CADR是什么,它和风量有什么差别?

当你在买空气净化器是,是否遇到有些供应商有时用风量有些用CADR来描述机器的效率? 但,这两种数据是同样的东西吗?我们能用‘A‘品牌的风量和’B‘品牌的CADR来做个比仑吗?

 

 

简而言之:

不!CADR和风量是两回事。要是有人告诉你它们是同等的(就如右边的照片),你就要审慎!

 

 

有兴趣知道更多吗?

其实,关键就在于测试CADR和风量的细节。

 

这些是需要做CADR测试的仪器。

 

 

(书呆子们:中华人民共和国国家标准对于空气净化器CADR的测试法)

 

测试CADR的步骤

  • 用香烟提高测试房的空气污染指数到一个很夸张的程度。(测试房要是气密的!)
  • 开空气净化器
  • 20分钟内,每两分钟记下房里的5指数。
  • 用所得到的数据算去CADR

从此能看去做CADR测试需要各种个样的仪器,一个大测试房,耐心和 数据分析技巧。

 

那,测试风量需要什么仪器呢?

 

 

对,我们只需要一个仪器:风速表。

 

测试风量的步骤

  • 把仪器放在过滤网上;记仪器上所显示的数字(风速)。
  • 乘风速和过滤网的面积在一起。

你拿到的数字是风量,就那么简单!

 

虽然风量有它的用处,但它还是有限度。应为风量只测量风速,我们能算出过滤网净化的空气量。但,有什么是它不能告诉你呢?

  • 被净化的空气多干净?
  • 净化器能有效的混合房里的空气吗?
  • 被测量的空气是否全都是应净化器而产生?
  • 空气净化器有重复的净化同样的空气吗?

 

以上的提问,风量测试方式都假设成完美的状态。一个例子就是被净化过的空气在风量测试里被假设成100%干净。但,我们知道这是不正确的。因此风量的数据往往会比CADR高多了。

 

总之:风量测试没像CADR测试的详尽。因此风量的数据往往会比CADR高多了.

 

我们就不能把风量转化成CADR吗?

生为个书呆子的我以为我们只需要乘风量和过滤网的效率(比如Smart Air 过滤网有99.9%效率)就能预计到净化器而产生的清洁空气(CADR)。但这个方式没考虑到一个重要英属:在真是的情况下,清洁空气会和在房里的空气混合。

 

当我用以上的方法算CADR时,我在假设房间的空气被过滤后不会再被吸进净化器。实时上,这是不可能的。房间里的空气是不停的在搅拌(就如你在咖啡里加糖后搅拌)。所以,被净化的空气很有可能再度别净化器净化。因为有一部分的空气会从夫的被净化,算去来的CADR往往比作测试而得到的结果还要高多。

 

这就是为什么你不能用‘A’品牌的CADR和’B‘品牌的风量做个对照。

 

CADR和风量的差别多大?

Smart Air 在测试净化器是,都会做以上的两种测试(风量测试方式相对来说比较快,可以预计净化器的效率。而CADR比较精确)。因此,我们有相关的数据来看CADR和风量平均差多少。

 

 

我们测试了很多不同的净化器后发现CADR平均是风量的60%

 

怎么选择净化器:尽量用CADR比较不同的净化器。注意卖家是否把CADR和风量混合起来。记住,CADR往往是第三方测试而风量通常是卖家测量。

芝加哥大学行为科学系的助理教授; Smart Air创始书呆子。

在 “CADR是什么,它和风量有什么差别?” 上有 4 条评论

  1. I just moved to China and I’m trying to sort out what I need for my apartment (61.3 sq m, 2 bedroom + 1 hall) assuming I use one of your filters at low or medium for reduced noise. But I need some information I can’t find on your site.

    1. What is the CADR for your products (especially the Blast and mini Blast) at low and medium speed? I’m assuming the amount listed on your website is for high speed.

    2. What is the calculation to determine one’s CADR needs? I found the following on a post by Dr. Saint from myhealthwellbeing.com posts: sq meters X ceiling height X 5 (because air purifying requires 5 air changes/hr) = CADR required. But this seems off because it means the Blast at high (with a CADR of 890) would only work for a room that is 71.2 sq meters assuming normal ceiling height of 2.5 m (71.2 X 2.5 X 5 = 890) while your site says it is good for 130 sq m. Even if the air changes/hr was 4, the calculation is still off (it would mean a room size of 89 sq m). So where is my mistake?

    3. Can a single air filter be used for an entire apartment even if the bedroom doors are usually closed? (I’m assuming the total area is within the CADR of the filter).

    Ps: would be great if you posted this calculation on your site in the “shop” section and eventually had a simple CADR requirement calculator on the site or an excel one that could be downloaded to determine one’s needs and which of your products to get.

    1. Hi Ak, great questions. Looks like you’re being smart about working out your clean air needs! To answer your questions:

      1. I’ve updated the Blast and Blast Mini pages to include the CADR on the different speeds. Thanks for pointing this out!
      2. There are many different methods for calculating area based on CADR, all based on different assumptions and for different countries. For calculating the area, we use the China Government Standard, along with our own real life testing. The China standard says to take the CADR (in cbm/hr) and multiply by 0.07 – 0.12. So a CADR for the Blast of 890cbm/hr would give a room area between 62sqm – 109sqm. Based on our own tests in Beijing we found these to be pretty conservative, so we use a slightly looser rule which is why we claim the Blast to be good for 130sqm. Bottom line: if you want to be conservative take the CADR and multiply by 0.12 to get roomsize.
      3. From our tests, we’ve found that closing a door means not enough clean air does travels between rooms. So our advice is to have a purifier in each room. Of course, it all comes down to how a) leaky your windows are in the room without a purifier and b) how tight the seal is round the door. If you were to leave your door ajar then you should be fine.

      And regarding your P.S. point – that’s a great idea and something we’ve wanted to do for a while. We’ll work on getting something like this up!

  2. I love your site and all the data you’ve collected. Two things I’m curious about:
    1) How much does the flow rate change between with the filter and without?
    2) How much does the noise level change between with the filter and without?

    I’m asking because I’m curious about using a different fan with a known flow rate but a lower known noise level. If your data is correct, you’ve beaten the competition in CADR, price. Do you think it’s possible to maintain this performance while reducing the noise to a whisper? (I have faith)

    1. Hey Vincent, thanks for the kind words. Two good questions!

      1) We’ve not done tests on the airflow without a HEPA, but if we look at the numbers for the Cannon, which claims a max airflow of around 700cbm/hr, we can see that the airflow is reduced at least
      2) This is a much more difficult question to answer, since sound is much more a subjective thing. In terms of actual sound levels (measured in dB(A)) there is little difference between the fan with and without a HEPA, but in terms of what kind of sound you get (‘windy’ sound with just a fan or a kind of ‘whooshing sound’ with a HEPA – sorry if that doesn’t make much sense!) it is very different. Generally, with a HEPA it sounds more pleasing/calming.

      In terms of making a super quiet yet super effective purifier, we think we did a pretty good job with the Blast and Blast Mini! Ultimately to reduce noise you need a big HEPA and a big fan. This means the air can move more slowly through the whole machine, reduce the noise it makes as it passes through the HEPA filter. Check the Blasts out if you haven’t already!

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