[Equipment] Resmed S9 Filters: Standard versus Hypo-allergenic

[me50]

I use ResMed DSP1011 Hypoallergenic filters. I don't use my insurance because, the in-network provider does not have this type. Even though they have what is claimed to be Hypoallergenic, they are not as good. I have dust allergies and it makes a big difference for me.

They may not have them in stock but they can order them. I asked the same question and the RT told me that what they carry is basically hypoallergenic even though they are not called that.

I am going to ask them to order hypoallergenic or I am going to find a DME that will. You would think that DME's would do whatever it takes to help their client but most of them are interested in the bottom line and that is to make as much money as they can.

[Kritiker]

My post about particulate transmission through different filters seems to have gotten lost in the discussion about where to buy what that followed.

I wondered if anyone had any interest, or could shed any light, on my questions about the relative specifications of the standard and hypoallergenic ResMed R9 filters.

Efficiency is the ratio of some desired or useful result divided by the total possible result.

Efficiency = amount of useful work / total possible work

Filter efficiency is the ratio of particles, of the specified size (or possibly sometimes larger), trapped by a filter divided by the total number of particles, of the specified size (or larger?), found in the air upstream of the filter.

A micron (μm, or micrometre or micrometer) is one millionth of a metre (meter). There are 25,400 microns to an inch.

We are not given any indication of which testing standard was used to obtain the ResMed filter efficiency values nor exactly what the given specifications mean. We don't for example, know whether the ratings apply to 7 and 0.5 micron mean diameter particles (which includes smaller and larger) or to particles of those diameters and larger, nor what mix of particle sizes.

HEPA filters are all rated for particles of 0.3 micron mean diameter. I have seen this expressed (on Wikipedia, incorrectly perhaps?) as particles of mean diameter 0.3 micron or larger.
I am unsure which applies to the ResMed specifications.

A filter's efficiency of 88% at 7 microns should probably mean that it will stop 88% of particles 7 microns mean diameter but it could mean that it will stop 88% of particles of 7 microns or larger, a looser specification;
A filter's efficiency of 89.9% at 0.5 micron should probably mean that it will stop 89.9% of particles .5 micron mean diameter or it could mean that it will stop particles of 89.9% of particles 0.5 micron or larger.

Either way, this represents a significant difference between the two filters.

What follows is based on the (looser) specification of particle size, i.e., mean diameter or larger. I am not sure how to do the same for the tighter definition and I haven't the time to pursue it right now. I offer what follows for what it is worth and I am not sure what that is.

I calculate efficiencies of 0.0 for both filters for, i.e, neither filter catches: viruses, pesticides and coal flue gases.

The following particles seem to be caught, to varying degrees, by the finer filter (efficiency is given) and not the standard one (efficiency is 0.0).

0.5μm 7μm Particle
89.9% 0.0% liquid droplets
89.9% 0.0% anthrax
89.9% 0.0% Lead dust
89.9% 0.0% Spider web
82.6% 0.0% Paint pigments
78.9% 0.0% Tobacco smoke
71.9% 0.0% various combustion byproducts
46.3% 0.0% Oil smoke
41.3% 0.0% Smoldering or flaming cooking oil

The following particles are caught significantly better (more than three times as many) by the finer filter than the standard one. Both efficiencies are given.

0.5μm 7μm Particle
89.9% 27.8% Insecticide dust
86.3% 26.7% Radioactive fallout

The following particles are caught better by the finer filter than the standard one. Both efficiencies are given.

0.5μm 7μm Particle
89.9% 48.9% Mold
89.9% 52.8% Red blood cells
89.9% 66.0% Antiperspirant
88.7% 67.7% Face powder
89.9% 71.5% Iron dust
88.8% 72.6% Atmospheric dust
89.9% 76.4% Talcum dust
89.9% 77.2% Yeast cells
89.6% 78.1% Bacteria
89.9% 78.5% Spores

The following particles are caught marginally better by the finer filter than the standard one. Both efficiencies are given.

