Air quality

[garygee]

Hi folks

I know that air for topping up Nitrox mixs need to be "Hydrocarbon free" but does air filtered to DIN EN12021 meet this as this is what our compressor filter stages give as a air purity.
I know that activated charcoal is used in our filter but I dont want to use this air unless it OK.

Also does anyone know of the "personal" air filters used for filling would help.

Thanks Gary

[Phil Laughton]

Gary,
Check your mail box. I have sent you some info.
Phil

Hi folks

I know that air for topping up Nitrox mixs need to be "Hydrocarbon free" but does air filtered to DIN EN12021 meet this as this is what our compressor filter stages give as a air purity.
I know that activated charcoal is used in our filter but I dont want to use this air unless it OK.

Also does anyone know of the "personal" air filters used for filling would help.

Thanks Gary

[PeteM]

Also does anyone know of the "personal" air filters used for filling would help.

Be very very careful about these, they normally have a max flow rate and this is often very low, i.e. well below normal fill rates. If you fill too fast you will destroy the contents and blow a portion of it into your cylinder

[John Williams]

Gary,
Check your mail box. I have sent you some info.
Phil

Phil,

Care to share your wisdom and experience with the forum?

It was a good question ...and I'm sure many would want to hear an equally good answer!

(especially in light of the caveat mentioned by the other early respondent)

John

[Phil Laughton]

:=Gary,
:=Check your mail box. I have sent you some info.
:=Phil

Hi John,
Nice to hear from you.
Re Gary's question on air quality for Nitrox blending. Compressor makers will all say that the air delivered through the comp filter system will meet the current BS EN 12021 std, but, this depends on the compressor and filter system being maintained in line with the manufacturers instructions. The filter cartridge will contain layers of silaca gel, activated carbon and molecular sieve. If the filter isn't changed regularly wet, oily air could be used to fill cylinders as the media degrades. Therefore to reduce the risk of oil contaminated air being mixed with O2 a double filtering system should be used and the air taken through a 100% carbon cartridge. As Gary is buying a small compressor with a low output a personal filter will be OK. If a club has a large static compressor and double filtering is required then a larger, wall mounted filter system should be used complete with non return valves and O2 compatible hoses and fittings. It must also be remembered that all filter media has a limited life and once a cartridge has been opened that life is reduced to approx six months even if the compressor isn't used.
Regards,
Phil

Phil,

Care to share your wisdom and experience with the forum?

It was a good question ...and I'm sure many would want to hear an equally good answer!

(especially in light of the caveat mentioned by the other early respondent)

John

[John Williams]

Phil,

I see many nitrox users placing their own personal filters into place between either their single-filtered club compressor (often big compressors).

I see many trying to be careful when using commercial compressors by using personal filters to give an "extra clean" to the air they get - just in case.

Finally, I see many personal filters being used to "protect" nitrox cylinders from single filtered air being decanted from a high pressure bank (sometimes being decanted far too fast for my liking)

Does your answer (and the other) mean that the use of a personal filter with all but low flow rate situations should be avoided - because it has more pitfalls than benefits?

John

[Nigel Hewitt]

I see many nitrox users placing their own personal filters into place between either their single-filtered club compressor (often big compressors).

I think the low flow rate is to stop the gas just blowing channels through filter medium. The fact that you can get gas through it fast probably just means you're kidding yourself that it is doing something.

Personally I would be deeply suspisious of putting activated charcol filters (if that is what these are) near a tank with boosted oxygen in it. Can somebody confirm what the filtering medium is in these things?

[Phil Laughton]

Pete, you are quite right. The max flow rate though these secondary filters can be as low as 140Lt/min and so great care must be used when using one.

Nigel, activated carbon "IS" the normal media used in the personal and large fixed seconary filters.

John, any one using a personal filter when decanting from a bank could have a real problem if the cartridge fails. Only seen it once, in a dive shop.

:=Also does anyone know of the "personal" air filters used for filling would help.

Be very very careful about these, they normally have a max flow rate and this is often very low, i.e. well below normal fill rates. If you fill too fast you will destroy the contents and blow a portion of it into your cylinder

[iain-hsm]

Hi folks

I know that air for topping up Nitrox mixs need to be "Hydrocarbon free" but does air filtered to DIN EN12021 meet this as this is what our compressor filter stages give as a air purity.
I know that activated charcoal is used in our filter but I dont want to use this air unless it OK.

Also does anyone know of the "personal" air filters used for filling would help.

Thanks Gary

In a word No! The mistake has been to confused Air and Nitrox. Air purity BS 4001, BS 4275 or EN12021 always was and still is just the physlogical agreed standard or limit that the human body can tolerate without harm to the various tested elements. It was never considered to be anything else with the possible exception of water vapour when using light weight thin wall steel cylinders and has always been with an oxygen concentration of up to or less than 21-22% It has nothing whatsoever to do with oxygen compatability.
The current EU legal requirement for any gas ie nitrox, heliox etc, with a percentage of oxygen greater than 22% is "Use no Oil" There is no legal difference between oxygen and nitrox.

Regarding filtration for the record just read its label too. The compressor says AIR, and the filter says its an AIR filter, the manufacturer is legally covered and this is his defence in a court of law is just that. "Read the label".
Filters by there very nature fail and an activated carbon filter being able to absorb oil vapour is just as ready to release this accumalated oil into the gas stream when a greater attractant (such as water) comes along.
To "manufactiure" (ie supply mix blend sell) a gas containing a percentage of oxygen greater than 22% is still "Use no Oil" That simply put statement must be 40 years old now.

