The efficient operation of equipment in modern materials processing and discrete manufacturing plants often depends on the accurate flow sensing measurement of gases, liquids and slurries. Accurate air flow measurement, for example, in OEM equipment such as boilers and burners is not only critical to achieving the necessary temperatures for operation, but also to operate as efficiently as possible and reduce energy consumption, pollution and cost. Applications include:
Air compressors
Many manufacturing plants depend on compressed air for aeration mixing and powering pneumatic equipment in assembly processes. Thermal flow sensors embedded within a process control loop, at main distribution points and point-of-use help ensure the compressors provide only the necessary and optimum amount of air and trap leaks. These sensors provide both a highly reliable and consistent airflow while minimising energy costs.
Gas compressors
In food processing plants where liquid nitrogen is used in cooling systems, thermal sensors measure nitrogen flow to ensure the right amount of gas is used to ensure process quality. Similar applications for flow sensors are found in large commercial ammonia refrigeration systems. In both applications, the wide turndown ratios (100:1), low flow sensitivity and negligible pressure drop, make thermal flow sensors an ideal solution.
Pump protection circuits
Pumps are expensive and can be maintenance intensive if they are allowed to run dry, causing excessive wear to the pump components. Thermal flow sensors added in a control loop or alarm system help ensure that pumps never run dry or achieve a graceful shutdown should the process media stop flowing for any reason. The sealed design of thermal flow sensors eliminates all contact with the process media to prevent contamination, and they are suitable for use in both liquids and slurries due to their no-clog sensor head.
Additive dispensing control
In pharmaceuticals processing, highly accurate thermal flow sensors within pumps support liquid additive dispensing. The precise measurement of additive flow helps ensure batch control quality essential in the pharmaceuticals industry. Designed to support line sizes down to 6 mm, these flow sensors are also suitable for prototyping and laboratory applications as well.
With their accuracy, excellent repeatability, and rugged construction, thermal dispersion flow sensors offer superior performance, reliability, long life, and low maintenance. They are simple to install and offer a low total cost and longest life-cycle solution in embedded OEM equipment flow sensor applications. In comparison to mechanical rotary, float or orifice plates, the no-moving parts design of FCI's thermal flow sensors eliminates clogging and sensor breakage requiring maintenance and replacement.
In comparison, FCI's thermal flow sensing element contains two thermowell-protected resistance temperature detectors (platinum RTDs). One RTD is heated and the other RTD senses the gas or fluid temperature. The temperature difference between the two RTDs relates to the fluid flow rate. They provide a true mass flow analog output (without pressure or temperature transducers), as well as temperature, totalising and alarm outputs. High measurement accuracy is achieved with the sensors never coming into contact with the fluid being measured. Simple to install, the sensors are minimally invasive, which reduces pressure-drop.
For more information contact Jerry Smits, Protea Automation Solutions, 011 719 5700, jerrys@protea.co.za, www.protea.co.za
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