What's Wrong With My Compressor Setup?

[loiq]

I have an 80 gallon Porter Cable compressor with a short 3/8 line to a regulator/filter, about a 6-inch 1/2-inch run to the 3/4-inch main lines. It runs up the wall, through to the other side.

I try to use small air tools like a cut-off wheel and mini grinder and the air line can't keep up. I can see the 25-foot hose go limp and when I stop the tool I can hear the line fill back up. I opened up the regulator so it's flowing as much as possible (the gauge is pegged).

There are no leaks I can detect and the line itself will still have pressure the next morning after shutting the valve off from the compressor.

I don't know what to do.

Pics of the setup:

 

[gmasterman]

I uspect your regulator will not pass enough air. Try removing it from the system or installing a bypass temorrarly

 

[Jay H 237]

Two things I can think of:

Regulator is defective and/or there is debris trapped in the line between the compressor and main line after the regulator.

Try shutting off the valve between the compressor and regulator. Drain the pressure from the line and then disconnect the orange air house. Open the valve slowly and see how the pressure is leaving the compressor. If that's good then you've narrowed it down to the regulator.

Something else to look for at the joints for the regulator is if any stay pieces of teflon tape got caught in the air passages. I've seen where this can reduce air flow.

 

[bmwpower]

(1) Get rid of that 3/8" hose going to the regulator. This is your bottle neck. If it were me, I'd make that whole run to the main line 3/4", including the hose.

(2) What's the CFM of the compressor?
(3) What's the CFM of the tool?

 

[JohnReynolds]

I used 3/4" Hydraulic hose to the regulator, then downsize/upsize the connections with bushings on either side of the regulator. Places like Tractor Supply have premade 36" pieces of that hose for $11 here in Michigan. I had mine custom made with a swivel on one end at an auto parts store for $35 (ouch!). I don't seem to have any problem with getting enough air and I have 100' of copper pipe to some connections - compressor is 80 gallon 2-stage Iron Force from Lowes (Campbell Hausfeld).

John

 

[loiq]

The biggest regulator I can find in any tool catalog only has 1/2-inch inlet and outlet so I don't know how I can make the line 3/4 the whole way. I don't really want to run it without a regulator...

Compressor specs:
Lubrication
Oil-Lube
Tank Size Gal.
80
HP (Run)
6.0
Amps @115 Volts
30
Max. PSI
175 SCFM Air Delivery
@40 PSI: 16.4
@90 PSI: 15.2
Pressure Release
YES
Globe Valve
NO
Gauges
1
Weight
401 lbs.
Shipping Weight
447 lbs.

 

[JohnReynolds]

The regulator doesn't have to be 3/4" since it is such a short run - just make sure all of the pipe/hoses are. Check your Private Messages.

John

 

[bmwpower]

CFM looks okay. How long do you use the tool before the air can't keep up?

I know I've seen 3/4" regulators somewhere...just can't remember where.

You may want to start here... that 3/8" hose should be replaced with a 1/2" hose. Also, what size if the 25-footer you using? You might want to up that to 1/2", too, if needed.

 

[loiq]

CFM looks okay. How long do you use the tool before the air can't keep up?

I know I've seen 3/4" regulators somewhere...just can't remember where.

You may want to start here... that 3/8" hose should be replaced with a 1/2" hose. Also, what size if the 25-footer you using? You might want to up that to 1/2", too, if needed.

LOL the tool rips for about a second then the rpms fall off. It's almost an instant drop. Let off and I hear the lines fill and the hose tenses up again. It does sound like I'm running the whole system dry so the hose right off the compressor might be ther problem. This compressor should be able to run a little 3-inch cutoff wheel all day long.

I'm going out to see what kind of hose I can get to eliminate that span of 3/8 immmediately after the compressor.

My hose in the shop is 3/8, too.