[Phil Laughton]

Hi All,
The current air purity standard is BS EN 12021 - 1999.
BS 4001 and BS 4275 no longer exist. The main changes were an incease in CO from 10ppm to 15ppm, and a decrease in oil vapour from 1mg/cu/m to .5mg/cu/m and water vapour to be no more that 25mg/cu/m at 300 bar. These are maximum limits. All these conditions can be met if the compressor filter is maintained in line with the makers limits and the compressor its self is also fault free.
Compressor operators must also be aware of correct operating methods.
Phil


:=Hi folks
:=
:=I know that air for topping up Nitrox mixs need to be "Hydrocarbon free" but does air filtered to DIN EN12021 meet this as this is what our compressor filter stages give as a air purity.
:=I know that activated charcoal is used in our filter but I dont want to use this air unless it OK.
:=
:=Also does anyone know of the "personal" air filters used for filling would help.
:=
:=Thanks Gary

In a word No! The mistake has been to confused Air and Nitrox. Air purity BS 4001, BS 4275 or EN12021 always was and still is just the physlogical agreed standard or limit that the human body can tolerate without harm to the various tested elements. It was never considered to be anything else with the possible exception of water vapour when using light weight thin wall steel cylinders and has always been with an oxygen concentration of up to or less than 21-22% It has nothing whatsoever to do with oxygen compatability.
The current EU legal requirement for any gas ie nitrox, heliox etc, with a percentage of oxygen greater than 22% is "Use no Oil" There is no legal difference between oxygen and nitrox.

Regarding filtration for the record just read its label too. The compressor says AIR, and the filter says its an AIR filter, the manufacturer is legally covered and this is his defence in a court of law is just that. "Read the label".
Filters by there very nature fail and an activated carbon filter being able to absorb oil vapour is just as ready to release this accumalated oil into the gas stream when a greater attractant (such as water) comes along.
To "manufactiure" (ie supply mix blend sell) a gas containing a percentage of oxygen greater than 22% is still "Use no Oil" That simply put statement must be 40 years old now.

[iain-hsm]

Hi All,
The current air purity standard is BS EN 12021 - 1999.
BS 4001 and BS 4275 no longer exist. The main changes were an incease in CO from 10ppm to 15ppm, and a decrease in oil vapour from 1mg/cu/m to .5mg/cu/m and water vapour to be no more that 25mg/cu/m at 300 bar. These are maximum limits. All these conditions can be met if the compressor filter is maintained in line with the makers limits and the compressor its self is also fault free.
Compressor operators must also be aware of correct operating methods.
Phil

Sorry as I am for being old sod over this, but the point is that even todays EN 12021 says nothing about increased oxygen concentrations It only discribes normal atmospheric air 21/22%. Just like the other old air standards for the last 40 years!

The question was does EN12021 meet a purity standard for Nitrox. The answer is still, No. It does not. It says nothing about Nitrox. The purity standard for elevated oxygen concentrations above 23% is not found in EN 12021,it never was.

[Phil Laughton]

From this old sod to another,
BS EN 12021 is for all air users inc fire and rescue services and as such has no bearing on nitrox blending. To ensure the air used for blending nitrox is oil vapour free, the air supply is usually passed through an additional filter. If the air is sampled after the double filtering there should be no trace of oil vapour in a detector tube. Filtration system manufacturers will tell you that providing maintenance guide lines are followed the air quality will be equal to the current standard.
Phil


:=Hi All,
:=The current air purity standard is BS EN 12021 - 1999.
:=BS 4001 and BS 4275 no longer exist. The main changes were an incease in CO from 10ppm to 15ppm, and a decrease in oil vapour from 1mg/cu/m to .5mg/cu/m and water vapour to be no more that 25mg/cu/m at 300 bar. These are maximum limits. All these conditions can be met if the compressor filter is maintained in line with the makers limits and the compressor its self is also fault free.
:=Compressor operators must also be aware of correct operating methods.
:=Phil

Sorry as I am for being old sod over this, but the point is that even todays EN 12021 says nothing about increased oxygen concentrations It only discribes normal atmospheric air 21/22%. Just like the other old air standards for the last 40 years!

The question was does EN12021 meet a purity standard for Nitrox. The answer is still, No. It does not. It says nothing about Nitrox. The purity standard for elevated oxygen concentrations above 23% is not found in EN 12021,it never was.

[iain-hsm]

From this old sod to another,
BS EN 12021 is for all air users inc fire and rescue services and as such has no bearing on nitrox blending. To ensure the air used for blending nitrox is oil vapour free, the air supply is usually passed through an additional filter. If the air is sampled after the double filtering there should be no trace of oil vapour in a detector tube. Filtration system manufacturers will tell you that providing maintenance guide lines are followed the air quality will be equal to the current standard.
Phil

Phil. Sadly I can agree only with your first sentence. That of BSEN 12021 having no bearing on Nitrox blending.

However the idea of double filtration being suitable for Nitrox production is just a myth. If the BSAC ever signs off this double filter process using oil lubricated compressors for Nitrox, they (as others) will be on very thin ice.
I recall how and when this ?double filter? myth started during the American ?Aquacorp? DEMA exhibitions my response then to be akin to ?Mixing on Elm Street? is still on record. Although I do understand that other divers have even paid good money to be taught this unqualified procedure. Sadly it is still just that. Unqualified.

Further your statement about filter manufacturers is misleading, No high pressure filter manufacturer will tell you (in writing) that there filters are suitable for the production of an elevated oxygen concentration (nitrox) when filtering from an oil lubricated air compressor, they can?t. They fail the first condition. It is just a myth.

The fact is that in the UK and Europe the production of any gas with an oxygen concentration greater than 23% requires for a full fail safe IPP process of manufacture and that the process compressor, compressors, LOX pumps, gas boosters or any thing else you use in the production process be suitable for oxygen, oil-free and/or oil-less.

Etiquette and forum rules preclude a more robust response but to coin Red Dwarf: SMEICC: Suitability and myth equating to an equal indefensible catastrophic condition. LOL.

