Inline Filter Questions | Apnea Board

Jun. 23, 2025

Inline Filter Questions | Apnea Board

Jake B

Posts: 28
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Machine: ResMed AirCurve 10 VAuto BiPAP
Mask Type: Full face mask
Mask Make & Model: ResMed AirTouch F20
Humidifier: ResMed
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CPAP Software: OSCAR

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Sex: Male
Location: Tennessee

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Inline Filter Questions Hello all,
I've recently been trying to use an inline filter to hopefully cut down on some allergy symptoms. I believe my dust mite allergies could be causing my issues and/or contributing to sleep problems. But that's a story for another day.

So I installed the bulb filter between the machine and the hose as you're supposed to do however when I put my mask on, I can hear a whistling sound coming from I believe the mask or hose. It's worse when I lay on my side, because I'm guessing the whistling sort of echoes off my pillow and seems louder.

I found on another site where it's possible to install the filter an alternate way - between the hose and the mask. I've not had any issues wearing it this way but this poses another question. Most filters (home A/C, car engine, etc.) are meant to be installed to where the air flows one direction, which seems to be the same with these filters (see attached)

According to this graphic, if I connect to the actual hose and mask like I'm doing, the filter is technically backwards of how it should be. Is this going to be an issue? Are there any solutions to make it not whistle when it's installed the 'right' way? Any assistance is appreciated.

Note- this is not meant to be a debate whether or not I should use this type of filter. I know some people are against them, however I am trying them to see if they work for me. Thanks!

Edit- for some reason it's not allowing me to attach the photo of the airflow direction, so here is the link
[Commercial Link Removed] Search amazon for Nispira line Outlet Bacteria Filter

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----- Jake B

Posts: 28
Threads: 5
Joined: Mar

RE: Inline Filter Questions Trying to attach photo

Attached Files Thumbnail(s)

Sleeprider
Wiki Editor

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Machine: Resmed Aircurve 10 VAuto
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CPAP Pressure: Vauto 9.6-18, PS 4.4
CPAP Software: ResScan OSCAR

Other Comments: गुरु

Sex: Male
Location: Florida

RE: Inline Filter Questions Remember to use the setting for an inline antibacterial filter on your machine settings. Keep an eye on the filter as they exist in a humid environment and need to be changed if you see any contamination. Consider adding Flonase to your therapy regimen. It might work wonders. Sleeprider
Apnea Board Moderator
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT. DaveL

Posts: 2,522
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Machine: S10 Autoset For Her (Aug 27, )
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Location: Canada/Toronto

RE: Inline Filter Questions

(02-14-, 11:48 AM)Jake B Wrote: Trying to attach photo

Jake the airflow arrows should be in the same direction...from the cpap machine to the filter to the mask.

I've seen all kinds of screw ups with air filters in air handling units. I'm an old mechanical engineer...

for instance, no filter; filters completely plugged; filters with blow by because they are built wrong. Noise problems because replacement filters weren't built right. Filters that weren't assembled right by the manufacturer.

I have a question....is there a highly efficient ResMed filter that would fit in the cpap machine inlet? That would be quieter.... DaveL
compliant for 35 years /// Still trying!

I'm just a cpap user like you. I don't give medical advice. Seek the advice of a physician before seeking treatment for medical conditions including sleep apnea.

http://www.apneaboard.com/wiki/index.php..._The_Guide

Jake B

Posts: 28
Threads: 5
Joined: Mar

RE: Inline Filter Questions

(02-14-, 10:41 PM)DaveL Wrote:
(02-14-, 11:48 AM)Jake B Wrote: Trying to attach photo

Jake the airflow arrows should be in the same direction...from the cpap machine to the filter to the mask.

That is the 'correct' way to use these apparently. Machine to filter to hose to mask.

But the way I have mine installed (attached to the mask end), the filter has to be reversed due to the fittings on each end so the airflow is technically backwards:

Machine -> Hose -> Filter -> Mask

So my concern was how effective it would be using it like this. I don't seem to be having much issue so far, so we will see.

Hopefully all this makes sense, it's hard to explain without having something to show visually. DaveL

Posts: 2,522
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RE: Inline Filter Questions Going back to drafting board days...a long time ago...

The transition is shown properly...it's shorter and steeper on the inlet side of the filter. It's longer and shallower on the discharge side. The filter is shown properly.

If you've reversed the filter, it's in backwards and may be the cause of the noise. Way back I used to design HVAC for schools, hospital and industry.

However, I wouldn't use a filter like that. I don't know how it's made inside. and the air velocity and velocity pressure are high.

I'd rather use a high grade filter on the inlet to the cpap where the velocity is lower. I have standard ResMed filters. If a higher grade filter is available, I'll change. I plan to check with my DME. DaveL
compliant for 35 years /// Still trying!

I'm just a cpap user like you. I don't give medical advice. Seek the advice of a physician before seeking treatment for medical conditions including sleep apnea.

