will new parts connecting to an air compressor hold steady pressure?


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Old 12-15-09, 10:53 AM
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will new parts connecting to an air compressor hold steady pressure?

I have a very old craftsman compressor i just purchased. It's operating pressure is 100psi and supposidly from a random part sheet i found online may have a max operating pressure of 125.

It has the control to shutoff when it reaches it's appropriate psi level however the reading gauge does not have any psi numbers, just an 'operating range' with a needle that points to various locations within a v-shaped area but nothing else to indicate what this means; other than to tell the motor to shut off after a period of time.

so, what I want to do is the following:

right now, the compressor has a pipe leading out of the tank with a fitting at the end to prevent air from escaping until a host is connected.

I want to take off that end piece and replace it with a few parts; those being:
-an in-line PSI gauge that would read the pressure in the tank, this would mean the pipe coming out of the tank would always be open up to this gauge.
-a tee after the psi-gauge so that I can connect two hoses to the compressor if/when necessary - each controlled by a shut-off ball-valve. (should not be a problem with 6 scfi @ 90 psi)
-after the shutoff valve i would like another PSI gauge that would read PSI so when either of the sides are open, there would be a reading for each line. presumably though, this reading would be the same as the first gauge i mentioned, so this might be a waste
-finally, on each side there would be the piece that prevents air from comming out until a host is connected.

Is this a safe project? i.e. can these types of parts withstand a consistent pressure or are they intended only for when air is moving only?

I am not intending to remove the pipe coming out of the tank, just the piece that connects to the pipe that stops air from coming out until a hose is connected and the expand from there.

so the goal is to read the pressure in the tank, and hoses if they will be different. (actually, there is a plus to this if I install psi regulators on each side to accomodate specific tool requirements, if this makes sense)

-i assume not to mess with this until all air is out of the compressor; it's safe when little to no air is flowing out?
-is it safe to release air from the tank in cold weather?
-did any concerns come up as you were reading this?
-i use teflon tape for threads? the same used for plumbing?

Thanks for your time.
 
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Old 12-15-09, 11:39 AM
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Yes, everything you want to do is safe with standard plumbing fittings. You can replace the existing gauge with one that has a standard psi scale, use a gauge with a scale 1-1/2 to 2 times the operating pressure of the compressor, i.e. if the compressor shuts off at 100 psi then use a gauge scaled to 150 or 200 psi. If the compressor shuts off at 125 psi then use a 200 psi gauge.

If you install hose quick-connects you do not need the ball valves as the quick-connects stop the airflow when the hose is disconnected.

Be absolutely certain that there is NO PRESSURE in the tank when you remove any fittings on the tank. There should be a water drain valve on the bottom of the tank and you need to periodically drain the water and oil that will accumulate. Have this drain open when removing fittings from the tank.

There should also be a safety valve on the tank, it will look like this.
(Image courtesy of Ereplacementparts.com)
When the compressor has filled the tank pull the ring straight up to test the valve.

Here is a link to that will give you some valuable information about air compressors. Air Compressors 101
 
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Old 12-15-09, 12:11 PM
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thanks for all of the info furd,

I am not 100% sure on that safety valve you speak of, the compressor is pretty old, i cannot find a single manual online for it (except a parts sheet for possibly a different but very similar compressor), the company who made the motor has exchanged hands and company names over the years since '99, so i know it's older than that...

You can replace the existing gauge with one that has a standard psi scale, use a gauge with a scale 1-1/2 to 2 times the operating pressure of the compressor,
well, the existing gauge i was referring to is not a gauge and it's not connected to the outgoing pipe from the tank. It's in between the motor and the pistons and the electrical is going through it. From what i was told, seen, and read, this is the gauge that turns on/off the motor when the PSI is too low - i am not sure if this is something i want to mess around with due to calibration and not understanding how (not why) it works.
 
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Old 12-15-09, 03:45 PM
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the first thing i would install would be a ball valve in case you had leaks or burst a hose. then i would install the gauges and other parts. i have one on mine that i shut off when i shut off the power at night.
 
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Old 12-15-09, 07:20 PM
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Several pictures of the compressor might help. To post pictures you need to first upload the pictures to a photo hosting site such as photobucket.com or villagephotos.com. and then post the public URLs for the pictures (or album) here. More pictures are always better than fewer. Please have CLEAR pictures and have both close up pictures and ones from a far enough distance that we can see how the various parts are interconnected.
 
 

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