Can Venta Airwasher Effectively Reduce PM2.5 or PM10?

There is not official tests state that whether Venta airwasher is able to reduce PM2.5 or PM10 effectly, hence, I made some tests with the help of Dylos air particle counter during the good weather, PM2.5 index less than 100 means good or moderate, PM2.5 larger than 100 which means unhealthy or even hazardous. My bedroom's door or window is closed all the time and it's a confined space.

The answer is partially efficient. In centain conditions, it works, other times, no.

When the PM2.5 outside is less than 100, Venta can effectly keep the indoor PM2.5 around 30 or even less.

However, when outside is unhealthy, which means the index is above 100 and beyond, it really can't effectly reduce the particles inside, and the metrics I got from Dylos indoor have positive correlation with outside index, sometimes, Dylos even get 100 or even more which is totally unacceptable for people in the bedroom.

Now, the answer is quite clear, if the weather outside is good, just keep the Venta open and it can handle. When outside is unhealty, you really need to turn on your air filter, and don't rely on it, you need HEPA filter.

What about PM10? Venta seems work all the time, no matter good or bad outside, it can keep the index under 100 or lower, most of time, my bedroom PM10 is around 50, sometimes, after long time filter without opening the door, you can see single digit.

Trips to HCMC, Nha Trang, Phnom Penh and Siem Reap

Last month, Kiki and I went for a vacation, here are some experience and tips.

For HCMC, it’s quite modern, as invaded by France before, it still exits a lot culture from France, like iced coffee and French baguette, both are delicious and cheap. HCMC is also famous for its French cuisine, we went to one of the best French restaurants in HCMC, but not so impressed, the only impression is so many ants on the desk, maybe we don’t know how to enjoy French cuisine.

Later, we flew to Nha Trang, the beach is fancy, we spent a few nights in Sheraton, it’s location is really good, walking distance to most of the restaurants, and Lanterns restaurant is one of the best we ever met, authentic Vietnamese cuisine, we went there many time, from breakfast, launch to dinner. We were too busy eating and drinking to enjoy the free beach chair, umbrella and the best public beach sections in Nha Trang provided by hotel, later we regretted. After that, we went to mia, the so called best resort in Nha Trang, generally speaking, its still better than others, but didn’t give us as much as we expected. It’s location is far aways from city center, and nothing when step out of the resort, so you need to take the shuttle bus to go into the city or just stay in the resort, enjoying its private beach. I had to say, the beach here is even better than those in the city, since the whole resort only holds about two dozens of customers, the beach is quiet and clean at any time, you can play canoe and surfing, but the food here is just the average level with top price. For drinks, they have happy hours, buy one get one free, so Kiki and I ordered 4 cups of mojito, watching the night sea view, till midnight, nobody but we two, totally drunk.

As saied before, the coffee here is wonderful and price is reasonable, so just pick up one when you need a rest. Also the mongo shake is worth trying, we tried dozens cups of shake during the staying in Vietnam, even later in Cambodia, we still ordered the same, most of them are between $1 to $2, enjoy. So many Russians, there are probably three languages in the city, Vietnamese, English and Russian.

We had a terrible experience while taking the Mai linh taxi. The first day when we arrived at HCMC airport in the midnight due to flight delay, we halled a Mai linh, and told him by meter, but when he took us to the hotel, he forced us to pay 100, 000VND, which was 30RMB, just a 5 minutes tour, we tried to explained to him, the only word he said is one hundred, well, we surrendered. Later, we only hall vinasun taxi, which was quite fair, by meter by default.

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Setup a AQI(Air Quality Index) Monitoring System with Dylos and Raspberry Pi 2

I have been using air purifier for years in Beijing, China. So far so good except the only problem troubles me, is that effective? is my PM2.5 or PM10 reduced? the answer is probably obvious, but how effectively is it? Nobody knows.

