Many water wells range in depth from 10 to 60 feet. However, other wells are drilled hundreds of feet deep! So when a customer needs a water level sensor in these deep wells, we recommend our submersible pressure transducer, the PT-500.
According to a market report published by *MarketsandMarkets.com, submersible pressure transducers are the favorite among water level sensors in the water and wastewater industry - and there's a reason. These water level sensors are inexpensive, versatile, and easy to install.
How This Water Level Sensor Works
The submersible pressure transducer rests at the bottom of a tank or well, and measures level by detecting the pressure exerted by the volume of liquid above it. This is converted to a level based on the dimensions of the tank or well, and the specific gravity of the liquid being measured. In this case, the specific gravity is 1 since the liquid is water.
The level reading is produced as the PT-500 water level sensor sends a 4-20mA signal to the controller. The two end points on the 4-20mA scale have to be calibrated to give an accurate measurement. This is done by setting 4mA to 0 psi and 20mA to the maximum psi.
Calibrating For Well Depth
Let’s say you have a well with a water depth of 100 feet. You need the signal to output 20mA at 100 ft. However, since the sensor measures pressure in psi, you will need to convert the pressure to level. You'll do this by multiplying the water depth in inches by the inches of water to psi ratio of .036063. The conversion is as follows:
100 ft. X 12 in. = 1200 in.
1200 in. X .036063 = 43.276 psi
So we will calibrate the water level sensor so that when it reads 43.276 psi it will signal an output of 20 mA, which in this case means a water level of 100 ft. Our PT-500 can have a maximum pressure range of 200 psi, which means they are capable of measuring depths over 450 feet!
It can take a while before water is reached when drilling a well. This is why some wells are so deep. So when installing water level sensors in wells, you may need a very long cable. We have built some of our PT-500 sensors with cable lengths well over 1500 feet! This is not an issue for the signal since a 4-20 mA signal is being used. Amplified signals can travel cable lengths well over a few thousand feet.
However, it does mean that the cable must be supported by a high tensile strength wire. This can be attached directly to the PT-500 water level sensor housing and used to raise and lower it into the well.
If you have any questions on measuring well water levels, let us know and we will be happy to help.
Ready to learn more about water level sensors? You can do it! Check out our awesome water level sensors below:
*Marketsandmarkets.com study "Level Sensors Market: Global Forecast & Analysis - Focus on Technologies [Contact Type (Magnetostrictive, Vibratory probe, Hydrostatic, Magnetic float) and Non Contact Type (Ultrasonic, Radar, Optical, Laser)], Applications and Geography (2013-2018)" http://www.marketsandmarkets.com/Market-Reports/level-sensors-market-926...