Home built compressor has no output

[okrobie]

I have been collecting parts for a while to eventually build a half way decent compressor. I finally got enough parts to start. 3 hp motor, 30 gallon tank, and a 2 cylinder pump. I mounted the parts on the tank making sure that I had the rotations set up correctly. I bought a nice new pressure switch at Grainger, wired it up and threw the switch. I got rotation, but it's not blowing even a whisper of air. The pump was working on the donor compressor, an old Speedaire, but I decided to put a new head gasket on it just on general principals. I did remove the head gasket just to make sure that I hadn't put it on backwards, but found that it was symmetrical so that even I couldn't put it on wrong. The motor is CCW from the shaft end, and the pump has an arrow on the flywheel. So, what's next? Thanks for any and all help. Regards, Jim

 

[reptilezs]

valves maybe?

 

[OccupantRJ]

Turn it by hand to see if it sounds like a frog strangling through the intake. Put your hand over intake to see if there is suction while turning by hand. Remove tubing to tank from compressor. Turn by hand while holding other hand over outlet, to hold back pressure. Report findings.

 

[El_Guapo]

Sounds like your reed valve between the stages is stuck open. Also make sure your check valve going into the tank isn't stuck (or backward), as that will cause them to just unload to atmosphere without building.

 

[American Locomotive]

Pictures of the pump?

 

[Coloshaver]

No offense intended, but is the motor turning the compressor the correct direction?

 

[The Cobbler]

I would look at the reed valves, especially since you had the head off.
direction of pump wouldn't cause no pressure but it could affect lubrication

 

[Lassen Forge]

I hate saying this, but it's a good example of "If it works, don't "fix" it". (Sorry, I know it doesn't help now, but it's true...)

I agree with the reed valve synopsis - folded, creased, torn, missing? Or if it's an old mechanical valve unit, something got dislodged on reassembly, holding the valves open. Maybe some old gasket material got adhered to the mating surfaces? Worse, the head may have warped or the head bolt holes may have gunk in them, causing it not to seat fully?

 

[okrobie]

When I took the head off, I checked the Reed valves and they we're gunked up so I cleaned them and re-installed.

Check valve? I don't see one. That angle has real possibilities. Where will it be? Is that part of the new pressure switch?

I don't think I have a check valve in the circuit. I can see where that would be a problem. Thanks for more check valve information.

Thanks, Jim

 

[El_Guapo]

If you don't have a standalone check valve in the discharge line (usually they're pretty obvious), it should be integrated in the pressure switch.

Might pay to check the head and deck surfaces for flatness with a 4R scale or other machined straight edge.

 

[okrobie]

I found a check valve in my junk box so after I get a few fittings, I'll install it and let you know how it goes.

 

[mikegt4]

I would look at the reed valves, especially since you had the head off.
direction of pump wouldn't cause no pressure but it could affect lubrication

And cooling if the pump pulley vanes are not turning in the proper direction.

 

[The Cobbler]

And cooling if the pump pulley vanes are not turning in the proper direction.

good point!

 

[okrobie]

I tried two different check valve, but neither of them made a difference. Then I took the head off again and discovered that the reed valve plate is a separate component. Naturally I spoiled the other head gasket so I'll have to get another one. I also found the other set of reed valves and cleaned them. Since I don't know anything about the two check valves I tried, I'll probably buy a new one and try it. Pictures to follow. Good night.

 

[okrobie]

My new check valve finally arrived and I installed it and turned it on and it actually built up pressure. Only problem is that when it reached about 100psig, the pump seemed to bog down and the belt started screech on the motor pulley. Any ideas?

 

[TRWham]

The load will increase with pressure, so the higher the discharge pressure goes, the more power the motor belt and pulleys must transmit to the pump. So, any of these things could cause you to run out of power:
1. Is the motor sized appropriately?
2. Is the drive ratio (pump speed) appropriate?
3. Is the belt the right size for the pulleys?
4. Is the belt tensioned correctly?
5. Are the pulleys aligned?
6. Is the belt worn or glazed and losing grip?

 

[Handyfarmer]

it is not stated, but kind of guess that the pump is a used pump? there could have been a reason it was "used".

I had a old speedy air pump, and one of the gaskets, was bad and started to fall part, and some of the gasket started down the air line and passages and plunged up the check /bleeder valve, and the passages in the head were restricted, as well, can was over loading even tho the tank was only showing about 80 pounds of pressure, there may have been a reason the pump was a take off, (if it was used).

