some air compressor questions

[FigureLLC]

Originally Posted by nuttyman

actually galvanized is not recommended as the galvanizing can, in some instances, come off the pipe on the inside & clog separators & regulators. do not use plastic (PVC) either. black pipe is recommended.

interesting you say that... black pipe rusts though. and i've read to use galvanized... i'll have to look more into it.

[FigureLLC]

"Black steel is used as it is cheapest of metallics. Its drawbacks are the fact that it corrodes on the inside."

"Galvanized is not worth mentioning due to cost, but it is a very good choice for corrosion resistance."

BUT then there's:

"Do not rely on so-called "galvanized" pipe. What is conventionally called galvanized pipe is merely galvanized coated (not "hot-dipped") externally. Hot-dipped is the only credible type of protection - and it is subject to visual and mechanical surface inspection. I have never heard nor seen any pipe hot-dipped internally; I can't imagine how anyone could inspect the pipe internally! And if it can't be inspected, it doesn't warrant any interest in any application." -this was supposedly from a "registered engineer"

and this from Air Power USA:
"Conflicting data on inlet and discharge piping

We are installing new 1000HP centrifugal compressors in our plant. We have received conflicting data on the proper material for inlet and discharge piping! The OEM recommends stainless steel, but the engineering firm wants to use galvanized schedule 40 pipe. What do you say? - Birmingham, Ala.

Air Power USA Answer:

The question of galvanized piping comes up often in compressed air system piping, as does the question of using stainless steel instead of schedule 40 black iron for the nominal 100 psig air systems. Let's look at inlet and discharge piping separately.

Inlet Piping:
The proper inlet pipe brings the air from the filter to the compressor with no pressure loss and should not create operational problems with any type of self-contamination on the inside. It is important to realize that the ambient inlet air condition may well dictate the selection of one type of pipe over another.

Galvanized inlet piping has the advantage of resisting corrosion better than standard iron pipe. However, over time when the corrosion does set in, the galvanizing material then peels off. The inlet pipe is now a producer of potentially very damaging, solid contaminants between the filter and the compressor. This would be particularly dangerous to the mechanical integrity of a centrifugal compressor.

During high-humidity weather it is quite conceivable that condensation will form in the inlet pipe (therefore, the OEM installation manual recommends a drain valve be installed on the pipe before the inlet). Condensation in the pipe will obviously accelerate the time frame before the coating breaks down. This time frame is dependent upon where the thinnest portion of the coating is applied.

Stainless steel inlet pipe is the best possible material for such large-diameter, low-pressure inlet air, as long as it is installed properly and the inside is properly cleaned.

There are also many grades of plastic material suitable for inlet air piping.

Summary: We recommend either stainless steel or proper plastic-type material for inlet piping and do not recommend galvanized piping." (goes on to say about the same for outlet piping)

we'll call it a draw.

what i learned from the above statements and some other stuff i just read: use copper, aluminum, or stainless pipe if you're real worried about corrosion.

[nuttyman]

agreed. stainless would obviously be the best bet, but damn would it be expensive!!

[FigureLLC]

i can't even imagine what stainless would cost. some of the articles i read could justify the expense for very large-scale companies. and the stuff is supposed to be pretty difficult to work with since threaded fittings don't work well with it. i'll do some research on what copper or aluminum would cost, but i'm guessing we'll just be back to the black or galvanized.

[tjespo22]

hey figure llc how was ur booth made out of pvc? held up good? would u recommend it over a booth made out of wood? i see you also had a dust collector, can i ask why? were u re using the powder? im new to this so i might sound stupid.
thanks alot
espo

[FigureLLC]

for an inexpensive fast-to-build booth, the pvc is really hard to beat. i'll upload some more detailed pics of some of the things that will help. pvc isn't meant to be structural, so we used 1/16in (i think) steel cable with turnbuckles across the diagonals. this eliminates any wobble and the turnbuckles allow you to adjust the length of the cables to square up the frame. some limitations of the pvc booth is you can only hang very light parts from it, and mounting anything to it requires some creativity. i plan to build a new booth soon, i think out of mdf.

the dust collector does two major things: 1) it provides some air flow through the booth (from the open end to the closed end) so that the powder cloud doesn't float out of the booth all over the shop, and 2) since the latest revision has the air inlet at floor level, it makes clean-up (for polishing, too) a snap, because we can just sweep everything right into the opening and it gets sucked up into the collector drum. this wasn't possible with the furnace filter system we previously used (we use a cyclone now).

[tjespo22]

well what i would do it just hang a chain or something from my ceiling and put it through the top of the booth to hang heavy parts(im doing atv parts). and prob get cut a hole somewhere in the tarp, put a fan with a hose on the other side going outside. how do you think this would be?

[FigureLLC]

a regular box fan will probably disappoint you. they're high-volume, low-pressure, so they stop moving air pretty fast once you introduce restrictions like filters, duct, etc. and since the motor is in the air stream, it could get caked up with powder and fail prematurely. good news is they're cheap so you can try it and not lose sleep if that happens. i'd recommend as large a flex duct as you can use.

[tjespo22]

what's a good dust collector for a booth a bit smaller than the PVC one u had. Mane u can link me

[tjespo22]

Also,with a box fan I wouldn't need a filter, the exhaust would just go outside. .