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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Minor gloat, Compressor w/ pneumatic valves - question
Recently I needed to replace the small hand carryable compressor that I
keep at a house that I am renovating. I was looking for something cheap and fairly light. I did OK on the cheap part but this little compressor is mightly heavy. The E-bay listing did not mention the motor size, I was expecting it to be 1/3 or 1/2 hp, hoping that it might be 3/4. Instead it has a real 1 hp (13.2/6.6 A, 1725) moptor. My winning bid was $4.25. I ended up paying the seller 9 bucks - I was so pleased to have gotten a good size motor. This is an old unit (the rubber tires have fallen off of the wheels) and there is no relay to turn the motor on & off. When the compressor is plugged in, the motor is running. When the compressor reaches the upper pressure limit, the compressor quits pumping (motor never stops running, compressor is always running). Once the low press limit is reached the compressor resumes pumping. Looking at the tubing going up to the valves, I presume that the compressor (pump) has pneumatic valves and that the pneumatic valves open & remain open once the high press limit has been reached. I have uploaded pics to the drop box: http://www.metalworking.com/dropbox/...win-Briggs.txt There is a problem with the compressor operation: there is either no check valve or it is non-functional when the compressor is not pumping. Once the high limit pressure is reached and the compressor pump quits pumping the air in the tank bleeds out (rapidly, under 10 seconds from 105 psi to 75 psi) thru the compressor air intake port. Once the low pressure limit is reached the air stops leaking out of the air intake. It takes about 8 sec for the two little tanks to fill from 75 psi to 105. Either a check valve is non-functional or one is needed. I am leary of tearing open either the pressure relief valve or the top of the compressor at the moment to see if there is a check valve since I need to use the compressor right now and I am not certain I would be able to diagnose a problem if I had either of the two valves apart. Suggestions on what to look for when I finally tear into this thing? As a short term work around, I am going to put a checkvalve on the input to an auxillary 4 gal tank that I have so that I can connect the aux tank to the compressor and maintain higher air pressure (instead of the pressure ossilating from 75 to 105 to 75 every few seconds. |
#2
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Minor gloat, Compressor w/ pneumatic valves - question
On Thu, 13 Mar 2008 22:25:37 -0500, aribert
wrote: Either a check valve is non-functional or one is needed. I am leary of tearing open either the pressure relief valve or the top of the compressor at the moment to see if there is a check valve since I need to use the compressor right now and I am not certain I would be able to diagnose a problem if I had either of the two valves apart. Suggestions on what to look for when I finally tear into this thing? It's typical on stationary compressors for the check valve to be screwed directly into the tank. At first glance it may look like an adapter fitting between the tank boss and the pump outlet line. Grainger carries inexpensive generic replacements. -- Ned Simmons |
#3
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Minor gloat, Compressor w/ pneumatic valves - question
On Thu, 13 Mar 2008 22:25:37 -0500, aribert
wrote: Recently I needed to replace the small hand carryable compressor that I keep at a house that I am renovating. I was looking for something cheap and fairly light. I did OK on the cheap part but this little compressor is mightly heavy. The E-bay listing did not mention the motor size, I was expecting it to be 1/3 or 1/2 hp, hoping that it might be 3/4. Instead it has a real 1 hp (13.2/6.6 A, 1725) moptor. My winning bid was $4.25. I ended up paying the seller 9 bucks - I was so pleased to have gotten a good size motor. This is an old unit (the rubber tires have fallen off of the wheels) and there is no relay to turn the motor on & off. When the compressor is plugged in, the motor is running. When the compressor reaches the upper pressure limit, the compressor quits pumping (motor never stops running, compressor is always running). Once the low press limit is reached the compressor resumes pumping. Looking at the tubing going up to the valves, I presume that the compressor (pump) has pneumatic valves and that the pneumatic valves open & remain open once the high press limit has been reached. I have uploaded pics to the drop box: http://www.metalworking.com/dropbox/...win-Briggs.txt There is a problem with the compressor operation: there is either no check valve or it is non-functional when the compressor is not pumping. Once the high limit pressure is reached and the compressor pump quits pumping the air in the tank bleeds out (rapidly, under 10 seconds from 105 psi to 75 psi) thru the compressor air intake port. Once the low pressure limit is reached the air stops leaking out of the air intake. It takes about 8 sec for the two little tanks to fill from 75 psi to 105. Either a check valve is non-functional or one is needed. I am leary of tearing open either the pressure relief valve or the top of the compressor at the moment to see if there is a check valve since I need to use the compressor right now and I am not certain I would be able to diagnose a problem if I had either of the two valves apart. Suggestions on what to look for when I finally tear into this thing? As a short term work around, I am going to put a checkvalve on the input to an auxillary 4 gal tank that I have so that I can connect the aux tank to the compressor and maintain higher air pressure (instead of the pressure ossilating from 75 to 105 to 75 every few seconds. You have a right to gloat, I paid $3 for my little Gardner-Denver and all I got was the compressor - no tank, motor, plumbing or controls. Probably a major cleanup will solve your problems, it is definitely a "keeper". Gerry :-)} London, Canada |
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