Air Compressor Output Questions

[Ozz316]

I wanted to pick the brain of some air compressor experts on this site. In my shop at work, it always seemed like air tools weren't running well, like we were running out of air. Based on our setup, there is no way we should be running out of air in the shop. We have a IR rotary UP6-15-125 that is we had bumped up to 135 PSI max feeding 2-120 gallon tanks. These are running through a filter regulator, 2 other filters, and an air dryer. The only reason for the main filter regulator was we had it regulated down previously from an old setup that was running more PSI. The line from the tanks is 3/4" DOT air line into the filters and such, then run into the piping in the building that is 1 1/2 Galvanized. This setup runs the actuators on the Ready Mix plant that is approximately 175 feet from the compressors. This runs into another set of regulators and oilers set at 80 PSI. Plant never has air issues. The shop air is about 15 feet away from the compressors, run into a 1/2 inch pipe through a wall to a hose reel with 50 foot of 3/8 air line and a tee from the 1/2" pipe to 1/2" air line for our bigger guns. When running the 1" gun we have to stop sometimes when pulling off lug nuts. Our 1/2" impacts always seem week. I checked the pressure at the end of the 3/8" air line and it was right at 115 PSI. I put a t fitting with High Flow fittings and a gauge right at my 1/2" impact and when I pull the trigger, it goes from 115 down to 65, no load. Sorry for the long post, just trying to give as much information. I feel like I have everything sized correctly, what are some of your opinions on why I'm loosing so much pressure and potentially CFM?

 

[Kaizen]

Clog or restriction. I’d work back and go 3/4 right to hose for gun. See what’s holding it up.

What’s the cfm on that rotary and can you isolate the shop air ? If the big tanks are emptying then that’s where it’s going. Isolate and test


Sent from my iPhone using Garage Journal

 

[Firebrick43]

Does the pressure drop that much at the regulator???. How long is the 3/8 hose??? The 1/2 impact should be fine with under 25' of 3/8 hose. Going to 50' will drop the cfm from 6.2 to 4.3 cfm. If over 25' use 1/2 hose and install a 4' 3/8 whip on the gun itself so its not so stiff/hard to maneuver. A one inch impact should have 3/4 inch hose.

 

[Ozz316]

The rotary shows max 52 cfm, no numbers next to 90 or 40 psi. The 2nd 120 tank is actually an old 15hp recip that we used to use, now just backup. I’ve got it on a 90 psi switch and it never kicks on, so the tanks aren’t draining down.
I’ve looked at the regulator on the wall and it doesn’t drop when we use the guns. It just drops at the test fitting right before the 1/2” gun. I’ve never seen anyone run 3/4 inch hose on a 1” impact, but I’ll look into it. But heck it might be a 3/4 hose with 1/2” fittings I will look on Monday. I will have to double check the 3/8 air line, but I do believe it is 50’. We need length to move around the big trucks.

 

[Ozz316]

Here are some photos of the setup. I forgot to take one on the other side of the wall where the hose reel and such are, but the one picture is the T that runs into the next shop and the 1/2” and 3/8 hose are plumbed directly into high flow fitting at the wall.

 

[Ozz316]

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[Jswain]

Start by running a 1/2" line right from the tank and see if the problem goes away. If it does start adding filters/regulators one at a time. It also appears in your photo the top filter is directional and the had line below it has an arrow pointing in the opposite direction so make sure nothing is plumbed in backwards

Did you have your shop air plumbed in to the higher psi compressor before you replaced it previously? This is where 175psi is handy

 

[Ozz316]

The flow direction is correct, the first two filters lead into the dryer and then come out of it up to the last filter then down to the 1 1/1 pipe. I have another hose reel that comes directly out of the main tank, I will hook up to that when I get some more high flow fittings in next week.
We have always had the pressure regulated down to 125 even before, but I’m pretty sure we’ve been fighting this for a long time.

 

[Firebrick43]

The rotary shows max 52 cfm, no numbers next to 90 or 40 psi. The 2nd 120 tank is actually an old 15hp recip that we used to use, now just backup. I’ve got it on a 90 psi switch and it never kicks on, so the tanks aren’t draining down.
I’ve looked at the regulator on the wall and it doesn’t drop when we use the guns. It just drops at the test fitting right before the 1/2” gun. I’ve never seen anyone run 3/4 inch hose on a 1” impact, but I’ll look into it. But heck it might be a 3/4 hose with 1/2” fittings I will look on Monday. I will have to double check the 3/8 air line, but I do believe it is 50’. We need length to move around the big trucks.

