3/8" regulator on compressor drops from 120 to 60 psi with trigger pull

[pipsters]

I have a 25 gallon 150 psi Craftsman pro compressor. Has a decent 1/4" regulator on it that when set to 105 psi or so it drops to 90 psi when using the tool. Not a big deal but I was looking to increase flow for S&G's. It's a little beefier than the standard 1/4" cheapie regulators you see for sale for $10 or so.

I use high-flow 1/4" fittings all around.

I bought a Husky 3/8" regulator. It advertises IIRC 42 CFM @ 90 psi w/ 5 psi pressure drop. I rolled the PSI up to 120 psi and it indicates 60 psi with the tool running (Harbor Freight 1/2" impact). Noticeable power loss at the tool as well.

Put my old 1/4" regulator on there and rolled it to 105 psi, 90 psi indicated with the trigger pulled, and the impact hits hard like it should.

WTF is going on? I thought it would flow a lot better but it doesn't seem to. It isn't behaving the way I thought it would.

 

[LincolnCont.]

*Warning* NOT AN EXPERT! LoL. My guess is that either the reg is junk, not set properly, or the upsize is having negative effects on flow when combine with 1/4 pipe. My two cents is that built up pressure is the same whether its in 1/4in pipe or 1/4in pipe thats been necked up to 100in pipe then back down to 20 in pipe, the difference in performance will be in air volume avalible from the tank and flow rate dictated by the piping&hose when the pressure is given a path to exit. I would install beefier 1/4 reg that can handle the 120 psi that you are going for and give it a whirl, make sure the pop off valve is the right psi so the damn thing dont just pop once you've turned up the psi and release all your air. *last thought... is it possible that the impact wrench has a saftey valve to bypass excessive pressures to the motor which might be venting your excess psi?

 

[larry_g]

It is likely that the regulator with the 3/8" inlet and outlet is the same or smaller on the inside as your 1/4" regulator. Look up the specs on a good regulator, http://www.norgren.com/document_resources/USA/11-002 20AG data sheet.pdf, and you will find the same regulator with various pipe sizes. So the pipe size may have little or nothing to do with flow characteristics of the regulator. It is the size of the internal passages that you have to worry about.

If I might suggest, try putting your regulator near the input of the tool, not on the tank

lg
no neat sig line

 

[monster1]

No ****, Wtf? Sounds like very similar things are happening to both of us. I still get about 90 psi on the regulator but can still keep a sockt from spin on my HF earthquake by holding onto the socket. This isn't rocket surgery. The pipe come out of the tank, passed the main gauge, through the regulator and hose to the guy holding the impact and shaking his head. Wth is there to really be going wrong?

 

[trboxman]

You ever think it might be the impact gun isn't good out of the box?

 

[tpolley]

mine does the exact same thing. i have a harbor freight central pneumatic air compressor. 150psi 29 gallon.

i actually have two regulators. the regulator on the tank, then i have about 15 feet of 3/8id hose with 1/4id fittings. that runs to an oiler and a regulator down by the hose reel. the hose reel has 100ft of 3/8id hose with 1/4id fittings.

both regulators are set for 90psi. i have a tee after the first regulator with a quick coupler. the reason i have two regulators is because at some point i might want to hook up a short hose with a blower nozzle. i might want more than 90psi to blow with. i figured i could set the first regulator for 120psi to blow stuff, then set the second regulator for 90psi for air tools.

well, that doesn't work. as soon as i hit the trigger on the impact the pressure drops to about 70psi. i can hear the tool slow down as pressure drops.

i can turn the pressure up and get it to drop to 90psi, but that seems odd. i've never had to do that before.

 

[tpolley]

could it be cheap air hose? i notice the air hose swells up when it reaches operating pressure, when i hit the trigger on the impact it shrinks. could the swolen hose allow more air flow for a brief second, then restrict air flow as it shrinks?

 

[Dale B]

All the shops I worked in ran 140 psi line pressure, set at the pressure switch.If you needed a lower pressure to spray paint , I had a cheap regulater with quick connects to put inline . I never saw any extra wear on the tools , still use the same ones after 10 years . REALLY improves the performance of the blowgun too !

 

[pipsters]

It is likely that the regulator with the 3/8" inlet and outlet is the same or smaller on the inside as your 1/4" regulator. Look up the specs on a good regulator, http://www.norgren.com/document_resources/USA/11-002 20AG data sheet.pdf, and you will find the same regulator with various pipe sizes. So the pipe size may have little or nothing to do with flow characteristics of the regulator. It is the size of the internal passages that you have to worry about.

If I might suggest, try putting your regulator near the input of the tool, not on the tank

lg
no neat sig line

Wow thanks for that link. I have been scouring all over trying to find info on various "good" regulators. When I look on the inside of the 3/8" regulator I find that the inlet is just *slightly* smaller than the 1/4" diameter pipe coming into it, so it's certainly not the pipe that is bottle necking it. When taking it apart it appears bigger inside but who knows. I think it must be the regulator, I am surprised.

The tank is a 25 gal compressor and portable so I need to mount the regulator right on the tank.

Also if you read the notes on that Norgren, it indicates a 15 psi drop from the setting. Which is what I get, if it's talking about the pressure drop you see when pulling the trigger which I think it is.

Thing is, the Husky regulator I picked up indicated a 5 psi drop, which clearly wasn't the case.

 

[pipsters]

Check this out:

http://www.garagejournal.com/forum/showthread.php?t=78541

Guy was having the same problem. Larry you even responded in the thread. He bought a better regulator and it didn't move one bit. The Craftsman he was using (a carbon copy of my Husky BTW minus the filter) was WAY overrated. Although he did step it up to 1/2" so that might have had more to do with it, we'll never know because he didn't test a Craftsman or other cheapie brand 1/2" as well.

I've been looking at Wilkerson and Norgren, he also bought a Speedaire, so looks like the name brand ones are much better. Good to know. I might keep my 1/4" though as it seems to do a semi-decent job.