13X molecular sieve storage life

[IyaDiver]

Hi All,

I might one day go to the filter re-packing route if I use a second tower.

I been reading this compressor section from post of day 1 ( dated some years ago ) to current and goes thru information on MS 13X.

Interesting what Pescador wrote :
As I reported on Scubaboard, tests of 13X show it will go dead in 24 hours when exposed to atmosphere.


I also read Bauer website, their dictionary that stated :

The molecular sieve must be store in an absolutely dry place immediately. Otherwise, the substance will absorb moisture from the surrounding air, reducing the absorption capacity. Storing molecular sieve in plastic bags is ineffective; plastics are water-permeable. Even aluminium-coated plastic envelopes are not entirely airtight. Therefore, drying cartridges should not be stored for more than six months.


Then I was looking at plastic permeability :

http://http://www.packaging-gateway.com/features/feature50/

I think Bauer is not all that bull$hit and I realized the reason behind aluminum foil wrapping on Bauer filter cartridges and two years shelf life reccomended.

Now the question is short of re-generating new/fresh MS 13X by heating as also indicated by Pescador ( to remove moisture but not to remove pollutant ), how do I as a consumer know that I am getting a fresh/dry MS 13X ? Its not only about cost but its about starting with a known fresh 13X and the repeatibility of calculating filter life based on ambient temperature, when I re-pack myself.

I can get a 2 gram resolution digital weighing machine to weight the MS 13X,
but how do I measure the density of something like MS which is round and can't be "compacted" like water to have a reference weight against stacked volume in a measuring container ....?...unless I measure before I oven dry the MS 13X and weight it again after that.

Any tips Gentlemen ?


Thanks
Iya

 

[frogman62]

I suggest you are making a scientific issue that can be practically solved instead of spending a lot of time trying to determine exact answer.
That said, I have been accused several times of being too simplistic because several individuals like the scientific approach and answers.
IF you have 2 filter chambers (or more) always pack the first one with 13x and use it only as a drying tower. Cook the 13 X in the oven (if your wife doesn't complain) at 275 degrees for 2.5 to 4 hours and then repack the cartridge. Don't worry about pollutants because you have another chamber to clean the air. I usually don't dry 13 x more than 3 times if used in a breathing air application, but several times for paint ball or air guns. I also "refresh" in about 15 hours which is usually over kill for a 6 cfm compressor.
I don't know how you assure that your supplier is giving you "fresh" 13X. Buy from a reputable supplier
Frogman62
Jim Shelden

 

[IyaDiver]

Hi Jim,

I am not trying to get scientific based answer, but I am trying to think that such a great moisture eater like 13X need special handling . Won't it be best to grill before use, if I am really concern to get 100% performance. Don't you agree ?

Where I am living, reputable supplier is not a guarantee because dive market for 13X is too small, Bauer rules here and its a throw away cartridge which is easier sourced actually.

I just completed a live on board trip last December. The LOB vessel has two 8CFM compresors and re-packed type of filter system. My group chartered the same vessel on last October, same 7day duration as December but December trip has lesser total dives due to full moon blasting 3.5+ knots current.

The December trip had a day where the air smells a bit and I told them to re-packed again by middle of the trip. The trips always started with new re-pack and October trip was completed without any re-pack. They carry the same MS and AC ( I think 5 liter container ) which were more depleted by December trip. So I guess storage issue for MS can be a concern, this was why I asked. Won't a wet MS do performance damage to AC ?

Thanks Jim

IYA

 

[iain/hsm]

Guys.

You may reject the science involved in breathing air filtration, it’s your call but it does offer valuable evidence and is the one if not the only way to verify adequate filtration.

Regarding molecular sieve we are the only company in Europe that supply non carcinogenic molecular sieve 13X that is non bound for medical hyperbaric and military diving use.

The type and brands you have been discussing are simple industrial “bound” sieves.

That is a large proportion of the active chemical matrix (the synthetic zeolite) is bound together with an inert binder. (It is this binder that is the carcinogenic portion of the chemical product.)

This binder being inert to your air or gas does not offer any adsorption properties and is purely used to bind the chemical together to achieve the required mesh size.

Depending with the two various vendors that you have been discussing both from USA and Germany you will find up to 30% of the total chemical weight from one vendor is pure inert binder.

Put another way non bound medical/military grade zeolite will process 30% more gas, for the same weight of chemical.

