Compressor pressure problems


Old 08-01-19, 07:32 AM
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Compressor pressure problems

Hello everyone. Got a question regarding a compressor tank pressure rating and the pump.

I own a Ingorsol Rand 60 gal 3hp compressor with a vertical dual cylinder pump. Last year the pump froze up(my bad) but the OEM replacement was WAY too expensive for my budget. So I bought a Harbor Freight pump replacement. Worked great at first, but now I notice it's not bringing the pressure up to the spec of the original pump. I believe the OEM spec was 135lbs, but now it never gets above 110. Even the spec for the HF pump said 135lbs, but doesn't reach it.

Moreover, the other day, the low pressure kick on got so low, I had to bang on the pressure switch to make it turn on. I'm wondering if it's the pressure switch that's keeping the pump from pumping the tank up to the original high pressure turn off, or if the HF pump just can't handle it. I could use some insight into how the pump/pressure switch interact. Also, can you adjust the high/low pressure settings? Thought maybe I should change out the pressure switch, but I'm not really sure it was sticking. All I know is the tank doesn't reach the original high pressure rating, and the low pressure kick on is REALLY low. Like it gets down to about 30 lbs before the motor kicks on.

I even thought about replacing the pump with a higher rated V cylinder pump but that would also require upgrading the motor to a 5hp. However, might as well get a whole new compressor for the cost. Can't afford it.

Also, can someone recommend an economy auto drain unit. I've researched a bit, but it appears these devices are very expensive. I couldn't find a cheaper unit.

Ok guys.. any insight would be appreciated.
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Old 08-01-19, 08:01 AM
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Is the pump running but not achieving the desired pressure or is it turning off at a lower pressure?
Old 08-01-19, 11:24 AM
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Hi, sounds like the P switch, is there a accurate pressure gauge on the system? how is this motor controlled? Post some pics of the motor and switch.
Old 08-01-19, 02:40 PM
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You do NOT want an auto drain. I have worked on air compressors from home-shop sizes to 1,500 horsepower (6000 CFM) models and ALL auto drains have problems. Simply get into the habit of draining the tank every time you use the compressor.

You may find it helpful to extend the drain to an easily accessible ball-type valve if you have the more common automobile type drain valve under the tank.
Old 08-01-19, 02:53 PM
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You may find it helpful to extend the drain to an easily accessible ball-type valve if you have the more common automobile type drain valve under the tank.
That's what I did with my 60 gallon air tank. I screwed in an elbow, a 4" nipple and a ball valve. It's a lot easier to just bend over and open up the valve to drain off any water than it was to get on my knees and reach in to turn the factory petcock.
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Old 08-02-19, 05:24 AM
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What manufacturer and model is the pressure switch?
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