If its not dropping at the regulator then it is definitely out running the flow capacity of 3/8 hose at that length. Step up to 1/2 hose. Using a flexible hose will help with complaints some(such as flexilla) but the best is to put a 3 to 4 foot 3/8 hose directly on the gun and the male ****** on the end of the hose.

You probably have not seen 3/4 inch hose on a 1" gun because everyone is a cheap ******* or ignorant of flow charasitics. Ingersol rand is a good resource and they recommend 3/4". It definitely makes a noticeable difference.

IR Rand air hose sizing

Just throwing this out however, have your guys not used the new fuel milwaukee impacts?? I haven't had my air impacts out in years now and the 3/4 high torque will do 22.5 tires and tractor tires. Admittingly I don't know how many tires a day you do, Its not something I do even once a week. But I do use my 1/2 high torque and 3/8 daily.

 

[Iron Beaver]

WARNING: Wall-o-Text ahead. I love nerding out about pressure drops and adding them up

I am thinking through your setup as described, with some estimates for pressure drop of each component, running a pretty typical 1" impact wrench (https://www.ingersollrand.com/en-us/power-tools/impact-wrenches/2850max)

1) filter regulator 10PSI drop, (Based on Wilkerson B28, see https://www.dixonvalve.com/sites/de...hures-literature/B28_Wilkerson_Spec-Sheet.pdf)

2) 2 other filters, 4PSI drop each, 8PSI total (Based on Wilkerson F28, see https://www.dixonvalve.com/sites/de...hures-literature/F28_Wilkerson_Spec-Sheet.pdf)

175 feet of 3/4" DOT air line, roughly 5PSI (based on https://www.engineeringtoolbox.com/compressed-air-pressure-loss-d_1014.html)

3) "This runs into another set of regulators and oilers set at 80 PSI" I'm going to assume it goes through one more regulator and one lubricator on it's way to your impact gun. This gives another 10 PSI pressure drop for the filter (based on Wilkerson R28, https://www.dixonvalve.com/sites/de...hures-literature/R28_Wilkerson_Spec-Sheet.pdf) and maybe 5-6 for the lubricator (Based on https://www.dixonvalve.com/sites/de...hures-literature/L28_Wilkerson_Spec-Sheet.pdf)

4) 15 feet of 1/2" pipe @ 70-ish PSI, maybe 1.5 PSI, from Engineering Toolbox above

Hose reel: ??? Say 10 PSI at a guess if it's as restrictive as many I've seen

5) 50 feet of 1/2" air hose, 12 PSI (based on https://www.engineeringtoolbox.com/air-hose-friction-d_1536.html)

6) Fitting for the gun. Please, please tell me you are using a Chicago fitting on that gun? If not I will be sad. Don't know what fittings you are using so here are some more numbers from Dixon: (https://www.dixonvalve.com/sites/default/files/product/pages/DQC221-DF-Series.pdf)
Chicago coupling: Minimal
1/2" DF-series: 5PSI
3/8" DF-series: 20 PSI
1/4" DF-series: Off the charts, like 40PSI

Total pressure drop:

With Chicago fittings on the gun and hose: ~ 60 PSI
If you're using 1/2" quick couplings: ~ 65 PSI
If you're using 3/8" quick couplings: ~ 85 PSI
If you're using 1/4" quick couplings: 100 PSI or more

So with your impact running full bore it might only be seeing 20PSI dynamic, or really, stretching the limits of optimism around 70-80PSI dynamic pressure if you're using Chicago fittings. Many of those are supposed to run at 125 PSI dynamic pressure and if so it will be pretty starved for air.

The above estimates are pretty optimistic. Let me know if any of this helps!

 

[nadogail]

Trying to run a large impact on a small size air hose will be about as successful as trying to **** a Golf Ball through a garden hose.

