In a number of technological processes, it is very important to have the flow of media in piping under control without necessity for exact measurement with the flowing/not flowing information (checking cooling circuits, idle operation of pumps, batch process, etc.). Flow monitors are applied for such purposes with advantage. Principally, all of our meters can be used for this purpose at the same time as flow monitors and the entire series of our induction and paddle wheel flow meters is equipped with such a feature.
Generally, the principles of flow monitors can be divided into mechanical and electronic ones. The frequent problem in mechanical flow monitors is the destruction of the flexible element (paddle switches), ensuring proper operation of the flow monitor, namely after quite a short period of using. In case of an electronic monitor, it is based on the calorimetric principle without any mechanical elements and thus with much less tendency to destruction of the flow monitors and with a very long service life. Exact adjustment of the switching point by the learning system is a great advantage.
Calorimetric flow monitors
The calorimetric flow monitors operate on the principle of different velocity of cooling down of the heating sensor immersed in the cross-sectional profile versus the flow velocity of the medium. If the immersed sensor cools down more quickly, this means that the flow of media is quicker and conversely, if the sensor cools down more slowly, the flow velocity is lower.
Advantages and applications
This measurement principle is very efficient namely for lower flow velocities and the highest efficiency is reached for velocities up to 150cm/sec. The flow monitors are equipped with adjusting elements for custom modification of the make/break threshold as required. According to type, the meters are capable of preliminary indication of the existing flow velocity (they can be completed with orientation current output 4-20mA). Thanks to absence of movable component, the meters reach very a long service life and reliability. Along with simple installation by means of user settings, the meters are an ideal solution for flow rate monitoring.
Paddle wheel flow monitors
These flow meters that can be used advantageously also as flow monitors. They are again designed for all liquids, i.e. for non-conductive ones as well. The separate paddle is completed with an evaluation unit with electronic contact giving pulses during the movements of the paddles along the sensing element, possibly according to the set flow-rate of the medium.
Advantages and applications
The sensor is provided with a microswitch for setting the make/break point of the flow monitor. In this mode, the output contact is on-state or off-state according to velocity of the medium in the pipeline. Furthermore, the meter can be equipped with the 4-20mA current output for velocity flow/flow rate transmission (according to type). The fundamental improvement is the absence of any magnetic components for picking up the movements of paddles and thus much longer maintenance-free operation. This type of meter is ideally used at flow velocities above 100cm/sec.