Iain Middlebrook.

[David Applin]

from another old sod.....
correct not Air standard exists for nitrox mixes... but the current accepted standard is as follows and is based on the BOC standards for 100%o2

Water 39ppm
Oil mist less than 0.1 mg/m3
gaseous hydrocarbons 15ppm
carbon monoxide 2ppm
everything else to meet BS EN 12021

why is this being complicated? just take the pure (99.5%) breathing grade o2 standard and apply it to the high nitrox use.... and yes ... there are many oil filled compressors out there which are regularly tested and meet this standard.

[David Walker]

Further your statement about filter manufacturers is misleading, No high pressure filter manufacturer will tell you (in writing) that there filters are suitable for the production of an elevated oxygen concentration (nitrox) when filtering from an oil lubricated air compressor, they can?t. They fail the first condition. It is just a myth.

Can I just clarify what you're talking about? Are we talking filters on a compressor producing compressed air that is suitable for use in topping off nitrox cylinders, or are you talking about putting enriched air through a compressor & filter?

If i'm understanding what you appear to be saying correctly, you're saying that all air which goes near a nitrox cylinder needs to have been nowhere near a oil based compressor. That would make sense if you were talking about compressing the already-enriched air, but never heard anything like that for clean air before...

David

[iain-hsm]

from another old sod.....
correct not Air standard exists for nitrox mixes... but the current accepted standard is as follows and is based on the BOC standards for 100%o2

Water 39ppm
Oil mist less than 0.1 mg/m3
gaseous hydrocarbons 15ppm
carbon monoxide 2ppm
everything else to meet BS EN 12021

why is this being complicated? just take the pure (99.5%) breathing grade o2 standard and apply it to the high nitrox use.... and yes ... there are many oil filled compressors out there which are regularly tested and meet this standard.

David: Thanks for this input. Re your comment regarding BOC (of all the examples why them?) this requires I disclose a small professional interest. BOC is a customer, we are responsible for the design, and maintain currently two main types of BOC oxygen compressor, One a 670 CuM/hr (424 scfm) reciprocating compressor design, the other a 927 scfm multi-stage oxygen compressor. Both types run 24 hours per day continues duty in the manufacture/production of oxygen. BOC currently operate over 500 gas compressors in the UK and for interest non use oil in the manufacture or production of compressed oxygen or any other oxygen enriched gas. I would therefore respectfully refer you to a specific BOC website <a href="http://www1.boc.com/uk/sds/" >http://www1.boc.com/uk/sds/</a> to download the relevant data sheets regarding BOC products.

Ok that over, now specifically onto your statement of gaseous hydrocarbons (as I see it) is the position of the BSAC and others for that matter, that the figure of 15ppm gaseous hydrocarbon and an oil mist of 0.1 mg/m2 taken from a BOC standard? (If so which one), has been somehow taken as OK? For blending nitrox using oil lubricated air double filtered from an oil lube compressor? Also are the BSAC stating that they have based this advise on double filter technique on someone else?s analysis. If so, this requires further explanation.

Specific sensors for process gas analysis for long chain hydrocarbons, and oils in air using solid electrolytes is increasing also the use of infra red, however I would suggest rare in a sports diving nitrox production. While your statement ?many oil filled compressors out there which are regularly tested meet this standard?. I agree, but the standard is for breathing Air, and nothing to do with Nitrox.

For another example (with my professional interest declared) One of our design/installation projects was for Diving Diseases Research Center. DDRC Plymouth. A large 2.5m diameter 50 msw Hyperbaric Chamber and two, 1.8m diameter 250msw saturation chambers. This project required the use of air, helium and oxygen mixed from low percentages &gt;20% for deep gas, to high oxygen percentages up to 100%. Under law we were required to use oil free or oil-less compressors for the project.

(Why?) The alternative as it stands to date is that if air produced from an oil lubricated compressor and used in mixing an elevated concentration of oxygen under law the provider has a legal duty for this air to have been sampled in real time (that is on-line) for particulate contamination at the point of supply by one of the following methods: 1. An calibrated light laser obscuration device on-line. In the case of breathing diving gas, particles of 10 micron maximum particle diameter shall not exceed 70,000 per M2 and there shall be nil particles over 10 micron. Or 2. By particle measurement devise to measure the quality of the air by passing 0.5 m3 through a pre weighed sample filter of a pore size of 0.8 micron. These cellulose filters allow cleaning and particle counting to the following limits: 1-3 micron not to exceed 0.6 particles per cm3. 3-10 micron not to exceed 0.1 micron per cm3 and for &gt;10 micron shall not exceed 0.04 particles per cm3. Or as we did take the safe reliable oil free route. Your call so to speak.
Sorry for the length of all this. No I don?t think it?s complicated it?s just the legal obligation, not my opinion and that I have been (ass kicked) reminded of my duty of care.

[Phil Laughton]

Just to step back a little,
we are talking about AIR purity, air having been compressed
through an oil lubricated machine and then passed through a filter system which "guarantees air quality standards including
DIN 3188, EN 12021 and BS 4275". These words are from a compressor makers sales leaflet!. What you do with the air after it has passed through the comp filter system is up to you. You can add whatever other gas you want but the basic AIR purity std must be met first. It's a belt and braces job, better to try and eliminate any oil vapour trace from the AIR supply by using a secondary carbon filter, than just relying on the comp main filter being up to the job, before mixing with 100% O2.
If you want to compress oxygen specific machines are available,
but this is not what we are talking about.
Phil

:=From this old sod to another,
:=BS EN 12021 is for all air users inc fire and rescue services and as such has no bearing on nitrox blending. To ensure the air used for blending nitrox is oil vapour free, the air supply is usually passed through an additional filter. If the air is sampled after the double filtering there should be no trace of oil vapour in a detector tube. Filtration system manufacturers will tell you that providing maintenance guide lines are followed the air quality will be equal to the current standard.
:=Phil
:=
Phil. Sadly I can agree only with your first sentence. That of BSEN 12021 having no bearing on Nitrox blending.

