Rain Sensor

Brijm

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Brijm
Join Date
May 2006
Location
St. Marys, PA
Posts
645
I thought I remembered a topic here, that was discussing rain sensors, but I was unable to find it, other than for gardening.

I have a lumber customer, with a fan shed, who wants to shut off the fans, when it is raining, so as to not blow water on the lumber.

They are currently using a humidity sensor, and an on/off controller, to shut off the fans, when humidity is above a certain percentage. This is not a fool proof system, but I'm not familiar with any transducers, that would be better for this application. Any body else know of a reliable sensor, to shut off, with minimal precipitation.

Thanks,

-MUR
 
Cannot think of anything better than humidity senser but usually when rain is on route there is a drop in barometric pressure perhaps a combination of the two
 
We used Rainwise equipment for a municipal wastewater treatment plant. Seems very nice, but we have not started this system up yet, so I cannot give you real experience at this point. They also use a fancy Doppler weather system to prepare for heavy storm flow.
 
Thanks, for the input,

I did see the threads about irrigation systems, and I don't think they will shut off quick enough, although I did consider rainclik.

I am interested in the rainwise precipitation and leaf wetness sensors. I'll contact them tomorrow, and talk to my customer, to see how much dew effects the product... and which one may work better.

The problem is that we want to run the fans as much as possible, but not blow water on the wood. The humidity sensors can take a while to reset after saturating at high humidity...

They are currently using a Veris humidity sensor (HO series), which is a capacitive type sensor, with a 4-20mA output, to a on/off controller. It works some what, but I was looking to make the system more reliable as they have to adjust it constantly.

Thanks again
-MUR
 
Jeev said:
Why don't your customers just install a shroud over the fans?
Click to expand...

I don't think, that a shroud would work, the fans are in the middle, with the wood stacked on either side of it. They reverse every few hours, to dry the wood evenly. There is probably about 16-18 5 foot fans in close proximity. Anything, that would keep rain from being sucked in, would also keep moisture from escaping. The idea is to dry the wood, as quick as possible.
-MUR
 
I would appreciate if you can attach a photo of the application...as for Rain sensor i have used Telemecanique make liquid level relay as rain sensor in one application.

it is low tech solution but works fine.

Part no is RM4LG01M for 220 vac power supply.
 
I Googled and found this http://en.wikipedia.org/wiki/Rain_sensor
The sensor uses ifrared light onto glass. I think it should be possible to reproduce this using an LED and detector.
Another idea might be to have a temperature detector with a small element to warm it up slightly. Any drops of rain that making contact would cool the sensor down. Once the rain stopped it would warm up again.
Let us know what you use
Good Luck
Roy
 
John Hawkins said:
Check www.vaisala.com Wont be cheap but an excellent product
Click to expand...

We used Vaisala recently, on a Vaneer dryer... Excellent product, but as you said not cheap.... While I do think, that I would not have the saturation problem at high humidity, that we are with the current sensor, I think there are still inherant problems, to this method, of trying to shut off for rain.
 

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