Compressor filter melting

[dbuggy]

I saw the canisters that had melted on a bench in the repair shed on that Monday and the anodization on the canister was intact and not discolored but the dessicant in the bottom portion of it was curled up and melted like a shrinky dink and the lower portion of the chamber where the dessicant used to be was black and sooty! There were 3 canisters about 2 1/2-3 ft long. I dont think the shed/compressor room temp had as much to do with it (there have been hotter days and they do have fans circulating the air) as much as a combo of temp and the sheer volume of fills they were doing that day. When I dropped off our tanks on sunday there were 15 sets of doubles about 25 single cylinders and I dropped off 16 cylinders. That in addition to the rental tanks that needed to be filled plus the mass of people that were behind me dropping off tanks. This was all just in the 10 mins I was there. The nitrox compressor was also not working so all those people who normally fill with nitrox had to use the regular air as well. They do have 3 compressors but i have never heard that shed quiet in the 3+ years ive been going there and this is the second time it has happened to me personally.

 

[Scuba Duck]

I was working with a dive shop to install a Nitrox System. Someone had performed maintenance on the drain system and installed the 3 way solenoid valve that operated the pilot valves in the autodrains backward. The original design of the autodrains used second stage outlet pressure to push the pilots in the autodrains to close the drain paths from the interstage separators. When the autodrain activated, the 3 way solenoid valve would vent the pressure that positioned the pilots and allow the system pressure in each of the interstage drains to push the pilot valves and allow the fluids to drain from the separators. When whomever put this 3 way valve back into the system, he installed it backwards, so that instead of venting the pressue from the pilot valves, it vented the pressue from the outlet of the second stage. It therefore sounded like the autodrains were working, when in fact the pilots never operated. Needless to say, it didn't take too long until the filtration system was entirely saturated with water. The filtration system had 4 filters in series. The second filter caught fire, and burned up the 2nd, 3rd and 4th filters, melting the filters into the filter housings. The elevated levels of oxygen associated with making nitrox didn't help matters. Needed a whole new filtration system and had to completely replace all the hoses in the fill system. This was an expensive mistake...

x13, the part of the filter that absorbs mositure is a zeolite. Depending on the size of the pours in the zeolite, the material absorbs different size molecules.

Zeolite - Wikipedia, the free encyclopedia

 

[IyaDiver]

Gents,

Currently my bauer Mariner 200E ( new model block ) is not positioned at a very good ventilation scenario due to limited space. I used forced air ( electrical blower ) and have been monitoring temperatures and been limiting the running to 1 hour maximum non-stop and at least 30 minutes rest after the 1 hour. Maximum 20 tanks a day at the most , averagely is 15 tanks and none is very empty. All day time running only.

Here is the data, hoping this will come handly for some. I will pick the worse, average and the best days

Measurement of hot spots are :
- Hottest part of 1st, 2nd & 3rd stage cylinder head
- The temperature of the cylinder head is not even, the inlet part is always hotter, temperature can be different by 10C easy.
- Meassurement is using infra-red thermometer in zig zag motion and read as the MAXIMUM. This way the hottest spot is the recorded one.
- Temperature of water separator 1 and 2 ( its a P41 system ) is also recorded


Example 1, 5th May 2010 Air only, no nitrox . 3000 psi maximum fill.
Ambient temperature : 31C .. Cy = Cylinder Head & Sep = Separator

04:28PM Cy 1 = 120C , Cy 2 = 126C , Cy 3 = 82C , Sep 1 = 51C , Sep 2 = 39C
04:39AM Cy 1 = 129C, Cy 2 = 129C, Cy 3 = 87C , Sep 1 = 51C, Sep 2 = 48C
10:47AM Cy 1 = 131C, Cy2 = 116C, Cy 3 = 88C , Sep 1 = 53C, Sep 2 = 44C




Example 2, 4th June 2010 Air only, no nitrox. 3,000 psi maximum fill.
Ambient temperature : 31C .. Cy = Cylinder Head & Sep = Separator

10:26AM Cy 1 = 124C , Cy 2 = 122C , Cy 3 = 75C , Sep 1 = 51C , Sep 2 = 37C
10:37AM Cy 1 = 126C, Cy 2 = 124C, Cy 3 = 88C , Sep 1 = 51C, Sep 2 = 40C
10:47AM Cy 1 = 129C, Cy 2 = 128C, Cy 3 = 79C , Sep 1 = 51C, Sep 2 = 46C
10:57AM Cy 1 = 126C, Cy 2 = 120C, Cy 3 = 82C , Sep 1 = 57C, Sep 2 = 47C
11:07AM Cy 1 = 118C, Cy 2 = 127C, Cy 3 = 81C , Sep 1 = 53C, Sep 2 = 40C


