Ingersol Rand Model B Compressor

Dear Forum Folk.

I have an old Ingersol Rand Model B Compressor it would run ok but for a missing pipe and fittings.
On the top of one of the cylinder heads there are two copper pipes with fittings, one of the pipes is around a 1/2 bore and runs from the top of one cylinder head to the top of the other cylinder head.
Then there is another much smaller copper pipe that runs from one cylinder head to underneath the start switch box, see image below.
I have marked fittings with a GREEN CIRCLE and the positions of the pipe and fittings in RED.
Can anyone please tell me what the thread type and thread pitch is of the two fittings that are on each end of that smaller bore copper pipe.
I need to find those two fittings or make some when I find out what the type and thread pitch are.
Also does any one have a manual for the Model B Compressor or even a PDF copy of the maual would be very helpful.

Merry Christmas to all.
ArthurD

Hello Arthur & greetings from the USA !

The smaller diameter copper tube you ask about is usually 1/4" outer diameter. It is an unloader line. The "switch box" is actually a pressure activated switch. As the air pressure in the receiver tank drops, this switch closes and starts the compressor motor. When the required pressure in the receiver is reached, this switch opens.

At the same time, there is a small "arm" off the switch contact mechanism which opens and closes a very small "poppet" type of valve located at the base of the switch. This is the unloader valve and has perhaps a 1/16" or 3/32" diameter discharge orifice. When the compressor is not running, this poppet valve is opened. When the compressor starts there is a slight time lag, during which the orifice remains open- allowing an unloaded start for the motor. Similarly, on shut down when required pressure is reached, this poppet valve opens and allows an unloaded shut down.

I imagine you have a UK version of the Ingersoll Rand compressor since you refer to it as a "Model B". In the USA, this would be known as a "Type 30" (unless I-R has changed their model designations- type 30 has been around forever). In the USA, these pipe connections would be 1/8" NPT (National Pipe tapered thread). In England, I imagine you'd be looking at a British tapered pipe thread, but stranger things have happened.

My advice to you is to go to a pipe supply or even a good automotive supply shop. Ask for some compression type tube fittings having 1/8" tapered male pipe threads x 1/4" diameter copper tubing. These should be brass fittings and relatively inexpensive- rather than trying to match up to what I suspect are the remains of two compression adapters (an adapter goes from one system of pipe joining and pipe to another- in this case, pipe to tubing and vice versa).

If you want to verify the thread size of the tappings in the head of the compressor, try screwing in a 1/8" threaded pipe nipple or plug. The bottom of the pressure switch usually has the male portion of the compression fitting made integral with the switch rather than pipe threads. Unfortunately, with compression type fittings, when the connecting piece of tubing is removed, so are the mating parts of the compression fittings. These would be the hollow ferrule (oldtime British term was an "olive", I believe), and the gland nut. You may have to buy a couple of compression fittings and see what parts work on that pressure switch's compression fitting body.

Otherwise, you are likely looking at replacing the pressure switch if nothing matches up. I have the same style pressure switch on an ancient Worthington Compressor in my home garage/shop. Using a micrometer and screw pitch gauge, you can get the thread data on the male end of the compression fitting that will be projecting from the underside of the pressure switch. Possibly, it is a commonly available fitting from one of the major manufacturers such as Parker or Weatherhead (in the USA, anyhow).

I used a new pressure switch when I built up my compressor unit. I bought the kind of pressure switch which has a manual lever for working the switch contacts aside from the automatic operation. I think I spent about $30 US Dollars, but that was close to ten years ago. Another word to the wise: do NOT use hard plastic or nylon tubing for the unloader line. Compressed Air coming off the cylinder head is HOT. A lot of times nowadays, when I walk into supply houses and ask for various fittings for small bore copper tubing, the salesmen try to sell me the fittings and hard plastic or nylon tubing.

I would make a fairly hefty wager you are looking at compression type tubing fittings. It is unlikely that flared type tubing fittings were used in this application.

Some/most of the brass fitting you get at the pipe shop are crap,when i wanted high quality stuff I used to buy bits from Westinghouse Air Brakes.At least the threads are right and the olives seal without just about cutting the pipe off.Also,if you get thin hard copper tube,it must be annealed to bend,or it will crack or kink.

