Instruments that measure fluid flow are collectively referred to as flow meters or flow meters. The flowmeter is one of the important instruments in industrial measurement. With the development of industrial production, the accuracy and range of flow measurement requirements are getting higher and higher, and the flow measurement technology is changing with each passing day. Various types of flow meters have been introduced to suit various applications. More than 100 flow meters have been put into use. From different perspectives, flow meters have different classification methods. There are two commonly used classification methods. One is to classify according to the measurement principle adopted by the flowmeter: the second is to classify according to the structural principle of the flowmeter.
Sort by measurement principle
a. Mechanical principle:
Instruments belonging to such principles have differential pressure type, rotor type using Bernoulli's theorem;
Impulse type using the momentum theorem, movable tube type;
Direct mass equation using Newton's second law;
a target using the principle of fluid momentum;
Turbine using the angular momentum theorem;
Vortex type using vortex principle of fluid oscillation;
Use the total static pressure difference of the pitot tube type as well as volumetric and sputum, trough and so on.
b. Electrical principle:
Differential capacitor type,
Strain resistance type, etc.
c. Acoustic principle:
d. Thermal principles:
Indirect calorimetry and so on.
Working principle and sensor parameters of ultrasonic external clamp flow meter
External clip type ultrasonic flow meter external clip type ultrasonic flow meter series measuring full flow of liquid flow meter, optional explosion-proof and intrinsically safe type, explosion-proof grade Exd[ib]IIBT6, and optional intrinsically safe remote control, explosion-proof grade ExibIIBT6, measurable medium: drinking water, river water, sea water, ground water cooling water, high temperature water, sewage, lubricating oil, diesel, fuel chemical liquid, other homogeneous fluid.
External clip sensor parameters:
The external clip type sensor is an installation method in which the sensor is directly bundled on the outer surface of the pipe to be measured to realize flow measurement, and has a diameter independent of the pipe diameter.
Simple installation, no need to stop production, no pressure loss and so on.
Fourth, the liquid turbine flowmeter put into operation the opening and closing sequence
1. The sequence of opening and closing of the operation
For flow sensors without a bypass line, first open the flow sensor upstream valve at a medium opening and then slowly open the downstream valve. Run at a small flow rate for a period of time (eg 10 minutes), then fully open the upstream valve, then open the large downstream valve opening to adjust to the required normal flow.
The flow sensor equipped with the bypass pipe first opens the bypass pipe valve to open the upstream valve at a medium opening degree, slowly opens the downstream valve, and closes the opening of the small bypass valve to make the instrument run for a period of time with a small flow rate. Then fully open the upstream valve, fully close the bypass valve (to ensure no leakage), and finally adjust the downstream valve opening to the required flow.
2. Activation of low temperature and high temperature fluids
The low-temperature fluid pipeline should drain the water in the pipeline before the flow, and then run for 15 minutes at a small flow rate, and then gradually increase to the normal flow. Slow down when stopping, so that the pipe temperature and ambient temperature are gradually approaching. High temperature fluid operation is similar to this.