However the idea of double filtration being suitable for Nitrox production is just a myth. If the BSAC ever signs off this double filter process using oil lubricated compressors for Nitrox, they (as others) will be on very thin ice.
I recall how and when this ?double filter? myth started during the American ?Aquacorp? DEMA exhibitions my response then to be akin to ?Mixing on Elm Street? is still on record. Although I do understand that other divers have even paid good money to be taught this unqualified procedure. Sadly it is still just that. Unqualified.

Further your statement about filter manufacturers is misleading, No high pressure filter manufacturer will tell you (in writing) that there filters are suitable for the production of an elevated oxygen concentration (nitrox) when filtering from an oil lubricated air compressor, they can?t. They fail the first condition. It is just a myth.

The fact is that in the UK and Europe the production of any gas with an oxygen concentration greater than 23% requires for a full fail safe IPP process of manufacture and that the process compressor, compressors, LOX pumps, gas boosters or any thing else you use in the production process be suitable for oxygen, oil-free and/or oil-less.

Etiquette and forum rules preclude a more robust response but to coin Red Dwarf: SMEICC: Suitability and myth equating to an equal indefensible catastrophic condition. LOL.

Iain Middlebrook.

[iain-hsm]

:=Further your statement about filter manufacturers is misleading, No high pressure filter manufacturer will tell you (in writing) that there filters are suitable for the production of an elevated oxygen concentration (nitrox) when filtering from an oil lubricated air compressor, they can?t. They fail the first condition. It is just a myth.

Can I just clarify what you're talking about? Are we talking filters on a compressor producing compressed air that is suitable for use in topping off nitrox cylinders, or are you talking about putting enriched air through a compressor & filter?

If i'm understanding what you appear to be saying correctly, you're saying that all air which goes near a nitrox cylinder needs to have been nowhere near a oil based compressor. That would make sense if you were talking about compressing the already-enriched air, but never heard anything like that for clean air before...

David

Sorry about all this I didn?t expect this from what started out as a small enquiry from Gary G about air and personal filters.
Firstly I am saying nothing, it?s not my opinion it?s just the legal position of work with a gas with an oxygen concentration above 23%. It doesn?t matter what I think here.

To clarify Yes I?m afraid it covers all and everything, "double filtering" partial pressure blending, continuous oxygen entrainment into a compressor. Any way you want to call it, it?s covered in the "blanket" clause: "Any gas with a percentage of oxygen greater than 23%" and the statement "Use no Oil". Its even written on 02 pressure gauges Pretty much cover?s the whole topic too.

This is not new information that?s what I am surprised about. I recall when this was first discussed in meetings I attended under the chair of Chris Allen further again with Bob Boler NDO. Also prior to the public launch of the Draeger Dolphin in Lubek the BSAC was invited and visited to discuss the implications, training etc. Included in that meeting in Lubek was the production and supply of Nitrox. I forget what year but with Ken Farrow and Dave Crockford invited me to go over with them. We all had a swim with the thing and as I recall it was all oil free then.

As a personal opinion, yes I do understand that there will be implications due to the BSAC stated (opinion) regarding Nitrox production and blending using oil lubricated compressors. Further the implication to other training agencies,Instructors, and dive shops. Look on the bright side though, some training agencies have generated quite a bit of cash with this. Some sadly have followed as "ditto heads" the myth.
May I respectfully suggest we leave it there and in the words of "Duke Nukem" let HSE sort out the mess

Iain Middlebrook.

[iain-hsm]

To step back a little.

Compressed Breathing Air.
The BSAC as others are required to fill breathing air cylinders with breathing quality air as specified in BSEN 12021(under that standard a certain small amount of oil is permitted as it was understood not to cause any pulmonary damage to the body).
The legal remit of BSEN 12021 covers only and is limited to. The quality standard of compressed breathing air.
(Nothing else. No other gas. No other gas mixture. No other breathing gas mixture).
This is the full legal scope of BSEN12021.

All Other Breathing Gases.
Be assured that as BSEN 12021 only covers compressed breathing air, any and all other breathing gas or breathing gas mixture including "nitrox" fall within other standards. For reference: medical oxygen, aviator breathing oxygen, diving grade helium.
Each of these specific breathing gases have there own specific specification, manufacturing inspection, process, analysis, procedures and requirements.

In response Phil, please name the air compressor manufacturer for reference, that in your words will "guarantee" there filter system, we will discuss this "claim" after you name them to enable specific references to be made. In the mean time I refer you to the seemingly opposing view made previous that "Filters by there very nature fail."

Further to your statement "What you do with the air after it has passed through the comp filter system is up to you!" etc. also your statement "you can add whatever other gas you want but the basic air purity must be met first". etc. I can only assume this is your own personal opinion.
Please with respect this is totally incorrect, it is misleading to others, and a potentially dangerous statement to make. We all have a duty regarding breathing gas quality and cannot "do what we like".

With respect it is probably more interesting to our peers to discuss how we got into this mess in the first place and to what extent external interests and influences managed to get us to the 02 v oil debacle in the first place.
Iain Middlebrook.

