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Increasing SCFM on a compressor

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trooper1954

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Nov 4, 2016
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Salmon Arm, BC, Canada
Hi All,
I have an older 60gal 13.5scfm @ 90 psi Cambell - Hausfeld 5HP compressor Model HS 5610.
I use this for sandblasting in a stand up cabinet, and am finding it falling a little short...also want to use this with a Pot blaster for sandblasting...I'm looking at ways to increase the CFM's to around 20+.
If I add another 60 gallon compressor and run it in series, I know I'll get greater volume storage, but does this translate to more scfm? For example, if I added another compressor the same, do I get 120 gals storage and 27scfm @ 90 psi?
What are my options here apart from buying a new compressor?
And does anyone have experience with linking two compressors and how its done?
Thanks for any advice.
 
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5ubtle

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tak1313

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I THINK if connected in series, the resulting potential SCFM is still 13.5. I believe they have to be connected in PARALLEL (ie. combine the OUTPUTS of the two) to double the SCFM.
 
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5ubtle

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@tak1313 - Depends on what he means by series. If he means to connect the output of compressor #1 to the pump input of compressor #2, then yes, only 13.5scfm and some crazy high final output pressure. Do you think that he intends to do that?

i think it likely that he means to connect the tank of compressor #1 to the tank of compressor #2, and then draw his air from the tank of compressor #2.
 
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Citation

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Air compressors are not batteries, they don't double the pressure if you connect them in series.

Series is fine so long as the connection is large but realistically you would probably connect in parallel and draw out from the connector. That is because most larger tanks have an inlet (occupied by the pump outlet), a tap to check pressure/place blow off valve, and a bung on the side were you can connect a large pipe to your air system. Some pipe connecting those bungs is likely the only realistic way to tie two larger compressors together. Since that is also the place air leaves the tank you are likely to have some T that goes between the two tanks and the rest of the air pipes.

Let's assume we have two bungs for connecting (one on each side of the tank), what would that do if the compressors were connected in series (Tank A into Tank B)? Well if the bungs are large enough to handle all the air flow then we would expect to see both tanks at the same pressure when nothing is happening. When air starts flowing, it leaves the outlet of Tank B. Since air is leaving tank B, there is a pressure drop and air from Tank A flows into B to make up for the loss. So long as the outlet of Tank B is big enough, tank B will have no trouble flowing out a lot of air, far more than the pumps can keep up with. If the connection between Tanks A and B is small (say really, really small) then it will be too restrictive to keep up with the flow leaving tank B and it will be almost like you have just one tank. However, if the connection is really big (say 6" ID) then it's flows so fast it's like the two tanks are really just one big tank.

So if your tanks have bungs on both sides and if your pipes are large enough (1" ID is likely fine) they will work like they are just one big tank. But if your connection is small (1/4" ID hose) then your flow rate is more like the rate of Compressor B + how ever much air you can squeeze through that small hose with the pressure difference between the two tanks.

Basically all is fine so long as the connecting hose/pipe is big.
 
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seber

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One thing you might consider is setting the start pressure on one of them lower than the other. That way, for lighter uses you will only be running one compressor.
 
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Citation

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seber said:
One thing you might consider is setting the start pressure on one of them lower than the other. That way, for lighter uses you will only be running one compressor.
Click to expand...
You will certainly want the motors to not start at the same time to avoid a large current surge. Ideally you would have a delay relay so they both can run but even when started from empty they would stagger start.
 
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tak1313

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5ubtle said:
@tak1313 - Depends on what he means by series. If he means to connect the output of compressor #1 to the pump input of compressor #2, then yes, only 13.5scfm and some crazy high final output pressure. Do you think that he intends to do that?

i think it likely that he means to connect the tank of compressor #1 to the tank of compressor #2, and then draw his air from the tank of compressor #2.
Click to expand...
I'm not sure. His post says SERIES, that is why I did my first post about having to be in PARALLEL to increase SCFM. Real world though, seems like it would be a real PIA to actually connect in SERIES (then you have to worry about the pressure limit of everything including the tank) - even PARALLEL seems like a somewhat pain but more doable.

I never thought of doing myself. In fact, I got my 60 gal on clearance at HD (Husky made by CH). Tested it, ran it a couple of times, then got into Milwuakee M18 and haven't touched it since. I'm just DIY, so my use was going to be somewhat limited anyway - i saw it on clearance, asked the manager if they would sell for $100 less than the stickered clearance price (thinking he would decline it), and he said "OK" right away so I didn't want to be "that guy" and suddenly back out. I figured if the reason why he accepted so fast was because there was a problem, I could fight for them to take it back anyway.
 
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