Black pipe 1/2" or 3/4"?

[Scoutman]

I didn't check the price of copper but when I was at Lowes the 3/4" 10' stick was $12.91 and the 1/2" 10' was $10.62 so very little difference in price. Of course they have pieces that are shorter than 10' that are more expensive and I believe I found a thread on here discussing that.

I'm leaning right now to go with 3/4" main horizontal lines and make the drops 1/2". My reasoning is that if I ever get a bigger (2 stage, more CFM) compressor or if I ever expand my air system then I'd have a bigger trunk line to branch off of. Let the parts gathering begin.

 

[OccupantRJ]

I didn't check the price of copper but when I was at Lowes the 3/4" 10' stick was $12.91 and the 1/2" 10' was $10.62 so very little difference in price. Of course they have pieces that are shorter than 10' that are more expensive and I believe I found a thread on here discussing that.

I'm leaning right now to go with 3/4" main horizontal lines and make the drops 1/2". My reasoning is that if I ever get a bigger (2 stage, more CFM) compressor or if I ever expand my air system then I'd have a bigger trunk line to branch off of. Let the parts gathering begin.

I think you are on the right track with this.

 

[LifeLongWNYer]

When you are comparing the prices of copper tubing, or pipe, remember that there are several grades, and each has a price difference, which is based in the actual wall thickness. A piece of 3/4" K has the same outside diameter as a piece of 3/4" L, and likewise the 3/4" M.

Type K has the thickest wall section of the three types of pressure rated tubing and is commonly used for deep underground burial such as under sidewalks and streets, with a suitable corrosion protection coating or continuous polyethylene sleeve as required by code. In the United States it usually has green colored printing.

Type L has a thinner pipe wall section, and is used in residential and commercial water supply and pressure applications. In the United States it usually has blue colored printing.

Type M has an even thinner pipe wall section, and is used in residential and commercial water supply and pressure applications. In the United States it usually has red colored printing.

Type DWV has the thinnest wall section, and is generally only suitable for unpressurized applications, such as drains, waste and vent (DWV) lines. In the United States it usually has yellow or light orange colored printing, common sizes being 1-¼" , 1-½", and 2" copper tube size.

 

[J4nss(WNY)]

1/2" black pipe will be fine for running 1 air tool or a sandblaster at a time. I buy and sell about 20,000 pounds of black pipe and fittings a year. Lately it's all been coming from China and surprisingly, it has been very good quality. I've had more sand hole casting leaks in domestic fittings than the imports. I would rather buy and sell domestic,but my customers won't pay the higher price.

 

[LS6 Tommy]

Just a point to consider... TFE tape & pipe dope are NOT sealants. Pipe thread connections seal based on an interference fit. The threads are tapered, so proper tightening is what seals the joint. The tape/dope is a LUBRICANT that allows proper tightening. It's not a "sealant". There are products labeled as "sealants". They harden after normal proper installation. Proper use of tape is ONE overlapping wrap...

Tommy

 

[mechan]

Just a point to consider... TFE tape & pipe dope are NOT sealants. Pipe thread connections seal based on an interference fit. The threads are tapered, so proper tightening is what seals the joint. The tape/dope is a LUBRICANT that allows proper tightening. It's not a "sealant". There are products labeled as "sealants". They harden after normal proper installation. Proper use of tape is ONE overlapping wrap...

Tommy

So ... why do you believe that PTFE should only be wrapped once and that pipe dope / PTFE is only for lubrication? I think Oatey would disagree.


To form a seal a medium does *not* have to harden.

 

[marinusdees]

I am so HAPPY you asked this question. There will be so many BS answers I can not deal with them. Do what you will, it'll work.

 

[mikefromme]

Just a point to consider... TFE tape & pipe dope are NOT sealants. Pipe thread connections seal based on an interference fit. The threads are tapered, so proper tightening is what seals the joint. The tape/dope is a LUBRICANT that allows proper tightening. It's not a "sealant". There are products labeled as "sealants". They harden after normal proper installation. Proper use of tape is ONE overlapping wrap...

Tommy

Your theory doesn't really apply when you consider that much of Europe uses straight threads with no taper.

 

[J Persons]

I prefer to use Rectorseal for pipe dope. I've had the best luck with applying a light coat to both surfaces, assemble and let it sit overnight. I have about 120' of 3/4" for the main lines and 1/2" for the drops, all black iron.