 

[Ozz316]

WARNING: Wall-o-Text ahead. I love nerding out about pressure drops and adding them up

I am thinking through your setup as described, with some estimates for pressure drop of each component, running a pretty typical 1" impact wrench (https://www.ingersollrand.com/en-us/power-tools/impact-wrenches/2850max)

1) filter regulator 10PSI drop, (Based on Wilkerson B28, see https://www.dixonvalve.com/sites/de...hures-literature/B28_Wilkerson_Spec-Sheet.pdf)

2) 2 other filters, 4PSI drop each, 8PSI total (Based on Wilkerson F28, see https://www.dixonvalve.com/sites/de...hures-literature/F28_Wilkerson_Spec-Sheet.pdf)

175 feet of 3/4" DOT air line, roughly 5PSI (based on https://www.engineeringtoolbox.com/compressed-air-pressure-loss-d_1014.html)

3) "This runs into another set of regulators and oilers set at 80 PSI" I'm going to assume it goes through one more regulator and one lubricator on it's way to your impact gun. This gives another 10 PSI pressure drop for the filter (based on Wilkerson R28, https://www.dixonvalve.com/sites/de...hures-literature/R28_Wilkerson_Spec-Sheet.pdf) and maybe 5-6 for the lubricator (Based on https://www.dixonvalve.com/sites/de...hures-literature/L28_Wilkerson_Spec-Sheet.pdf)

4) 15 feet of 1/2" pipe @ 70-ish PSI, maybe 1.5 PSI, from Engineering Toolbox above

Hose reel: ??? Say 10 PSI at a guess if it's as restrictive as many I've seen

5) 50 feet of 1/2" air hose, 12 PSI (based on https://www.engineeringtoolbox.com/air-hose-friction-d_1536.html)

6) Fitting for the gun. Please, please tell me you are using a Chicago fitting on that gun? If not I will be sad. Don't know what fittings you are using so here are some more numbers from Dixon: (https://www.dixonvalve.com/sites/default/files/product/pages/DQC221-DF-Series.pdf)
Chicago coupling: Minimal
1/2" DF-series: 5PSI
3/8" DF-series: 20 PSI
1/4" DF-series: Off the charts, like 40PSI

Total pressure drop:

With Chicago fittings on the gun and hose: ~ 60 PSI
If you're using 1/2" quick couplings: ~ 65 PSI
If you're using 3/8" quick couplings: ~ 85 PSI
If you're using 1/4" quick couplings: 100 PSI or more

So with your impact running full bore it might only be seeing 20PSI dynamic, or really, stretching the limits of optimism around 70-80PSI dynamic pressure if you're using Chicago fittings. Many of those are supposed to run at 125 PSI dynamic pressure and if so it will be pretty starved for air.

The above estimates are pretty optimistic. Let me know if any of this helps!

You have most of that correct but the 175’ run is through 1 1/2 pipe that’s run over to the plant, doesn’t really affect the shop air but wanted to share all information. To be honest on the fitting to the 1” gun all I remember is ordering a D style fitting I believe from Napa, it is 1/2”. On the 3/8 air line, I’m using a Parker High Flow Fitting I get through Grainger. https://www.grainger.com/product/PA...me-_-Purchased_Products-_-HPMPPZ&cm_vc=HPMPPZ. The run from the compressor to the shop area is only like 8 feet through the 1 1/2 pipe. The 3/4” air line is probably around 15-20 feet, I added some extra coming straight out of the tank to the regulator based on recommendation to cool the air before it gets to the dryer. Could probably shorten this up since the tank that feeds the regulator is the secondary after the actual compressor tank.

To Firebrick, I did find the Ingersol link last night where they referenced using 3/4 air hose, was very surprised by that. Figured our tire shop would be using 3/4” with all the use they do with their 1”. I do have a plethora of battery tools. Started with the 3/8” non fuel Milwaukee years ago. Used it so much that has to replace the brushes in it 3 times before our loader guy ran it over. I just like the weight of the air 1/2” when using it constantly, that high torque Milwaukee will wear you out holding it over your head on your back.

This is all great information. Thank you.

 

[Iron Beaver]

Yeah, the 175' of pipe wasn't a big pressure drop. At 1-1/2 it'll be pretty negligible. My main goal was to show how pressure drops might add up throughout the system to starve a 1" impact

 

[Ozz316]

Got ya. Thanks for your input. It’s helping me understand how much loss we may be getting. You see shops all the time with one small compressor running everything fine using 3/8 hose, that is what had me scratching my head so much. Maybe they have their compressors pumped to 175 and that is helping the drop. Makes me wish I had specked a higher psi rotary when we bought this one. May have to question my Ingersol dealer a little bit.
I’ve thought about putting a small 20-30 gallon helper tank on the shop side of the building. Don’t know yet till I get to work Monday and check a few more things out.

