Flow meter type
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.
Classified by flowmeter structure principle
Volumetric flowmeter
A volumetric flow meter is equivalent to a standard volume container that measures the flow medium continuously. The larger the traffic, the more times the metric is, and the higher the frequency of the output. The principle of the volumetric flowmeter is relatively simple and suitable for measuring fluids with high viscosity and low Reynolds number. According to the shape of the rotary body, the products currently produced are: an oval gear flow meter suitable for measuring liquid flow, a lumbar flowmeter (Roots flowmeter), a rotary piston and a scraper flowmeter; a servo type suitable for measuring gas flow Volumetric flowmeters, membranes and flowmeters, etc.
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.
Installation of plug-in electromagnetic flowmeter
The plug-in electromagnetic flowmeter sensor installation upstream straight pipe section is not less than 5D (D means pipe diameter), the downstream straight pipe section is not less than 2D:
1. Vertical installation. When the sensor is inserted into the pipeline, it should be less than 5° from the vertical diameter of the pipeline section. It is suitable for measuring the cleaning medium with small vibration of the pipeline.
2, inclined installation, the axis of the sensor and the axis of the pipe to be tested is 45 °, suitable for large pipe diameter and measuring the flow of liquid containing other impurities in the medium, the installation method is small, not suitable for entanglement.
There are two ways to insert the insertion point of the electromagnetic flowmeter sensor: one is inserted into the central axis of the pipe to be tested (ie 1/2 times the diameter of the pipe); the other is inserted into the inner wall of the pipe at 1/4 of the pipe.
Sensor installation:
1. Clean the welding slag and burrs of the base of the pipe to be tested.
2. Turn off the upstream flow control valve or use low pressure water supply.
3. Install the DN50 ball valve on the mounting base. Pay attention to the long cavity of the ball valve. Check whether the ball valve can be fully open and fully closed. Install the screw seat, compression nut and rubber sealing ring onto the ball valve and loosen the positioning nut. Insert the sensor into the rod through the ball valve and insert it into the pipe to be tested. At the same time, it should be noted that the direction of the sensor direction indicator rod should be consistent with the flow direction of the fluid. Ordering Information Please specify the name of the tested medium, working pressure, medium temperature, flow rate (flow rate) range, pipe diameter and the pipe network to be tested.