Just to step back a little,
we are talking about AIR purity, air having been compressed
through an oil lubricated machine and then passed through a filter system which "guarantees air quality standards including
DIN 3188, EN 12021 and BS 4275". These words are from a compressor makers sales leaflet!. What you do with the air after it has passed through the comp filter system is up to you. You can add whatever other gas you want but the basic AIR purity std must be met first. It's a belt and braces job, better to try and eliminate any oil vapour trace from the AIR supply by using a secondary carbon filter, than just relying on the comp main filter being up to the job, before mixing with 100% O2.
If you want to compress oxygen specific machines are available,
but this is not what we are talking about.
Phil

:=:=From this old sod to another,
:=:=BS EN 12021 is for all air users inc fire and rescue services and as such has no bearing on nitrox blending. To ensure the air used for blending nitrox is oil vapour free, the air supply is usually passed through an additional filter. If the air is sampled after the double filtering there should be no trace of oil vapour in a detector tube. Filtration system manufacturers will tell you that providing maintenance guide lines are followed the air quality will be equal to the current standard.
:=:=Phil
:=:=
:=Phil. Sadly I can agree only with your first sentence. That of BSEN 12021 having no bearing on Nitrox blending.
:=
:=However the idea of double filtration being suitable for Nitrox production is just a myth. If the BSAC ever signs off this double filter process using oil lubricated compressors for Nitrox, they (as others) will be on very thin ice.
:=I recall how and when this ?double filter? myth started during the American ?Aquacorp? DEMA exhibitions my response then to be akin to ?Mixing on Elm Street? is still on record. Although I do understand that other divers have even paid good money to be taught this unqualified procedure. Sadly it is still just that. Unqualified.
:=
:=Further your statement about filter manufacturers is misleading, No high pressure filter manufacturer will tell you (in writing) that there filters are suitable for the production of an elevated oxygen concentration (nitrox) when filtering from an oil lubricated air compressor, they can?t. They fail the first condition. It is just a myth.
:=
:=The fact is that in the UK and Europe the production of any gas with an oxygen concentration greater than 23% requires for a full fail safe IPP process of manufacture and that the process compressor, compressors, LOX pumps, gas boosters or any thing else you use in the production process be suitable for oxygen, oil-free and/or oil-less.
:=
:=Etiquette and forum rules preclude a more robust response but to coin Red Dwarf: SMEICC: Suitability and myth equating to an equal indefensible catastrophic condition. LOL.
:=
:=Iain Middlebrook.

[Phil Laughton]

Iain, please re-read my previous comments!!. The first section on your latest posting is what I have been saying all along.
With regard to the compressor manufacturers who "guarantee" air purity to a certain standard, how many do you want?. If these guarantees were not in place, would you buy a machine to fill your aqualung not knowing what quality of air the machine was producing. And as for filters being used for oxygen, this has at no time been mentioned by me.
Phil

To step back a little.

Compressed Breathing Air.
The BSAC as others are required to fill breathing air cylinders with breathing quality air as specified in BSEN 12021(under that standard a certain small amount of oil is permitted as it was understood not to cause any pulmonary damage to the body).
The legal remit of BSEN 12021 covers only and is limited to. The quality standard of compressed breathing air.
(Nothing else. No other gas. No other gas mixture. No other breathing gas mixture).
This is the full legal scope of BSEN12021.

All Other Breathing Gases.
Be assured that as BSEN 12021 only covers compressed breathing air, any and all other breathing gas or breathing gas mixture including "nitrox" fall within other standards. For reference: medical oxygen, aviator breathing oxygen, diving grade helium.
Each of these specific breathing gases have there own specific specification, manufacturing inspection, process, analysis, procedures and requirements.

In response Phil, please name the air compressor manufacturer for reference, that in your words will "guarantee" there filter system, we will discuss this "claim" after you name them to enable specific references to be made. In the mean time I refer you to the seemingly opposing view made previous that "Filters by there very nature fail."

Further to your statement "What you do with the air after it has passed through the comp filter system is up to you!" etc. also your statement "you can add whatever other gas you want but the basic air purity must be met first". etc. I can only assume this is your own personal opinion.
Please with respect this is totally incorrect, it is misleading to others, and a potentially dangerous statement to make. We all have a duty regarding breathing gas quality and cannot "do what we like".

With respect it is probably more interesting to our peers to discuss how we got into this mess in the first place and to what extent external interests and influences managed to get us to the 02 v oil debacle in the first place.
Iain Middlebrook.

:=Just to step back a little,
:=we are talking about AIR purity, air having been compressed
:=through an oil lubricated machine and then passed through a filter system which "guarantees air quality standards including
:=DIN 3188, EN 12021 and BS 4275". These words are from a compressor makers sales leaflet!. What you do with the air after it has passed through the comp filter system is up to you. You can add whatever other gas you want but the basic AIR purity std must be met first. It's a belt and braces job, better to try and eliminate any oil vapour trace from the AIR supply by using a secondary carbon filter, than just relying on the comp main filter being up to the job, before mixing with 100% O2.
:=If you want to compress oxygen specific machines are available,
:=but this is not what we are talking about.
:=Phil
:=
:=:=:=From this old sod to another,
:=:=:=BS EN 12021 is for all air users inc fire and rescue services and as such has no bearing on nitrox blending. To ensure the air used for blending nitrox is oil vapour free, the air supply is usually passed through an additional filter. If the air is sampled after the double filtering there should be no trace of oil vapour in a detector tube. Filtration system manufacturers will tell you that providing maintenance guide lines are followed the air quality will be equal to the current standard.
:=:=:=Phil
:=:=:=
:=:=Phil. Sadly I can agree only with your first sentence. That of BSEN 12021 having no bearing on Nitrox blending.
:=:=
:=:=However the idea of double filtration being suitable for Nitrox production is just a myth. If the BSAC ever signs off this double filter process using oil lubricated compressors for Nitrox, they (as others) will be on very thin ice.
:=:=I recall how and when this ?double filter? myth started during the American ?Aquacorp? DEMA exhibitions my response then to be akin to ?Mixing on Elm Street? is still on record. Although I do understand that other divers have even paid good money to be taught this unqualified procedure. Sadly it is still just that. Unqualified.
:=:=
:=:=Further your statement about filter manufacturers is misleading, No high pressure filter manufacturer will tell you (in writing) that there filters are suitable for the production of an elevated oxygen concentration (nitrox) when filtering from an oil lubricated air compressor, they can?t. They fail the first condition. It is just a myth.
:=:=
:=:=The fact is that in the UK and Europe the production of any gas with an oxygen concentration greater than 23% requires for a full fail safe IPP process of manufacture and that the process compressor, compressors, LOX pumps, gas boosters or any thing else you use in the production process be suitable for oxygen, oil-free and/or oil-less.
:=:=
:=:=Etiquette and forum rules preclude a more robust response but to coin Red Dwarf: SMEICC: Suitability and myth equating to an equal indefensible catastrophic condition. LOL.
:=:=
:=:=Iain Middlebrook.