At the morment, Dylos is the only manufacturer that provides consumer level product with accurate air quality index, so, not many choice. I got a Dylos air quality counter from Amazon, there are many products, if you want to export the index data from the black box into your desktop for later process , you'll need at least a DC 1100 pro with PC interface or higher version. Strongly not recommend buying from Taobao or the similar online stores, as far as I saw, None of them can provide the correct version, most of them exaggerate for a higher sale.

Now, half done. You need to Raspberry Pi, at the time of writing, Raspberry Pi 2 is coming to the market. I got a complete starter kit with a Pi 2 Model B, Clear Case, power supply, WiFi Dongle and a 8GB Micro SD.

In order to make the Raspberry Pi up, it's better to find a screen monitoring, or it will take huge pain to you.

After turning Dylos and Raspberry Pi on, the left process is quite simple. You need to connect the Dylos and Raspberry Pi with a serial to USB interface, the serial to USB cable is uncommon these days, if you are a network engineer, you should be quite familir with the cable, else, you can get one from online or somewhere else.

Now, write a tiny program to read the data from Dylos. You can make use of Python's pyserial module to read the data with a few lines. Here is mine. Besides that, you can use other language to implement, such as PHP. The interval depends on your Dylos collecting data interval, the minimum is 60s, ususally 3600s is enough.

Once got the data, you can feed them into different metric systems like Munin, or you can feed them into highcharts to get a more pretty look.

totobobo 运动版(supercool) 口罩简单测评

13 年冬买了第一个 totobobo 的口罩,用起来非常爽,完爆 3M,为此我专门写了一篇博客,后来到了 14 年夏天,大热天的带着口罩走路不大舒服(这个问题现在来看是世界性难题没有一个口罩能彻底解决),像下面这样

于是对比了下几种比较适合在夏天戴的,最终买了 totobobo 的运动款(supercool),像下面这个样子

可以看到跟普通 totobobo 不一样的地方是它需要口吸鼻出,跟游泳一样。买回来之后发现 HEPA 滤网跟贴合它的两个塑料片之间有很大的间隙

这也就意味着过滤的性能可能大打折扣,因为脏空气不经过滤网直接进呼吸系统了。为此特意跟官方的工作人员交流下此事的意见,答复是这是正常的,不会影响过滤效果,如果实在需要贴合的话,可以用热水重新塑形,于是我就用热水把两边的重新塑形了一遍,发现效果还是有的,确实贴紧了。接下来该到路上走两步了,于是每天带着 supercool 走着上下班(单程 3 公里左右),虽然我游泳能适应口吸鼻出的情况,但是在马路上也这么搞,还真有些不大习惯,好在一周之后基本适应。奇怪的是,这段时间的空气质量并不好,但回去肉眼观察到 HEPA 几乎还是白白的,如果是之前戴的非 supercool 的 totobobo,一天就开始发灰了,本着科学的态度,继续带了接近三周,最终的结论是:连续带了一个月,HEPA 的颜色如上图第二章所示,也就是说,这一个月我人肉替它吸了不少烟尘雾霾 ;-(

以上实践证明,supercool 在我这儿的效果非常差。除此之外,由于北方干燥气候加上嘴吸气,所以不管空气好不好,呼吸一段时间时间后嗓子都会明显感受到发干发痒,这是我后来抛弃 supercool 的第二个原因。

根据科学测评(1, 2),totobobo 的舒适性没话说,但是实际的过滤效果在众多的口罩型号中只能说可以接受,大概是中等稍稍偏上的水平,综合考虑的话,还是 3M 的更加靠谱些。