 

[bmwpower]

I used to use 3/8" hoses exclusively, mainly for the weight savings. I hadn't seen the real power until I switched to 1/2" rubber hose from HF. A very noticeable difference, especially with an impact wrench. I wouldn't get what you're describing though, which sounds like a major supply problem.

 

[ultgar]

That looks like a 3/8" regulator....upgrade it to 1/2". I have filters and regulators with ports up to 1" but you really don't need them for a compressor this size. SD

 

[Charles (in GA)]

Grainger, MSC, etc have regulators in all sizes and air flows. Here's one from Surplus Center, a little overkill but at 700 cfm capacity you won't have any restrictions either. Only two in stock so hurry........

http://www.surpluscenter.com/item.asp?UID=2006060411111326&item=4-1683&catname=air

Get rid of that small hose from the compressor to the regulator, and use as short of a hose as you can to the air tool itself. Indeed the regulator may be a bottle neck also.

Charles

 

[gmasterman]

That short 3/8" hose should be fine. You consider that the air going theough the hose is at 175#. The regulator is the problem. Bypass it to see if there is a change. Rig up a pressure gauge just upstream of the regulator and watch for a DP

 

[loiq]

I went to the local implement and got a 1/2-inch hydraulic hose to run from the compressor to the regulator and it works much better now. No one has 1/2 air hose so i had to go with the hydraulic hose. The pressure still drops so I think I will get a regulator with 1/2 inch inlet/outlet and up the size of the leg to the regulator to 3/4. If that doesn't do it I don't know what will. More money!!

Thanks for everyone's help.

 

[DIGGER_DAVE]

That short 3/8" hose should be fine. You consider that the air going theough the hose is at 175#.

The regulator is the problem.

Bypass it to see if there is a change. Rig up a pressure gauge just upstream of the regulator and watch for a DP

As gmmasterman suggests; check the COMPRESSOR outlet presure. It JUST might show that someting is WRONG with the compressor!! A unit that big shouldn't have ANY problem keeping up!

Or as he says; "Either the regulator is defective.", or something is plugging one of the lines.

Normal shop practice does not use a pressure regulator "UP STREAM" of the air lines. Regulation should take place as close to (or AT) the "demand" point as possible. i.e. - as close to the tool air line outlet as possible.

If your concerned about TOO high a pressure in your supply lines; RE-SET the compressor PRESSURE KICK OFF SWITCH to a lower setting.

ONE more thing; do you drain your tank often??
Moisture build-up in the tank COULD be causing what your experiencing. If the tank is full of water, (condensate) it won't put out.

 

[AndrewM]

One thing you could try (temporarily) is bypassing the regulator. That'd tell you if it's your pipe or your regulator.

I'd point out that opening the ball valve might help but that's probably too smart-a$$ of a reply.

I use air tools on 1/4" fittings, no problems here...

 

[tommy]

Why do you need 2 regulators that close together? The compressor has a regulator and 3 feet away you add another? I'd mount that regulator at the end of a run to bring the pressure down to a lower level such as for painting. All the rest of the disconnects get full volume and pressure for high CFM grinding and sanding. If you are not sure which connection you want to use for painting, put a male and female connector on the regulator so that it can be plugged into any quick disconnect. That is an unnecessary redundent bottle neck IMHO.

 

[pgreen]

Two things to check. First, be sure your airflow is going through the regulator in the proper direction. There will be arrows cast into the regulator showing flow direction. If this is correct, I would assume that you have a defective or clogged regulator/filter unit. It is not a huge unit by no means, but it should flow enough air to at least keep your grinder running. The 3/8" line should be fine as long as you don't have 100' of it, or are trying to run a 1" impact gun. Most of the average shop tools will run fine with 3/8" air lines. Check your regulator first before you put more money and time in the system.

Phil

 

[loiq]

It seems to be working good now. Just spent a few hours grinding/welding/sanding/sandblasting and it ran the tools fine. It was running through the regulator. So, if I'm not using a spray gun I can take that regulator off and put it on a separate line for use with a spray gun, is that correct? And run everything else straight off the compressor?