Back to science. A simple scientific test for effectiveness or you chemical you require two small coffee cups a 100C thermometer and water:

1. Half fill one cup with room temp tap water and the other with chemical sieve.
2. Take temperature of the water, it should be at room temperature.
3. Pour the chemical into the water.
4. Temp will rise to around 60C your chemical is good to go.

Storage will degrade the chemical as it will adsorb water vapour from the atmosphere.
For long term storage of repack chemical I would suggest using a steel container or drum depending on the amount of chemical stored.
For instant use storage in double 500mu plastic bags, heat sealed and vacuumed: 3 days
For short term storage in hard plastic container: 3 months
For longer term storage in steel drum: 5 years if full unopened and 3 years from opening.

Hope it helps Iain Middlebrook

 

[IyaDiver]

Hi Ian,

I been waiting for you to chime in actually. Many thanks.
Believe it or not I been compiling a lot of information on scubaboard and other sources for my learning.

So Bauer reccomendation is true about common re-packing material shelf life in plastic container is at approx 6 months from date of packing, unless you want to grill it.

I read on scubaboard about your medical grade 13X for hyperbaric. Its very interesting reading.

Do allow me to quote you :

1. The increase in cost for the chemical from £4.00/kg ($8) to £11.00 /kg ($22) was largely balanced out by the increase in filter life.

2. Also reduction of inert clay binder alone increased the filter life output depending on the type and percentage of clay binder used, by another 20% to 30%

So to be fair it was not entirely the clay binder quartz issue that was in question it was just a factor in the decision of chemical quality chosen.


I run a dive training facility and air-fill. Not much action, probably no more than 15-20 tanks per day at the most for Monday to Saturday on average at high season where the west monsoon wind is not blowing hard. So its like 9 months a year "busy".

I am about to receive my new Bauer 200 L/M and have upgraded it with P41 filter system. The more I read scubaboard and other sources, the more I realized that air quality for my 30 -32 ambient temperature will be expensive if I want to keep it within EN or Grade E grade at all times.

I do not really make money on air-fill, its part of the service infrastructure.
However I like to offer the best air quality possible and a consistent one, now that I understand better about air filtration. I feel its a sin to ignore the obvious , which is air quality, if I have learned more about it and have better grasp.

I ordered the P41 filter housing due to the fact that the processing capability is 1,600 M3 ( at 20 Celsius ambient at 300 BAR ) whereby the P21 can only handle 130 M3 of air processing. I have to admit that its very unlikely that majority of Indonesia air-fill operators will follow reduction table "accurately" to compensate filter life against ambient temperature and rate it down to 200 BAR, unless they use a Bauer Securus system and keep that humidity sensor running.

I am even ashamed that I have not been reading the newer Bauer manual closely because I have got used Bauer-s since 1995 and the literature back then was not so detail on filter life. I use "my nose sensor" mainly...
The age of internet finally made me able to access data where back then I could dot have done easily and plenty.

Air fill operators sell at approx US$4 here per 80CF tank fill with Mariner 200 pumping thru a small P21 filter. If adjusted at my 30 Celcius ambient and +10 Celsius tower temp, that is about maximum 20 air fills based on 2,000 liters of air per bottle. At US$40 per filter cartridge, we are looking at US$2 each air fill. Its common that they use it untill about 80 air fills...

So by being educated by scubaboard in house experts and days and days of reading from other sources this past 60 days, I have to admit I been a sinner for air quality even though I have reduced the filter life...but never reduced enough.

I paid approx US$1,000 extra for P41 filter system is to improve air quality at reduced running cost per air fill by spending more initial investment. P41 filter cartridge cost US$180 here with Hopcalite, unlike in the US where you can get it for US$85, which I learnt too late because I have paid for 10 P41 cartidges, 5 without Hopcalite and 5 with Hopcalite.

I ordered the filter with Hopcalite because my air-fill is in the middle of the city with EPA non-approved 2 stroke motorcylces running on the streets. So I go for a reduction of 15% air processing capability of the P41 with Hopcalite to protect C0 seepage to the tanks.

In my calculation I can follow Bauer P41 filter life tabel with all the masssive life reduction factors and still within US$2 per air fill benchmark for filteration cost.
So I am almost back to square one, a bit of savings with approx US$180/140 fills = US$1.28 per air fill but quality should be within Grade E or EN 12021 at end of filter life.

