How do I test this old compressor?

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ilyaz

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Hello Everyone

We just bought a house and found there an old Sanborn B07FL350-20 air compressor. I know nothing about compressors. How do I test it? When I plug it in, it immediately starts running/charging and I cannot switch the on/off switch into the off position. Does it mean it's broken? What else can I do to test it? I don't have any air tools to connect to it. TIA!PXL_20210103_125909196.jpgPXL_20210103_125921410.jpgPXL_20210103_150112231.jpgPXL_20210103_150228549.jpg
 

Snoonyb

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The switch is replaceable, so you can tell if the limit switch is operating by simply turniing the air pressure adjustment knob counterclockwise.
 

bud16415

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Watch the gauge on the right. Plug it in and let it run. That gauge should keep going up and shut off the electric motor when the max pressure is reached. Some have a red line, yours doesn't seem to have that. If it is working properly it will shut off if it gets all the way to the top pressure 120 PSI and after a minute doesn't shut off pull the plug.

The other gauge is to set the pressure going out the hose. Say you were filling a tire and didn't want over 50 PSI you could limit it there. Most people I know have them set to max. You do that by pulling the knob out and turning it while watching the gauge to the right.

Go to Harbor Freight and get a starter kit that has a few fittings and a tire chuck for airing your car tires and a tire pressure gauge it should also have a blow nozzle. Those are handy beginner air tools. Then you can go from there.

It was a nice find and even if it needs a little work it is worth having around. Great for filling a basketball also.
 

ilyaz

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Watch the gauge on the right. Plug it in and let it run. That gauge should keep going up and shut off the electric motor when the max pressure is reached. Some have a red line, yours doesn't seem to have that. If it is working properly it will shut off if it gets all the way to the top pressure 120 PSI and after a minute doesn't shut off pull the plug.

The other gauge is to set the pressure going out the hose. Say you were filling a tire and didn't want over 50 PSI you could limit it there. Most people I know have them set to max. You do that by pulling the knob out and turning it while watching the gauge to the right.

Go to Harbor Freight and get a starter kit that has a few fittings and a tire chuck for airing your car tires and a tire pressure gauge it should also have a blow nozzle. Those are handy beginner air tools. Then you can go from there.

It was a nice find and even if it needs a little work it is worth having around. Great for filling a basketball also.
Thank you! I plugged it in and it did shut off when the pressure reached 120 PSI. However, the pressure adjustment knob in the middle does not seem to be working. Rotating it cw or ccw does not seem to do anything. Pressing on it produces a slow leak of air, see,ms to be coming from the knob itself. Does it mean it's broken? Or operator error and ignorance? :)
 

Snoonyb

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Some models are press to turn, some are not.

On mine it can be set so that the compressor stops at an adjusted value and deal not pump to the factory max.
 

bud16415

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Thank you! I plugged it in and it did shut off when the pressure reached 120 PSI. However, the pressure adjustment knob in the middle does not seem to be working. Rotating it cw or ccw does not seem to do anything. Pressing on it produces a slow leak of air, see,ms to be coming from the knob itself. Does it mean it's broken? Or operator error and ignorance? :)
Yours says (Pull to adjust pressure). Try pulling out on the knob and turning it.
 

ilyaz

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I turned it on again, brought pressure to the max. Then checked a couple of hours later and pressure was 0. Where are possible places it could leak?
 

bud16415

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Most compressors will leak down over a few hours. Sometimes you can hear an air leak when it's not running. Look around fittings and around the drain hole on the bottom. You should open that drain from time to time and let the air pressure blast out the oily water that builds up inside the tank.

When I was a young man and an apprentice they asked me to work Christmas Eve as there was no one in the factory and I was to walk around and put tags and record where air was leaking. It was always to loud to find them when everyone was working. I must have marked over a 1000 leaks and barely even made a start at it.
 

bud16415

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As a side note I have a larger compressor that i ran lines around my garage shop to three locations. I wired it back to a outlet I turn on and off with a switch. I also have a lamp plugged into the outlet that hangs over the compressor. It reminds me to turn the compressor off. When I'm done out there for the day I flip the switch off and I plumbed the drain valve on the bottom to a hose that runs down to a plastic gallon milk jug that catches the water. After I shut the power off I open the valve.

You should also check the oil level in the pump from time to time.
 
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Jim_in_JAX_FLA

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there is usually a CHECK valve where air comes from compressor into the tank, those can go bad and leak back into compressor cylinders and OUT.....slowly leaks out....
 

BuzzLOL

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Don't leave the compressor turned on or the air will leak out and it will cycle on and off until it overheats or wears out.
That looks like a diaphragm type compressor, don't know if they have oil in them like the heavier duty piston type compressors that look and work like an automobile or lawnmower engine...
I have a rebuilt '5 HP' Samborn 2 cylinder piston type compressor that was painted black and resold under "Rocket" name. Those are prolly about actual 3 1/2 HP. They used to really lie about HP on home use units. 2 HP compressors eventually got called as high as "7 1/2 Compressor HP"!
If it runs on plug in 120 volts it's prolly no more than 2 HP, otherwise it would melt the plug and outlet down. 220-240 volt plug in models are prolly no more than 3 1/2 - 4 HP... no matter what they are labeled...
If the tag on the motor says SPCL (Special) in the HP box, then it's prolly less actual HP than what it says on the tank or housing.
True 5 HP and UP compressors are usually hard wired rather than plugged in...
 

bud16415

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Don't leave the compressor turned on or the air will leak out and it will cycle on and off until it overheats or wears out.
That looks like a diaphragm type compressor, don't know if they have oil in them like the heavier duty piston type compressors that look and work like an automobile or lawnmower engine...
I have a rebuilt '5 HP' Samborn 2 cylinder piston type compressor that was painted black and resold under "Rocket" name. Those are prolly about actual 3 1/2 HP. They used to really lie about HP on home use units. 2 HP compressors eventually got called as high as "7 1/2 Compressor HP"!
If it runs on plug in 120 volts it's prolly no more than 2 HP, otherwise it would melt the plug and outlet down. 220-240 volt plug in models are prolly no more than 3 1/2 - 4 HP... no matter what they are labeled...
If the tag on the motor says SPCL (Special) in the HP box, then it's prolly less actual HP than what it says on the tank or housing.
True 5 HP and UP compressors are usually hard wired rather than plugged in...
I believe it is a piston compressor but one where there is no belt where the motor is separate from the compressor. This type has an eccentric mounted to the motor shaft and that runs a connecting rod to the piston. Kind of a in between design. So it may well not have any crankcase lube.

It is good advice to cut the power as you mentioned and it is also really easy to forget and leave it plugged in. I can't count how many times when it was below freezing out I was back in the house nice and warm and she would tell me the compressor is running. I finally did as I mentioned above putting an indicator light on it that lets me know when it is powered up.
 

BuzzLOL

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My belt drive compressors are much quieter than some of the direct drive ones that obnoxiously sound like a machine gun firing... way too loud...
 

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