Air compressor flow and plumbing question

[RickDel]

Hello, I'm pluming my Quincy 5 HP compressor. I'm going to run 35-40' of 3/4" copper for cooling in a vertical radiator layout. I'm not clear on a few things.

My compressor outlet is 1/2". I'm planning to use 3/4" copper pipe to help maintain the cfm but the regulators and filters will be 1/2" inlet / outlets.

My question is, will there be much advantage to using a 3/4" x 36" jumper hose from the compressor to the regulator versus a 1/2" x 36" jumper. The cost is significant, tho, I'd rather pay more and do it right the first time if it makes a difference. (the 3/4" to 1/2" fittings are like $18 a piece and the Jumper hose is like $20 cheaper for the 1/2")

Thanks

 

[Hornman]

If the compressor outlet is 1/2", the is no good reson to use anything larger than 1/2" downstream.

 

[RickDel]

So, no difference in 1/2" vs 3/4" jumper hose? I do see an advantage to the 3/4" in the plumbing because it will have less reduction of cfm at the bends, right??

I tried to use one of those engineering charts to determine cfm lose with bends, but it was over my head. So, I figure it wouldn't be any harder to just use 3/4".

 

[matt_i]

Without going too far into fluid mechanics, the straight pipe also has friction. One "neck" doesn't completely defeat the purpose of having a larger trunk line.

Best is to use as large as is economically feasible, imo. A hex ****** into a 1/2" bell reducer to 3/4" would be good enough, could be black iron/steel pipe or bronze if you like the copper-theme.

 

[RickDel]

thanks matt i,

I'm trying to follow your advice, but need to ask another question. I think you're suggesting use 3/4" where I can and a 3/4 to 1/2" reducer to the tank would be best.

However, I currently have a 1/2" 45° fitting to a 1/2" shut off valve on the compressor (arrived that way). Do you think I should remove that and install a 1/2 to 3/4" 45° fitting with a 3/4" shut off valve and a 3/4" Jumper hose? Or just leave the 1/2" shut off valve and use a 1/2 to 3/4" fitting to fit a 3/4" Jumper?

Sorry if I'm over thinking this.. I just want to set it up the best I can from the start and have no regrets.

Thanks

 

[mizzoutrover]

I agree with Matt, the short piece 1/2" doesn't reduce flow as soon significantly as a long run would.
For example, if your house has natural gas service, all of your natural gas is probably running through a 1/4" hole at your service tap to the gas main, your much longer service line up to the house is 5/8 or 3/4", the short reduction has a very slight reduction in the overall flow.

 

[RickDel]

Ok, maybe I misunderstood..... So, a short 36" x 1/2" jumper hose would be fine, but try to use 3/4" as much as possible (the long copper pipe runs should definitely be 3/4")

 

[tcianci]

You're wasting your money going to 3/4 on any part of your system. A 5 HP compressor is likely in the 10-12 CFM range at best and you can pull 10 CFM through 1/2"tubing or iron pipe for about a mile before it's going to bother anything.

 

[Kaizen]

I think the only thing the 3/4 will do is provide more surface area for cooling. You are limited to half inch so whatever cfm gets through that is it no matter how big you make downstream. You sure you don't have a removable reducer on the tank?


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[RickDel]

You sure you don't have a removable reducer on the tank?

The manual states 1/2" outlet and it it doesn't look to have a reducer.

 

[tjdux]

.75 inch cant hurt. I do feel .5 inch for 5000+ feet may not be ao good but foe short runs (1 ft or less it makea very little difference)

If the money's close go .75 for the small hose run. Same with the hardlines. The overall money is probably not a huge difference.

Where it really pays off is peace of mind. You then never have to worry your hardlines are too small.

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[Bondo]

Ayuh,.... With Air, the larger the lines ya use, the greater the volume is available, period,....

In the extreme, a 4" trunk line would be like havin' another pressure tank,...
Doesn't change the total cfm of the pump, but the pump will kick on later,...

 

[Citation]

You're wasting your money going to 3/4 on any part of your system. A 5 HP compressor is likely in the 10-12 CFM range at best and you can pull 10 CFM through 1/2"tubing or iron pipe for about a mile before it's going to bother anything.

A true 5hp is going to be rated closer to 17 cfm and the tank certainly can do even higher bursts.

 

[pcmeiners]

Go along with Matt use 3/4", 40 ft does not give significant pressure loss for 1/2", but does increase volume for high flow uses...

Gas flow calculator
http://www.freecalc.com/gasdiafr.htm

 

[RickDel]

Thanks guys. Although, I'm already going 3/4 lines, my main question was whether or not a 1/2 versus 3/4 jumper hose off the tank would make a significant difference. Thanks.

 

[Sarki]

Ayuh,.... With Air, the larger the lines ya use, the greater the volume is available, period,....

In the extreme, a 4" trunk line would be like havin' another pressure tank,...
Doesn't change the total cfm of the pump, but the pump will kick on later,...

I believe Bondo's got it right.
At least that's my thinking and I'm about to run some copper lines from my compressor as well.
Planning on running 3/4" on my horizontal main line and drops.
As others said, at the end of the day the price difference isn't that much unless you're really running some long lines and lots of drops.

 

[Sarki]

Thanks guys. Although, I'm already going 3/4 lines, my main question was whether or not a 1/2 versus 3/4 jumper hose off the tank would make a significant difference. Thanks.

I'm going with a 1/2" jumper as already have one and I don't think it will be an issue.