106 South Elm Street, Newkirk, Oklahoma 74647
A very interesting and informative article appeared recently in The Iron Men Album by Mr. H. S. Fox, in which he gives an excellent description of the injector and explains the technical principles of its operation.
In this little piece I will try to tell something of the troubles that can be encountered in the use of these handy and useful devices. The advice I will try to give is not for the old timers who used to make their living running steam engines, as most of them perhaps know more about injectors than I do; but unfortunately not many of these men are around any more, and maybe I can help some of the younger people who are restoring old engines and building models.
My experience began in the year 1906 when I was 12 years old firing an old Garr-Scott traction engine in a sawmill operated by my father and my uncle; and when I retired a few years ago, I owned a sawmill that was driven by a Skinner steam engine with cylinder-dia. 14', stroke 15'. The boiler was 5' diameter, 23' long, and carried 200 lbs. pressure. Water was supplied to the boiler by a steam pump that worked through an exhaust heater. However, I strongly advise against pumping cold water into a boiler. It will cause leaking flues and sometimes worse damage, so I always had a couple of injectors to use when the engine was shut down with no steam in the heater.
During the years from 1906 to 1966,I had to do with a good many injectors, and maybe some of the younger folks will be helped in getting these very useful but sometimes ornery devices to behave.
Now back to the old Gaar-Scott. It was equipped with a Hancock Inspector. A Penberthy was in the junk box that the former owner said was worn out, but few people knew anything about repairing injectors in those days, so it probably needed a new delivery jet that could have been bought for about $1.75. The Hancock Inspirator was never furnished as original equipment on a traction engine. The Hancock is a 'Double Tube,' sometimes called 'Positive Type,' and while they possess some advantages over the 'Automatic single tube' such as the Penberthy, U. S. and others for stationary boilers, they are not suitable for traction engines. The reason is that with a double tube injector the overflow valve is closed by hand when it is working to the boiler, and in case a traction engine moving on a rough road gives it a severe jolt or if the intake hose or supply pipe in the tank is momentarily exposed, the inspirator will 'kick off,' and since the overflow valve cannot open, steam will be blowing into the tank. So if the operator does not notice it immediately, he will have a tank full of hot water and low water in the boiler. With the Penberthy, U. S. or other good automatics, if the water intake is exposed or the engine gets a severe jolt, the overflow will open for a few seconds and then restart to work automatically. For this reason the 'automatics' such as the Penberthy and U. S. were developed. When I was firing the old Gaar-Scott, we were not moving on the road so the old inspirator didn't get any jolts, but the steam supply pipe was tapped into the main steam line to the engine. A hard pull in a big log would often cause it to kick off. Taking steam from the main steam line is not a good practice. Any injector will perform better if it has its own steam line.
Now I will try to give some advice about how an injector should be connected. In restoring an old engine the original plan should be followed if possible. Most people like to see an authentic restoration, and the engine builders generally had a pretty good idea of how to do the job. The injector should be placed in easy reach of the operator. All piping should be direct and short as possible and should be the same size as the connections. The only exception to this is that the steam supply pipe can be one pipe size smaller if it is short and direct. The steam should be taken from the steam dome at as high a point as practical and should not be connected to any pipe leading elsewhere. If two injectors are used they should be completely independent of each other. A shut-off valve must be placed close to the dome at the highest point in the line so it can be shut and the piping drained in cold weather. This should be an angle valve screwed on a nipple about two inches long that is tapped into the dome. (As stated before, most people prefer an authentic restoration, I would also, but this plan of piping was generally followed.) The valve stem should extend outward. This will make it possible to renew the packing if necessary with steam up and also will be more convenient. The pipe should extend downward several inches to a little above the top of the boiler and back in a horizontal direction to where the injector will be in easy reach of the operator. A valve must be located here to turn the injector on and off. This is usually an angle valve screwed directly on the injector. This horizontal pipe should have a drain to keep it from freezing in cold weather if the engine should be in a position that it would not drain through the injector. Most injectors have a drain in the bottom, but if there is none, the piping must be arranged so it will drain. There must be a shut-off valve close to the boiler where the feed water enters. A gate valve is preferable but angle or globe valves are often used. The check valve should be only two or three inches from the shut-off and there must be a drain between so that water will not be trapped between them. In general, plenty of care must be taken to prevent freezing. Burst pipes are bad but frozen valves or injectors are disastrous. The feed water should enter the boiler forward near the smoke stack where the heat is not so great, and at a point on the side a little below half down the side in the vertical direction. Some real old engines had the feed water entering the boiler at the bottom of the fire box, but all modern boilers of the fire box, sometimes called 'locomotive' type put the water in well up forward on the side.