Example 3, 16th June 2010 Air only, no nitrox. 3,000 PSI maximum fill
Ambient temperature : 28 C ..Cy = Cylinder Head & Sep = Separator
10:16AM Cy 1 = 119C , Cy 2 = 104C , Cy 3 = 70C , Sep 1 = 44C , Sep 2 = 34C
10:35AM Cy 1 = 121C, Cy 2 = 112C, Cy 3 = 79C , Sep 1 = 45C, Sep 2 = 35C
10:49AM Cy 1 = 119C, Cy 2 = 122C, Cy 3 = 77C , Sep 1 = 46C, Sep 2 = 39C
10:54AM Cy 1 = 124C, Cy 2 = 121C, Cy 3 = 77C , Sep 1 = 46C, Sep 2 = 40C


Note :
Water separator temp always changes, when vented it will be cooler.
Water separator #2 never get vented to lower by 400 psi, its thrifty micro venting method
When changing tank, separator #1 sometimes get totally vented, but never separator #2
BPV set at 2,000 psi

Due to position of the #2 separator, not only it gets hot by pressure build up, but the Bauer fan blades is blowing hot air from cylinders and block towards it too...

I am still unable to hook up my permanent thermometer with wire type thermo couple, still got to machine a few more stuff to allow the wire to sit at the worst hot spot. I will report when I get them up & running. I can list the thermal chnage per second, its data logging capable.


One more interesting test I did. My toys are still not complete until today, Swagelok parts just arrived and so on, so I cant hook up my dew point sensor yet. So I deviced a method to try to verify filter life by measuring the weight of the filter cartridge when new and after X hours of use. Interesting find.


FILTER # 1
Filter cartridge number : 062665 ( P41 with no Hopcalite )
Weight of Filter as new, 24th March 2010 is 1417 grams
Filter weight as per Bauer label is 1,380 grams ( supposedly )
Weight of Molecular Sieve as per Bauer data is 809 grams
Weight of Activated Carbon..... no data

Filter life predicted by Bauer software is with 40C intake temperature final separator and ambient of 30C is 55 hours at 207 BAR ( 3000 psi ) working pressure and 200 L/M air flow. Filter life rating at 20C ambient and 30C final separator is 92 hours.

Removed filter at 55 hours service life.
Weight becomes 1682 gram on 8th May 2010
Measurement using Tanita digital kitchen scale maximum 2000 grams. Supposedly accurate by 2 grams. Model is not legal for trade...
The very same filter left lying around and re-weighted today have gone up in weight by 6 grams in approx 40 days, it is now 1688 grams.



FILTER # 2
Filter cartridge number : 062665 ( P41 with no Hopcalite )
Weight of Filter as new, 8th May 2010 is 1402 grams
Weight as per Bauer label is 1,380 grams ( supposedly )
Weight of Molecular Sieve as per Bauer data is 809 grams
Weight of Activated Carbon..... no data

Filter life predicted by Bauer software is with 42C intake temperature final separator and ambient of 30C is 49 hours at 207 BAR ( 3000 psi ) working pressure and 200 L/M air flow.

Removed filter at 49 hours service life on 16th June 2010
Weight becomes 1658 grams
The very same filter left lying around and re-weighted today have gone up in weight by 4 grams in 12 days, it is now 1662 grams.


Now the big question is......., based on 809 grams of molecular sieve capable of adsorbing 20% , the water weight in there should be 162 grams.
Filter #1 and #2 registered extra weight of 265 grams and 256 grams respectively.
So there are some oil, some dust and whatever the activated carbon captured at between
96 - 103 grams. If only I had my dew point sensor running, I want to know how dry is this filter at such weight ?

If the molecular sieve adsorb 25% of water, it is still only 202 grams of water vapor and 54 to 63 grams of xyz trapped.

Oil used is Bauer reccomended synthetic. Oil filter first change is after 77 hours running from new. Next change will not be more than 250-300 hours, this is the plan, even though Bauer reccomended 2,000 hours. This is a 2.8 liter crankcase oil capacity block.

Swamp and Ian, any ideas ?

PS. I am setting 137C as maximum temperature. This will occur on either cylinder #1 or #2. It has occured but the other earlier log book is not with me.


Thanks
IYA

 

[oxyhacker]

This should not be possible. Hopcalite is a catalyst actually converts the CO into CO2 and sends it on its merry way, rather than ad or absorbing it, so there is nothing retained to be released.

filters get so hot the hopcalite releases the CO back into the air,

 

[Zodiacdiverdave]

This is all quite interesting, I have been carrying out compressor maintenance & inspections on fire department, scuba shop and industrial breathing air compressors for several years and I always take temp. readings on all stages following the maintenance. The Ingersoll Rand T-30s run alot hotter then Bauer and Makos, sometimes with outlet temps close to 400 deg. F and I have yet to see a filter cartridge melt down. I suspect in the case of this incident there was a large amount of water released into the filter causing a sudden rise in the internal temperature. At the Bauer school they have a filter canister that has a hole in the side of it that was caused by this. When I was attending the MAKO course the instructor poured water into a can of mole-sieve (x13) and the temp went well above 250 deg. C
If this shop did have a fire inside the filter housing and that filter housing was made of alluminum then I would advise them to replace these as Al. looses it's tinsiel strenth at high temperatures.

ZDD