Is there a Plumber in the Room (how to hook up an air fitting??)

Sparky · Jul 8, 2008

So- it's been a few years since I installed copper 1/2 lines deep deep inside the walls of my space - running all the way to my darkroom. I'm getting bored of using canned air. So now's come the time to hook up mr. compressor...! Has anyone done this in their space...? I'd imagine there'd be at least a FEW... any suggestions from transitioning from the copper to the compressor and a coiled hose fitting..? Any suggestion for guns at the darkroom end - ones that won't blow the neg clean out of the film holder?? Also - what about filters...? Suggestions? THX.

Photo Engineer · Jul 8, 2008

I use a tank of Nitrogen for my DR and have an ordinary welding guage on the tank. This transitions neatly to a standard fitting which I then use to pipe the nitrogen the 20 ft or so into my darkroom. I set the pressure on the tank at 10 psi and have a spring actuated nozzle on the end of the line. When I want nitrogen, I press the lever on the nozzle and get a burst of nitrogen directed just where I want it.

Nitrogen is more versatile than air! My one tank has lasted over a year, and refills are about $30. I own the tank and valves.

PE

resummerfield · Jul 8, 2008

My compressor is in the basement, bolted to the floor. A flexible hose connects to the copper pipe which passes a few condensate drains on its way to the upstairs darkroom. I have installed a regulator and gauge in the DR, and reduce the pressure to 8 to 10 psi before terminating in an ionizing “blow gun” with an integral filter.

Remember that all air compressors (except the oil-less diaphragm models) will slightly contaminate the compressed air with oil. You must use some type of filter system at the air outlet in the DR.

I recently installed a Nitrogen tank, similar to the setup PE describes, for purging the Oxygen from chemistry. Now I find myself using Nitrogen more and more in place of air for cleaning negs. It has no moisture and is free of oil contamination. If I were building the DR again, I would probably eliminate the air supply in favor of the Nitrogen.

Sparky · Jul 8, 2008

Wouldn't using a lot of nitrogen for cleaning in such a small space (my exposing room's pretty tiny) lead to any sort of issues with staying conscious...? Seems oxygen would make one much more energetic to print..!

Sparky · Jul 8, 2008

That's why I was asking about the filter though... I need to use it for other stuff - not just photo stuff... so if anyone can help with the fitting info - that'd be awesome.

Steve Smith · Jul 9, 2008

I don't know what the rules are in the US but in our factory copper is never used for compressed air. I don't know why but I was told it was not a good option many years ago. We use either iron with threaded joints or, for short runs, rubber hose specifically for air fittings. This is the most flexible approach for possible future modifications.

Steve.

Sparky · Jul 9, 2008

Well - I don't really have a choice. I'm not interested in two more years of work to rip out all the walls and wiring, etc just to change it to something better. It's what I have and I have to work with what I've got....

Steve Smith · Jul 9, 2008

When I am back at work tomorrow I will ask why we don't use copper. It could just be that our system has too much pressure for copper. It may be fine for a lower pressure domestic application.

Steve.

Curt · Jul 9, 2008

I don't know what the rules are in the US but in our factory copper is never used for compressed air. I don't know why but I was told it was not a good option many years ago. We use either iron with threaded joints or, for short runs, rubber hose specifically for air fittings. This is the most flexible approach for possible future modifications.

You are correct, the first thing that caught my eye was Copper and Compressed Air, steel/iron pipe yes, copper pipe no.

Dan Henderson · Jul 9, 2008

I purchased a very small air compressor and installed it just outside the darkroom door. I used a short length of rubber hose after the regulator and condensate filter to connect to a union that I sort of custom fitted (read jerryrigged) into a standard plastic wall plate. The coiled hose fits on the darkroom side of the plate and ends in a standard blow gun. Before deciding to go that route I contemplated running copper lines from a shop compressor at the other side of the basement. I am not a plumber but am unaware of any rules against using copper for air lines.