There must be a regulating valve in the suction line close to the injector. It should be closed when not in use to prevent the suction pipe or hose from becoming heated should the steam valve or the check valve leak. An injector will not work through a hot suction line and it will not do much good to pour water on the injector unless the line is cooled also, but more about hot water later.
All the pipe fitting must be done carefully so that the unions will fit perfectly. There must be no leaks, this applies especially to the suction side. No injector will work if air is getting into the suction pipe or hose. The overflow valve must not leak. There is suction on the outside of this valve when water is going into the boiler, and if air leaks in the vacuum in the combining chamber it will be weakened, and the injector will work poorly or not at all. All the parts inside must fit perfectly. If the machine is new or in new condition, the joints will be good, but if it is an old one there can be inside leaks. Mr. Fox in his article shows good inside views of places where leaks might be found.
Now assuming that the injector is in good condition and properly connected, everyone knows that it will not work coal cinders or saw dust. The suction pipe must be fitted with a good strainer. The strainer may become clogged if the tank gets full of trash or chaff, so it is a good idea to have a coarse screen over the opening where water is put in the tank.
If an injector that has been working well suddenly becomes balky, it will often be found that in spite of a good strainer, small pieces of stone have lodged in some of the small openings in the jets; or sometimes scale or rust from the steam line may lodge in the steam jet. If composition discs are used on the valves in the steam line they may break, and small pieces lodge in the steam jet. If no obstruction can be found, the trouble may be that an air leak has developed in the suction pipe or hose. If an old hose is used, the lining may have come loose and shut off the opening. The packing on the stem of the water regulating valve is a frequent offender, but where ever it comes from, the injector won't stand much air.
If trouble develops slowly, it is likely due to lime formation in the inside tubes and jets, and check valve. The best way to remedy this condition is to remove the injector, and soak it overnight in a solution of ten parts water to one part muriatic acid. Often it may not be necessary to soak the whole machine. Sometimes the delivery jet (this is the long tube that reaches' to the bottom) may be removed and soaked in the solution. Never try to clean the jets by running tools of any kind through them. Damage is sure to be the result.
The jets or tubes inside will wear out finally from use, and if the water contains sand they may wear out fast. Back in the old days when thousands of injectors were being sold every year it was easy to get replacements, but now I'm not sure that anybody is manufacturing them. Penberthy was still making several sizes of injectors, but not a full line, and they may have quit altogether. Be careful with your injector, or you may be hunting a fine machinist to make a new tube. Quite often when an injector gets to be balky the trouble will be found in the check valve. Lime formation can cause plenty of trouble and sometimes is more trouble to remove than it is from the injector. A leaky check valve is bad. If it leaks it should be re-ground or fitted with a new disc if it is the kind that has renewable discs.
Now I wish to discuss a very important characteristic of the injector. No injector will work HOT WATER. Some will work hotter water than others, but when the water gets above 110 degrees, the ordinary automatic injector will give trouble. The reason for this is that the water must be cool enough to condense all the steam before the mixture of water and steam reaches the smallest part of the opening through the delivery jet. When steam is condensed, the water that is formed only occupies about one 1/000 th. as much space as the steam from which it came. This makes a vacuum and increases the velocity of the stream of water so that it can overcome the pressure and enter the boiler.
