New project compressor

[p0689109]

I recently picked up this beauty. I could not resist. It had been advertised in the local paper about 6 months ago and I went to have a look at it. No motor persuaded me to not bother at the price he wanted. He had tried to sell it a couple of times after that but had no takers.Then lo and behold its at the auction last week. I left a bid and was the lucky punter. Boy its heavy. Luckily they have an overhead crane so getting it in my LDV was not too difficult. Getting it out was a little bit tricky but I removed the pump and some pipes and stuff and managed to offload without too much trouble.
The pump is a twin cylinder Broom & Wade DCL15, bore 25/8 and stroke 2in and normal rpm 950. The tank was supplied by Cotton Bros from the Crown Works here in Stoke on Trent at Longton.
As you can probably see there is something amiss with the blowoff valve(red tape holding it together). A spring seems to be missing at the very least. It has two belts and would think that the original motor was a three phase unit. I was wanting to put a single phase one on. What rating do you think it will take? I had a scan of ebay and on there there is a Broomwade compressor with the same pump as mine. The seller reckons it has a 2.5hp motor on but he reckoned a 1hp would do. Any advice on that and the broken blowoff valve would be much appreciated.

 

[p0689109]

A couple of more photo's. As well as the broken blow off valve there appears to be two more air release valves. One is part of the big gauge and its stack pipe and the other is right in the middle of the tank and it has a small bore pipe that is connected to an assembly on top of the pump. Could anybody advise me of each of their functions?

 

[rtbcomp]

Motor power is related to cfm x pressure. A 1 hp motor running that pump at 950 rpm will probably start labouring at 20 psi. Most popular compressors with a 3hp motor use a single belt so I would say it's safe to assume you'd be looking at a 4hp motor at least to realise the potential of that beast. You can fit any motor and select the pulley sizes to gain more cfm at the expense of pressure or vice-versa, but I'd go for the biggest you can, bearing in mind cost and whether or not your electricity supply can deliver the power.

The valve next to the pressure gauge looks like an adjustable safety valve.

 

[brightspark]

they had one of them pumps on a sewage plant i was working on, it was fitted with a 3hp motor and had a 4 inch pulley fitted pulley and took a size belts

 

[Rig Pig]

The pump is a proper old school one, it's designed for continues running, the two top valves are unloaders that prevent the pump from pumping at a set pressure. It's an ideal candidate for an engine to drive if you can put up with the noise!

 

[p0689109]

Managed to get a few more photos taken. The last 2 are of the suspect blowoff valve. The white stuff was crumbly and seemed to be something like asbestos cloth under which was the red bits which I think are the remains of a seal of sorts. I thought that the mechanism on top of the pumps might be an offload system of sorts. There is a photo of the pump and the valve that are connected together with the "control" pipe.
I have two sources of generators, one of which is a combined mobile arc welder/generator, the type often seen being towed to sites and the other a more modern one that I got to supply a reliable source of electric for my mig welder. Whether either of these will supply enough for a 4hp motor I don't know but both came with 32Amp plugs on them.

 

[p0689109]

I measured the tank and it is a 100litre tank give or take.(36in long and 15in diameter) It is domed convex at one end and concave at the other so its not totally accurate but close enough. So what do you think the valve is that the control pipe to the head goes into?

 

[Bill Edwards]

The two units on top of the head consist of a diaphragm with a plunger underneath. When air pressure is applied to the top of the diaphragm it pushes the plunger down which presses the inlet valve so no air is compressed - the compressor basically free-wheels.

The pipe from these units will go to a valve which will probably have some adjustment to let you tweak the pressure that the compressor builds up to. This valve will be connected to the receiver and when the pressure reaches the certain level will send air down the pipe to the units on the head. It cuts off this pressure once pressure has dropped to a certain level again so air will build up again. I don't know if this is the valve that has the red tape on, it could be. Should be possible to figure it out from what it's connected to?

There should (must!) also be a simple pop-off valve fitted somewhere for in case any of this system fails, so it can't go bang. I would expect this to be completely separate and easy to identify.

 

[rtbcomp]

.........

