How to pick a car air purifier?

[paulcai-canton]

How to pick a car air purifier? CADR is the key performance indicator.

The Clean Air Delivery Rate, or CADR for short, is an indication of the volume of filtered air delivered by an air purifier. CADR is given through a process called the ANSI/AHAM AC-1 standard:

(1) The purifier is placed in a testing chamber of a specified size.
(2) Before the purifier is activated, the amount of contaminants in the room is measured.
(3) The purifier is activated for a period of twenty minutes, during which time the amount of contaminants is periodically re-evaluated.
(4) Finally, the reduction in contaminants is compared to their natural rate of decay

Why is the purification rate of "99.xx%" not reliable?

Just by reading the end result of "99.xx%", you do not know its testing process:

(1) the size of the testing chamber
(2) the amount of contaminants
(3) the working hours of the air purifier

In simple words, any air purifier can show a result of "99.99...%" if you put it in a tiny chamber and let it work long enough.

 

Edited November 22, 2019 by paulcai-canton
change a word

[paulcai-canton]

Here is a scientfific explanation on how air fresheners/spray work:

Molecules that you can smell tend to be highly volatile.  That is, they easily turn from liquid to gas, even at room temperature.  That's what the sense of smell is for: it's tuned to detect the kinds of molecules that drift in the air.

Spray air fresheners are aerosols.  The name "aerosol" means "dissolves in air".  That refers to the propellant, which is liquid when under pressure, but a gas at standard pressure. When allowed to escape, what are tiny particles at first quickly evaporate.

They mix in the fragrance molecules, which are carried along with the propellant as it escapes. They're now spread out into the air, where you can smell them, and covering up whatever bad odors are in the air.

Some also include "odor counteractants", which reduce your sensitivity to all smells.  The goal is to slightly anesthetize your nose so that the bad smells don't seem so bad.

(from Quora)

[paulcai-canton]

  On 12/13/2019 at 1:52 PM, paulcai-canton said:

Here is a scientfific explanation on how air fresheners/spray work:

Molecules that you can smell tend to be highly volatile.  That is, they easily turn from liquid to gas, even at room temperature.  That's what the sense of smell is for: it's tuned to detect the kinds of molecules that drift in the air.

Spray air fresheners are aerosols.  The name "aerosol" means "dissolves in air".  That refers to the propellant, which is liquid when under pressure, but a gas at standard pressure. When allowed to escape, what are tiny particles at first quickly evaporate.

They mix in the fragrance molecules, which are carried along with the propellant as it escapes. They're now spread out into the air, where you can smell them, and covering up whatever bad odors are in the air.

Some also include "odor counteractants", which reduce your sensitivity to all smells.  The goal is to slightly anesthetize your nose so that the bad smells don't seem so bad.

(from Quora)

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In short and plain words, air fresheners/spray do not remove odor for you. They just mask odor, so you won't smell it.

[SaaraWilliam]

Get Valuable great info from this post....!

[paulcai-canton]

Now we understand what CADR is. So, let's dip further into this concept.

CADR depends on two important factors:
(1) filter: the bigger it is, the better
(2) motor: the bigger airflow it generates, the better

By looking at the two visible components of an air purifier, you'll be able to estimate its airflow, and the clean air it can produce. A small machine with a small filter and motor is unable to generate enough CADR.

 

[paulcai-canton]

  On 3/11/2020 at 4:28 AM, Jolie said:

Your information is useful but I think it's much better if you can make it more related to car

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I see. But if I am too specific, this post would become an ad😃

The video below is very related to cars. It explains a fact:

Contrary to popular belief, the cabin, a safe haven as it may seem, is actually a chamber of pollutants – for example, exhaust fumes from vehicles in front of you.

https://youtu.be/0-nGqqBykHo

[Kklee]

  On 3/13/2020 at 10:02 AM, paulcai-canton said:

I see. But if I am too specific, this post would become an ad

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You can be specific without including the brand/model.  
More importantly,  price vs performance. 

 

[dontstopnow]

Then how could I apply this to my car?

[Kklee]

  On 3/22/2020 at 1:54 AM, dontstopnow said:

Then how could I apply this to my car?