I am now concerned about the oil contamination. Does anyone know about the filter that resummerfield mentions?
Dan

Sparky · Jul 9, 2008

Hmmmm... these guys seem to think it's not such a bad idea... they seem to know what they're talking about too...! Maybe I can learn something here. Nothing on air line filters though...

http://bbs.homeshopmachinist.net/showthread.php?t=123&highlight=shop+air+design+guide

bobwysiwyg · Jul 9, 2008

The only limitation on copper for gases that I am aware of is flammable gases. Particularly acetylene.

Steve Smith · Jul 9, 2008

bobwysiwyg said:
The only limitation on copper for gases that I am aware of is flammable gases.

In the UK the same copper we use for water is used for the gas supply. That's fairly flammable! Iron should be used for gas where it passes through joists - but rarely is.

I'm sometimes envious when I see US house restoration TV shows where the 1/2" copper pipe is soft annealed on a roll and is fairly flexible. We use hard annealed pipe in 10' lengths which have to be formed to shape with a pipe bender - a ridiculously designed piece of equipment that requires you to have three hands to operate it correctly.

Steve.

Steve Smith · Jul 9, 2008

I honestly don't think you will have a problem with copper despite my initial reservation as this is a fairly low volume, low pressure application.

Somewhat related, a friend of mine has an engineering business. He does occasional work for a company making carbon fibre body panels for Aston Martin DB9 cars. The moulds for these parts are infilled with a metal loaded concrete and embedded in the concrete are ordinary copper pipes which carry heating oil at high pressure. The pipes expand at a different rate to the concrete and occasionally burst. When this happens the concrete has to be removed by shot blasting and new pipes installed. The repaired assembly then has to be pressure tested to 600 psi. I think it only operates at about 80 psi.

My friend decided to do his own test and connected a piece of copper pipe with an end cap soldered on to his pressure testing machine. When he got to 3000 psi (I couldn't believe it either!) he decided to go no further.

I still don't know what the alleged problem with air and copper is but I intend to find out tomorrow.

Steve.

resummerfield · Jul 9, 2008

I used to work in the aviation industry, and our commercial hangar (built in 1990) used 3/4-inch type-L copper pipe for the shop air supply. There are 3 grades of copper pipe, K, L, and M. Type-K is the stoutest, then type-L, and finally type-M being the thinnest and commonly used in most residential situations. Although I cant remember all the details, I checked the specs when I built my darkroom (and garage with plumbed air supply), and type-M (the weakest), with common sweat fittings which are the weakest link, was capable of withstanding at least 600 psi. I plumbed my DR air supply with 1/2-inch type-M, and my compressor generally pressurizes it to around 150 psi.

Any absorbent filter will catch the oil contamination. Check with a paint supplier (or an auto parts supplier like NAPA) for an inline filter which just screws onto your blow gun. The oil contamination is almost insignificant using the very small quantity and pressure for the darkroom, but it is present. The filter should remove it.

Sparky · Jul 9, 2008

I'm sure mine is Type M eric... it's just the regular water line stuff at home depot... how did you transition the ends from the copper to 'regular' air fittings...??

glbeas · Jul 9, 2008

You can buy threaded transitions that are sweated to the end of the copper pipe. A large variety of connections and thread sizes can be had.
Dead Link Removed

resummerfield · Jul 9, 2008

Sparky said:
.... how did you transition the ends from the copper to 'regular' air fittings...??

I terminated my 1/2-inch copper line with a 1/2-inch sweat to 1/2-inch NPT elbow with "ears" that could be firmly mounted to the stud behind the wall. But like glbeas said, the variety of fittings available is amazing. Most air line fittings are 1/4-inch NPT, but check your specific "blow gun", regulator, and filter and get the fittings and adapters that work for you.

Here is a picture of my setup. I come out of the wall with a short length of 1/2-inch NPT pipe, 1/2-inch NPT elbow, 1/2-inch ball valve to shut off the air, 1/2-inch to 3/8-inch bushing to match the regulator inlet thread, regulator, 3/8-inch to 1/4-inch bushing, 1/4-inch tee to attach a gauge, and finally the air hose to the blow gun. When possible I used brass NPT fittings to avoid any possibility of rust. Its all shown on the attachment, except for the blow gun.

Sparky · Jul 9, 2008

nothing showed up on that link... what term should i search for... or is there a product id number..?