[iain-hsm]

Phil thanks for all your input and information, it does look a bit of a mix up with the BSAC position on nitrox production.
So to step back one point at a time:
Start with the "claims" and "guarantee" from the specific compressor companies. I asked you to name the company so I could take reference. (Quote: "from the maker?s sales leaflet") That?s all. "How many do I want"? Just one would be a start, other wise it's just your opinion and you?re taking all the flak. I await your disclosure.

Agreed we are talking Nitrox production here, but with the air component from an oil lubricated compressor. The "guarantee" fail safe position required is that in the event of the filter or double filter failing, or other problem, the oil in the process system cannot be part of an ignition triangle. I.E. fail safe, in keeping with the original question on the thread. As this cannot be "guaranteed" without a. expensive analysis in real time monitoring production or b. an oil-free or oil-less production system, I therefore suggest that some are mistaken with air compressor claims and have mistakenly transposed this to a fail safe approved nitrox production procedure.
Iain Middlebrook.

Iain, please re-read my previous comments!!. The first section on your latest posting is what I have been saying all along.
With regard to the compressor manufacturers who "guarantee" air purity to a certain standard, how many do you want?. If these guarantees were not in place, would you buy a machine to fill your aqualung not knowing what quality of air the machine was producing. And as for filters being used for oxygen, this has at no time been mentioned by me.
Phil

:=To step back a little.
:=
:=Compressed Breathing Air.
:=The BSAC as others are required to fill breathing air cylinders with breathing quality air as specified in BSEN 12021(under that standard a certain small amount of oil is permitted as it was understood not to cause any pulmonary damage to the body).
:=The legal remit of BSEN 12021 covers only and is limited to. The quality standard of compressed breathing air.
:=(Nothing else. No other gas. No other gas mixture. No other breathing gas mixture).
:=This is the full legal scope of BSEN12021.
:=
:=All Other Breathing Gases.
:=Be assured that as BSEN 12021 only covers compressed breathing air, any and all other breathing gas or breathing gas mixture including "nitrox" fall within other standards. For reference: medical oxygen, aviator breathing oxygen, diving grade helium.
:=Each of these specific breathing gases have there own specific specification, manufacturing inspection, process, analysis, procedures and requirements.
:=
:=In response Phil, please name the air compressor manufacturer for reference, that in your words will "guarantee" there filter system, we will discuss this "claim" after you name them to enable specific references to be made. In the mean time I refer you to the seemingly opposing view made previous that "Filters by there very nature fail."
:=
:=Further to your statement "What you do with the air after it has passed through the comp filter system is up to you!" etc. also your statement "you can add whatever other gas you want but the basic air purity must be met first". etc. I can only assume this is your own personal opinion.
:=Please with respect this is totally incorrect, it is misleading to others, and a potentially dangerous statement to make. We all have a duty regarding breathing gas quality and cannot "do what we like".
:=
:=With respect it is probably more interesting to our peers to discuss how we got into this mess in the first place and to what extent external interests and influences managed to get us to the 02 v oil debacle in the first place.
:=Iain Middlebrook.
:=
:=:=Just to step back a little,
:=:=we are talking about AIR purity, air having been compressed
:=:=through an oil lubricated machine and then passed through a filter system which "guarantees air quality standards including
:=:=DIN 3188, EN 12021 and BS 4275". These words are from a compressor makers sales leaflet!. What you do with the air after it has passed through the comp filter system is up to you. You can add whatever other gas you want but the basic AIR purity std must be met first. It's a belt and braces job, better to try and eliminate any oil vapour trace from the AIR supply by using a secondary carbon filter, than just relying on the comp main filter being up to the job, before mixing with 100% O2.
:=:=If you want to compress oxygen specific machines are available,
:=:=but this is not what we are talking about.
:=:=Phil
:=:=
:=:=:=:=From this old sod to another,
:=:=:=:=BS EN 12021 is for all air users inc fire and rescue services and as such has no bearing on nitrox blending. To ensure the air used for blending nitrox is oil vapour free, the air supply is usually passed through an additional filter. If the air is sampled after the double filtering there should be no trace of oil vapour in a detector tube. Filtration system manufacturers will tell you that providing maintenance guide lines are followed the air quality will be equal to the current standard.
:=:=:=:=Phil
:=:=:=:=
:=:=:=Phil. Sadly I can agree only with your first sentence. That of BSEN 12021 having no bearing on Nitrox blending.
:=:=:=
:=:=:=However the idea of double filtration being suitable for Nitrox production is just a myth. If the BSAC ever signs off this double filter process using oil lubricated compressors for Nitrox, they (as others) will be on very thin ice.
:=:=:=I recall how and when this ?double filter? myth started during the American ?Aquacorp? DEMA exhibitions my response then to be akin to ?Mixing on Elm Street? is still on record. Although I do understand that other divers have even paid good money to be taught this unqualified procedure. Sadly it is still just that. Unqualified.
:=:=:=
:=:=:=Further your statement about filter manufacturers is misleading, No high pressure filter manufacturer will tell you (in writing) that there filters are suitable for the production of an elevated oxygen concentration (nitrox) when filtering from an oil lubricated air compressor, they can?t. They fail the first condition. It is just a myth.
:=:=:=
:=:=:=The fact is that in the UK and Europe the production of any gas with an oxygen concentration greater than 23% requires for a full fail safe IPP process of manufacture and that the process compressor, compressors, LOX pumps, gas boosters or any thing else you use in the production process be suitable for oxygen, oil-free and/or oil-less.
:=:=:=
:=:=:=Etiquette and forum rules preclude a more robust response but to coin Red Dwarf: SMEICC: Suitability and myth equating to an equal indefensible catastrophic condition. LOL.
:=:=:=
:=:=:=Iain Middlebrook.

