depict only three of nearly a dozen valve configurations that Stanley manufactured.  While the ones shown depict valves with ports tapped for 1/8" pipe, Stanley also manufactured valve bodies that were flared and threaded to accept 1/4" and 9/32" copper tubing.

Many of the multitude of valves necessary to operate a Stanley were located in difficult to reach positions either physically or because they were near hot surfaces.  As a result the valve stems were made from a 1/2" length up through several feet in length to move the valve wheel to an easier to reach and safer position.  Initially the 1/4" diameter valve stems were made of brass but that was later changed to steel.  Today most replacement valve stems are made of stainless steel.  The end of the valve stem is machined to a 30-degree taper all though some later Stanley valves incorporated a 15-degree taper.

See the discussion on the Fuel Pressure Relief Valve for a photo of assorted Stanley valves along with additional information.

One of the mistakes often made in operating Stanley valves is to open them more than necessary.  The construction of a Stanley valve and valve seat, with the tapered cone design, is that in two complete revolutions of the valve handle the valve is fully open.  In most cases one full rotation of the valve handle is sufficient.  There is no need to open the valve more than two turns to achieve full flow through the valve.

Likewise, when closing a Stanley valve some have the tendency to apply a lot of rotational pressure to the valve handle to insure the valve is "tightly closed".  Again, the design of the valve stem and valve seat insures that with only a moderate amount of force the valve is closed.  Attempting to "crank down" on the valve handle not only damages the soft brass valve seat but in the case of steam valves, when the steam valve cools it will be nearly impossible to open the valve because the metal components have contracted and are even more tightly bound. 

In the case of blow-down valves it is good practice to close the valve until the valve stem and seat just mate and close off the majority of the water and steam flow.   Sometimes small bits of grit and rust can get lodged on the valve seat during the blowing down operation.  These debris will not allow the valve stem to seat properly and if the handle is closed tightly the debris may be ground into the soft brass valve seat.  The rotation of the valve stem on the valve seat will also cause the debris to cut grooves in the seat which become the pathways for the valve to leak.

A recommended practice is to close the valve just to the valve stem reaches the valve seat.  At that point it is good practice to open the valve a quarter turn and reseat the valve stem on the seat.  If with a little bit of pressure the valve closes then that is how it should be left.  If the valve does not close off then repeat the opening and reseating a couple more times.  Observe the end of the blown down line connected to the valve for leaking but remember that it may appear to be leaking when it is really the remaining steam and water in the line draining.  If the valve continues to leak then it will be necessary to dress the valve seat and the end of the valve stem to make a better seal.

Stanley valve handles or valve wheels were mostly of a cast aluminum construction.  However some early Stanleys (until about 1909) used a lace pattern valve wheel (see image at left).  An alternate valve handle design was a wire spring wrapped around a metal hub.  Stanley valve stem ends were machined with a 1/4" square so that the valve wheel could be peened onto valve stem.

The packing nuts for the valves included enough space for two rings of packing to be used.  The packing was carried inside the packing nut such that the packing nut also served as the packing stuffing box.  When the packing nut was screwed down on the valve body it allowed the required pressure to be applied to the packing to prevent leaking at the valve stem.  A locking nut insured that the packing nut would not work loose with operation of the valve.  An alternate design used on some valves that typically saw higher use such as fuel or pump control valves moved the packing stuffing box to the valve body and incorporated a packing gland collar to press directly against the packing in the stuffing box.  The packing nut then tightened down on the packing gland to apply the required pressure.

The proper selection and installation of packing in valves (and for pump pistons and engine rods as well) is important.  The packing material must seal properly without damaging the shaft that it is sealing.  When Stanley cars were manufactured a basic graphite impregnated yarn was the the most common packing material in use.  Most of the packing applications on the Stanley use a 1/8" x 1/8" square packing material.  Today there are many types of packing available for all sorts of applications.  While many of the newer materials will work, staying with the graphite impregnated yarn is perfectly acceptable.  A basic graphite impregnated yarn from Garlock still provides excellent service in most Stanley packing applications such as valves and pumps. 

Often overlooked is the proper installation and maintenance of the various packings found throughout the car.  Packings have a finite life and need to be replaced occasionally as they dry out and get hard.  Packing should be cut in "rounds" or bands that circle the valve stem or pump piston and not wrapped around the valve stem or pump piston like a spring.  Newly installed packing should have the packing nut snugged up such that leaking is limited initially.  This allows the packing to "work in" during initial operation until the packing nut is tightened up to eliminate any leakage.  It can not be stressed strong enough that over tightening of a packing nut will apply undue pressure to the packing material and usually results in scoring of the valve stem or pump piston upon which the packing rides.

Periodic checking of the packing is required and if leakage is observed it is generally only necessary to tighten up the packing nut "one flat" (tightening a nut "one flat" involves rotating a six-sided nut one-sixth of a turn or the equivalent of moving the flat surfaces of the nut 60 degrees).  Over time the process of snugging up the packing nut will use up all the adjustment designed into the nut.  At this time the packing nut (or packing nut and packing gland collar) should be backed off and another ring of packing added.  After several years of operation and use, and especially when a great deal of force is required to tighten the packing nut to get leaking stopped, all the packing in the packing gland should be removed and replaced.  Old packing looses its lubricating properties and gets hard and will can score and prematurely wear the valve stem or pump piston upon which the packing rides.

The Garlock company provides excellent instructions describing proper installation and maintenance of packing materials.  A copy of those instructions in PDF format is available by clicking on this link: GARLOCK PACKING INSTRUCTIONS.

See the article on the Fuel Pressure Relief Valve for a additional discussion on Stanley valves.  See the article on the Burner Fuel System Strainer, Check Valve, and Shut-off for a discussion of the pipe and copper tubing used on Stanley cars.  See the discussion of the Boiler Check Valve for a description of the design and operation of Stanley check valves. 

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