去年底,带了一年多的口罩(上第一张图)遗失在了欧美汇的某个角落里,于是现在我又开始消耗家里之前屯了一大盒子物美价廉的 3M 9501 了 ;-)

venta 水洗机半定量使用测评

北京的空气有多么糟糕,我已经花了三个(1, 2, 3)篇幅来描述,并且给出了一些具体的防范措施。
为了解决覆盖范围小的问题,我买了台升级版的加湿器,最大的特点是水箱大,5L。但是新的问题又来了,一夜下来,由于过度加湿,整个卧室都是一股霉味,南方的同学应该深有体会吧。工程师应该定量的分析这些问题,所以我又搞了台湿度计来看看我的卧室究竟是什么情况,基本每天早上醒来的时候都是 75%+ 的湿度,还是加湿器离我床头有 3m 远的情况下,太恐怖。
情况至此,穷则思变。隔行如隔山,要在大陆混又不被坑,只能自己研究了。过程就不说了,结果很明显,出雾的直接排除,主流行业,基本是 Venta, Honeywell 以及其他。德国货看了下大概的原理,其实就是中学物理学的百叶(其实所有的净化器的基本原理都不复杂)。淘宝有家据说是大陆独家授权的,跟 一比较差距刺瞎人的双眼。并且好笑的事,大陆究竟有几个 venta 官方授权的代理商,哪些是被吊销代理资质的,这几个问题我花了点时间研究了下,觉得水太深。最终决定还是去美帝买吧。
半个月到家之后,拆箱,有点小失望,发现结构异常的简单,下面这个是 LW25 7L 水箱的构造

直接放清洗液加自来水,最初的两天数据显示效果不是很好,正常情况下,不开任何的加湿器,平均湿度在 15% 左右,21 度的室温已经部分达到人体舒适环境的标准了,结果开了两晚之后发现湿度也就在 45% 左右,离 50% 的舒适湿度还有不少差距,并且这是在卧室门密闭的情况下。
第三天把说明书翻了个遍,也没发现什么遗漏的细节。神奇的是,第三天晚上开始,湿度开始维持在了 60% 左右。确实好神奇的样子,为什么会这样我猜测可能是需要让卫生液充分混合才能发挥功效。后来就正常了。官方建议半个月换一次卫生液,下图是我用了 13 天水箱的情况(北京的情况还是一周一换吧):

效果还是很明显的,大颗粒的也就是我们肉眼看到的都沉淀在水下面,其实就是吸附 PM10 以下的物质了,老屋子甲醛之类的可以忽略,官方称的是可以吸附 10 微米的颗粒。这个我没法定量确定,一个靠谱的 PM2.5 counter 在 2k 左右(1k 以下大陆厂商的嚎头产品就别信了,ikair 的,曾经货没到手就让申请退款了,那什么墨迹的空气果也就只能当玩具而已,不能做科学定量)。不过可以肯定的是,每天早上醒来身体都很舒服,北京咳也消失了。我用了两年的 Honeywell 暂时可以退役了。另外,提醒一下各位,想靠 venta 做 pm2.5 清洁工作的还是别指望了,目前没有任何的证据表面水可以吸附 2.5,靠谱的还是传统的 HEPA 过滤网,venta 用来做加湿工作还是非常靠谱的,顺带清洁了一些大颗粒的物质。


5 月发生的事,6 月补充完,9 月发出来 ;-)

5 月 13 日周二
开始我们另外一个核心 IDC 最后一次常规性 10G 升级,下面的一部分我们后来把他总结成了《5 月故障总结(post-mortem)》
回家睡了会儿,3:00 am 起床,4:00am 开始连续干了 6h
回公司休息了 1h,塞了点巧克力复活
中午去水立方进行了常规的 1h 训练
回来面(对了,我们目前招高级应用运维工程师 PE,有兴趣的给我简历,邮箱是 w 在 umeng 点 com)了一个候选人,结果在我问到第二个问题的时候就怂了,第一个问题是常规性的自我介绍,第二个问题也是我最喜欢问的问题之一,最近半个月在做什么
由于 uplink 依然在老的网络环境中,我们老的 3750X 到新的 Nexus 中间的 8G port channel 链路中的一条物理链路由于 LB 的算法不科学,导致其打满丢包的状态,当机立断,直接让 NE 更改了 LB 的算法,效果明显