[Phil Laughton]

Iain, the sales bumph I quoted from is for CompAir machines, fitted with MDE filtration systems. Bauer and Hamworthy also give the same guarantee. I could scan the leaflet and send it to you direct if you wish to have a closer look. Keep thinking air!.
Phil

Phil thanks for all your input and information, it does look a bit of a mix up with the BSAC position on nitrox production.
So to step back one point at a time:
Start with the "claims" and "guarantee" from the specific compressor companies. I asked you to name the company so I could take reference. (Quote: "from the maker?s sales leaflet") That?s all. "How many do I want"? Just one would be a start, other wise it's just your opinion and you?re taking all the flak. I await your disclosure.

Agreed we are talking Nitrox production here, but with the air component from an oil lubricated compressor. The "guarantee" fail safe position required is that in the event of the filter or double filter failing, or other problem, the oil in the process system cannot be part of an ignition triangle. I.E. fail safe, in keeping with the original question on the thread. As this cannot be "guaranteed" without a. expensive analysis in real time monitoring production or b. an oil-free or oil-less production system, I therefore suggest that some are mistaken with air compressor claims and have mistakenly transposed this to a fail safe approved nitrox production procedure.
Iain Middlebrook.

:=Iain, please re-read my previous comments!!. The first section on your latest posting is what I have been saying all along.
:=With regard to the compressor manufacturers who "guarantee" air purity to a certain standard, how many do you want?. If these guarantees were not in place, would you buy a machine to fill your aqualung not knowing what quality of air the machine was producing. And as for filters being used for oxygen, this has at no time been mentioned by me.
:=Phil
:=
:=:=To step back a little.
:=:=
:=:=Compressed Breathing Air.
:=:=The BSAC as others are required to fill breathing air cylinders with breathing quality air as specified in BSEN 12021(under that standard a certain small amount of oil is permitted as it was understood not to cause any pulmonary damage to the body).
:=:=The legal remit of BSEN 12021 covers only and is limited to. The quality standard of compressed breathing air.
:=:=(Nothing else. No other gas. No other gas mixture. No other breathing gas mixture).
:=:=This is the full legal scope of BSEN12021.
:=:=
:=:=All Other Breathing Gases.
:=:=Be assured that as BSEN 12021 only covers compressed breathing air, any and all other breathing gas or breathing gas mixture including "nitrox" fall within other standards. For reference: medical oxygen, aviator breathing oxygen, diving grade helium.
:=:=Each of these specific breathing gases have there own specific specification, manufacturing inspection, process, analysis, procedures and requirements.
:=:=
:=:=In response Phil, please name the air compressor manufacturer for reference, that in your words will "guarantee" there filter system, we will discuss this "claim" after you name them to enable specific references to be made. In the mean time I refer you to the seemingly opposing view made previous that "Filters by there very nature fail."
:=:=
:=:=Further to your statement "What you do with the air after it has passed through the comp filter system is up to you!" etc. also your statement "you can add whatever other gas you want but the basic air purity must be met first". etc. I can only assume this is your own personal opinion.
:=:=Please with respect this is totally incorrect, it is misleading to others, and a potentially dangerous statement to make. We all have a duty regarding breathing gas quality and cannot "do what we like".
:=:=
:=:=With respect it is probably more interesting to our peers to discuss how we got into this mess in the first place and to what extent external interests and influences managed to get us to the 02 v oil debacle in the first place.
:=:=Iain Middlebrook.
:=:=
:=:=:=Just to step back a little,
:=:=:=we are talking about AIR purity, air having been compressed
:=:=:=through an oil lubricated machine and then passed through a filter system which "guarantees air quality standards including
:=:=:=DIN 3188, EN 12021 and BS 4275". These words are from a compressor makers sales leaflet!. What you do with the air after it has passed through the comp filter system is up to you. You can add whatever other gas you want but the basic AIR purity std must be met first. It's a belt and braces job, better to try and eliminate any oil vapour trace from the AIR supply by using a secondary carbon filter, than just relying on the comp main filter being up to the job, before mixing with 100% O2.
:=:=:=If you want to compress oxygen specific machines are available,
:=:=:=but this is not what we are talking about.
:=:=:=Phil
:=:=:=
:=:=:=:=:=From this old sod to another,
:=:=:=:=:=BS EN 12021 is for all air users inc fire and rescue services and as such has no bearing on nitrox blending. To ensure the air used for blending nitrox is oil vapour free, the air supply is usually passed through an additional filter. If the air is sampled after the double filtering there should be no trace of oil vapour in a detector tube. Filtration system manufacturers will tell you that providing maintenance guide lines are followed the air quality will be equal to the current standard.
:=:=:=:=:=Phil
:=:=:=:=:=
:=:=:=:=Phil. Sadly I can agree only with your first sentence. That of BSEN 12021 having no bearing on Nitrox blending.
:=:=:=:=
:=:=:=:=However the idea of double filtration being suitable for Nitrox production is just a myth. If the BSAC ever signs off this double filter process using oil lubricated compressors for Nitrox, they (as others) will be on very thin ice.
:=:=:=:=I recall how and when this ?double filter? myth started during the American ?Aquacorp? DEMA exhibitions my response then to be akin to ?Mixing on Elm Street? is still on record. Although I do understand that other divers have even paid good money to be taught this unqualified procedure. Sadly it is still just that. Unqualified.
:=:=:=:=
:=:=:=:=Further your statement about filter manufacturers is misleading, No high pressure filter manufacturer will tell you (in writing) that there filters are suitable for the production of an elevated oxygen concentration (nitrox) when filtering from an oil lubricated air compressor, they can?t. They fail the first condition. It is just a myth.
:=:=:=:=
:=:=:=:=The fact is that in the UK and Europe the production of any gas with an oxygen concentration greater than 23% requires for a full fail safe IPP process of manufacture and that the process compressor, compressors, LOX pumps, gas boosters or any thing else you use in the production process be suitable for oxygen, oil-free and/or oil-less.
:=:=:=:=
:=:=:=:=Etiquette and forum rules preclude a more robust response but to coin Red Dwarf: SMEICC: Suitability and myth equating to an equal indefensible catastrophic condition. LOL.
:=:=:=:=
:=:=:=:=Iain Middlebrook.

