# Do we divide by the wet or the dry ?

1. May 19, 2010

### hashmos

Do we divide by the wet or the dry ???!!!

Hi Guys,

I am not sure if this is the right fourm to post my question in, but I hope it is.

When I first went to calibrate a moisture sensor used in Sand Bins in A readymix plant, I used an equation I cannot that I dont feel is correct, yet all the world uses it.

It states that to calucalte the moisture in the labrotory, you have to take a sample of wet sand, weight it, then dry it and weigh the dry sand.

Afterwards, we take the difference of both weights. which gives us the weigh of the moisture in the wet sand sample. Now, and wherever I look for, I find that the division is over the dry weight, not the wet, then ofcourse you multiply it by a hundred to get the precent of moisture.

I cannot see why we divide by the dry and not the wet. It's driving me crazy. Lets say I have a basket of fruit, 3 apples and 3 oranges. When I want to know the percentage of apples, I divide 3 by the total number of fruits, which is 6. In the sand moisture application, and according to the fruit example, we should divide by the wet not the dry, since the mixture of both is the wait of the wet, and I want to know the percentage of the moisture in the wet.

The equations is %moisture = ( weight of the wet - weight of the dry ) / weight of the dry.

Thanks.

2. May 21, 2010

Re: Do we divide by the wet or the dry ???!!!

This way 100% moisture is a quantity that could actually happen. I agree that calling it percentage is not very good, but this also happens with 100% inclines that are actually 45 degrees and not 90 degrees.

3. May 22, 2010

### hashmos

Re: Do we divide by the wet or the dry ???!!!

Makes sense, and yes the terms were not chosen carefully. It is confusing.