Lab hood control by heat sensor
Lab hood control by heat sensor
(OP)
I'm in the process of designing the ventilation systems for a lab. A couple of the lab hoods simply vent heat from heat generating equipment. Is anyone aware of a sensor I could use to operate the hoods by detecting the radiant heat from the equipment? I'm assuming I can't use a temerature sensor because the airflow through the hood would immediately cool the sensor and shut off the fan.





RE: Lab hood control by heat sensor
RE: Lab hood control by heat sensor
RE: Lab hood control by heat sensor
http://www.mikroninfrared.com/products/process/mi-n500.htm
RE: Lab hood control by heat sensor
RE: Lab hood control by heat sensor
RE: Lab hood control by heat sensor
In my opinion, the air should first be cooled down to cool any other thing. If your apparatus are continuously adding heat to the air stream, then there should not be any chance that your temperature sensor can be cooled off.
You have two options here.
1. You can reduce the air flow to avoid quick on/off s.
2. You can lower your temperature set point.
ASHRAE Journal December Issue(as I remember) dealt with some good techniques about controlling ventillation hoods of restaurant kitchens. It may be of help to you.
Regards,
Eng-Tips.com : Solving your problems before you get them.
RE: Lab hood control by heat sensor
Therein lies the rub. The heat sources they use under these hoods isn't always continuous. Also, I will guess there's 24" between the heat source and the inside top of the hood. If I put the sensor at the top of the hood, it will heat-up (say 90°F). The ventilation fan would energize and the air temperature around the sensor would immediately drop as 75°F air replaces the 90°F air. I imagine this cycle would continue and the fan would stop-start. If i can sense a rise in radiant heat I wouldn't have to depend on air temperature for control.
Also, these are existing hoods with fans and I can't go to a variable-speed type.
RE: Lab hood control by heat sensor
RE: Lab hood control by heat sensor
RE: Lab hood control by heat sensor
RE: Lab hood control by heat sensor
No, I don't work for them, just had a good presentation by them for all of the lab work I used to do.