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SarcasticDave94

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Sex: Male
Location: Nowhere near Normal IL, US, probably in PA drinking coffee

RE: Inline Filter Questions Given that these are directional, I'd say it's not working well enough to bother with if you can't install it with right airflow direction in mind. If I'm not mistaken, these AB filters are expected to be near the machine outlet. Example on an NIV the AB filter is on the machine outlet. That placement otherwise that is intentional on your part, but I think the filter project overall here is a bust. I think it's asking for some trouble to reverse flow this filter intentional. Mask Primer

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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEBSITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT. DaveL

Posts: 2,522
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Joined: Apr

RE: Inline Filter Questions

(02-15-, 12:39 PM)SarcasticDave94 Wrote: Given that these are directional, I'd say it's not working well enough to bother with if you can't install it with right airflow direction in mind. If I'm not mistaken, these AB filters are expected to be near the machine outlet. Example on an NIV the AB filter is on the machine outlet. That placement otherwise that is intentional on your part, but I think the filter project overall here is a bust. I think it's asking for some trouble to reverse flow this filter intentional.

Thanks.

You've stated it better than I could.

DaveL DaveL
compliant for 35 years /// Still trying!

I'm just a cpap user like you. I don't give medical advice. Seek the advice of a physician before seeking treatment for medical conditions including sleep apnea.

http://www.apneaboard.com/wiki/index.php..._The_Guide

SarcasticDave94

Posts: 15,562
Threads: 22
Joined: Mar

RE: Inline Filter Questions Just doing my part to make the name Dave look awesome. Mask Primer

Positional Apnea

Attach OSCAR, etc.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEBSITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT. DaveL

Posts: 2,522
Threads: 38
Joined: Apr

RE: Inline Filter Questions You dun good. ;-)

I'm still working as an engineer. Getting new schools built at about $12M a pop.

DaveL DaveL
compliant for 35 years /// Still trying!

I'm just a cpap user like you. I don't give medical advice. Seek the advice of a physician before seeking treatment for medical conditions including sleep apnea.

http://www.apneaboard.com/wiki/index.php..._The_Guide

What type of air filter does your compressed air system need?

There’s no doubt for manufacturers in the Middle East that regular maintenance of your air compressor system will keep it running smoothly and more efficiently. Because compressed air filtration is an important part of meeting your production requirements, they require special attention. This article will give you an insight into the types of compressed air inline filters that are available and their suitability for your applications. The most important thing for improving your compressor’s air filter is to both understand the needs of your compression system and the right equipment to meet those needs. That way, you can have a high quality air compressor system that is cost efficient and easy to maintain.

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The application and use of your compressed air will decide which filters you need. Not all applications that use compressed air require the same level of filtration, that is why having this information is the first step to choose the correct filter. If you are using compressed air in the manufacturing of electronics or creating of food or food packaging, you will want a higher quality of compressed air with as little contaminates as possible. If you are using compressed air to power pneumatic tools or fill tires, the compressed air can be slightly less "clean" and still protect your equipment.

Let us firstly get a better understanding of what contaminants are and how they affect the compressed air system. Contaminants within a compressed air system can originate from ambient air that is utilized, as well as the system (compressor) itself. There are three main contaminants that are found in compressed air: particulates, aerosols and vapors.

Particulates: Particulates in compressed air system are small pieces of solid material such as dust, dirt and or pollen from the ambient air, as well as loose metal particles that can be caused by pipe corrosion. Depending on the sensitivity of your application and or process, contact with particles can be damaging to the end product, therefore causing delays in production and quality control issues, not to mention potentially unsatisfied customers.

Aerosols: Aerosols consist of small droplets of liquid that can be found within the compressed air system, especially in those using oil-injected compressors. Aerosols are created from the lubricant, in this case, the oil used in the compressor and can be harmful to both products and people if not treated properly.

Vapors: In the compressed air system, vapors consist of lubricants as well as any other liquid that has converted to a gas. Such vapors require a special carbon activated filter in order to be removed from the system.

Now that we have a better understanding of the contaminants above, let us take a look at what types of filters are used in eliminating each type of contaminant. The different filter types are as follows:

Coalescing filters are used for removing water and aerosols. Small droplets are caught in a filter media and merged into larger droplets that are then taken out of the filter. A re-entrainment barrier prevents these droplets from reentering the air. Most of the liquid coalescing filters remove is water and oil. These filters also remove particulates from compressed air, trapping them within the filter media, which can lead to pressure drops if not changed regularly. Pressure drop means an energy loss in the compressed air system. Every 1 bar of differential pressure an air compressor must overcome is equal to approximately 7% increase in electrical consumption. Coalescing filters remove most contaminants very well, reducing particulate levels down to 0.1 micron in size and liquids down to 0.01 ppm.

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Adsorption filters are typically used to remove gaseous lubricants that will go through the coalescing filter. Water and aerosols will quickly saturate this type of filter, rendering it useless in a matter of hours. Sending air through a coalescing filter prior to the adsorption filter will prevent this damage. The adsorption process uses activated carbon granules, carbon cloth or paper to capture and remove contaminants. Activated charcoal is the most common filter media because it has a large open pore structure; a handful of activated charcoal has the surface area of a football field. Because of the use of activated charcoal, however, a dust filter needs to be used after this type of filter to remove the dust particulate.

Dust removal filters are usually used to remove desiccant particles after an adsorption dryer. They can also be implemented at point of use to remove any corrosion particles from the compressed air. Dust removal filters operate in a similar technique as a coalescing filter, capturing and retaining particles within the filter media to provide up to 99.% particle removal efficiency. However, they do not remove liquids or aerosols.

At different points of use, different compressed air purities might be needed, depending on the application. The various air purity classes are provided in the table below, which clearly shows the various Atlas Copco filters and dryers that meet all the different classes.

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