Measurement & Automation Why Innovative Fixing of Level Transmitters is So Important

Author / Editor: S. N. DESHPANDE / Dominik Stephan

You have got the know–how, you have got the infrastructure and you have got state–of–the–art measurement and automation equipment – but it's not time to kick back and relax... The next – and perhaps most important – step is to ensure your assets are set up and functioning without any hindrances. Measurement equipment like level transmitters...

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Fixing cage for a project at Aden pumping station in Yemen.
Fixing cage for a project at Aden pumping station in Yemen.
(Source: Nivelco Instruments India)

In today’s world ‘water’ is a very precious substance as the resources of the water on the earth are reducing drastically. It is well understood in the industry, and leads to the necessity of accurate measurement of the water levels in the open reservoirs. Hence, the importance of ‘automation’ is very much increasing in the Indian water industry nowadays.

Level measurement by general pressure or differential pressure transmitter is not practically possible in open reservoirs, like – dams, lakes, rivers, ponds, fore-bays, bore-wells, sumps, under- ground reservoirs etc. In the past, here in India, mechanical float operated level instruments like ‘float and board’ or ‘float and tape’ type level gauges were being used. Due to practical limitations for installations, these can be provided up to three to five metres of range, and can have considerable problems of getting the float stuck due to possible objects flowing with the water – (say for example) like pieces of cloth or paper that may be present in the raw water reservoirs.


Capacitance Type Level Transmitters

For automation, a continuous signal is preferred, and hence people started using low cost capacitance type level transmitters for these applications. But, there are practical difficulties for bigger reservoirs for calibration of such instruments. Also, these types of transmitters are not preferred – as those are not convenient to be used for bore wells, and do not have good practical accuracy.

Trends in Measurement and Automation

The ultrasonic level transmitters are nowadays very popular in water industry due to non-contact method and easy installation. But for open reservoirs, these transmitters have limited usage as there can be very strong wind streams – which can affect the ultrasound waves or signals – resulting in malfunction of the transmitters, if the range is more than eight to ten metres. This probability is more when the transmitter is installed in an extremely open atmosphere.

The use of radar or microwave level transmitters is increasing nowadays in water industry due to contact as well as noncontact methods, good accuracy and easy installation. But in India, the difficulty at the user's end is high cost for non contact radars, and non-availability of properly trained manpower at the remote places like dams, rivers etc. Such manpower also costs a considerable investment.