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Compressor - maximum hose length

Techoholic

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Hi

Further to my first post about a roll cab, I also need to buy a compressor for my workshop - similar to the first question, the workshop is far from where I will actually need the tools. My idea was to store the compressor there, and have a hose reel that I can extend all the way to the front of the house. We're talking about maybe 30 metres. Is this too long for your average DIY/Semi Pro compressor to work properly?
Thanks
 
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Lucid Moments

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One thing to remember is that the smaller the size of the hose, and the longer the hose is the more it will restrict air pressure. Given the limitations that you are facing I would look into one of two different solutions.

1. A portable compressor. There are plenty of portable compressors in the 20 to 30 gallon range that you can roll out to your worksite and run close to where you are working. They will have plenty of flow to handle normal air tools like impact wrenches and such, but probably not enough for extended use like an air sander or die grinder.

2. Run a large diameter line possibly buried from where you want to keep the compressor to where you will actually be using the tools. I don't know what is available in the UK, but I expect there are plenty. I like the products from Rapid Air just as one example. Run that in 3/4" or even larger if you want minimal restrictions.

Anyway those are my suggestions. I am sure others will chime in with other ideas.
 

Snapped-off

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You'll have some pressure drop. I wouldn't bother with a small pancake style compressor, but a ~20 gallon should be fine with ⅜" hose for normal DIY stuff.
 
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Techoholic

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If I can avoid laying pipe to bury that would be good, I'll likely be getting like a 50-100L compressor, not high end but not dirt cheap either, but don't want to do that if the pressure drop would be too much. How can I work this out? Anyone know?
 

larry_g

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Add a receiver tank in the workshop. That will give you a burst of air for using intermittent tools like a impact or ratchet.

lg
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beemerphile

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A receiver tank tee'ed into the line closer to the point of use would help. An old Freon tank can be converted into an air tank with one of these. With this arrangement, if your air use is intermittent, the tank can rebuild pressure during the non-use interval offsetting the line loss. Loss is a function of flow. Low flow = low loss. With a tank at the point of use, the tank supplies the intermittent volume and the hose supplying the tank averages the flow like a capacitor in an electrical circuit.
 
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whateg01

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With a long line, as others have said, the pressure is going to drop. Putting a receiver at the work end helps. I've used an old compressor tank that the pump died on. I've also used a little air bubble. The importance also depends on what you are doing. If you are airing up tires, none of it will matter. If you are operating a D/A, it will. Iow, the higher the cfm, the more the pressure drop. Just like with electricity, where the higher the current the more voltage is dropped in the wire.
 

dnschmidt

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I have run 100 foot of 3/8" line without issue in the past but then again I have an 80 gallon two stage Quincy Compressor that produces 17SCFM that I can turn up to 125PSIG to allow for the line loss and still get 90 PSI at my spray guns and air sanders. Sort of a different question than the one you're asking.
 
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Techoholic

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Well I guess the follow on question is what sort of compressor should I buy that is suitable for home use (16a supply) but might help minimise my losses across the hose?
 

GeoBruin

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Your choice of compressor will really not affect your line loss issue. The fact is, whatever pressure reads at the compressor is going to drop significantly at the end of a hose that long. To give you an idea, if you have your regulated pressure at the compressor at 90 psi, and you have a 100 foot long 3/8 diameter hose, assuming you can free flow at 40 CFM, you'll see a pressure drop of over 86 psi at the end of that hose. That's not even usable. You could a 1/2" hose to minimize those losses but a 100 foot long 1/2" hose reel is very expensive and unwieldy.

A member above mentioned he's able to crank up the PSI to offset some of the loss but that's not really an ideal solution, and it likely won't fix your problem. Let's say you crank the pressure up to a maximum 150psi (likely the limit of a compressor in the class you're looking for) and otherwise use the same assumptions as above. You'll see a 55 psi loss at the end of your hose. Now you're thinking "that's still 95 psi left, that's plenty!" but remember that your tank pressure has to be maintained at 150 psi to get that. That means the instant you start using air, the tank pressure will drop below your regulated pressure and again, your usable pressure at the end of the hose will drop. Also, your compressor will run constantly since the cut in pressure will need to be the same as the max tank pressure.

Several people here have mentioned a receiver tank closer to where you will actually be doing the work. That is the most practical and efficient solution to the problem you would otherwise have.

This doesn't have to be something expensive, nor does it have to be some sort of cobbled together repurposed solution. There are lots of tanks available that will serve this purpose and are relatively affordable. Based on the fact that you are using liters as your unit, I assume you are not in the US, so you may not have access to Harbor Freight but this is just an example of something that's out there which can surely be found local to you.


So you would go ahead and purchase your long hose/hose reel, plumb a tee on the receiver tank with a male quick disconnect on one side and an inexpensive reulator/female QD on the other. Now you can set the regulator on your little tank to whatever your working pressure is, (90 ish psi for many tools) and hook a very short hose up between the tank and your tool.

You will get very little pressure drop between the small tank and your tool, and your compressor will have time to "rest" while you draw down the pressure in the receiver tank to the related pressure.

Now all of this assumes use of tools like nailers, air ratchets, impacts, etc. A high flow, constant use tool like a die grinder or DA sander is going to draw down the receiver tank so fast it really won't make a difference.