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For simplicity, just get a good cabin (aircon) filter and one of those air purifier that fits on the cup holder (e.g. Plasmacluster Ion Generator).

[paulcai-canton]

Just back from a Qingming home trip☺️

Aircon filter can serve as a prefilter. Theoretically speaking, the more efficient a filter is, the more airflow resistance it will have. So, in order to ensure good air conditioning, the aircon filter cannot have too much wind resistance.

As for a cup-holder purifier, it's the same old question: what is its CADR?

[Kklee]

  On 4/6/2020 at 3:01 AM, paulcai-canton said:

As for a cup-holder purifier, it's the same old question: what is its CADR?

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For a cup-holder type of purifier,   what is a reasonable CADR ? 
If cup holder purifier has ionizing feature,  will it skew the CADR ?
 

[Noah_yap]

Thank you for sharing this helpful information. Really appreciate it

[paulcai-canton]

  On 5/5/2020 at 5:22 PM, Noah_yap said:

Thank you for sharing this helpful information. Really appreciate it

Expand  

Thank you! Notified by email, I realized I have an unfinished post here :-)

I will answer the questions above.

What is a reasonable CADR?

An air purifier should be able to filtrate air inside a targeted space 3-5 times per hour. Let's say the average space inside a car cabin is 3 cubic meters. Then a car air purifier should have a CADR of 9-15 m3/h.

In many cases, people just stay in the car for only 10-20 minutes. The CADR of a car air purifier should be bigger than 15 m3/h, preferably 20 m3/h at the time of power-on, in order to purify the inside air quickly.

Limited by the size of a car cup holder, the cup-holder purifer is relatively small in size, which means the diameter of its motor and filter is small. It's quite difficult to raise its CADR to a satisfactory level, unless you let its motor rotate at a very high speed, but its noise would be unbearable for most drivers.

to be continued...

[oktaviatan]

Thanks for your sharing, very helpful

[paulcai-canton]

In the process of purification, negative ion has two functions:
(1) refreshing
Generally speaking, an air-conditioned space lacks negative ions. An area around PC monitors also lacks negative ions. Diffusing negative ions is helpful to improve air quality.

(2) dust precipitating
Particles with negative charge, attached to particles with positive charge, are easier to precipitate.

Key question: is negative ion able to replace CADR?

Negative ion is a helpful factor. However, it does not filtrate pollutants. So, it is unable to replace a filter.

Negative ion does not break down pollutants. So, it is unable to replace ozone.

[paulcai-canton]

Can I use an air purifier with UV to disinfect?

Technically speaking, to use UV to kill bacteria and virus, you've got to expose them to UV for 30-60 minutes. However, air passes through an air purifier in less than 1 second. Obviously, UV won't be able to do anything in such a short time :-)

 

[paulcai-canton]

Some vendors present their products in this way: showing zero PM2.5 reading at the air outlet of an air purifier. Does it make sense?

The answer is simple and clear. Can you keep your nose close to the air outlet of an air purifier all the time? If you can’t, the PM2.5 reading at the air outlet does not matter to you. It is the PM2.5 value of the entire space that matters to you.

What decides the PM2.5 value of the space you are in? The CADR of the air purifier you are using!

[Throttle2]

  On 11/22/2019 at 5:30 AM, paulcai-canton said:

How to pick a car air purifier? CADR is the key performance indicator.

The Clean Air Delivery Rate, or CADR for short, is an indication of the volume of filtered air delivered by an air purifier. CADR is given through a process called the ANSI/AHAM AC-1 standard:

(1) The purifier is placed in a testing chamber of a specified size.
(2) Before the purifier is activated, the amount of contaminants in the room is measured.
(3) The purifier is activated for a period of twenty minutes, during which time the amount of contaminants is periodically re-evaluated.
(4) Finally, the reduction in contaminants is compared to their natural rate of decay

Why is the purification rate of "99.xx%" not reliable?

Just by reading the end result of "99.xx%", you do not know its testing process:

(1) the size of the testing chamber
(2) the amount of contaminants
(3) the working hours of the air purifier

In simple words, any air purifier can show a result of "99.99...%" if you put it in a tiny chamber and let it work long enough.

 

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what you trying to sell. Be upfront lah

 

M uayhahahaha

 

Everyone of us can see through this …

🤣😅