# Back to Basics. Setting up belt driven air comp



## Dave76 (May 3, 2016)

Hi guys. I recently got my hands on a portable 70lt air tank. No pump no motor. A quick check on Ebay and I got me a 375L Twin Cylinder air compressor pump suitable for 3HP 12 CFM max.11bar. After that came the Electrical motor single-phase 240v 2.2kw 3PH 24mm shaft. (Ref photos)
Now top of tank has 3 openings, 1 separate and the other 2 on a T fitting. (Ref photo)
So, from pump to single opening in tank with a piece of copper. Now not sure where pressure switches and check valves and gauges and regulators and anything else. And yes there is a drain plug underneath. Anyone care to explain to me the basic parts and their location on this unit????


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## stevon (Mar 5, 2019)

Dave76,

well, a check valve and a fill pipe from head to tank to start. a pressure switch rated for a 3 hp poly phase or two phase motor. 125psi shutoff or more depending on tank ASME rating. A metal tag or directly stamped in the tank somewhere. A pressure regulator w/ water filter (harbor freight)
The 50 hertz motor will run differently on 60 hertz so drive pulley size will have to be checked for correct speed.
"50Hz motor will run 20% faster on 60Hz power supply as the motor's torque is not going to change significantly with the increase of frequency, it will now output 20% more power. A 10kW 50Hz motor will be a 12kW motor on 60Hz power source"
See: What happens if 50Hz motor is driven at 60Hz?

I would look at or borrow someone else's compressor to get an idea how everything works. Contact me if you have more questions

Stephen


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## stevon (Mar 5, 2019)

Dave76,

I think this is a neat project, kind of like rebuilding a car engine. That being said, without the skills, tools and experience knowing fabrication, machining, plumbing, electrical, engineering skills etc. this type of project should not be attempted. For all the hassle, expense and learning curve required it would be more expedient and cost effective to buy a new or lightly used compressor. I myself have all the requirements and love to do projects even if I know that is not the best/fastest/easiest route. Point being, I see it as what it is (a hobby project) not a practical solution, have fun!

Stephen


Dave76 said:


> Hi guys. I recently got my hands on a portable 70lt air tank. No pump no motor. A quick check on Ebay and I got me a 375L Twin Cylinder air compressor pump suitable for 3HP 12 CFM max.11bar. After that came the Electrical motor single-phase 240v 2.2kw 3PH 24mm shaft. (Ref photos)
> Now top of tank has 3 openings, 1 separate and the other 2 on a T fitting. (Ref photo)
> So, from pump to single opening in tank with a piece of copper. Now not sure where pressure switches and check valves and gauges and regulators and anything else. And yes there is a drain plug underneath. Anyone care to explain to me the basic parts and their location on this unit????


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## Dave76 (May 3, 2016)

Hi Stephen
Thanks for finding the time to reply to my post. The information you provided has been a great help. So to the web address. I found another one was was quite useful. 
https://fix-my-compressor.com/air-compressor-problems-and-fixes/
So I have got me a 1/2 inch piece of copper pipe that runs from the pump head to the tank which is fitted to a check valve. This valve also has a 1/8 inch pipe that acts as a unload valve which that runs to my pressure switch. That switch has 4 fittings.
Can you offer any advise regarding the mounting of the pressure switch. I know a copper pipe connects it to the tank but I have welded "T" connection on the tank. If I plum it to the vertical what about the horizontal or visa versa. Please refer to photos. The head pipe will run to the single opening on the left side. 
Thanks again
Dave


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## stevon (Mar 5, 2019)

Dave 76

I would plug one end of the welded T in the tank. The other hole in the top of the tank I would buy a reduction nipple to 1/4 pipe fitting and a close nipple for the pressure regulator switch. Most regulator switches have a 1/4" NPT manifold that includes an over pressure safety valve set just past the shutoff pressure. If the switch gets stuck the valve will vent before the tank ruptures, that's why you need a safety valve. A picture of your pressure switch and piping completed will help me see what extra or not is needed. Are you running at 60 or 50 Htz? that will help determine what drive pulley size is required. Is the motor thermally protected? (shuts off if beyond a safe operating temperature)

Stephen



Dave76 said:


> Hi Stephen
> Thanks for finding the time to reply to my post. The information you provided has been a great help. So to the web address. I found another one was was quite useful.
> https://fix-my-compressor.com/air-compressor-problems-and-fixes/
> So I have got me a 1/2 inch piece of copper pipe that runs from the pump head to the tank which is fitted to a check valve. This valve also has a 1/8 inch pipe that acts as a unload valve which that runs to my pressure switch. That switch has 4 fittings.
> ...


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## motormonkey (Jul 10, 2016)

Do you know where that tank came from and why it wound up being sold stripped down? Has it been damaged, or have any rust inside? Does it have a data plate on it. Unless you know these things, it might be wise to at least do a hydrostatic pressure test on it.


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## stevon (Mar 5, 2019)

*1\8 NPT hole*

Save76,

The 1/8 hole in the check valve is open to the head pressure and tubing before the the check valve, it requires 1/4 tubing (copper or nylon) to connect the the release valve on your pressure switch

Stephen



Dave76 said:


> Hi Stephen
> Thanks for finding the time to reply to my post. The information you provided has been a great help. So to the web address. I found another one was was quite useful.
> https://fix-my-compressor.com/air-compressor-problems-and-fixes/
> So I have got me a 1/2 inch piece of copper pipe that runs from the pump head to the tank which is fitted to a check valve. This valve also has a 1/8 inch pipe that acts as a unload valve which that runs to my pressure switch. That switch has 4 fittings.
> ...


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