 

[Milton Shaw]

Nobody else has pointed this out but you need a unloader also. Some times they are built in the pressure switch and let the pressure in the discharge line off when the compressor turns off. Some times on cheaper units they are an automatic check valve that unloads when the air flow stops. Check pulleys for wear as when worn they let the belt tighten up but worn they don't let the tight belt grip on the sides to transfer power. The belt should never be bottomed out in the pulleys either.

 

[okrobie]

Thanks

1. Is the motor sized appropriately?

Good point. This pump has been working perfectly in combination with a 1 hp motor and now I have teamed it up with a 3 hp motor.

2. Is the drive ratio (pump speed) appropriate?

I don't know but the motor speeds are the same and the pulley sizes are the same as they were on the 1 hp setup.

3. Is the belt the right size for the pulleys?

Yes

4. Is the belt tensioned correctly?

I think so

5. Are the pulleys aligned?

Yes, I set them up with a carpenters square

6. Is the belt worn or glazed and losing grip?

No, it's a brand new belt.

 

[TRWham]

So if it was working before, but isn't working now, the examination always starts with: what changed? Can you post pictures?

 

[okrobie]

Here is a picture of the current configuration. I'm presently redesigning it using a different pump. Results of the latest revision will be ready this afternoon.
IMG]http://thewebplace.com/images/IMG_20190112_184544.jpg[/IMG]

 

[Citation]

Here is a picture of the current configuration. I'm presently redesigning it using a different pump. Results of the latest revision will be ready this afternoon.

fixing the link

 

[gungatim]

output looks way undersized tapping off like that, if you disconnect everything plumbing-wise from the pump, does anything come out of it when it is running? I can't see from the pic where the unloader line is either, regardless, if it spins, air should come out.

is the reed plate installed in the correct orientation?

here is a similar pump schematic I have, maybe the plate is backwards, upside down, the reeds missing the hold down's, or just plain broken rings...

 

[okrobie]

Yes, it has output. It pumps up to 100 psig before it starts squalling and bogging down. The unloader is behind the output line. It's a 1/4" line that connects to the pressure switch.

 

[TRWham]

That kink in the discharge line isn't doing anyone much good, but I doubt that's causing your problem. Also, it looks like the belt may not be engaged completely. The sides of the belt need to be in full contact with the sheave. It could be the wrong size or loose, but it's not easy to tell from the photo.

 

[Citation]

I would assume the problem is belt slip vs the load on the pump is too high. The pump and motor are very close together. You might not have enough belt wrap around the pulley. The motor sheave might also be too small for the hp load. It's also possible you have a flow restriction so the pump sees pressure that's much higher than the tank pressure.

Speaking of pump outlet your pipe looks kinked. I would suggest a longer run with a loop in it. It reduces cyclic stress on the tube and would reduce the restriction in that bend.

 

[MacMcMacmac]

It looks like you have a Load Genie on the line. You can't use that and a pressure switch unloader and a check valve all at the same time. I would need to see how your blowoff/unloader line is plumbed in, and where. Just a theory at the moment. The pump is pumping ok, the air is getting to the tank, so it sounds like a control issue to me. Unless the motor is severely overgeared. Is it a 3450 rpm? You should limit a single stage pump like yours to about 120psi max.

 

[gungatim]

Yes, it has output. It pumps up to 100 psig before it starts squalling and bogging down. The unloader is behind the output line. It's a 1/4" line that connects to the pressure switch.

could be your check valve stuck open or not working. if you disconnect the line so you have the tank pressurized through the line to the check valve, but with the pump disconnected, does it leak? work backwards from the tank once it's pressurized and starts to slip. shut it off. be careful the line will be HOT.

 

[Stedlin]

It appears that the copper tubing coming out of the pump head is kinked and undersized considering the sharp bend. At over 100 PSI the air is flowing less then 20 to 25 percent of the time. Therefore the peak flow rate is very high which causes significantly more motor load.

 

[okrobie]

Thanks for all of your help, but I saw a 5hp Campbell Hausfelt listed for $75 so I snapped it up

On the original one that we started this thread about... I put a smaller pump on it and converted the belt over to a "V" belt instead of the ribbed and it ran really well for about a week, but then the pump failed and I gave up. I'm now using the tank an auxiliary to the new one because the CH only has a 20 gallon. Thanks again, Jim