Controlling Humidity in a Textile Testing Laboratory

[Abdul Ghaffar]

Hi
Iam a new to the forum,i got this link through my best friend Mr Amanbhai.
I have question regarding Control Humidification in Textile Lab which is as per the standard RH 65% +/- 2. (or from 63 to 67 %) and Temperature 21 C +/- 1
Question is that if we are using thermohygro graph for monitering the humidity
and it shows up/below to the given uncertainity like lower value 61-62 % and higher value 68-69% then in this case we deviate from the standard values.
Requesting you please guide me how we can solve this problen even it is some difficult to maintained under given low tolarance values.

Thanks and best reqards
Abdul Ghaffar

 

[Dale D. Barnes]

Re: Control humidification in Lab

Abdul,
I had a similar problem with my lab. I was trying to control the temperature at 68 degrees F. plus or minus 2 degrees and humidity at 40%RH plus or minus 10%RH. I started having problems controlling both aspects especially humidity. I bought a Dayton 65pint dehumidifier and set it on 40%rh. The model I bought has a temperature reading and RH reading. I am able to control my humidity within plus or minus 2% and my temperature stays on 68 degrees F. constantly. This unit is capable of being hooked up to a hose for automatic draining or you can use the bucket. When I first got the unit I had to use the bucket until I got the hose hooked up. I would empty the bucket twice a day. (close to 6 gallons a day of water it would pull out of the air)
The cost is inexpensive at about $250.00 USD.

Hope this helps
Dale

 

[Jerry Eldred]

Re: Control humidification in Lab

If I understand correctly, it sound like the issue is that perhaps your measuring instrument is not accurate enough for your requirement. Many of the hygrothermographs (such as Newport, Dickson, Omega, etc.) have accuracies of +/-2%RH or sometimes more. There are some high accuracy instruments available. But since this is not a commercial website, I don't want to recommend specific companies.

Regarding the uncertainty issue, You could use a higher accuracy instrument and set your control limits to include the uncertainty. In the semiconductor industry, we used to do that a lot -- If we had a product limit, we woulld set control limits with smaller limits. When ever our control limits were exceeded, we had an out-of-control action plan (what was the product impact). Our control limits were set small enough so that we almost never exceeded product tolerance limits.

 

[BradM]

Re: Control humidification in Lab

Jerry's post is a good one. In addition to the accuracy of the measuring instrument, there is the basic consideration of whether the room and the environmental control equipment can even monitor/maintain those considerations.

Also, where you locate your measuring equipment should be considered. If it is by a door or high-traffic area, everyday movement might unduly affect your readings.

 

[Ken K]

Re: Control humidification in Lab

This link might help you.

http://www.veriteq.com/humidity/index.htm

 

[Abdul Ghaffar]

Re: Control humidification in Lab

If I understand correctly, it sound like the issue is that perhaps your measuring instrument is not accurate enough for your requirement. Many of the hygrothermographs (such as Newport, Dickson, Omega, etc.) have accuracies of +/-2%RH or sometimes more. There are some high accuracy instruments available. But since this is not a commercial website, I don't want to recommend specific companies.

Regarding the uncertainty issue, You could use a higher accuracy instrument and set your control limits to include the uncertainty. In the semiconductor industry, we used to do that a lot -- If we had a product limit, we woulld set control limits with smaller limits. When ever our control limits were exceeded, we had an out-of-control action plan (what was the product impact). Our control limits were set small enough so that we almost never exceeded product tolerance limits.

You are right. I believe that the tolerance limit set maybe too tight, we go out of the limits very frequently. But like my Manager says long as it goes out of the limit momentarly it is alright.

 

[HarrySen]

Nice discussion going on! I may be late but for future viewers, this might help ! This has info. on humidifiers ---> xxxx
Thanks for letting me in!

 

[tony wardle]

Also a bit late - but, the way we sorted our issue out was to use a conditioning cabinet.

In textiles they have to pre condition a samples at a set temp / RH for mass and test in a controlled environment.

The conditioning takes at least 4 hours, so for a 30 lab minute test where the environment may be out by 1- 2% or 1 - 2 degress, the result will be acceptable, and the UOM would take this into account anyway.

 

[miles ross]

hey guys. just love what am seeing here...

 

[LUV-d-4UM]

Hi
Iam a new to the forum,i got this link through my best friend Mr Amanbhai.
I have question regarding Control Humidification in Textile Lab which is as per the standard RH 65% +/- 2. (or from 63 to 67 %) and Temperature 21 C +/- 1
Question is that if we are using thermohygro graph for monitering the humidity
and it shows up/below to the given uncertainity like lower value 61-62 % and higher value 68-69% then in this case we deviate from the standard values.
Requesting you please guide me how we can solve this problen even it is some difficult to maintained under given low tolarance values.

Thanks and best reqards
Abdul Ghaffar

Apologize for indruding this unfamiliar space. But do you calibrate your Thermo hygrometer? If so what is the tolerance? If this parameter is critical to your testing, then you have to increase the frequency of calibration or buy a new measuring equipment. I've seen this type of equipment in the diagnostic lab and there is a calibration schedule on the label. I hope this helps. This is just my own opinion.