humidity measurement

If your doing something you consider critical, you need a professional grade instrument. With a cheap gauge, you can't be sure of any reading. May I suggest:

http://www.newark.com/01J3094/test-measurement-equipment/product.us0?sku=TENMA-72-6785A

Inexpensive, but not cheap.

In manufacturing you need consistancy and control of variability. This is achieved either having state of the art equipment or having forgiving processing conditions. A good process is one in which one has defined critical parameter/ or parameters ( which is not more than three ever I have seen and most of the time is one) controlling that is important. If humidity is issue one can control by proper storage and after using one can purge with Nitrogen and store under closed conditions. Define usable life and plan manufacturing cycle based on usability limitation of the raw materials.

First thing is to understand it this is what the pain is I have not seen working but I was in Chennai and know how high humidity gets and also I know this polymer is how bad it can get

Masyood

Just about all manufacturers of gauges will list in the specs the accuracy of their gauges if they don't I would not buy it.

Use zinc oxide based ceramic humidity sensor to control they are very accurate

Masyood

Your question is innocent sounding, but you need to provide more information to receive a good answer. It would be helpful to know the volume of your chamber and how closely you want to control the humidity. First, you should be aware that saturated salts are the lowest cost method to establish a known moisture content in a closed volume. If you need to provide active control, you must concern yourself with the response time of your sensor. In a room size volume, moisture content won't change rapidly, and a response time of a few minutes is adequate. In a very small chamber, you will need more rapid sensor response time to achieve stable control.

Many thanks for your reply. In fact I am measuring the humidity with a commercial sensor, and according to the sensor specifications, I should be doing it ok. Only, I heard that a "correct measurement" of low humidity is quite complicated, and that most sensors do not provide a veritable response for low humidities, and I am concern about this statement.