 

[DIGGER_DAVE]

PULL BOTH regulators! (I didn't spot the one on the side of the receiver the first time)
Thanks tommy for pointing THAT out!

Screw a pressure gauge DIRECTLY into the compessor air outlet. (side of receiver) But your compressor SHOULD have a receiver PRESSURE GAUGE already!
If it shows anywhere between 120 and 140 pounds pressure; the compressor is probably OK.

Hook your NEW hose directly from the receiver (tank) to the shop air lines.
Make SURE your receiver doesn't have ANY moisture in it.
(Not wanting to assume; you DO drain it regularly don't you?? )

NOW - try your air tool(s), they can stand full pressure from the compressor. (for a moment or two)

STILL got a problem? ... It's somewhere in the air lines.

Solve that; ... mount ONE regulator at the outlet you use for your air tool(s); and a filter / moisture trap with an automatic line oiler would be a GOOD investment if you want the tools to last.

If you live in a VERY humid area; an AIR DRYER is also a good investment; most small moisture traps can't keep up.

 

[Charles (in GA)]

So, if I'm not using a spray gun I can take that regulator off and put it on a separate line for use with a spray gun, is that correct? And run everything else straight off the compressor?

Is this a single stage, 125 psi max unit? or is this a two stage, 175 psi max unit? If it is a two stage, you need the regulator to get the pressure down to 90-100psi for the air tools. running air tools on 175 psi would be dangerous and it would probably overspeed them.

If this is a single stage unit, you probably could get away with running the tools on 125 psi, as you are probably seeing only 100 or so at the end of the hose where the tool is anyhow.

Charles

 

[DIGGER_DAVE]

Is this a single stage, 125 psi max unit? or is this a two stage, 175 psi max unit? If it is a two stage, you need the regulator to get the pressure down to 90-100psi for the air tools. running air tools on 175 psi would be dangerous and it would probably overspeed them.

If this is a single stage unit, you probably could get away with running the tools on 125 psi, as you are probably seeing only 100 or so at the end of the hose where the tool is anyhow.

Charles

Charles, checking the specs he posted ...

Tank Size Gal. - 80
HP - 6.0 (Run) / @115 Volts - 30 AMPS
Max. PSI - 175 SCFM Air Delivery
@40 PSI: 16.4
@90 PSI: 15.2

Gauges - 1 (I thought it should have one)

It isn't a TWO STAGE.

Compressor manufacturers INFLATE (pun NOT intended)
RUN HP.
An electric motor running on 115 Volts AC - and
ONLY consuming 30 AMPS is never going to be able to generate a TRUE 6.0 horse power!!
That would defy the "laws of physics!!"

My single stage 5 HP (motor) driven compressor draws 35 AMPS @220 VOLTS AC under full load!!

I'll hazzard a guess that max air pressure output on that unit is around 120 - 125 PSI. And more than likely around 95 PSI in normal demand conditions.

EDIT: I decided to check Porter Cable's site just to see if I had missed something....

Here is what I found...

Porter-Cable 175 PSI, Two-Stage - 80 Gal. Compressor
- Model C7550
Specifications: Tank Size (Gal.) -80
HP (Peak/Run) 7.0/6.0

Amps - 30 @ 240 Volts

Max. PSI - 175
SCFM Air Delivery @ 100 PSI 16.4
SCFM Air Delivery @ 175 PSI 15.2

SO .. I may just have to "EAT CROW!" His may be TWO STAGE.
BUT .. note the voltage is 30 AMPS @240 VOLTS AC!

 

[kartracer55]

Ditch the little hose to isolate the compressor and get some larger hose... I used braded steel hydraulic hose 3/4 id with 3/4 npt threads, same as compressor outlet. About 30$ from grainger good to well beyond what the compressor makes. Make sure thats at least a 1/2 regulator, mine has 3/4 but the compressor is a bit larger anyway.

Jim

 

[loiq]

OK, I'm confused now. Do I need the regulator or not?

