2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

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2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

November 29, 2013, 02:35:43 pm

I continue to work on cleaning the desiccant powder out of my air system. Here is a description of my recent adventure along with photos.

Back in June when the problem was first discovered, I replaced the air dryer with a refurbished unit with the expectation that, as time permitted, I would work through cleaning the entire air system. Here are links to the threads on my June experiences.

2003 U320 HWH O-rings installed - no leaks

Desiccant powder in air system - anybody else with this experience?

This week I finished cleaning the three air tanks and the air supply lines between the air dryer and the wet tank and from the wet tank to the front air tanks.

To clean the air tanks, I first removed all the plumbing connections and broke down all the "Christmas trees". Photo 1 shows the front two air tanks with their fittings in place. Photo 2 shows the wet tank with the air lines disconnected. Photo 3 shows a water hose in place for rinsing and drying.

The tank cleaning process consisted of first spraying the insides with Simple Green (about a quart per tank) and letting it sit for a few minutes. The tanks were pressure washed using a special built nozzle that would fit inside the 1/2" openings. Next the tanks were filled with water and drained several times. Finally the blower output of a shop vac was connected to each tank to dry them out (about an hour per tank). A tiny USB camera was run inside the tanks to be sure they were dry and clean. All I could see were a few rusty spots with no sign of the white powder.

The air line from the air dryer to the wet tank was cleaned by running water through it and then pulling a wet piece of cloth through it several times (it is a 5/8" diameter line). It was dried in the same manner as the tanks.

The air line from the wet tank to the two front tanks was cleaned with Simple Green and water followed by air drying. The line is much smaller in diameter than the air dryer line and much longer, so I was concerned that trying to pull a cloth through it might get me in trouble. However, I'm having second thoughts about that and may try pulling something through it later.

I washed out all the fittings from the "Christmas trees" and scrubbed them with a brush. The powder is fairly easy to remove. It is not compacted and hard. Just a small amount of rubbing will remove it. It has the consistency of talcum powder.

All check valves, pressure protection valves, shuttle valve, and relief valve were replaced with new.

All threaded joints were sealed with Locktite 567 (corrected 12/2). Teflon tape and most other common thread sealants are never to be used on your air system.

Amazingly, when I pressured up the system and slopped on the soap solution, there were no leaks!

To give you an idea of the degree of contamination, the last four photos show one of the 1/2" check valves coated with powder. The last photo shows how much powder I was able to scrape out of the check valve (there is a penny in photo next to the pile of powder).

Two full days of work.

The next step will be the HWH system (air lines, manifolds, check valves, and the 18 solenoid valves).

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #1 – November 29, 2013, 04:51:41 pm

Jim, those check valves in pics 6 and 7 are the ones I replaced along with the one on dryer and they had a big positive effect on air retention. I have a feeling these are hardly ever checked by anyone even FOT.
Lotsa mess you have there. Working on those tanks is easy by standing under with my pit.
John H

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #2 – November 29, 2013, 05:53:18 pm

I am concerned by your statement;

Quote

All threaded joints were sealed with Locktite 467. Teflon tape and most other common thread sealants are never to be used on your air system.

In replacing the air springs at the rear of my coach, I used Rectorseal T Plus 2 on the pipe threads of the brass elbow to Air Spring sleeve connection. Their data sheets indicate that it is appropriate for compressed air and other forums that I searched seemed to have a high opinion of it for compressed air applications. Just wondering what problems I may encounter because of it...
Thoughts?
Don

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #3 – November 29, 2013, 07:27:56 pm

I think if you are careful and don't slop the sealant outside the threads (like into fitting opening) you should have no problems.

What you must avoid is any type of joint sealant that can generate small pieces inside the air system. Teflon tape is a real no-no.

I based my choice on a government proposal request for work on an air brake system that stated the only acceptable thread sealant was Loctite 567 (corrected 12/2).

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #4 – November 29, 2013, 07:39:42 pm

You will be fine Don, just don't put any on the insides of air lines.

Richard B

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #5 – November 29, 2013, 09:06:03 pm

Thanks for the reassurance! I was very careful not to get any on the inside of the fitting... I don't want to be disassembling those parts again anytime soon. However, before I start on the front, I will definitely pick up some Loctite 467! The fittings in front of the front are a royal pain to get at, though perhaps when I make access panel, it won't be such an issue...
Don

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #6 – November 29, 2013, 09:52:56 pm

We stopped using Teflon tape for water and air tapered threaded fittings, as we found that threads may cut the tape enough to not do a perfect seal and pieces my break off and spread flow with air or water. We do use Teflon for some sealing connections, but will only use Oatey brand white, pink & yellow tape, depending on the thickness desired. I found non-branded blue cases too thin and not worth the cost saving.

We used to use Oatey plumber sealant with Teflon, but later decided to only use Permatex Thread Sealant. We now carry several small tubes of 467 purchased from auto parts stores. While 467 is more expensive, we don't use very much with any single project. We smear a little on all threads, except the first few rows.