 

[nadogail]

When you have a long skinny pipe run and a high volume demand you will run into problems. Sometimes raising the pressure will help, sometimes you need more tank volume, once I helped reduce pressure fluctuations by adding distributed storage. A remote tank connected to the system will smooth out the pressure variations just as a large capacitor can improve voltage regulation.

Without a site visit, I don’t have enough information to make a better recommendation.
Call your compressor supply engineer for a professional opinion.

 

[stonesfan68]

I wanted to pick the brain of some air compressor experts on this site. In my shop at work, it always seemed like air tools weren't running well, like we were running out of air. Based on our setup, there is no way we should be running out of air in the shop. We have a IR rotary UP6-15-125 that is we had bumped up to 135 PSI max feeding 2-120 gallon tanks.

The UP6-15-125 has a maximum discharge pressure of 125 PSIG. What do you mean when you say "we had bumped up to 135 PSI max?" Did someone come and install a new pulley? If so then the output of the machine will go down.

These are running through a filter regulator, 2 other filters, and an air dryer. The only reason for the main filter regulator was we had it regulated down previously from an old setup that was running more PSI.

Get rid of the regulator, or replace it with a high quality flow controller that will keep the system pressure constant and act as a "firewall" between the supply side and demand side of the system.

The ideal setup would be

Compressor -> wet tank -> filter/dryer -> dry tank -> flow controller-> to system

Run the compressor at the minimum pressure possible so as to minimize the cost of electricity. Every 2 PSIG of pressure increase results in a 1% power increase, which doesn't sound like much until you start to calculate how much that compressor actually costs to run.

The line from the tanks is 3/4" DOT air line into the filters and such, then run into the piping in the building that is 1 1/2 Galvanized. This setup runs the actuators on the Ready Mix plant that is approximately 175 feet from the compressors. This runs into another set of regulators and oilers set at 80 PSI. Plant never has air issues.

Those DOT hoses aren't doing you any favors in terms of pressure drop. What is the discharge size out of the air compressor? I think that it is 3/4" NPT.

The shop air is about 15 feet away from the compressors, run into a 1/2 inch pipe through a wall to a hose reel with 50 foot of 3/8 air line and a tee from the 1/2" pipe to 1/2" air line for our bigger guns. When running the 1" gun we have to stop sometimes when pulling off lug nuts. Our 1/2" impacts always seem weak. I checked the pressure at the end of the 3/8" air line and it was right at 115 PSI. I put a t fitting with High Flow fittings and a gauge right at my 1/2" impact and when I pull the trigger, it goes from 115 down to 65, no load. Sorry for the long post, just trying to give as much information. I feel like I have everything sized correctly, what are some of your opinions on why I'm loosing so much pressure and potentially CFM?

Upsize the air line size and remove as much hose as possible.

Also, that is a desiccant air dryer. If I recall correctly, that particular series consumes about 18% of the compressed air to regenerate the desiccant. Assuming that you have a 50 CFM dryer, that means that nearly 10 CFM is being blown to atmosphere. Do you need a desiccant dryer? I see that you're in KC, so if you have outdoor piping then you may need the desiccant dryer to keep the condensate in the air lines from freezing during the winter. I'd consider replacing it with a refrigerated dryer if you don't need the air to have a pressure dew point of -40F.

 

[pcmeiners]

For your cfm needs, your setup is not high flow anywhere I can see, Your regulator/dryer etc are under sized; rarely do the manufacturers give you the correct sizing for high flow. Best to get all regulators/dryers etc for a larger pipe size and use adapters to get to your pipe size, from a respected manufacturer. Any valves should be high flow valves, if you order them online and you cannot see the valve internally, it is a good chance it is not a high flow valve, many suppliers are deceptive. 1/2" pipe is only a good size for occasional use by a homeowner. Search for a pressure loss calculator on Google, make sure it takes into account different fittings and internal pipe roughness .

 

[Iron Beaver]

One note, you will often see ratings on a filter or regulator like "200 SCFM @ 100 PSI" These are technically true, but also pretty useless. As I understand it they are saying "If you hook up unlimited 100 PSI air at the inlet and nothing to the outlet, 200SCFM will flow through this"

Put another way
Inlet pressure=100PSI
Outlet pressure=0PSI
Pressure drop = inlet-outlet=100PSI

So yes, you technically can push 200SCFM through it but with a 100PSI pressure drop. To get useful information you need a chart or a graph such as the ones I linked from the Dixon site.

