Flow, level & control


Whilst some flow meter manufacturers have developed devices capable of measuring low flows in liquids at high pressures, very few of them perform to a high standard overall. Looking at total installation and life time cost, they are often too expensive and uneconomic to consider as a credible low- flow, measurement solution, as Titan Enterprises explains

Therefore, some care should be taken when specifying this form of technology. Some ultrasonic low-flow measurement devices require zero point adjustment in order to prevent the device showing flow, when there is none. Ultrasonic flow meters are typically calibrated at the factory, but their readings will change with temperature or even mounting methods. In recent developments at ‘Titan flow measurement technologies’, we have addressed these issues. The new Titan 100Bar low-flow Process Atrato does not require ‘in-situ tuning’ whilst recording very low flows. This device is also capable of recording the lowest flow ranges currently available in the flow measurement sector, for this type of technology. But what are the alternatives for the


measurement of low-flow rate, high pressure fluids?

ltrasonic flow meters, sensors and indicators are new to low-flow/high pressure flow measurement of liquids.

PELTon WhEEL TurbinE basEd FLoW sEnsors Pelton wheel turbine based flow sensors, packaged in stainless bodies are capable of measuring low flows in liquids at high pressures. They will give the required pressure ratings, reasonable performance and with consistent fluid characteristics. However, they are Reynolds Number dependent. This dictates that complicated electronics and temperature sensing is necessary to accompany the flow meter. These additions are necessary in order to achieve consistent performance during changes in fluid characteristic – or even flow rate. Pelton wheel turbine based flow sensors will not handle viscous fluids at all.

PosiTivE disPLacEmEnT FLoW mETErs Positive displacement flow meters are also capable of measuring low flows in liquids at high pressures, but again there are limitations.

To work well, the fluid being monitored should have some viscosity – and be perfectly clean, par ticularly when using oscillating piston flow meters housing relatively-large areas of sliding surfaces. Sliding surfaces wear and are subject to static friction with long term use. We often specify our oval gear meters for these applications as these have relatively small rubbing areas relative to their driving force, and are therefore suitable even for non-viscous liquids.

corioLis FLoW mETErs Coriolis meters are very good but expensive. These meters will give ±0.5 per cent accuracy over a wide flow range at pressures up to 100 Bar. To discuss specific high pressure, low-flow

measurement requirements, projects or problem solving, contact Titan Enterprises

Titan Enterprises


flow rates and ultra-pure materials and always with the absolute requirement for hygienic, sterile and sanitary conditions. So, challenged with flow measurement within a pipe, par ticularly an existing pipe, how does the site engineer respond? As the purity of the fluid increases, the conductivity often decreases, so technologies such as electromagnetic flow metering will not always work. Then there is the interruption to production and the difficulties of re- establishing the sterile conditions required to re-commence operations. Invasive flow measurement instruments can even provide sites for microbial and algal growth to flourish. Non-invasive, clamp on flow measurement using ultrasonic techniques provides a method to measure reliably and repeatably without interrupting the process and without compromising the sterility of the pipe. Clamp-on, non-invasive ultrasonic flowmeters are clean, easy to install and


use, and versatile. The rise of the distributed factory made possible by Industry 4.0 and Industrial Internet of Things (IIoT) technologies, the increased

harmaceutical manufacturing presents some of the most difficult challenges for process instrumentation. There are all the usual requirements – flow, level, temperature etc, but often with low

demands of continuous over batch production and the drive to reduce product returns in a high-value environment such as pharmaceuticals means that reliable process measurement that can be easily incorporated into an existing process is becoming more and more essential. The clamp-on flowmeter is set to be an important part of that growth.


Instrumentation Monthly January 2019


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