Air Compressor piping 3/4" down to 1/2" at filter/regulator

[Beaupr]

Hi All, I'm working on the piping of my air compressor in the shop.

Compressor is rated for 18SCFM, and has a 3/4" outlet from the compressor, then goes into a 3/4" copper water-separator manifold.
Then into the filter and regulator (planning to use separate rather than combined).
Then into 3/4" Maxline air lines to the rest of the shop. (it's actually the Canadian Princess Auto version of Maxline.)

If I neck down the piping at the filter / regulator down to 1/2" - is that going to be an issue with flow, pressure, CFM, etc ? Again, after the regulator, the lines go back to 3/4".

I did try to find any answers to this question and really couldn't find anything specific.

Thanks for any input.

 

[mike93lx]

Necking down at one place doesnt negate the larger piping elsewhere.

What is the flow rating of your filter/regulator? If it is above 18 scfm, it won't be your bottleneck

 

[PoorUB]

Hi All, I'm working on the piping of my air compressor in the shop.

Compressor is rated for 18SCFM, and has a 3/4" outlet from the compressor, then goes into a 3/4" copper water-separator manifold.
Then into the filter and regulator (planning to use separate rather than combined).
Then into 3/4" Maxline air lines to the rest of the shop. (it's actually the Canadian Princess Auto version of Maxline.)

If I neck down the piping at the filter / regulator down to 1/2" - is that going to be an issue with flow, pressure, CFM, etc ? Again, after the regulator, the lines go back to 3/4".

I did try to find any answers to this question and really couldn't find anything specific.

Thanks for any input.

1/2" black iron pipe will flow 20 CFM at 100 PSI, out to 50 feet. A few inches of 1/2" at a regulator may cut down your CFM slightly, but not at 15 CFM, 35 CFM maybe.

https://www.engineeringtoolbox.com/air-line-pipe-sizes-d_1522.html

This a good chart to have for air line sizing. It really proves that most hobbyist shops don't even need to go with 3/4" pipe.

I remember one guy telling people to put in a 2" main for air, for a hobby shop. He recomended it for more air volume. 2" pipe holds 1.6 gallons per ten feet. In my shop I would have a tough time hanging 30 feet of 2" so not quite 5 gallons and a whole **** load of work and extra expense for fittings. $20 for a tee versus $3.50 for a 3/4 tee.

 

[Beaupr]

Thank you for your replies. @PoorUB I completely agree 3/4" to my tools is overkill but the Maxline (PA version) kit was $90CAD for 300 feet plus with the better connectors (screw-on, same as Maxline, not the push-in ones).

I'm planning to use a Lincoln regulator 600008 and filter 600108P. None of the Lincoln products listed in the Grainger.ca website show their CFM flow rating. Is that something I should think twice about (if I don't know the CFM rating)? or is something at 1/2" going to suit my needs? One man shop, my max consumption tool will likely be a sandblaster.

 

[PoorUB]

Thank you for your replies. @PoorUB I completely agree 3/4" to my tools is overkill but the Maxline (PA version) kit was $90CAD for 300 feet plus with the better connectors (screw-on, same as Maxline, not the push-in ones).

I have no issues going 3/4" line, I probably would too. Just making the point that 3/4" is over kill for most of use, and some guys want to go larger!