Homemade air compressor

[Fritz Maurer]

Like I said I will make sure it works before I trust it.

Looking at the compressor that you have pictured, that is the type that unloads through the control switch....I was wrong in saying you couldn't use that; that is the exact item need if the new pump you purchased does not have a centrifugal or a remote unloader.

But....

It will require an electrical solenoid to operate the throttle with the pressure switch. Because you will need to separate unloader devices, one for the pump and one for the throttle; it will be very nearly impossible to make them both work at the same instant, which they need to do. If the pump unloads first, pressure building will cease and the engine will never decelerate. If throttle unloads first, the pump will stop, but remain against tank pressure and require a lot of HP to restart when air is called for. The second scenario is not impossible to overcome, you just need a robust clutch and a lot of HP. I would say that for a 20 cfm pump, 8 HP would be about the lower limit.

 

[Frankmn]

I did think of using a electric clutch.

The one we have has no electric switch. It has an air solenoid that works the throttle on the motor. Motor goes to idle and clutch disengages.
Motor only runs pump when pressure is below set point and rpm is high enough to engage clutch. I worked pretty well and was easy om fuel as it idled with mo load unless using air.

 

[buickanddeere]

Hi, guys.
Right now I,m waiting for it all to come in, but I ordered all the stuff for a homemade air compressor. Its going to be a 20CFM compressor with a gas engine. Every thing is going to be new besides the air tank, I found a non-working 60 gallon air compressor cheap ($200) for the air tank. when everything has come in I will post a picture of it all.


View attachment 123312

Obtain a generator large enough to operate the compressor with the electric .
The generator will also be handy during utility power outages .

 

[Jeremiah's Tractors]

Looking at the compressor that you have pictured, that is the type that unloads through the control switch....I was wrong in saying you couldn't use that; that is the exact item need if the new pump you purchased does not have a centrifugal or a remote unloader.

But....

It will require an electrical solenoid to operate the throttle with the pressure switch. Because you will need to separate unloader devices, one for the pump and one for the throttle; it will be very nearly impossible to make them both work at the same instant, which they need to do. If the pump unloads first, pressure building will cease and the engine will never decelerate. If throttle unloads first, the pump will stop, but remain against tank pressure and require a lot of HP to restart when air is called for. The second scenario is not impossible to overcome, you just need a robust clutch and a lot of HP. I would say that for a 20 cfm pump, 8 HP would be about the lower limit.

I have a 7.5Hp engine.

 

[Jeremiah's Tractors]

Obtain a generator large enough to operate the compressor with the electric .
The generator will also be handy during utility power outages .

There is a few reasons why that would not work. First of all that air compressor didn't work out, second I don't think it had enough cfm, third I have all ready ordered all of the stuff.

 

[Jeremiah's Tractors]

Do you guys think a propane tank would work? They are rated for 250 psi (air compressor tanks are rated for 200psi).

 

[Fritz Maurer]

Would actually be better, wouldn't be full of rust like a used receiver might be.

What are you doing that 20 cfm might be inadequate?

 

[Russ from MN]

Do you guys think a propane tank would work? They are rated for 250 psi (air compressor tanks are rated for 200psi).

My 2 best compressors have fork truck propane tanks now, they work great. Maybe you mentioned it, but you also need to have a safety relief valve, in case all your other controls fail.

 

[Dave in NY]

I pieced this one together twenty some years ago. Found an almost new Craftsman pressure tank where the pump had failed. Bolted on a used two stage Wayne pump, brand new Harbor Freight motor, new pressure switch, unloader valve and safety pop valve. I adjusted it conservatively to shut off at 125psi and start up at 80psi. Have used it a lot, works reasonably well, no complaints. But, I will just replace it with a new brandname unit when/if it gets tired. I drain the tank of condensation frequently.

 

[Jeremiah's Tractors]

Would actually be better, wouldn't be full of rust like a used receiver might be.

What are you doing that 20 cfm might be inadequate?

I was going to be using it for sand blasting. A 10 cfm would work, but it would be running all the time. BTW I looked at some propane tanks, but they actually cost more then a air tank.