Hope this helps.
 
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Techoholic

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That’s very comprehensive and extremely helpful to explain why I need to do it that way, or perhaps go for a smaller compressor that I can move with my tool cart. Thank you for that information. I am in the uk you’re right, but I’m sure I can get similar here.

I do like the idea of a small receiver tank mounted in my tool cart which gives me a connection point for the tools directly, so I might look at that route. I’m looking at my options for a tool cart at the moment so I will factor that in to the plans.

Thanks again
 

whateg01

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Another reason not to crank the pressure up to make up for losses during use is that when you are not using air, the hose and all equipment attached will be subject to that higher pressure. So if you crank the pressure up to 150 psi to get 90 at the other end with the impact, when you stop using the impact the pressure is going to go up to 150.
 

GeoBruin

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That’s very comprehensive and extremely helpful to explain why I need to do it that way, or perhaps go for a smaller compressor that I can move with my tool cart. Thank you for that information. I am in the uk you’re right, but I’m sure I can get similar here.

I do like the idea of a small receiver tank mounted in my tool cart which gives me a connection point for the tools directly, so I might look at that route. I’m looking at my options for a tool cart at the moment so I will factor that in to the plans.

Thanks again
You're welcome! I have a small shop with air drops every 6-8 feet around the perimeter and a hose reel that reaches anywhere inside or just outside of my shop and I still have a little tank. It's a little smaller than the one I linked and it's aluminum so it's pretty light.

I bring it out to the driveway to fill tires, use it to run the Brad nailer if I'm doing a piece of trim in the house, and use it with a blow gun to clean off the patio table, blow out keyboards, etc.
 
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Walkers

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I have 250’ of 3/8 on one of mine with nary a problem. I have it regulated at 90, but could bump it up to 175 if needed.
 
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Techoholic

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I have 250’ of 3/8 on one of mine with nary a problem. I have it regulated at 90, but could bump it up to 175 if needed.
So that seems to go against the previous posts about needing a receiver tank. That’s way more than I’d need but I guess it still depends on the compressor.
 

Walkers

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So that seems to go against the previous posts about needing a receiver tank. That’s way more than I’d need but I guess it still depends on the compressor.
I think it all depends on your needs. Most tools are going to want 90psi or less. Yes impacts work great at 175 psi, but they are really not rated to be run that high. I can’t think of a single tool in a normal hobby garage that would be super sensitive to a pressure drop due to a hundred feet of hose. It’s not like you are going to be using a blast cabinet with a small compressor and a long hose.
Just get your compressor situated, get your hose on there and try it out. Adjust your reg as needed to make you happy. Then, if you have issues that bother you plumb in a tank. I can almost guarantee that once you are hooked up and running you are going to forget about this thread and you will be happy.
 

sparky 1971

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I've put all my 3/8 hose (four 50' and one 25', 225' total) together with the cheap standard couplings to get to the end of my driveway and used a 1/2" drive impact before.
 

PoorUB

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Hi

Further to my first post about a roll cab, I also need to buy a compressor for my workshop - similar to the first question, the workshop is far from where I will actually need the tools. My idea was to store the compressor there, and have a hose reel that I can extend all the way to the front of the house. We're talking about maybe 30 metres. Is this too long for your average DIY/Semi Pro compressor to work properly?
Thanks
A big question nobody has asked is what tools do you use? A brad nailer, a 3/8" line might be just fine. A 1/2" air drill or a DA sander, nope, not going to work.
 
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Walkers

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A big question nobody has asked is what tools do you use? I brad nailer, a 3/8" line might be just fine. A 1/2" air drill or a DA sander, nope, not going to work.
I haven’t used an air drill for decades, but I’ll put my money on a DA with my 250’ of 3/8”
 

Citation

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I was going to suggest something like GeoBruin suggested but he did such a nice job I don't feel the need to type much :D

I frequently use about 100' of hose on my compressor when filling tires. That's 50' of 3/8 run in my garage as a poor man's air drop and then 50' of 1/4 coil hose if I'm just airing tires or a second 3/8" hose if I'm going to use the impact. I'm certain I loose operating pressure with this setup but it's one of those things you can always try. Tire inflation doesn't really care and it just takes a bit longer to air up the tires. The impact almost certainly looses power but it's sufficient to pull lugnuts so I don't care.

In my garage the first 50', my poor man's drop, are made from PVC air hose (not PVC pipe). It's the type of hose everyone says not to buy because it's stiff when cold. Not an issue since it never moves. Worst case you buy two long hoses, join them without a quick coupler (save the flow losses) and give it a shot. At worst you are out the cost of the two hoses. It if works then get the real etc. You might save yourself the cost of the real by using a garden hose holder, something that just holds the hose vs actually winds it up.

It's not an ideal setup but if your air needs aren't too high it will probably work well enough (like my poor man's drop). The second tank idea also might be handy if you need to take air to a car or small air gun project that is out of reach of the 30m hose.
 

MarkH

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Sometimes not knowing is the best. No calcs just a 300 foot hose at the door of the main shop. For when you need air outside. For the last 40 years we have done everything we needed to do outside with it. At times ignorance is bliss. The only time we had issues was if someone was doing a high volume job inside the shop. Still everyone else in the shop was having issues inside the shop when that happened too. So nothing related to air outside the shop.
 
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