0.5μm 7μm Particle
89.9% 81.7% Textile dust
89.9% 81.8% Asbestos
89.9% 82.7% Coal dust
89.9% 84.4% Cement dust
89.9% 87.4% Metallurgical fumes & dust
89.9% 88.0% Mold spores
89.9% 88.0% Pollen
89.9% 88.0% Dust mites
89.9% 88.0% Beach sand
89.9% 88.0% Glass wool

To test a filter, particle counters measure the size and quantity of upstream particles per known volume of fluid, as well as the size and quantity of particles downstream of the filter. The number of particles trapped by the filter can then be computed as Particles Upstream - Particles Downstream.

Filter Efficiency = Particles Trapped / Particles Upstream = (Particles Upstream - Particles Downstream) / Particles Upstream

I have had to make some assumptions and ignore some variables:

• I have assumed here that the efficiencies refer to particles of the specified diameter and larger. The results are not applicable if the efficiencies refer to mean particle diameters.
  
• I have had to ignore the effects of actual operating conditions, e.g., flow surges and changes in temperature.
  
• I had to assume that the particle sizes are uniformly distributed throughout the entire size range. This is not realistic.
  
• I had to assume that a filter's efficiency is constant for all particle sizes. This is unrealistic. It seem reasonable that a filter should do better at stopping larger particles than smaller ones.
  
• I had to assume that a filter's efficiency is constant for all particle types. This is unrealistic. It seem reasonable that a filter might do better at stopping some particles than others, e.g., due to shape, stickiness.

As well, a filter's efficiency does not indicate its dirt-holding capacity, the total amount of contaminant that can be trapped by the filter throughout its life, nor does it indicate its stability or performance over time.

There may be other, implied, assumptions I haven't even discovered yet.

Having calculated all this, I am now left wondering whether it is of interest or use to anyone or was just an academic exercise.

Particle Diameter (microns)
min max Particle
0.5 5 Liquid droplets
1 5 Anthrax
2 2 Lead dust
2 3 Spider web
0.1 5 Paint pigments
0.01 4 Tobacco smoke
0 2.5 various combustion byproducts
0.03 1 Oil smoke
0.03 0.9 Smoldering or flaming cooking oil
0.5 10 Insecticide dust
0.1 10 Radioactive fallout
3 12 Mold
5 10 Red blood cells
6 10 Antiperspirant
0.1 30 Face powder
4 20 Iron dust
0.001 40 Atmospheric dust
0.5 50 Talcum dust
1 50 Yeast cells
0.3 60 Bacteria
3 40 Spores
6 20 Textile dust
0.7 90 Asbestos
1 100 Coal dust
3 100 Cement dust
0.1 1000 Metallurgical fumes & dust
10 30 Mold spores
10 1000 Pollen
100 300 Dust mites
100 10000 Beach sand
1000 1000 Glass wool
0.08 0.2 Coal flue gas
0.005 0.3 Viruses
0.001 0.001 Pesticides & herbicides

Sources
Filter Arrestance and Efficiency
Filter efficiency definition
Particle Sizes

[Peter_C]

I mean this most sincerely when I say that the above is too much thinking for me. I've been on a machine for more than a dozen years now, and have simply used whatever filter I have been given, plus I even have been known to wash (and dry) and reuse filters too. Granted, I do not have severe allergies or the like either.

I use a 'filter' simply to extend the life of my machine, rather than to try to filter the air I breathe - isn't that what my nose is for??

[me50]

I mean this most sincerely when I say that the above is too much thinking for me. I've been on a machine for more than a dozen years now, and have simply used whatever filter I have been given, plus I even have been known to wash (and dry) and reuse filters too. Granted, I do not have severe allergies or the like either.

I use a 'filter' simply to extend the life of my machine, rather than to try to filter the air I breathe - isn't that what my nose is for??

It was over my head! My brain was tired after reading it and that didn't include what it would have felt like if I tried to comprehend it!

[DOOM_NX]

OK, I read and understood what Kritiker is trying to say.

1) Neither of the ResMed filters belong to any HEPA class.

According to the European Standards EN 1822:2009, a HEPA filter has to trap at least 85% of particles at the given most penetrating particle size (MPPS) -- class E10 (EPA). That particle size is around 0.3 μm, but differs for every filter tested.

