Compressed Air Piping 1

[NickE]

Theyve moved my Lab from a production facility to an office. The first difficulty was finding a compressor to deliver teh required amount of air, at pressure, while not being to loud, or requiring extensive filtration and drying.

Found that... (Dental grade compressors arn't cheap, but they do what I need.)

Now time to figure the piping.

1) Size: Will 1/8NPT flow 3-4SCFM @80psi? (Sch40)

2) Material: I want Stainless, 304/304L Sch40 particularly. Mainly because I think its cool and pretty. Galvanized or Black pipe is also an option, though it's not much cheaper. (~600' total runs, w/ drops and etc.(This is the R&D/Prototype lab, and will occasionally be shown to customers.) Sch80 PVC has been presented as a lower cost option. I dont like the idea of sitting no more than 6' (and possibly as close as 6") from a plastic pipe with 80psi compressed air in it. Scares the S*** out of me to be exact.

(The environment is 70F +/-2F <40%RH 24/7/365)

Any helpful codes/standards/anecdotes/data I should know about?

Nick
I love materials science!

 

[Montemayor]

Nick:

You're not talking about pipe for this size of flow. On a practical, engineering basis, you're dealing with 1/2" SS tubing that is silver-soldered. It's that simple and plus it is very strong and tough - stronger and tougher than you would imagine. You'll have nothing to worry about putting 100 psig air through it. You can get by with 18 gauge SS or if you can't afford the SS tubing than I would install 1/2" copper piping - also silver-soldered. Both are perfect for the application. I would never recommend you use screwed fittings - or much less steel or black iron - in this type of application. I've done the same kind of small, dental-grade comprssor for my friend and next door neighbor who happens to be a dentist. The installation came out great. You can't hear the compressor since we installed it as far away as we could. And exposed SS or polished copper give an attractive aesthetic look to a Lab.

There is no common sense reason to even use schedule 40 piping. It's too much of an over-kill and when applied to stainless, it's needless expense. Use tubing if you are going with SS. In the diameters you are talking about, all you need is the minimum wall that allows you to support and solder the tubing. The smaller diameter tubing can safely take well over 150 psig pressure with a good contingency.

I agree with you that SS tubing is called for in an R&D Lab. The cleanliness and sturdyness of the material pays back for itself. And soldering is faster and less expensive than screwing because of the much less labor costs.

I hope this experience helps.

 

[NickE]

Sorry thsts 600" total run.... Big mistake there.

Monte- does that change anything?

Meanwhile Nick grabs his estimate from the boss' desk and starts googling stainless tubing, and copper.

(Water Pipe?)

 

[Montemayor]

The length of the total run of tubing doesn't change the diameter or the recommendations.

Copper pipe is available in three basic types:

Type M is a thin walled pipe. It is the most common type of copper tube sold, used mainly behind walls inside homes to route water from the service line and water heater to the fixtures. Trunk lines are typically run in 3/4-in. type M copper with 1/2-in. type M branching away to serve individual fixtures. I don't recommend this type.

Type 'L' (hard or soft) for thicker wall tube, considered standard piping for use for water services inside and out, especially outside or wherever the pipe will be exposed.

Type 'K' (hard or soft)the thickest, used mainly between water mains and the meter (underground), for heavy-duty vacuum pump lines and underground lines.

Type 'L' is preferred by some contractors for home use and even industrial applications. Local codes will dictate which type of pipe is required for the work being planned and type L is usually acceptable. Copper is very durable and lasts for many decades of years. It is usually connected by soldering - lead-based or silver. Silver is much stronger and the preferred joint.