I agree with John.K

When I do not have to match a tubing fitting to something existing, I use a very high quality line of tubing fittings made by "Swagelok". These use a two-piece wedging type of ferrule, and are what is known as a "gaugeable fitting". We used Swagelok fittings almost exclusively on tubing work in powerplants and I spec and use them elsewhere. Swagelok fittings are a gold standard in the USA for tubing fittings, used in high purity pharmaceutical systems, aerospace, nuclear, and anywhere else that tubing is being run where a reliable fitting of consistent accuracy is required.

In a funny incident years ago, we learned about NOT re-using compression fittings. We were on a job in a smaller hydroelectric plant, and the governor and servomotors on those turbines used fairly high pressure turbine oil. The system was made up using stainless steel tubing of varying diameters up to maybe 1". The original fittings were some kind of compression fitting, not Swagelock. At some point, modifications to the system had to be made. Not being able to match up the fittings, the mechanics on the job apparently drove the ferrules off the tubing and re-used them (steel ferrules). The system ran OK for a few years. We were in the plant and re-starting the units following a routine maintenance outage which had no reason to take apart or do anything with the governor hydraulic lines. As the system was operating the turbine's wicket gates and blades, there was a normal pressure spike. What was not normal was one of the high pressure oil supply lines blew out of its fitting. All of us got drenched in warm turbine oil, head to toe, just that quick. My house was closest to that plant, and there were no lockers nor shower facilities in the plant as it normally ran unmanned by remote control. I called my wife and asked her to drive down with old towels, soap, and plenty of my old work clothes including socks for the crew. My wife arrived and we all got cleaned up and tossed our oily clothing into a large garbage bag. The crew had a hell of a cleanup, going through bales of absorbent mats and wiping rags and cans of solvent.

Needless to say, we cursed the guys who had re-used the fittings and ferrules, cursed the design of those particular fittings as the ferrules- even when new- did not get much "bite" on the tubing, cursed the ancestry of the people who'd designed those fittings and the people who spec'd them for the job. We kept the unit off line until I got new tubing and Swagelok fittings. Then, we took the other unit off line and retrofitted Swagelok fittings. I use Swagelok on anything requiring tubing, even in my "retirement". The extra money up front is well worth the price on something like compressed air, steam, or hydraulics. I try to leave compression fittings with the "olives" for the "homeowner" jobs.

I also buy what is known as "refrigeration grade" copper tubing here in the USA. This is a bit heavier wall than the stuff sold in plumbing and homeowner types of stores. It is also sold as dead soft (fully annealed). Years ago, when we were building our house, I was putting in the copper tubing for the propane service. I had gotten a coil of 1/2" OD copper tubing and unrolled it, straightened it, and began using a tubing bender. I was surprised to find that tubing was good for one bend, then seemed work-hardened if I needed to adjust a bend. I took to locally annealing the tubing with a plumber's air/acetylene torch. I asked the mechanics at the powerplant, and they all had similar experiences. The consensus is, like so much else in recent times, the product was cheapened. I looked closer at that tubing and found it had a thinner wall than odd pieces of tubing I had from jobs done with my father years earlier. My guess is the new tubing, having that thinner wall, is likely sold in the "half-hard" condition to minimize chances of denting or kinking. Word to the wise on this one- try to get refrigeration grade tubing, dead soft condition.

If I need a compression fitting, I go to the local "Parker" store. These fittings are a much high quality than what you'd get in the "home improvement" stores or similar. Compression fittings sold in retail stores like home improvement stores or hardware stores tend to be- as John.k notes, low quality. They are usually made for home type jobs like running tubing for water supply to an ice-maker in the fridge, or similar. Nothing critical or too high a pressure. The "Parker" stores (at least in the USA) are an industrial supplier, and their fittings are made for applications like airbrake lines on trucks, fuel lines, and industrial pneumatics. Parker is a company making a full line of "O" rings, seals, hoses for hydraulics, as well as other related items for this sort of thing. The only kicker that I can foresee is the match-up of the "olive" and gland nut to the male end of the compression fitting integral with the pressure switch on Arthur's compressor.

The pipes he is missing will be to lift the intake valves when the motor stops ,to stop a buildup of pressure inside the compressor cylinders,and stalling out the motor at start.There is sometimes a non return valve in the delivery,but they dont last as the delivery air is very hot,and the valve pounds on its seat.......