5 月 14 日周三
由于 uplink 这个不稳定因素的存在,开会讨论最后一次也是最重要的升级以及收尾工作,由原本的周四凌晨升级提前到了周三凌晨进行
10G 的最后一次也是最重要的升级,应为涉及到切换我们的 uplink,迁移我们的 GW 以及我们两地双机房中间的互联链路迁移
晚上去和颐休息了 3h,凌晨 3 点干到早上 7 点,期间除了 uplink 切换成功之外,其他的均已失败回滚告终,回酒店休息了 3h
中午回公司继续,讨论了凌晨出现的一些问题以及解决方案,其中我们两地双机房互联链路不通的问题最后发现是 HSRP 的问题
凌晨 GW 迁移失败之后,我跟我们 ne, director 回公司模拟了一下当时出现问题的场景,想了几种可能的原因,不过都被实际的模拟结果所否定,唯一的可能性就是服务器会自动的更新 arp 表,找到新的 GW 地址
下班之前,上面遇到的所有问题都已经找到了问题的根源,想到了对策,唯独 GW 的问题,这个对我们整个生产环境的影响绝对是毁灭性的,一旦 GW 迁移失败,我们所有跨 VLAN 的访问都将失败,由于当时时间太紧迫,根本没有时间让我去 debug 就回滚了,我也就无法得知当时真正的现象以及后续的细节
临走之前,我们 director 问我要不要他过去帮忙,我当时是拍着胸脯说的「相信我,你回家休息吧」,虽然我当时有 95% 的把握确认了上面提到的迁移失败的原因以及 80% 左右的把握让我在非常短的时间内 debug 找到问题并且修复,其后者是最具有挑战性的

现在看到的我们的还是 1G 的上联,等你看到这篇博客的时候,应该已经升级到了 10G 的上联了

5 月 15 日周四
这次升级提前预留了充足的时间,从 3:30 – 6:00,我觉得 3h 的时间足够我 debug 一个中等难度的线上问题了
跟昨晚一样,先是回酒店休息了一下,凌晨 2 点开足马力一直干到了早上 8 点多,GW 的问题也在我们开始的第一步被我很快的发现了问题的原因并且修复,两地双机房互联 HSRP 的问题也后续被我们 ne 一举解决,「基本完美」收官,为什么这么说?因为后续的几天出现了若干的问题,好在都不是我们核心的 Nexus 引起的
回酒店休息到 11 点,打车回家准备继续休息,结果在车上就收到报警说我们的一台前端的 ngx 挂了,当时电话跟我们工程师沟通了下,看现象不大像是新升级的网络造成的,回家又花了 1h 时间救了把火,最后查明原因发现确实跟网络没有关系,只不过在这个敏感的时间点上,出现任何的问题,正常人都会不由得往网络上面倾斜
下午先赶到公司跟我们 director 沟通了进展的,然后赶到清华,在那儿度过了下午剩余的时间,干嘛的了?我花了 3h 的时间去拜拜 RMS 大神,花了 1h 的时间跑到教室外面的走廊插上了 3G 网卡排查了一起路由问题
RMS 大神确实蛮有意思的,下面这三段视频是我当时在现场拍的,虽然 RMS 说不要把这些视频照片传到 youtube, instgram 上,但我还是本着共享的精神跟大家分享了:

  1. Windows is malware
  2. Dancing during class break
  3. St. iGNUcius avatar

下午在会场收到反馈说,我们某个 storm cluster 的处理性能出现了问题,时间点跟我们升级网络的时间几乎吻合,但是从我们内网的各项监控指标来看,数值得到了前所未有的好转,pkg loss 由原来的 8% 直接变为了 0,latency 也由原来高峰时期动辄 4, 5ms 直接下降到了 0.2ms 以下,直觉告诉我几乎不可能是核心网络引起的,但是,没有更有力的数据来证明这些
看码农们在邮件里面以 「猜测」、「推脱」的姿态开始了问题的 debug 之后,我直接以「明天人齐了一起讨论下吧。」结束了这场闹剧

两个出口的 ngx 都挂了


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