[David Applin]

Ok,

What your basically saying is that you are using oxygen greater than 22% everyone who adds any other gas should ensure "in real time" that the other gas complies with the purity standards for the oxygen, with particular emphasis on the fact that the data sheets for oxygen contain the words "use no oil"

We also seem to have all agreed that there is no BS / EN standard for nitrox

in your post below you state

if air produced from an oil lubricated compressor and used in mixing an elevated concentration of oxygen under law the provider has a legal duty for this air to have been sampled in real time (that is on-line) for particulate contamination at the point of supply by one of the following methods........


Please reference the "law" that you are refering to

Question 1, If a standard for nitrox blending was to be developed, do you believe that the relevant bodies would look at the track record over the last 10+ years of nitrox mixing taking into account the reletive lack of problems? thus developing a standard in which "use no oil" had a different meaning to yours?

Question 2, If I vented all the gas from a BOC "J" of oxygen and examined the cylinder for traces of hydrocarbons - would I find any? (ps I know the answer I just want to see if you admit it in public)

Question 3, Whilst you are no doubt in your professional capacity an expert on this subject and it is unlikely that anyone here can challenge you on anything you have written. what are your motives? are you suggesting we should all stop using nitrox unless supplied and analysed in the way you describe? or are you mearly pointing out, for the record, that the Industry norm and everyones perception of the situation is incorrect.

Question 4, Whats your view on all the filling systems out there which have been professionally installed, have a written scheme of examination and have even been inspected by the HSE.


respectfully

David: Thanks for this input. Re your comment regarding BOC (of all the examples why them?) this requires I disclose a small professional interest. BOC is a customer, we are responsible for the design, and maintain currently two main types of BOC oxygen compressor, One a 670 CuM/hr (424 scfm) reciprocating compressor design, the other a 927 scfm multi-stage oxygen compressor. Both types run 24 hours per day continues duty in the manufacture/production of oxygen. BOC currently operate over 500 gas compressors in the UK and for interest non use oil in the manufacture or production of compressed oxygen or any other oxygen enriched gas. I would therefore respectfully refer you to a specific BOC website <a href="http://www1.boc.com/uk/sds/" >http://www1.boc.com/uk/sds/</a> to download the relevant data sheets regarding BOC products.

Ok that over, now specifically onto your statement of gaseous hydrocarbons (as I see it) is the position of the BSAC and others for that matter, that the figure of 15ppm gaseous hydrocarbon and an oil mist of 0.1 mg/m2 taken from a BOC standard? (If so which one), has been somehow taken as OK? For blending nitrox using oil lubricated air double filtered from an oil lube compressor? Also are the BSAC stating that they have based this advise on double filter technique on someone else?s analysis. If so, this requires further explanation.

Specific sensors for process gas analysis for long chain hydrocarbons, and oils in air using solid electrolytes is increasing also the use of infra red, however I would suggest rare in a sports diving nitrox production. While your statement ?many oil filled compressors out there which are regularly tested meet this standard?. I agree, but the standard is for breathing Air, and nothing to do with Nitrox.

For another example (with my professional interest declared) One of our design/installation projects was for Diving Diseases Research Center. DDRC Plymouth. A large 2.5m diameter 50 msw Hyperbaric Chamber and two, 1.8m diameter 250msw saturation chambers. This project required the use of air, helium and oxygen mixed from low percentages &gt;20% for deep gas, to high oxygen percentages up to 100%. Under law we were required to use oil free or oil-less compressors for the project.

(Why?) The alternative as it stands to date is that if air produced from an oil lubricated compressor and used in mixing an elevated concentration of oxygen under law the provider has a legal duty for this air to have been sampled in real time (that is on-line) for particulate contamination at the point of supply by one of the following methods: 1. An calibrated light laser obscuration device on-line. In the case of breathing diving gas, particles of 10 micron maximum particle diameter shall not exceed 70,000 per M2 and there shall be nil particles over 10 micron. Or 2. By particle measurement devise to measure the quality of the air by passing 0.5 m3 through a pre weighed sample filter of a pore size of 0.8 micron. These cellulose filters allow cleaning and particle counting to the following limits: 1-3 micron not to exceed 0.6 particles per cm3. 3-10 micron not to exceed 0.1 micron per cm3 and for &gt;10 micron shall not exceed 0.04 particles per cm3. Or as we did take the safe reliable oil free route. Your call so to speak.
Sorry for the length of all this. No I don?t think it?s complicated it?s just the legal obligation, not my opinion and that I have been (ass kicked) reminded of my duty of care.