Hence I been busy asking this forum about Bauer Air-Kool refrigerated dryer cooler but at my small 200 L/M air output, the Euro 2,300 FOB Singapore price is not worth it..... yet.

I then think of looking at exra filtration tower as next solution but it must be a re-pack one, so that I can further increase my P41 filter life. Most likely it will be from ColtriSub MCH36 family of filter housing.

This is why I asked about 13X storage life without needing to grill it before use. The technical data is so obvious, this thing suck water vapor so good at ambient RH that it scares me for a self packing use....unless I grill it first.


Now Ian a few question if I may :

01. Do you have any agent in Asia for your medical grade 13X, prefer Singapore based one and what is the minimum size packing ? I can't buy 55 gallons drum version....

02. Can I grill your 13X assuming I am storing it longer than allowed because I don't use much of it ?

03. If I use your 13X in a filter tower before the Bauer P41, I guess the original Bauer that uses industrial 13X will still release all the bad stuff to the tank ? If I reverse the position, P41 filter first and then second filter tower then the tank...will it help ?

Or rather I make or buy a P41 filter canister made of stainless steel and I re-pack that too. I rather not repack the P41 because of the Hopcalite concern. If it can only work well in very dry air, I assume its handling and storage is similiarly sensitive to 13X in general. I been reading Hopcalite MSDS but no specific data on its storage.

Sorry for the long post and thank you for your time.


Thanks
Iya

 

[iain/hsm]

Iya.

Your not supposed to look back at old posts as some of us cant remember what we said LOL. But starting with the easy questions. Regarding regenerating sieve in general:

When regenerating sieve you will over time break up the chemical matrix turning the spheres into powder, you should IMHO also fit a 2Mu high pressure filter at the outlet of your filter tower to protect the BPR regulator and the pipe work etc including the cylinder downstream.

This filter should use a replaceable (cleanable) sintered bronze (nitrox) or sintered stainless steel (for air) filter element and it MUST be an oversize reduced cone type element.

Don’t ever use the flat plate or welded mesh type filters, you cant inspect them or clean then and the flat face will block very easy. This blockage increases the back-pressure until the element fails in a massive catastrophic failure of the mesh.

However here’s the kicker. I would only recommend this regeneration of molecular sieve process when using oil-free or oil-less compressors.
The reason is quite straightforward. Oil free and oil-less compressors only produce pure distilled water nothing else during the compression process. So the chemical is not contaminated.

Oil lubricated compressor including the Bauer Mariner 3 stage produce imulsified oil and water and your unit uses splash lubrication on the lower stages but oil vapour on the upper. It is this oil vapour “carry over” that degrades the molecular sieve rendering is pretty useless for regeneration.

The oil vapour in essence “coats” the external surface of each of the molecular sieve spheres with a thin oil film, this effectively blocks that bit of the filter matrix so the dirty wet gas has to find a clean "ball" of chemical to first strip the oil film out of the gas stream before the next clean chemical in the flow chain can get to work on stripping the water vapour.

By regenerating the chemical you fail to remove the oil film and in effect “cook” it to the chemical matrix. When you replace the chemical back in the filter tower on the next fill this “bond” is broken due to pressure and vapour pressure and all this oil crap re enters back into the gas stream. In effect a double dose of trouble for the secondary filter tower to deal with. Iain Middlebrook

 

[IyaDiver]

Hello Ian,

I am not saying to regenerate a used medical MS, I am saying if I buy new ones and its kept long in storage, can I grill it before use to get its maximum water adsorbing quality ?

Yes, the dust issue. I have seen many Bauer Pressure Regulating Valve had this problem when the filter use is exceeded. This will jam open and make things worse for the filter cartridge.
I think its also the AC that produced sulphuric acid when its wet. Bauer tech did tell me that something will ooze out if filter life exceeded and ruin the PMV but I can't remember if that is MS or AC.

Yes, a 2 micron filter as you adviced will be good. More budget... ha ha ha.

So back to your medical grade 13X, do you have a Singapore agent ?

Thanks
IYA

 

[iain/hsm]

Sorry no agent in Asia, Your it I guess LOL

Our take on using Hopcalite for CO conversion is again different to both the States and probably everyone else as well. LOL so here goes:

It’s pretty darn hard to convince a compressor operator to fit a CO catalyst due to the high running cost at the best of times. Also the low price they get for breathing air is also a factor. In the UK some dive shops even supply “Free Air” so it's almost impossible for them to spend money on compressor equipment.

