Rapid moisture meter method is a quick method for determining the water content of a soil sample. This method is performed by an equipment called Rapid moisture meter. It is a suitcase type portable equipment and can be conveniently used in the field.
The equipment box consists of a balance, calcium carbide bottle, a scoop, few steel balls and a metallic bottle type vessel which has a sealing cup to make it air tight and this vessel is fitted with a pressure gauge which is calibrated to produce gas pressure in the percentage of amount of water present in the total weight of soil.
Firstly we take some 5-6 gm of soil sample into the pan of balance. After balancing the weight we place the weighed sample into the metallic bottle. Next we insert 3 – 4 steel balls into the bottle and deposit a scoopful of calcium carbide inside the bottle. Clamp the bottle air tight and shake it for 2-3 minutes.
By this vigorous shaking both soil and calcium carbide get mixed completely and the calcium carbide reacts with the free water present in the soil sample and produces acetylene gas.
This produced gas develops pressure into the bottle which gets notified on the gauge meter.
For this reason this test is also called Calcium Carbide Method.
Meter gives the value of percentage of amount water present in the soil sample. That is if we get the value on the meter as 4 % then that means in the soil sample 4 % is water and 96% is solids.
Lets say meter reading is wr %.
so water content being weight of water to the weight of solids will be this.
And multiplied by 100 for the percentage value.