Keeping an eye on Moisture

[ElectricAl]

Anyone who wants to know what the Relative Humidity is in a room or chamber, this Radio Shack meter will get you close.
It will give you a general idea of what is going on.
Priced at around $25, it will tell you the current temp and RH plus the high and low temp and RH.




We have 8 units sitting around. Retail lumber show room, sawshop, woodshop, kiln, air dry shed, home, plus spares.

When you go to buy yours, get three and when you get home put all three in a zip plastic bag. Zip the bag over night. In the morning before opening the bag look to see if any give a different reading. Keep the 2 that read the same.

Once you know what the RH% is in a room you can easily convert the RH% to a Lumber Moisture Content % .  An example is 30% RH is approx. 6% MC in lumber.

In the kiln we use the meter to double check the Wet/Dry Bulb controller.

We have a customer who builds very high end Mission Style out of Quartersawn White Oak. He has two meters, one for his shop and one he takes to the customers house to get a feel for what the environment will be like.  

[Den Socling]

gee whiz Al,

I've been arguing with the professor about these things for years!  :D Your idea of buying three and then keeping the two that agree is good but watch them as they drift with time and temperature. Laboratory grade (which are guaranteed for accuracy) cost in the neighborhood of $500.

Den

[ElectricAl]

Den,

Good point on the drift.  My point is the meter has more accuracy then licking your finger and counting the seconds for it to dry ;D

All 8 are within 4 degree and 4% of each other.

If there off, at least they are consistanly off :D

And @ 25 bucks it's not the end of the world if I use it for a wheel chock for the forklift, then forget it's there.

[ElectricAl]

Here is a link to a chart we use to convert RH% to EMC%

Thanks to Jeff for setting it up so it is printable.

www.forestryforum.com/media/emcchart.pdf

[Jason_WI]

I can make a lab grade Temp/RH meter that is NIST traceable for about 100 bux. With data logging capabilities through RS232 at no charge ;D

Jason

[Frank_Pender]

Jason, were do I sned in my order? ;D

[East_West_Dan]

At www.forestry-suppliers.com I got a digital unit similar to the Radio Shack model but it comes with one wireless sensor and can handle up to three for each base unit.I've used them in a kiln and right now there in my shop set up in various places and you can get your readings from one spot which is handy.The range is around 100'. Their stock # is 94539.
Dan