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Topic: C02 to clean projectors...Pro or Con?

Adam Fraser
Master Film Handler

Posts: 499
From: Houghton Lake, MI, USA
Registered: Dec 2001

posted 04-02-2002 12:52 AM

Most compressed air tips for compressors are sold OHSA approved for 30 PSI, the way you can tell is if they have 3 Holes drilled into the side of the tip to release the pressure when they are blocked by fingers, arms etc. The only air tips that usually dont have the 3 holes are Brake Piston remover tips. At least has been in my experience.

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Adam Fraser
www.pinestheatre.com

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Jerry Chase
Phenomenal Film Handler

Posts: 1068
From: Margate, FL, USA
Registered: Nov 2000

posted 04-02-2002 12:52 AM

Pressure washers are commonly used with a distance of less than a foot from nozzle to surface (when cleaning concrete roof tiles and pressure washing sidewalks). I've used them many times.

More likely the pressure washer industry lobbied hard to keep regulations away. High pressure washing is the only way to properly clean some items, and a 30 psi limitation would immediately be met with howls of indignation. Pressurized air OTOH has no "protector" industry and gets the maximum limitations thrown at it that OSHA thinks it can get away with.

IMO, OSHA does some great things for safety, but suffers from overkill and political influence like the rest of U.S. government.
It sometimes reminds me of the mother in "A Christmas Story."

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David Koegel
Film Handler

Posts: 55
From: Alexandria, VA
Registered: Jun 99

posted 04-02-2002 08:23 AM

Just came across a very enlightening story that illustrates what can happen when the valve breaks off of a CO2 cylinder:

www.pp.okstate.edu/ehs/MODULES/cylinder/theone.htm

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 04-03-2002 01:42 AM

I used to use Kenair 'air duster' compressed air spray from Jack Roe on optical sound pickup heads only. I was taught to always hold the can vertically and to direct the spray across the surface of the cell rather than directly against it in order to prevent the force of the blast damaging the cell, or the propellant from contaminating it. One brief squirt (i.e. half a second) as part of the start-of-day cleaning routine was fine. There again, this was in an especially dusty box with quite an exposed soundhead (the projectors were FP-20s), so it might not be necessary in some other situations.

I really can't see a health and safety issue here - in a ventilated projection box of 100 cubic metres or so, the odd cubic centimetre of Co2 is hardly going to kill you (unless you squirt it up your nose or practice some other similar fetish). True, you can drown with a teaspoonfull of water in your lungs, but that's got to get in there somehow. In much larger quantities, i.e. from a compressor situated in the box, I can see that C02 poisoning might be an issue.

I agree with John P that compressed air is a waste of time for anything except surfaces which are too fragile to make physical contact with a cloth or a brush of some description - you're only moving the dust, not removing it.

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Dave Macaulay
Film God

Posts: 2321
From: Toronto, Canada
Registered: Apr 2001

posted 04-03-2002 07:34 AM

Re: installing compressed air service in a booth...

Make sure this is done by someone who knows what is necessary! Compressed air tends to produce quite a bit of water in the lines, and they must be plumbed properly to drain properly.
I've seen booth installations where the air nozzle turns into a rusty water nozzle, one in particular would be fine for months and suddenly supply at least a gallon of nasty rustwater that had collected at a low point in the piping until it finally reached a siphon level.
Unless your compressed air plant uses a chilled or dessicating air dryer you WILL get condensation in the air lines. Try to insist on correctly plumbed pipes and self-draining droplegs.
Also.. unless you have an oil-free compressor (rare!) or you use a coalescing oil filter, the air will also carry a fog of oil droplets.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 04-03-2002 07:59 AM

Spraying a high-pressure stream of rusty water or oil droplets at a lens or bearing is NOT a good idea.

Likewise, spraying cold liquid CO2 or FREON will likely cause damage and condensation. (Although it can be used to diagnose thermally intermittent problems in electronic components):
http://p2library.nfesc.navy.mil/P2_Opportunity_Handbook/3_IV_3.html
http://es.epa.gov/oeca/fedfac/fflexp2/techtip/env-fs2.html
http://support.tandy.com/support_supplies/doc2/2968.htm

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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002

posted 04-03-2002 04:34 PM

I had adjusted my air pressure based on what the nozzle said it could handle. It said "less than 90psi" so I chose 85psi. (This is a Campbell-Hausfeld attachment.)

I will now adjust it downward to 30psi now that I've read your input.

Thanks.

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And, hey! Let's be careful out there.

~Manny.

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John Hawkinson
Film God

Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002

posted 04-03-2002 04:51 PM

Yup, there's a lot of plumbing stuff to worry about...our Facilities folks have a lot of experience with this, they provide air to many labs on campus, etc., etc.

The McMaster-Carr catalog has some good overview text about how you're supposed to build together compressed air systems, along with this nice diagram:

But yes, the quotation for what they're installing includes a filter and a regulator...

--jhawk

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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002

posted 03-15-2004 12:29 PM

Nearly two years later, I thought I would post a follow-up:

Without a doubt, that compressor of mine came in handy during the early days when I was rehabilitating the machines I inherited. However, once we got into a regular maintenance schedule, I found a small Shop-Vac that I liked and stopped using the compressor.

I found it true that using the compressor for general cleaning did more harm than good, as it transferred the dust/dirt from the operator side of the projector into the gears.

So, now I'm more or less a convert. A compressor can come in handy during an overhaul but use a vacuum cleaner for regular cleaning. Get a cool set of nozzles.

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Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999

posted 03-16-2004 08:23 AM

We have a compressor with a regulator and an oil and particulate filter, but I don't use the compressed air for cleaning. I have a sprayer attachment that I adjust to release a narrow stream of cleaner -- sometimes alcohol, sometimes 111 Tech, depending on the area that I am cleaning. Basically I use the compressor/spray unit in one hand to squirt the cleaner at the surface and with the other hand I wipe away the dirt and liquid together. For some really nasty accumulations, the available pressure that you have at your command will let you flood away any amount of dirt and oily grim. With this method, the liquid can be controlled to flow only where you aim it; the dirt is captured by it (rather than being blown away as it would by using just air) and then it is removed by the good old fashion shop rag.

What's nice about it is that a good spray can is fully adjustable and so the flow can easily be controlled with one trigger finger, allowing just enough liquid with just enough force to spray the surfaces.

I do admit though that I use the air nozzle with air alone to blow out that chunk of dirt that appears in the gate while a show is running, especially in the 16mm projector. There is nothing quite as effective as a good blast of air to dislodge it. I used to see guys trying to blow away gate dirt themselves, but you just can't get the pressure that the air compressor will produce for that particular job. Again, a good nozzle gun will give you very precise regulation of how much of a blast it will produce. Start off with just a little pressure and then increase it until the little bugger gets blasted to kingdom come.

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System Notices
Forum Watchdog / Soup Nazi

Posts: 215

Registered: Apr 2004

posted 09-04-2007 03:16 PM

It has been 1267 days since the last post.

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John Hawkinson
Film God

Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002

posted 09-04-2007 03:16 PM

*bump*

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