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #7 – November 29, 2013, 11:09:45 pm

When I was working in England in the Deltic Diesel Engineering we used Locktite (different #s) for almost all bearing placements and thread sealing. I seem to remember that it would seal a gap of up to 10 thousands of an inch. I still have some of the small bottles from 47 yrs ago and use it now and again. Still good.
John H

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #8 – November 29, 2013, 11:29:31 pm

Jim, one area I did not mention in having this problem was that the air springs (bags) continued to be a reservoir for dust. When replacing them a year after cleaning all else, ane new check valves due to permanent coatings there, we found the bags would puff out dust if you stepped on one with a sharp push down with your foot. Like a bellows with dust.

Even after all this, remember to drain the wet tank after each trip. I find some small amount of dust in it after 400 miles or so. Technicians say that normal, just emphasize to blow it out so it goes no further.

Mike

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #9 – November 29, 2013, 11:42:35 pm

Quote from: Barry & Cindy – November 29, 2013, 09:52:56 pm

We stopped using Teflon tape for water and air tapered threaded fittings, as we found that threads may cut the tape enough to not do a perfect seal and pieces my break off and spread flow with air or water. We do use Teflon for some sealing connections, but will only use Oatey brand white, pink & yellow tape, depending on the thickness desired. I found non-branded blue cases too thin and not worth the cost saving.

We used to use Oatey plumber sealant with Teflon, but later decided to only use Loctite 467. We now carry several small tubes of 467 purchased from auto parts stores. While 467 is more expensive, we don't use very much with any single project. We smear a little on all threads, except the first few rows.

I second your opinion on the tape. The plumber's sealant with teflon works very well and does a neater job. Quite a few aircraft instruments failures occur because of tiny bits of teflon tape are sucked into the instrument. (several instruments are powered by a vacuum pump in a typical light aircraft)

Pierce

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #10 – December 01, 2013, 03:41:10 pm

I have been looking for the Locktite 467 that Barry mentioned, in his post. I have been unable to find that Number. I did find Locktite 567. Is it the same?
Al

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #11 – December 01, 2013, 04:09:25 pm

I stopped at numerous places the other day trying to find Loctite 467..., there was no such thing even on a Web search. I do believe that the correct number is Loctite 567 (perhaps 467 is an old number and has been superseded by 567?). Unfortunately, in this area, that is not even available except at exorbitant prices at Fastenal ($26!). I'm going to use the Permatex thread sealer for the rest of my project instead because I can get that at AutoZone.
Don

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #12 – December 01, 2013, 07:30:20 pm

Quote from: acousticart – December 01, 2013, 04:09:25 pm

I stopped at numerous places the other day trying to find Loctite 467..., there was no such thing even on a Web search. I do believe that the correct number is Loctite 567 (perhaps 467 is an old number and has been superseded by 567?). Unfortunately, in this area, that is not even available except at exorbitant prices at Fastenal ($26!). I'm going to use the Permatex thread sealer for the rest of my project instead because I can get that at AutoZone.
Don

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Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #13 – December 01, 2013, 07:39:21 pm

Been using Rectorseal #5 for years on air and propane. Never had a problem.

What are the thoughts of the chemists among us?

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #14 – December 01, 2013, 07:41:51 pm

Yep, my bad. It is Loctite 567.

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #15 – December 01, 2013, 07:49:51 pm

Sorry to say that the good thread sealant we said we used is not Loctite. It is Permatex 59214 High Temperature Thread Sealant, and the attachment is what our package looks like.

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #16 – December 01, 2013, 09:21:46 pm

Happy to say that that is the stuff that I ended up with!

Quote from: Barry & Cindy – December 01, 2013, 07:49:51 pm

Sorry to say that the good thread sealant is not Loctite. It is Permatex and the attachment is what our package looks like.

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #17 – December 01, 2013, 09:51:37 pm

From what I read on various web sites, Permatex 56750 is equivalent to Loctite 567.

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #18 – December 02, 2013, 09:09:23 am

The reason I used Permatex is it was the only automotive thread sealant being sold by the auto parts store we went into. I decided to simplify and just carry one product for sealing air & water tapered (NPT) threads, so when the package said high temperature, and was expensive, I figured this would fit the bill. Glad to hear that the Permatex and Loctite products are similar.

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #19 – December 02, 2013, 09:17:34 am

The product part number posted by Jim is a different part number than the the one that I bought (or the one posted by Barry L.)... The one Jim posted states "Maximum Temperature", whereas the one I got says "High Temperature". I can't see where it would make a difference in this application though.
Don

Re: 2003 U320 - Phase 2 of Desiccant Powder Cleanup Complete

Reply #20 – December 02, 2013, 07:07:23 pm

alright I give up! I needed to go by Fastenal today anyway, so I ended up buying a tube of the Loctite 567. Turns out, it wasn't as expensive as it appeared... The tube of 567 that cost $24 at Fastenal is about five times the size of the Permatex that I got at AutoZone for six dollars. I suspect that as long as any appropriate sealer is used correctly, it would be fine... But as this particular project has just been a PITA, I'm not taking any chances

Don

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