Humidity in the lab - Page 1
Forum section: electronics / general

author: JS
author_rank: Frequent Contributor
timestamp: July 07, 2018, 04:57:28 am
content: Hi, I'm trying to set up my lab as a more workable place, projects are getting more serious and out of the hobby level so better to get things under control. I'm not working with high voltage, solder paste or anything that's particularly highly sensitive to RH that I know, but still too high is too high.My question is how low do I need to get and how do I get there?more on the topic:The thing I'm asking at this point is about recommended RH in an electronics lab. I know it isn't good to go too low, ESD becomes a serious problem and all that, but that's not my problem.I'm more concerned about how high can it get before it becomes a problem and how to keep it down. Right now the place I was using as lab is at 95% RH, which is clearly too high, granted, temp is 13ºC as I'm not using it but still, I get those levels of RH even when it's nice and warm outside, not needing any heating. Heating the room from those 13ºC to 20ºC should take humidity to about nice 60%. Taking down relative humidity in a room is energy expensive and that's why I want to know how low do I need to get, I do have installed cold air-cond and natural gas heating (do you call it balanced draft? combustion gases comes and goes out to the outside of the room exclusively). The room hasn't been used for about two weeks so it's probably it's "natural" state. Rainy winter day. Outside RH is lower in summer but averages are still over 60%I had a broken DMM while it was stored and unused for a few month, I think it was humidity, it got drifty to an unusable point, reading nonsense all around (UNI-T stuff, not to worry about it but still)All and all, those RH levels are no good for a working or storage eviroment. I guess I could get a controlled dehumidifier but those are kind of expensive here, over $200 for a unit I don't know if will cope with my needs, as are specified for 30ºC 80% and once temps gets lowers they can suck quite a bitJS

author: PTR_1275
author_rank: Frequent Contributor
timestamp: July 07, 2018, 07:03:38 am
content: http://download.flukecal.com/pub/literature/NCSL%20environmental%20controls%20paper.pdfThis is what the upper end of the scale looks like. It’s a pretty good insight and might give you some answers, although no need for anything this precise at home.

author: JS
author_rank: Frequent Contributor
timestamp: July 07, 2018, 02:01:57 pm
content: Quote from: PTR_1275 on July 07, 2018, 07:03:38 amNice article, they should sent me the old system and I'd be fine with it...The final result shows +/- 0.3°C and +/-2%RH within a day, that's quite nice indeed! The hot/cold spots is a real pain with such tight specs to match.As usual, there is data for overkill solutions for my needs but hard to determine the actual needs I have.JS

author: xaxaxa
author_rank: Regular Contributor
timestamp: July 07, 2018, 02:15:05 pm
content: above 80% RH is extremely uncomfortable so that can be your absolute maximum limit

author: JS
author_rank: Frequent Contributor
timestamp: July 07, 2018, 02:23:10 pm
content: Quote from: xaxaxa on July 07, 2018, 02:15:05 pmThat's quite subjectove, I lived all my life in a place that's normally well over that, I'm quite confortable in wet enviroments, in fact I'm usually not fine with too dry, ok with some hours of air con but expending days in dry places when I travel is not comfortable to me at all.Yesterday I was checking the historical records of the area, averages are about 70% in summer and about 90% in winter.JS

author: rdl
author_rank: Super Contributor
timestamp: July 07, 2018, 02:47:19 pm
content: Both AC and heat will tend to dry the air. I live in the deep south of the US and it gets pretty humid here in summer, but not too bad in winter. Indoors usually stays below 60% in summer and hopefully above 20% in winter. I leave water in the tub and sinks during the driest parts in winter but it really doesn't help much. Humidity right now is 86% outside and 49% inside.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 07, 2018, 06:48:03 pm
content: I wouldn't recommend too much, it's my experience that soldering is messy at high humidity. Something about tip oxidation and/or poorer flux performance? Probably 20-50% RH is best, or maybe not as low as 20% for ESD purposes, depending.Tim

author: Messtechniker
author_rank: Frequent Contributor
timestamp: July 07, 2018, 09:51:57 pm
content: For living rooms a relative humidity level between 40% and 60% is recommended for health reasons.See here (German only):https://www.luftfeuchtigkeit-raumklima.de/raum/in-wohnraeumen.php.In my basement lab relative humidity used to be easily over 80% in summer with water condensing on the tiled floor.Not good for me and my valuable test equipment.After cobbling together 2 temperature and rel. humidity meters based on BME 280 sensors, oneoutdoors and one indoors, and calculating the absolute humidity I now open the basement windowswhen the absolute humidity outside is lower than inside. This has allowed me to cut the relativehumidity level down to around 63% after several months. Maybe I can reduce this level even furtherin the next few months. Luckily this summer is extremely dry so that I can open the windows frequentlyand for a long time. As a side effect some toads - bufo bufo - come in to visit me and frighten the life out of the missus.I could of course install a dehumidifier, but that would only be half the fun.

author: JS
author_rank: Frequent Contributor
timestamp: July 08, 2018, 05:33:32 am
content: Quote from: Messtechniker on July 07, 2018, 09:51:57 pmWell, I like the idea!I'm thinking in some automatic system that turns on one of those bathrooms extractors and circulates air from the outside. I've just bodged together something to measure humidity and temp in that room with one of those DHT sensors, not metrology grade but good enough for me! It would be matter of getting one extra sensor, a fan and write some code. Installation should be quite straight forward as one of the walls is MDF so a dull beaver would cut it fine.The only thing I'm concerned is if this would be good enough, as at night time, when temp drops humidity is usually close to 100%, so absolute humidity is always around dew point for night temps, given that even keeping the inside absolute humidity at check with the outside one wouldn't help much. I might have some broken peltier fridge to put together a dehumidifier for the inlet or just inside the room, but this would be getting overly complicated.JS

author: Eka
author_rank: Regular Contributor
timestamp: July 09, 2018, 11:10:10 pm
content: I don't know what is preferred for electronics, but I try to have the humidity in my place between 35% and 45%.