According to the American standards, in order to be called HEPA, a filter has to trap at least 99.97% of the particles at 0.3 μm.

There is a defined standard deviation in the size of the particles used to test the filters, but that's negligible for our discussion.

2) The hypoallergenic filter is at best an F9 class filter under the European Standards, corresponding to MERV 15 in the US.

The standard filter is likely an F5-F6 class filter, MERV 9-11. It's difficult to be more specific, we'll have to ask ResMed for this.



3) The standard filter will keep away: insects, hair, textile fibers, dust, cement dust, pollen, dust mites, sand, plant spores, some mold spores, some pet dander, some bacteria and generally particles over 7 μm.

The hypoallergenic filter will keep away: most tobacco smoke, bacteria, insecticide dusts, pet dander, mold spores, house dust mite allergens and generally particles over 0.5 μm.

My suggestion: If you are not allergic to pets, dust mites or mold, then you should be fine with the standard filter. However, I highly doubt that you haven't taken measures to eliminate these allergens from your house.

Don't wash the filter. Replace it every 6 months.

[me50]

[quote='DOOM_NX' pid='47506' dateline='1382486514']
OK, I read and understood what Kritiker is trying to say.

1) Neither of the ResMed filters belong to any HEPA class.

According to the European Standards EN 1822:2009, a HEPA filter has to trap at least 85% of particles at the given most penetrating particle size (MPPS) -- class E10 (EPA). That particle size is around 0.3 μm, but differs for every filter tested.

According to the American standards, in order to be called HEPA, a filter has to trap at least 99.97% of the particles at 0.3 μm.

There is a defined standard deviation in the size of the particles used to test the filters, but that's negligible for our discussion.

2) The hypoallergenic filter is at best an F9 class filter under the European Standards, corresponding to MERV 15 in the US.

The standard filter is likely an F5-F6 class filter, MERV 9-11. It's difficult to be more specific, we'll have to ask ResMed for this.



3) The standard filter will keep away: insects, hair, textile fibers, dust, cement dust, pollen, dust mites, sand, plant spores, some mold spores, some pet dander, some bacteria and generally particles over 7 μm.

The hypoallergenic filter will keep away: most tobacco smoke, bacteria, insecticide dusts, pet dander, mold spores, house dust mite allergens and generally particles over 0.5 μm.

My suggestion: If you are not allergic to pets, dust mites or mold, then you should be fine with the standard filter. However, I highly doubt that you haven't taken measures to eliminate these allergens from your house.

Don't wash the filter. Replace it every 6 months.
quote]

I replace my filters every 2 weeks or 2 times per month since I am allowed 2 filters per month and they are inexpensive. It helps extend the life of the machine and helps my allergies

[DOOM_NX]

The more you leave your filter alone, the more it clogs and the more effective it becomes at filtering. However, the pressure drop can become too big for your machine and it may overheat or not deliver the prescribed pressure at the mask. To sum up, your respiratory system would benefit from a dirty filter and less frequent changes, but your machine needs a clean filter to work properly. So you are changing the filters for your machine, not for your allergies.

By the way, me50, what are you allergic to?

[me50]

The more you leave your filter alone, the more it clogs and the more effective it becomes at filtering. However, the pressure drop can become too big for your machine and it may overheat or not deliver the prescribed pressure at the mask. To sum up, your respiratory system would benefit from a dirty filter and less frequent changes, but your machine needs a clean filter to work properly. So you are changing the filters for your machine, not for your allergies.

By the way, me50, what are you allergic to?

olive trees and other outdoor stuff. I don't remember everything now but I couldn't afford the shots so I tough it out.

[DOOM_NX]

I'm allergic to grasses, olive trees, planes and cypress (at least those are what I get shots for). The standard filter would work for us fine. But it feels better to know you're breathing even cleaner air, doesn't it?

[me50]

I'm allergic to grasses, olive trees, planes and cypress (at least those are what I get shots for). The standard filter would work for us fine. But it feels better to know you're breathing even cleaner air, doesn't it?

well, since I have nasal sprays and eye drops, I suppose my goal would be to preserve the machine and make it last as long as I can. They are expensive :-)