 

[Jeremiah's Tractors]

My 2 best compressors have fork truck propane tanks now, they work great. Maybe you mentioned it, but you also need to have a safety relief valve, in case all your other controls fail.

I was also thinking of wiring a emergency pressure operated electric shut down in to the ignition of the engine, just in case...

https://www.amazon.com/Compressor-Pressure-Switch-Pessure-Controller/dp/B07T8YXQ34/ref=sr_1_6?

 

[Mule Meat]

I was also thinking of wiring a emergency pressure operated electric shut down in to the ignition of the engine, just in case...

https://www.amazon.com/Compressor-Pressure-Switch-Pessure-Controller/dp/B07T8YXQ34/ref=sr_1_6?

You know that every time the tank pressure reaches 120 psi. That switch will shut the engine off right??

 

[farmersamm]

Hey.................I really just now read the thread. My Bad. I'm sort of self centered these days, what with my own problems.

This isn't a lecture,, it's just a heads up.

Pressure vessel welding involves exacting welding procedures, and usually some NDT(non destructive testing).

I would avoid, at all costs, welding on the air tank. You can connect to inlets/outlets, and mount anything you want on the existing pedestal..........but avoid welding on the tank itself. These tanks have an incredible amount of potential energy stored in them when fully pressurized. Welds tend to create problems in the metal directly adjacent to the weld.

When that compressor comes to you, it's usually been tested, and it will, to the best ability of the manufacturer, preclude any liability issues to that manufacturer. You alter it in any way, and you're on your own when it comes to any recourse for injuries, or other damages.

 

[buickanddeere]

How about this ?

 

[Jeremiah's Tractors]

You know that every time the tank pressure reaches 120 psi. That switch will shut the engine off right??

That one turns off at 150psi.

 

[Jeremiah's Tractors]

Hey.................I really just now read the thread. My Bad. I'm sort of self centered these days, what with my own problems.

This isn't a lecture,, it's just a heads up.

Pressure vessel welding involves exacting welding procedures, and usually some NDT(non destructive testing).

I would avoid, at all costs, welding on the air tank. You can connect to inlets/outlets, and mount anything you want on the existing pedestal..........but avoid welding on the tank itself. These tanks have an incredible amount of potential energy stored in them when fully pressurized. Welds tend to create problems in the metal directly adjacent to the weld.

When that compressor comes to you, it's usually been tested, and it will, to the best ability of the manufacturer, preclude any liability issues to that manufacturer. You alter it in any way, and you're on your own when it comes to any recourse for injuries, or other damages.

Yeah, I was wondering if welding on the tank would do that.

 

[Jeremiah's Tractors]

How about this ?

There is a few reasons I didn't go with one like that, first that one costs more then the one I am making, second that one does not have the capacity that I was hoping for, third I like making stuff, and finely I have already ordered all the stuff for the one I am making.

 

[Fritz Maurer]

Yeah, I was wondering if welding on the tank would do that.

I hadn't seen that mentioned. What welding do you have to do?

 

[Mule Meat]

That one turns off at 150psi.

Do you know how those switches work?
You must wire it to one of two things to shut the engine off. Coil or the fuel shutoff solenoid..

0 to 119 psi the circuit is open. Engine will run.
Once it reaches 120 psi the circuit will close. This will either ground the coil or put power to the fuel shutoff solenoid. Thus shutting down the engine.

Simple example.. Compressor is running. It builds 120 psi. The switch turns a light on. When the compressor reaches 150 psi the switch turns the light off..

 

[Fritz Maurer]

Do you know how those switches work?
You must wire it to one of two things to shut the engine off. Coil or the fuel shutoff solenoid..

0 to 119 psi the circuit is open. Engine will run.
Once it reaches 120 psi the circuit will close. This will either ground the coil or put power to the fuel shutoff solenoid. Thus shutting down the engine.

Simple example.. Compressor is running. It builds 120 psi. The switch turns a light on. When the compressor reaches 150 psi the switch turns the light off..

Based on the available information, it appears to be a N/C switch that opens at 150psi and closes when the pressure drops to 120psi.... but i didn't understand the relevance of 12 and 24 volts so I may not be on the right track here.