A technical manager and assistant professor at the Bannari Amman Institute of Technology (India) wanted to measure the level of a 200-litre tank. As such, he believes he must detect the level quickly. Thus, he states, “we planned to install an array of optical sensors with ip68 protection in the tank.”

An instrument engineer from Indonesia responds. “In this case,  you try to make level calibration for water draw tank, perhaps connecting to the piston prover. I agree that optical level switches would be the best choice.  This is because the piston prover itself uses optical switch.”

He adds that you can do a Google search for an optical level switch. “There are many of them that submerge into the tank,” he says.

EcoMeter S Ultrasonic water cistern level sensor with separate digital display
in the shop from 123 €

You can read more about ultrasonic level transmitter in our product review of Ecometer S here

Accuracy is a priority

In regards to the materials used, an E&I engineer with 10 years of experience suggests an ultrasonic level transmitter. Specifically, “a non-contact type with good accuracy. If you use any sensor immersed in liquid, make sure the material has no chemical reaction with liquid,” he suggests.

However, solving this issue requires the appropriate skill. A senior engineer from Nicaragua weighs in on this. He believes it’s a bad idea to make a flow calibration considering volume across flow meter in X time. “This is because the level inside the tank when you start to pump is not stable, especially if you want good calibration accuracy,” he explains.

Instrumentation Details to Consider

According to an automation engineer from United Arab Emirates, radar sensors have pretty fast responses. He says, “according to your process connection, you can select Endress Hauser or Vegapuls 64. We commonly use this for 25 litre vessels to 2000 litre vessels. Hygiene instruments are also suitable for pharmaceutical applications. Properly calibrate it so that you don’t need to calibrate data sensor in its lifetime.”

A consultant from Saudi Arabia also weighs in. Since it is a very small capacity tank, he considers some critical details. These are the conductivity of the liquid, the material and dimensions of the storage tank, the budget for the instrumentation and requirement of interlocks, and protecting the system. Whether it is indoor or outdoor would also help decide the type of level instrument. 

Lastly, an instrument engineer from Texas obtains volumetric flow measurement accuracy using devices with the Coriolis effect or turbine meter. “In my experience, the Coriolis type devices are quite reliable and accurate, no matter what fluid/gas is measured. The fluid must be gas or liquid, but not both to ensure accuracy. There are several manufacturers of such devices. The best part is there are no internal restrictions using a Coriolis type device,” he concludes.

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