Photo Engineer · Jul 9, 2008

Steve Smith said:
In the UK the same copper we use for water is used for the gas supply. That's fairly flammable! Iron should be used for gas where it passes through joists - but rarely is.

I'm sometimes envious when I see US house restoration TV shows where the 1/2" copper pipe is soft annealed on a roll and is fairly flexible. We use hard annealed pipe in 10' lengths which have to be formed to shape with a pipe bender - a ridiculously designed piece of equipment that requires you to have three hands to operate it correctly.

Steve.

Steve;

I have not seen the same programs you have and I must be behind the times. My copper pipe is hard annealed in 10' lengths that I cut with a copper pipe cutter with 2 rollers, a circular cutter and a pressure adjust knob. I've used it for years and plumbed my entire darkroom.

I never had to use a bender, but I have one. I bought copper elbows that I soldered in place. Too hard otherwiise.

Our gas is in galvanized pipe with screw fittings.

And, I use flexible plastic tubing in my darkroom for nitrogen which is more flexible in use than air. You can only use air to blow off dust, but you can use tanked nitrogen for that and for putting an inert head on developers and fixers.

So, although I have a compressor, I don't use it in the DR!

At about $120 for the valve and $25 for the tank plus about $10 for the tubing, I've had nitrogen for over a year.

PE

Steve Smith · Jul 10, 2008

Photo Engineer said:
I have not seen the same programs you have and I must be behind the times. My copper pipe is hard annealed in 10' lengths that I cut with a copper pipe cutter with 2 rollers, a circular cutter and a pressure adjust knob. I've used it for years and plumbed my entire darkroom.
I never had to use a bender, but I have one. I bought copper elbows that I soldered in place.

Same cutter here. Sounds like in the US you can get either hard or soft annealed pipe. In the UK the only pipe available soft on a roll is 8mm and 10mm diameter usually for short runs connecting up gas appliances. It can be used to connect central heating radiators to a central manifold but I always use 22mm and 15mm (3/4" and 1/2") for this.

The air conditioning guys here use flexible copper 1/2" for condensate draining but it never seems to be used for domestic water.

Despite my complaints about pipe benders, I do like to use them instead of using up fittings. It's an accomplishment to accurately bend a complex shape into a single piece of pipe to fit round some obstacles. Sometimes the resulting piece is quite a work of art. Pity it is usually covered up!

Steve.

Sparky · Jul 10, 2008

Photo Engineer said:
At about $120 for the valve and $25 for the tank plus about $10 for the tubing, I've had nitrogen for over a year.

PE

I'm not sure I could afford to use that in my DR - only because I'd be using it to clean film holders too! That's why I want to go with the compressor. I reckon that I need at least 5-10 mins of full-running air to clean a set of film holders. I could see going through a tank of Nitrogen pretty quickly at that rate!

eddym · Jul 10, 2008

Photo Engineer said:
You can only use air to blow off dust, but you can use tanked nitrogen for that and for putting an inert head on developers and fixers.

Hey Ron, my chemistry's pretty rusty, but I don't remember nitrogen as being an inert gas. I guess it's just less active than oxygen?

willem · Jul 10, 2008

hi,
I use an oil-less Gude prof airbrush compressor. It is strong enough for the cleaning and the negative stays in the holder. It does not fit another piece of equipment I bought a few years ago though: A simco anti-static (ionzing) air top gun. This needs a lot more air and I think that amount will be too much for my film. I am not sure though, so maybe will eventually hook it up to a compressor.

So the best thing for me is a not too heavy compressor with an antistatic air gun that does not need too much air. There is one I know of. The labokey 5200, see picture. Very hard too find though..

Photo Engineer · Jul 10, 2008

eddym said:
Hey Ron, my chemistry's pretty rusty, but I don't remember nitrogen as being an inert gas. I guess it's just less active than oxygen?

For all practical purposes, nitrogen is inert. A bold of lighning will ionize it and create nigrogen oxides, but since you don't usually have one in the lab it is inert. And before you comment, no, static discharge on the film is not powerful enough.

Even inert gases are now found to react though, so they can make "salts" of them with other compounds. But, Argon and Neon are rather expensive for our purposes.

PE

Is there a Plumber in the Room (how to hook up an air fitting??)

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