There should (must!) also be a simple pop-off valve fitted somewhere for in case any of this system fails, so it can't go bang. I would expect this to be completely separate and easy to identify.

I guess it's the one I identified in post #3?

 

[eil]

The valve on the tank is called the governor, which is adjustable for cut out and cut in pressure that feeds the suction valve unloaders that's on the cyl head.

 

[p0689109]

So of the 3 valves you lads have identified the safety valve by the big gauge and the controller valve(governor) that offloads the pump. As someone mentioned that these pumps were made to run all the time and just offloaded when pressure was met that all ties in. So what is the valve with the red tape for then? This valve is in the line of the pipe that exists the heads and enters the tank at the side so is the feed line to the tank.

 

[sardine]

How much air tool running time would you get from a tank like this ?

The idea of a portable air tank is interesting, could be a good future project. Maybe charged from a compressor on a vehicle engine ?

 

[brightspark]

How much air tool running time would you get from a tank like this ?

The idea of a portable air tank is interesting, could be a good future project. Maybe charged from a compressor on a vehicle engine ?

depends on what size tank u use and can u fill it to 150 psi also what u are running off it . i run a windy gun and blow tires up with mine and use it on the end of the line to remove water and cooling for blasting

 

[Bill Edwards]

I guess it's the one I identified in post #3?

Yes.

If I were the OP I would be stripping it apart and making sure the ball/valve is not rusted in place and is free to move. Not worth taking chances, they're simple devices and not likely to block up, but if they do and something goes wrong the consequences are potentially deadly.
I'd count the threads on the adjuster to set it back to where it is, at the least. However, if this was my setup I'd really be wanting to see what the SWP is of the receiver, checking that it appears strong (i.e not dangerously rusted on the inside), connect a known to be accurate pressure gauge and let it build up the correct working pressure.
I'd then slacken the safety valve until it started to let go, and give it a turn so you know it will operate at just above the correct working pressure. For all you know someone may have fiddled with it in the past, it may not blow off 'til 200 psi for all you know!

 

[Bill Edwards]

I can't give anything precise on the valve in the line from the pump to the receiver, that's got red tape round it.

My only thoughts are that it looks like it may be a non adjustable relief (safety) valve, that screws into an adapter piece that takes it to the right size threads to screw into the T piece on the pipe.
My thoughts are that it may have been leaking, perhaps somebody tried putting the seals/fiber washers or whatever they are in help it seal. Perhaps they blocked it up with the white cloth to reduce the leakage. Can't say why the tape is there though, unless perhaps to avoid people trying to take apart the bodged and blocked up mess - i.e a 'do not fiddle/tamper' marker.

I can't see why it should need a safety valve there though if that pipe goes straight into the receiver, which has its own safety valve elsewhere already.
That's currently my best line of thought on it though.

 

[p0689109]

Bill, that's what I thought ref the "dodgy" valve. The tape was there as the top piece was wobbling and so I thought the thread had stripped but upon inspection it is fine. As regards checking the other valves I will do that once I have sourced a power source. I have checked ebay and there is a chap who can supply new(Chinese?) motors of just about any size. He has two 4 hp single phase motors, one 2 pole and one 4 pole, on offer at £161 and £192. Current draw 17Amps. I have just to work out the rpm match to the pump as they are 1400 and 2800rpm. Painted on the cylinder is the figure of max pressure 155psi.

 

[p0689109]

Sardine, make me an offer and it could be yours!!

 

[paulmitchell1984]

love the idea of portable air, how much tyre will it blow up on one fill? i have 33" tyres on my landy and want to run lower pressures when offroad say 18psi, then go to 30psi for going home, any info would be good regarding whats involved for the setup..

 

[p0689109]

This set is portable in that it has its own wheels but I would not class it as portable in the sense you mean. It is very heavy and would run off mains electric!

 

[roofman]

I have the very same pump here on one of my comps mated to a 3HP single phase...to obtain your pump rpm its motor speed times motor pully diameter divided by pump pully diameter and that gives you final pump RPM. Good little pumps actually but dont like running fast