Although I think it fair to say we all agree that the conversion of CO to C02 and water by a Hopkilite catalyst is the way to go for all petrol (gas) engine and diesel driven compressors. Period.
We would however also go further to have it fitted on all compressors used on diesel driven boats and yachts etc due to air intake positions and wind change.

Now if I read your post correct you pay US$40 for a standard MS P41 filter throw away cartridge and USD $180 for a P41 cartridge MS AC HOP that includes the hopcalite catalyst.

Now as your filter process biggest problem is ambient heat, high approach temperatures and low filter life your “Dessert Chiller” idea will help but you are still left with the problem that when the drying portion of the filter fails the expensive hopcalite portion is still OK

As we have the same problem just how it is resolved is where we differ with everyone else. On petrol compressors etc rather than using hopkalite in the main tower we just use an additional very small length filter tower but identical in diameter.

Cost for the filter tower is £140GBP (USD $220) not much more than that of your P41 cartridge and when you scrap out the hopkalite from your P41 filter, rip out the chemical and save it. That part of repack I am happy with and operators also can see the benefit and cost effectiveness of using this method. Note: I have not costed the price of a stainless repack cartridge for this, say £40. (USD $60)

Important to disclose that with the small filter, the diameter should be the same as the large filter due to dwell time velocity and flow issues also the spigot is the same Bauer female spigot so you get in effect more chemical in the cartridge tube.
Dont confuse this idea those "personal filters" it will not work.

But the total filter length is only 10” long 255mm hence its called a P10 (or P8 I will check) compared with the Bauer main P41 filter tower of 33” long 840mm. Agreed it does increase the weight of a portable petrol engine compressor but with a filter change or the hopkalite every two years the running cost in minimal.

Also for the main P41 filter cartridge on your compressor you go back to the cheap $40standard MS AC cartridges. Also should advise that the HOP filter should be protected by an upstream 10/20/30% relative humidity indicator so add $60 (£30) for that and another $15 (£10) for the stainless steel fitting adaptor as Hopcolite will not work if wet. If I get time I will set one up in the workshop and photo the set up arrangement. Iain Middlebrook.

Edit: Not quite the photo I wanted but it shows the P8 filter and the vis indicator although if used as a CO filter the indicator has to go on the intake side not the outlet. iain

 

[IyaDiver]

Hi Ian,

I think you misread my post...I know its awfully long.

The P21 filter cartridge is the US$40 one. 68 Gram MS
The P41 filter catridge without hopcalite is US$125 approx. 812 gram MS
The P41 filter cartrige with hopcalite is US$180 approx. Maybe 700 grams MS.
So US$55 just for the extra hopcalite, maybe 70-90 grams. Hopcalite cost like US$200 a Kg if I read correctly somewhere.

Bauer manual stated that CO above 25PPM not reccomended even if there is Hopcalite in filter. Lawrence factor claimed it can handle to 300PPM and theirs is called Monoxycon, both are probably same thing manganese dioxide. Who is the correct one ? 25 ppm versus 300 ppm is a lot of difference. Bauer afraid of law suit if someone feeding the Honda exhaust gas to the snorkel ?..

What I do not understand yet is, this Hopcalite/Monoxycon is a catalyst not adsober. How does one calculate its useful life ? Did you say two years probably it will last when rigged as you pointed out.?...that is a very long time Ian.

scubaengineer.com also stated that real operasional data sheet is very difficult to get
for hopcalite and they use the common bench mark CO to CO2 coversion like this :
5 liter/min of air being processed per 1 gram of hopcalite at 150 BAR, but also no data on hopcalite life.

Your baby RIX housing idea is brilliant Ian. What if I do get a second tower from Coltri Sub, I can re-pack the additional tower with the used Hopcalite from the P41 right ? If the additional tower is upstream of the P41 which is without hopcalite , I should be safe from possible contamination of the hopaclite...if there is any. I can then do alternate use of P41 cartridges without hopcalite and with hopcalite say 2 to 1 or 3 to 1 ratio. This way the used hopcalite will never see more than 3 times the life of a P41 filter cartrige or less than 6-8 months. While at the third life cycle of the used hopcalite at additional tower, I have a fresh hopcalite at the P41 filter cartdrige dowstream.
Make sense no ?

Thanks
IYA