 

[Iron Beaver]

The light came on for me with cumulative pressure drops when I tried to run an IR 2161 (46CFM at load) on two 25 foot 3/8" hoses all hooked together with 1/4" couplings and the tank at 90PSI. Instead of going TTTTTTTT it went T.....T......T......T......T. So I went to my local hose and fitting store and got 1/2" quick couplings. Then to Harbor Freight and got a 1/2" Diablo air hose. I plumbed my whole air system with 1" pipe, regulators, and filters. What a difference! Even for smaller tools I would never go back.

 

[Iron Beaver]

Got ya. Thanks for your input. It’s helping me understand how much loss we may be getting.

I love nerding out about these things

You see shops all the time with one small compressor running everything fine using 3/8 hose, that is what had me scratching my head so much.

I hear people complaining all the time about how their 3/4" impact wrenches cost more and perform less well than their 1/2" models. Also see them turning the pressure way above the rated working pressure

Maybe they have their compressors pumped to 175 and that is helping the drop.

Entirely possible. Even probable

Makes me wish I had specked a higher psi rotary when we bought this one. May have to question my Ingersol dealer a little bit.

I drool over higher spec compressors. That said some 1" or even 1-1/4" pipe, regulators, and filters might be cheaper. Or for ultimate cheapskatery, see below

I’ve thought about putting a small 20-30 gallon helper tank on the shop side of the building. Don’t know yet till I get to work Monday and check a few more things out.

If I were you and my use of the big impact were intermittent, I might try to source a 60 gallon or larger air tank and have it within about 50 feet of where you will be using the 1" impact wrench. One input hooks into your current air supply, regulate that to 125 PSI (or whatever the working pressure of your impact is). Then for the output get a Chicago fitting and put it into a threaded bung in the tank. Maybe add a full flow ball valve for convenience. Then put a Chicago fitting on your 1" impact and run the whole thing with a 3/4" jackhammer hose. Those are often 50' long.

This will give your 1" impact a good few seconds of good, solid almost full power impacting. For many things, that might be all you need. The tank can recharge at lesiure without worrying so much about flow restrictions

 

[Ozz316]

Yes the desiccant dryer does eat a lot of air. We ended up adding another compressor to the system when we bough it, we were running out of air on the one reciprocating compressor. We have had problems in the past with the plant freezing up in the winter, without the dryer. That is why we went with it instead of a refrigerant dryer.
I've watched our pressure gauge on the rotary multiple times while running the plant and it cycles fine and builds air pretty quickly when it cycles on. We go from 130 to 110 I believe and then it builds back up pretty quickly to 130. They didn't change the pulley, our tech came out and did something and we gained a few more max PSI, sorry mistated the 135 max earlier. I agree with deleting the regulator, just something else to restrict flow, that we don't really need any more. We are running 3/4 NPT to the 3/4 plastic DOT style line, not sure if it's actually DOT line or not. So if I remove the regulator, it will go Compressor - Wet Tank - Dry Tank- 3/4 line to first filter w/ auto drain- Dryer- 3/4 line to second filter-3/4 line to 1 1/2 black pipe on the wall. The run of 1 1/2" black pipe to the first fitting for the guns is about 15-20 feet. The 1/2" pipe that I referenced earlier is only about 6-8" that runs through the wall to Ts. I will post a picture of the other side of the wall when I get a chance. I'll let you guys know how things go when we remove the regulator.

 

[Metal-Marc]

I have an old pancake tank right after the regulator, which feeds my air tool. It works great to provide the extra humph needed.

 

[Jswain]

If it were me for the shop air I would probably bypass the dryer system altogether.
Wet tank, dry tank, filter, shop air

As long as you guys didn't have any problems freezing up in the shop. For the plant that does then you could run it wet tank, dry tank, filter, dryer

If needed add auto drains to the tanks

 

[Ozz316]

If it were me for the shop air I would probably bypass the dryer system altogether.
Wet tank, dry tank, filter, shop air

As long as you guys didn't have any problems freezing up in the shop. For the plant that does then you could run it wet tank, dry tank, filter, dryer

If needed add auto drains to the tanks

I thought about that, but the whole place is plumbed with the 1 1/2 pipe already so I would have to rerun a bunch of lines to the other shop.

 

[redmondjp]

As stated above, you need a local receiver tank. I've been watching a lot of abandoned silver mine exploration videos lately - they had auxiliary receivers placed all over in the mines so they would be closer to the air drills. Plumb out of this receiver using a high-flow path to that air gun.