Home > Knowledge > Content
Proper installation of liquid flow meters
Dec 13, 2018

Proper installation of liquid flow meters


Liquid flowmeter type (hereinafter referred to as the sensor) is based on the principle of torque balance and belongs to the speed flow meter.It is widely used in petroleum, chemical industry, metallurgy, water supply, papermaking and other industries. It is an ideal meter for flow measurement and energy saving.

(1) working principle of liquid flow meter

Fluid flowing through the sensor shell liquid flowmeter, as a result of the impeller blade and flow to a certain point of view, the fluid force makes the blade with rotational torque, to overcome the friction torque and fluid resistance, blade rotation speed stability after the moment balance, liquid flowmeter under certain conditions, the speed is proportional to the velocity of flow, because the blade has a magnetic conductivity, it is in the signal detector (consists of permanent magnets and coils) magnetic field, rotating blade cutting lines, periodically changing coil magnetic flux, so that the coil ends induction electrical pulse signal, the signal after amplifier amplification plastic, formation has certain amplitude of continuous rectangularPulsed waves can be transmitted as far as the display instrument to show the instantaneous flow or total volume of the fluid.Within a certain flow range of the liquid flowmeter, the pulse frequency f is proportional to the instantaneous flow rate Q of the fluid flowing through the sensor.

fProper installation of liquid flow meters

Liquid flowmeter type (hereinafter referred to as the sensor) is based on the principle of torque balance and belongs to the speed flow meter.It is widely used in petroleum, chemical industry, metallurgy, water supply, papermaking and other industries. It is an ideal meter for flow measurement and energy saving.

The sensor and the display instrument are used together to measure the liquid in the closed pipe which has no corrosive effect with stainless steel 1Cr18Ni9Ti, 2Cr13, corundum Al2O3 and hard alloy, and has no impurities such as fiber and particle.If it is matched with the display instrument with special function, quantitative control and over-alarm can be carried out.The explosion-proof type of this product (Exm = 2 * ROMAN IIT6) can be used in the environment with explosion risk.

The sensor is suitable for medium with viscosity less than 5 * 10-6m2/s at operating temperature. For liquid with viscosity greater than 5 * 10-6m2/s, the sensor shall be used after solid liquid calibration.

If the user needs to use special form of sensor, can negotiate order, need explosion-proof sensor, explain in the order.The liquid flowmeter type sensor should be installed in a place that is convenient for maintenance and free from vibration, magnetic interference and thermal radiation.Installation in the outdoor, should avoid direct sunlight and rain measures.

(2) installation requirements and matters needing attention

Turbine meter level sensor installation requirements of pipeline should be visually perceived inclination, vertical installation of sensors (within 5 °) piping vertical deviation should be less than 5 °, under the direction of flow shall be upward.

Where the flow cannot be stopped, bypass and globe valves should be installed.

If the fluid contains impurities, a filter should be installed on the upstream side.If gas is present, a damper should be installed upstream.Filter and degasifier outlets and outlets to a safe place.

Flow control valve should be installed in the sensor downstream, upstream globe valve in the measurement should be fully open, and do not produce vibration and leakage.Check valves should be added to processes where reverse flow may occur to prevent reverse flow.

The sensor shall be concentric with the pipe and the sealing gasket shall not protrude into the pipe.The sensor should not be at the high point of the horizontal pipeline, so as to avoid the accumulated gas in the pipeline (such as mixed air when the flow stops) staying at the sensor, which is not easy to discharge and affect the measurement.

The front and rear pipelines of the sensor shall be firmly supported without vibration.Heat preservation measures should be taken for the sensor and its front and rear pipelines for the condensable fluid.

Proper installation of liquid flow meters

Transmission cables are usually double-core or three-core with shielded signal cables. Shielded signal cables shall be grounded at the end of the display instrument (flow integrator or flow calculation controller). The transmission path should not be parallel to the power supply line, nor should it be laid on the power supply. The area where the line is concentrated.

Therefore, the correct installation of liquid flow meter, must pay attention to the following points:


1. The direction of liquid movement in the device shall be different from the direction of arrow indicating the flow direction on the sensor housing, and the upstream straight pipe segment shall be greater than or equal to 20DN, and the downstream straight pipe segment shall be greater than or equal to 5DN, where DN is the inner diameter of the pipe.

2. The instrument device adopts flange connection, thread connection and clamping type;

3. In order not to affect the normal delivery of liquid during maintenance, bypass pipe should be installed outside the straight pipe section at both ends of the sensor;

4. The sensor should be away from the external magnetic field, if not prevent, should take necessary measures;

5. For the connection between the sensor and the display instrument, the connection mode shall be selected according to the power supply of the amplifier. Please refer to the "operation instructions" for details.

Proper installation of liquid flow meters

6. When the sensor outdoor device, please do a good job of amplifier plug waterproof disposal;

7. If the fluid is unstable and pulsating, a buffer can be installed to prevent pulsating flow in order to ensure a good measurement of the rotor flowmeter.Rotor flowmeter in the use of, should first slowly unscrew the flow meter upstream pipe control valve, and then use the conditioning valve conditioning flow, so as not to suddenly open the formation of float rapid rise damage cone pipe.

8.Liquid flow meter sensor can be degree, vertical device, vertical fluid direction must be up.The liquid should be filled in the pipe without bubbles.When installing the device, the direction of liquid movement should be different from the direction of arrow indicating flow direction on the sensor housing.The upper end of the sensor shall have at least 20 times the nominal diameter of the straight pipe segment, the lower end shall have at least 5 times the nominal diameter of the straight pipe segment, its inner wall shall be lubricated and clean, without indentation, scaling and peeling defects.