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Specs on an air compressor

06/03/2008 8:49 PM

I was given an old Speedaire (2z203). It runs fine but cuts off at about 60 PSI although my research tells me it's a 125 PSI unit. How do I know what the tank can hold and how can can I increase the PSI before cut off? FYI: other than warnings and maintainence info, there is nothing written on the tank.

Thanks in advance.

Jerry

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#1

Re: Specs on an air compressor

06/04/2008 8:21 AM

The cut off pressure switch sounds like its set at 60 psi...

Try adjusting it for 100 psi - which is about the average for a standard air compressor.

The cut off pressure switch is usually housed in the output regulator body and is set by turning a screw, usually clockwise increases set pressure...

If it really is old I would check all the usual things like oil in the compressor and drain the tank etc...

John.

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#16
In reply to #1

Re: Specs on an air compressor

06/06/2008 3:20 AM

I've looked for a pressure cut off switch and think it's a small metal plate that is connected to the step-down generator. There's a trigger that looks like a bicycle brake line that trips the switch at pressure... or so it seems; usually I'm too busy at the other end to check if my theory is correct. The "bicycle-line" assembly is driven through a fixed bracket on the tank with what seems to be adjusting nuts. My thought is that the pressure in the tank drives the "bicycle-line" out and at a set pressure the inner cable will hit the metal plate, thus cutting off power to the step-down generator. My thought is to adjust the nuts to bring the cable back, switch off the compressor once it reaches 100PSI, then re-adjust the cable until it trips the switch. Others have suggested that the adjustment is made via a screw, but having worked with air compressors before but never having had to adjust one before I am, basically, in the dark.

Thank you in advance.

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Guru

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#17
In reply to #16

Re: Specs on an air compressor

06/06/2008 4:08 AM

Your post comments indicate you have no business messing in any way with that compressor.

For your own safety, if you are not happy with its present pressure setting, if you are not sure as to the integrity of that tank, take the unit to somebody that specializes in such.

AGAIN! I is obvious you will place yourself at risk if you do anything to that compressor. Take it to a specialist.

j.

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#18
In reply to #17

Re: Specs on an air compressor

06/06/2008 8:43 AM

I agree entirely with Jack's post...

I didn't realise you weren't an engineer, please do as he says and don't meddle with it if you aren't sure what you are doing!!

John.

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#19
In reply to #17

Re: Specs on an air compressor

06/06/2008 9:32 AM

Good post, I agree with you, always go for safety as you never know the knowledge level of the person concerned! This could be terminally dangerous!!

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#2

Re: Specs on an air compressor

06/05/2008 12:08 AM

Except for one little problem. If you don't know the pressure rating of that tank and if it has been de-rated because of its age, the setting of that pressure switch might just save your neck.

Do not change the settings on that switch until you know that the tank will hold a higher pressure without blowing up in your face.

j.

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#3
In reply to #2

Re: Specs on an air compressor

06/05/2008 12:17 AM

I believe the Speedaire's were sold in two main options, first was a cheap compressor with an ASME labeled tank, and second as a cheaper version with an un-stamped tank. You paid extra to get the ASME label. Otherwise, the size, weight and rating of the package was identical.

I'm assuming you have the second version. Try to determine if there is any significant corrosion problems inside the tank, or other damage that might affect the integrity of the tank.

I doubt that anyone would "formally" de-rate the tank, just someone being cautious with the pressure switch setting. A hydrostatic test using water would be somewhat safer than air up to 120 psi, then you could probably use it at 100 psi without a problem.

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#4
In reply to #3

Re: Specs on an air compressor

06/05/2008 7:27 AM

i would suggest you check from speedaire for design&working pressure rating of tank or ask them for pressure test certificate before playing with pressure switch settings, i had a bad experience of splinters in my fore arm while playing with compressed air.

crm

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#6
In reply to #4

Re: Specs on an air compressor

06/05/2008 8:56 AM

In this case, a check on Grainger site http://www.grainger.com/Grainger/items/2Z203 indicates the part number is compressor alone, no tank or motor included. A reasonable guess is the tank was originally fabricated to be good for 125 psi, but was not ASME labeled.

Now ask yourself a couple of questions,

1. How lucky do you feel with this guess?

2. Is the tank in the same condition as when it was manufactured?

You might want to try to look inside for excessive corrosion. You also might want to water test the tank to confirm pressure capability. Water is less explosive than air if something pops loose.

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#7
In reply to #2

Re: Specs on an air compressor

06/05/2008 8:59 AM

Jack Jersawitz is absolutely correct. Never adjust your pressure switch without knowing the Maximum Working Pressure of the Pressure Vessel. You may find yourself waking up in a hospital.

All ASME coded tanks have a data plate on the pressure vessel with a maximum working pressure and has also undergone hydorstatic testing. The absense of such a data plate suggests that it is not an ASME coded Tank. As such, you will need to determine the maximum working pressure of the air receiver for safety purposes before attempting to operate at a higher pressure. Chances are that you will be ok at 100 PSIG, but I would still try to get confirmation from the manufacturer. Playing will compressed air is like playing wil a bomb.

