humidity control methods


Thread Starter

chehboub tarek

we want Help controlling oven that works with gas

this oven is uses for heating tobaco in other term we want to control the humidity at 13% inside the oven what is the best methode to control this system
If I understand your problem you want to control humidity by temperature. To do this you can use a standard controller and a relative humidity probe. A good control in this case could be a PI regulation, heater should be activated when relative humidity is too high.

Anyway in tabacco drying temperature and humidity are both important to get a quality product.
Many moons ago before I got into controls & drives, I worked for an electronics company that specialised in environmental measurement, namely humidity. Although I believe they are no longer in this field there may be links on the web if you type in Lee Integer (Kettering, England). Please excuse my lazyness as I haven't looked myself. LI, have now become Counting Solutions Ltd - if your struggling for an off the shelf solution etc, try giving them a call, they might be able to point you in the right direction.

From memory, their humidity probes comprised of a PT100 temp sensor & a 'CCH' humidity sensor using Op-amps etc. Zero to span Calibration of these probes was performed by forcing gas through crystals into a sealed chamber obtaining upto 100% RH. I am unsure how heat from an oven would effect this (and what operational temperature the sensors are rated at). Unfortunately, I can't remember the gas or the 'crystals', however this method of calibration is obviously a method of humidity control. I'll place another post if I remember/find out more details.

In the mean time I hope I've been of some slight help & good luck.

Best regards,

Royce (UK)