If compressed air is blown through an injector it will create suction that will pick up water and discharge it through the overflow with considerable force, but not near enough to make it enter the tank from which it came.
As stated before, some injectors will work hotter water than others. An old catalogue that I have says that a Hancock Inspirator will work water at 150 degrees if it flows to the suction chamber. They don't mean under pressure. They mean with just enough force to fill the suction chamber. I have never seen this demonstrated, but I doubt that Hancock Inspirator makers would make any false claims.
During the 'heyday' of the steam era about 1905, large steam plowing engines, in fact all steam traction engines were introduced that carried higher pressure. Also the big plowing engines used steam jet pumps to carry the water from the wagon tanks to the engine tank. The jet pumps warmed the water, so, a need arose for injectors that could handle high pressure steam and warm water. To meet this need, Penberthy and others bought out special models to meet the demand for injectors to work at pressures up to 200 lbs. They were marked SPECIAL and the Penberthys were fitted with a drain cock in the bottom. The J. I. Case engines that came out in 1911 and later were equipped with the BB-330 SPECIAL in the smaller and medium size and with the CC-332 SPECIAL in the larger sizes. Before the SPECIAL Penberthy was introduced, the makers of the U.S. Injector claimed that it would work hotter water than any other. This might have been true, and perhaps was part of the reason that the Penberthy Company brought out the SPECIAL.
During this era when steam was in almost universal use, manufacturing injectors was big business. An old catalogue that I have lists 16 sizes each of automatics. There were also several other makes. Traction engines were all equipped with the automatic type, and many of the portable and small stationary steam plants used them, but most of these preferred the double tube type. The chief advantage that the double tube possesses is that it will work through a much greater pressure range. The Hancock Inspirator can be started at 15 lbs. pressure and will work to 250 lbs. without adjustment. They will also continue to work as the pressure goes down. There were several makes of double tubes. The LEADER was widely used. The Garfield was also well known.
Large stationary steam power plants didn't have much need for injectors. They nearly always used condensing engines. This means they condensed the exhaust steam instead of turning it into the air or the smoke stack. It went into a chamber where it came into contact with tubes carrying cold water. This condenses it and as the water that is formed only occupies a small fraction of the space the steam did, a vacuum is formed. This causes what you might call a suction on the piston which adds a lot to the power obtained. This water that is formed is only allowed to cool slightly below the boiling point before being pumped back into the boiler. An injector with its dislike for hot water is useless.
Now probably the biggest injector business. The steam locomotive was riding high on the rails and every one of them had two one on each side. They were almost always of the double tube type. The motion of a locomotive on the rails was not violent enough to interfere with the operation. The NATHAN was one well known make and the OHIO was another.
After World War I, the use of steam traction engines and all small steam power declined so abruptly that the injector business almost disappeared. Penberthy cut their line from 16 sizes to 9. Most of the others quit altogether.
Now I have something to tell. Since I started writing this article a couple of months back, I thought that it might be a good idea to order an extra delivery jet for the BB-330 SPECIAL that we have on our old Case engine. Well it came and the bill!!!! WHOOEE!!!! $70.47!! This delivery jet, a little over 2' long cost about $2.00 in 1916 when the engine was built!
Another thing about our old CASE. We have it completely authentic from the draw bar to the spark arrester, except that on the right hand side in the place where the earlier Case engines had their Penberthy, we have a Leader. We find that this injector is so handy. It will work down to 15 lbs. steam pressure and this saves quite a bit of fuel when filling up the boiler at the end of a day at the engine show. The Leader operates on the same principles as the Hancock but it is much handier as one lever controls the operation.
The A.S.M.E. code, which is the law in most states, requires all boilers containing as much as 300 square feet of heating surface, to have two means of feeding water into the boiler that are independent of each other. Common prudence should indicate the same.
All in all, if you do not wish to be embarrassed by having your injector take out on you just as you are getting in line for the parade at the steam engine show, keep the pipes tight and the water clean and cool.