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#8
In reply to #7

Re: Specs on an air compressor

06/05/2008 9:04 AM

Whilst I agree that safety is paramount, any manufacturer that puts a pressure vessel on the output of a compressor without it being tested or rated for the compressor's output, as well as for any unintentional output is asking for a court case against them.

As its old(how old ?) as I said check the tank drain for condensate and the condition of the condensate - tells you a lot about the internal tank condition - and adjust to your required pressure...

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#5

Re: Specs on an air compressor

06/05/2008 8:41 AM

The cut off pressure switch sounds like its set at 60 psi...

electroman is right,

you also can check if you can set it higher than 60 psi or you cant,

then you will have to change it...

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#9

Re: Specs on an air compressor

06/05/2008 9:14 AM

If the compressor is in good shape and runs well, but you are uncertain of the tanks integrity you could always purchase a new or used tank that you know is rated properly and mount your compressor on that. I inherited an old compressor with a 30 gal. tank, that belonged to my Grandfather and thats what I had to do. Works great. I use it in my garage to run air tools at 105 psi.

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#20
In reply to #9

Re: Specs on an air compressor

06/06/2008 2:15 PM

Hi, Guest!

Great response. Solves the original problem assuming the company Moi takes it to can determine how to reset the pressure cut-off level on the new tank when he gets it and shows him how to do that. He'll probably need to replace the motor to a bigger one with lower rpm's as well. Once the installer shows Moi how to operate the thing safely, he won't need to be an engineer to use his compressor. GA.

Mark

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#10

Re: Specs on an air compressor

06/05/2008 9:15 AM

Check with the manufacturer first but I would make sure the pressure relief valve is in working order. You may want to check the rating on the pressure relief valve first, they are usually sized for the tank and compressor. Safety first.

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#12
In reply to #10

Re: Specs on an air compressor

06/05/2008 9:25 AM

Ahhh good point Redneck, YES check the pressure relief valve fitted to the tank it should be rated at 100+ psi.

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#14
In reply to #10

Re: Specs on an air compressor

06/05/2008 11:56 AM

Great answer, and an oversight on my part. I vote GA.

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#11

Re: Specs on an air compressor

06/05/2008 9:24 AM

The Speedaire compressors were and still are manufactured by Champion Commpressor. The number 2Z203 is a Grainger number. I have dealt with Grainger for upwards of thirty-five years. I have purchased many compressors and I was once affilliated with Champion Compressor. I have never know Champion or Grainger to offer a tank, whether ASME Code stamped or not, that wasn't rated at least 125 psi. However, as you are aware from the answers already posted, there are dangers in pressurizing and old, unfamiliar tank to any great extent. The 60 psi limitation, as stated by others, is probably resettable to a higher value. The former user may have used a tool or device that required only that amount of pressure. Who knows. As for the capacity of the tank, you can figure that by using the standard volumetric formulae that you would use for any vessel. As stated previously, BE CAREFUL. We all want to hear from you again, not read about you.

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#13

Re: Specs on an air compressor

06/05/2008 9:46 AM

The part number you gave is for a compressor pump only. If the tank and pump were sold as a unit, you will have to match your assembly to the items in the Grainger catalog, or go online at www.grainger.com. It is most important to check the condition of the tank. If there is any signs of metal pitting from rust, don't risk your life on it. The price of a replacement tank is cheap compared to the rest of the compressor.Contact Grainger they will help you if you need to identify it or need replacement parts. Good luck.

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#15

Re: Specs on an air compressor

06/05/2008 7:19 PM

As mentioned, you need to make a pressure test with water, usually it needs to be made at twice the pressure you want to run at.

If you wish to do the test, provided you put on eye protection, maybe you can add a tiny bit of air to the tank using a good foot pump or similar after filling it completely with water.....preferable have it on the other side of a wall.

Never test with just air, its lethal.

But the correct way is with a small but powerful hand water pump as if the tank bursts, even a tiny amount of air at 200 psi will be very loud!!! Get a gauge that reads up to at least 250 psi.....

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#21

Re: Specs on an air compressor

07/23/2008 8:32 PM

You should be able to adjust the pressure switch on the package with either a lock nut on a threaded rod over a spring, ore a small screw on the switch, right / tightening will increase pressure settings, should adjust slowly 1/4 to 1.2 a turn at a time, allowing the compressor to blled down and pump up between adjustments, there also should be a smaller screw next to the larger one to adjust range between cutin and cut out pressures.

As far as the tank pressure there should be a name tag on the tank that will identify a MAWP which is defined as Maximum allowable working pressure this is the maximum rating for this tank.

I hope this helps

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Andy Germany (2); Anonymous Poster (2); billybolbol (1); bob c (1); crm (1); Electroman (4); Jack Jersawitz (2); MarkTheHandyman (1); Moi (1); N6377B (1); Redneck engineer (1); Ried (3); The Commoner (1)

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