 

[bmwpower]

OK, I'm confused now. Do I need the regulator or not?

Replace the hose first. Check the operation. If it doesn't operate as expected, up the regulator and try again.

 

[kartracer55]

OK, I'm confused now. Do I need the regulator or not?

I forgot to mention that I think it might be too far away from your point of use, which might be contributing to your problem... just a thought


Anyway, yes you do. Most manufacturers recommend running tools around 90 psi for a reason... Im thinkin tool life and efficiency. Sometimes you need that extra kick though.

Also, many abrasives reach a point where turning them faster only wears them faster and loads them up more, so it doesnt make much sense to run them at 20K rpms if they grind just as well at say, 10. Listen to the tool at half throttle, and adjust the regulator so having the tool at "full throttle" gives you that half throttle sound. Same with some mounted stones... if youve got a 22k rpm die grinder but the stone is only good for 20, then its probably not the best idea to run it at full throttle... just turn the regulator down so you know its not turning as fast. Sure is easier than trying to maintain half throttle the whole time

Thats just me

Jim

 

[gmasterman]

You need ONE regulator at the pump. Set it at 100 -125# or so. Cances are that there is already one there from the factory. Then if you have a need for a point of use regulator, such as for a spray gun or beadblast cabinent, then instal one whereever you hook your hose up.

BTW, manufacturers have been using some funny system for ratinf P for air compressors for years now. The ratings never match the amps needed for a full HP. I have two "5 HP" compressors that pull less than 30 amps-together on 220VAC

 

[kartracer55]

You need ONE regulator at the pump. Set it at 100 -125# or so. Cances are that there is already one there from the factory. Then if you have a need for a point of use regulator, such as for a spray gun or beadblast cabinent, then instal one whereever you hook your hose up.

BTW, manufacturers have been using some funny system for ratinf P for air compressors for years now. The ratings never match the amps needed for a full HP. I have two "5 HP" compressors that pull less than 30 amps-together on 220VAC

I think your refering to something else.

Your regulators regulate the flow of air through the system "downstream" of where they are installed.

A pressure switch is a switch that controls the compressor kicking on and off. Im not exactly an expert on how these work, but they rely on tank pressure...

One way or another, when the pressure drops, the contacts close giving the starter the "ok" to turn the motor over and get the compressor pumping. When the set pressure is reached (130-140 SS, 175 for 2 stage) the contacts open breaking the circuit killing the motor.

Something along those lines lol

Jim

 

[gmasterman]

The purpose of the regulator at the tank is to give you a steady air pressure in your piping and to reduce the pressure surge from affecting your unregulated tools as the pressure switch turns on the comp and the pressure builds. Without this regulator, every point of use would have to have a regulator. Me, I do not want 175# on my manifold throughout my shop when 125# is plenty. If a POU regulator fails, and I've seen this happen and you have no regulator at the tank you may have 175#PSI at your hose.

 

[loiq]

I forgot to mention that I think it might be too far away from your point of use, which might be contributing to your problem... just a thought

The pictures show the setup. The compressor is right on the other side of the wall. There's maybe 20 feet of 3/4 inch hard line before the hose connection.

 

[loiq]

I think I'll just go by this:

 

[DIGGER_DAVE]

Follow the diagram; and you should be good!!

 

[kartracer55]

The purpose of the regulator at the tank is to give you a steady air pressure in your piping and to reduce the pressure surge from affecting your unregulated tools as the pressure switch turns on the comp and the pressure builds. Without this regulator, every point of use would have to have a regulator. Me, I do not want 175# on my manifold throughout my shop when 125# is plenty. If a POU regulator fails, and I've seen this happen and you have no regulator at the tank you may have 175#PSI at your hose.

Makes sense I guess, but I havent seen it. A quality sweat wih copper pipe and 95/5 solder is good to well beyond 200psi anyway, so Im not too worried. I prefer having a POU regulator, but thats just me.

Whatever works