Metal tube float flowmeter is widely used, suitable for measuring liquid, gas, steam and other media, with high accuracy, good stability, small pressure loss, easy maintenance and other advantages, can be installed horizontally, vertically for various occasions. In order to ensure the measuring accuracy of the metal tube float flowmeter, it is necessary to install the float flowmeter strictly according to the requirements.

I. Installation requirements of metal tube float flowmeter

(1) Installation direction

The vast majority of metal tube float flowmeters must be installed vertically on the non-vibrating pipe, there should be no significant tilt, fluid flow through the meter from bottom to bottom. The verticality is better than 2°, and the horizontal Angle is better than 2° when installed horizontally. There is no strict requirement for the length of the upstream straight pipe section of the instrument, but some manufacturers require 5D length, which is not necessary in fact.

(2) The measured medium contains impurities

If the medium contains ferromagnetic material, magnetic filter should be installed; If the medium contains solid impurities, it should be considered to install a filter between the valve and the straight pipe section;

(3) Installation of pulsating flow

For the pulsation of the flow itself, if there is a reciprocating pump or regulating valve upstream of the intended instrument location, or there is a large load change downstream, the measuring position should be changed or remedied in the pipeline system, such as adding a buffer tank; If the oscillation of the instrument itself, such as the gas pressure is too low when measuring, the upstream valve of the instrument is not fully opened, the regulating valve is not installed in the downstream of the instrument and other reasons, should be improved to overcome, or change the instrument with damping device.

(4) When the measured medium is gas

When used for gas measurement, the pipeline pressure should be ensured not less than 5 times the pressure loss of the flowmeter to make the float work stably; If the gas is discharged directly into the atmosphere at the outlet of the meter, a valve should be installed at the outlet of the meter, otherwise there will be a drop in air pressure at the float which will cause data distortion.

Two, metal tube float flowmeter installation precautions

(1) The metal tube float flowmeter installed on the process pipeline should be bypassed, which is convenient to deal with faults or do not affect the production when blowing;

(2) The metal tube float flowmeter should have a straight pipe section at the entrance of more than 5 times the pipe diameter, and a 250mm straight pipe section at the exit to ensure the measuring accuracy of the instrument;

(3) If the temperature of the measured medium is higher than 220℃ or the fluid temperature is too low to crystallization, heat insulation protection measures should be taken, jacket type should be selected for cooling or heat preservation;

(4) Pipe flanges, fasteners, gaskets and flowmeter flanges can be installed and operated normally;

(5) The product generally does not need maintenance after the normal operation of the device. The fault occurs when the device is just started, because the pipeline is not clean, and the float is stuck by solid particles. At this time, the pointer of the indicator stops in a position. At this time, the valve on both sides of the flowmeter should be closed first, and then the upper flange should be removed, the float should be removed for cleaning, and then it should be installed again. Pay attention to tighten the nut of the upper flange in a balanced manner, and pad the washer;

(6) In order to avoid the deformation of the flowmeter caused by the pipeline, the flange of the process pipeline must be coaxial and parallel to the flange of the flowmeter, and the pipe support should be appropriate to avoid pipeline vibration and reduce the axial load of the flowmeter. The control valve in the measuring system should be installed in the downstream of the flowmeter;

(7) Since the instrument transmits signals through magnetic coupling, in order to ensure the performance of the instrument, no ferromagnetic substances are allowed at least 10cm around the installation;

(8) The instrument for measuring gas is calibrated at a specific pressure. If the gas is discharged directly into the atmosphere at the outlet of the instrument, it will produce a pressure drop at the float and cause data distortion. If this is the case, a valve should be installed at the outlet of the instrument;

(9) Special care should be taken when installing PTFE-lined meters. Because under the action of uneven pressure, PTFE will deform, so the flange nut evenly tightened symmetrical;

(10) With liquid crystal display instrument, installation should try to avoid direct sunlight display, so as not to reduce the service life of the liquid crystal.