Hi sorry to jump on a thread from so long ago, not sure if anyone will see this but I have the same type of compressor here in the UK but I can't find out what type of oil it needs does anyone know?
Thanks in advance

Joe Michaels said:

Hello Arthur & greetings from the USA !

The smaller diameter copper tube you ask about is usually 1/4" outer diameter. It is an unloader line. The "switch box" is actually a pressure activated switch. As the air pressure in the receiver tank drops, this switch closes and starts the compressor motor. When the required pressure in the receiver is reached, this switch opens.

At the same time, there is a small "arm" off the switch contact mechanism which opens and closes a very small "poppet" type of valve located at the base of the switch. This is the unloader valve and has perhaps a 1/16" or 3/32" diameter discharge orifice. When the compressor is not running, this poppet valve is opened. When the compressor starts there is a slight time lag, during which the orifice remains open- allowing an unloaded start for the motor. Similarly, on shut down when required pressure is reached, this poppet valve opens and allows an unloaded shut down.

I imagine you have a UK version of the Ingersoll Rand compressor since you refer to it as a "Model B". In the USA, this would be known as a "Type 30" (unless I-R has changed their model designations- type 30 has been around forever). In the USA, these pipe connections would be 1/8" NPT (National Pipe tapered thread). In England, I imagine you'd be looking at a British tapered pipe thread, but stranger things have happened.

My advice to you is to go to a pipe supply or even a good automotive supply shop. Ask for some compression type tube fittings having 1/8" tapered male pipe threads x 1/4" diameter copper tubing. These should be brass fittings and relatively inexpensive- rather than trying to match up to what I suspect are the remains of two compression adapters (an adapter goes from one system of pipe joining and pipe to another- in this case, pipe to tubing and vice versa).

If you want to verify the thread size of the tappings in the head of the compressor, try screwing in a 1/8" threaded pipe nipple or plug. The bottom of the pressure switch usually has the male portion of the compression fitting made integral with the switch rather than pipe threads. Unfortunately, with compression type fittings, when the connecting piece of tubing is removed, so are the mating parts of the compression fittings. These would be the hollow ferrule (oldtime British term was an "olive", I believe), and the gland nut. You may have to buy a couple of compression fittings and see what parts work on that pressure switch's compression fitting body.

Otherwise, you are likely looking at replacing the pressure switch if nothing matches up. I have the same style pressure switch on an ancient Worthington Compressor in my home garage/shop. Using a micrometer and screw pitch gauge, you can get the thread data on the male end of the compression fitting that will be projecting from the underside of the pressure switch. Possibly, it is a commonly available fitting from one of the major manufacturers such as Parker or Weatherhead (in the USA, anyhow).

I used a new pressure switch when I built up my compressor unit. I bought the kind of pressure switch which has a manual lever for working the switch contacts aside from the automatic operation. I think I spent about $30 US Dollars, but that was close to ten years ago. Another word to the wise: do NOT use hard plastic or nylon tubing for the unloader line. Compressed Air coming off the cylinder head is HOT. A lot of times nowadays, when I walk into supply houses and ask for various fittings for small bore copper tubing, the salesmen try to sell me the fittings and hard plastic or nylon tubing.

I would make a fairly hefty wager you are looking at compression type tubing fittings. It is unlikely that flared type tubing fittings were used in this application.

Click to expand...

Hi Joe sorry to reply to a old thred do you know what type of oil I could use in a Ingersol Rand Model B I can't find anywhere online that says what it needs

Byron:

I replied to the PM you sent me. Non-detergent, mineral based (non synthetic), SAE 30 oil (not multi viscosity) would be fine. Other choices are ISO 46 or ISO 68 DTE series oils. ISO 46 = approx SAE 20 wt, ISO 68 = approx SAE 30 wt. Avoid synthetic oils since your compressor is old and has a leaky oil seal from your description.

I'd drain the crankcase and fill with kerosene ( parafin ? in the UK) or diesel fuel and run the compressor for maybe 2 minutes at most. Drain the crankcase and fill with 30 wt non detergent oil or ISO 68 oil. ISO 46 if the compressor is to be run in winter in an unheated building.

Best regards-
Joe Michaels