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How to correctly install the intelligent electromagnetic flowmeter

Jan 18, 2017

How to correctly install the intelligent electromagnetic flowmeter

1, the installation site requirements of intelligent electromagnetic flowmeter

Usually electromagnetic flow sensor housing protection and other very  IP67, on the installation site has the following requirements.

1) Where mixed phase fluids are to be measured, select locations that  do not cause phase separation; when measuring bicomponent liquids, avoid  mixing downstream of the mix; while measuring chemical reaction piping  downstream of the fully completed reaction zone;
2) as far as possible to avoid the measurement tube into a negative pressure;
3) select the place of small vibration, especially for the one-meter;
4) to avoid the vicinity of a large motor, a large transformer, so as not to cause electromagnetic interference;
5) easy to achieve a separate place sensor grounding;
6) as far as possible to avoid the surrounding environment with high concentrations of corrosive gases;
7) Ambient temperature in -25 / -10 ~ 50/600 ℃ range, one-piece  structure temperature is also subject to electronic components, the  scope should be narrower;
8) Avoid direct sunlight as far as possible;
2, the installation of straight pipe requirements

First  of all, pay attention to the sensor itself can not be used as a load  support point, it can not support the work of the adjacent pipeline,  should hold its pipe load. In order to obtain the normal measurement accuracy, the  electromagnetic flow sensor upstream also have a certain length of  straight pipe, but its length and most other flow meter compared to  lower requirements.

90  ° elbow, T-shaped tube, concentric reducer, after the full-open gate  valve from the sensor inlet flange connection surface 5 times the  diameter (5D) straight pipe length, different valve opening requires  10D; (2 ~ 3) D; But to prevent the butterfly valve piece into the sensor measuring tube. The  standard or test procedures proposed by the upstream and downstream  straight pipe length is also inconsistent, and some electromagnetic  flowmeter requirements than the usual requirements. This is because in order to ensure the accuracy of the instrument to achieve the current 0.5 level requirements.

3, the installation location and flow direction

The  sensor mounting direction is horizontal, vertical or tilted (the fluid  must flow horizontally or obliquely upward) without restriction. But to ensure that the measuring tube and the process pipe coaxial. Its axis deviation shall not exceed 2MM. Measurement of solid-liquid two-phase flow is best vertical installation, bottom-up flow.

This can avoid the horizontal installation of the lower part of the  local liner wear serious low-speed solid-phase precipitation and other  shortcomings.

In  the sensor adjacent to the pipeline for welding or flame cutting, to  take isolation measures to prevent lining heat, and must confirm that  the instrument converter signal cable is not connected to prevent damage  to the converter horizontal installation to make the electrode axis  parallel to the horizon, do not be perpendicular to Horizon, because the electrode in the ground is easy to cover the  deposit, the top electrode is easy to be liquid bubbles in the  occasional cover cover electrode surface, the output signal  fluctuations.
4, the installation of negative pressure pipe system

Fluorine  plastic lining sensors should be used with caution in the negative  pressure system. Positive pressure piping should be protected against  negative pressure. For example, if the liquid temperature is higher than  room temperature, the fluid cooling shrinkage will be negative after  closing the sensor upstream and downstream shut-off valves. Pressure,  should be installed in the vicinity of the sensor to prevent negative  pressure valve, a manufacturer of PTFE and PFA plastic lining used in  the pressure pipe system can be used in the 200C, 1000C, 1300C absolute  pressure must be greater than for non-conductive pipe, ground The flange clamp is located between the sensor flange and the pipe flange.

5, grounding

The sensor must be separately grounded (10 Ω or less). Separation  principle In principle, the grounding should be on the sensor side, the  converter grounding should be in the same grounding point. If  the sensor is mounted on a cathodic corrosion protection pipe, in  addition to the sensor and ground ring together with the ground, but  also with the coarser copper wire (16mm) cross sensor pipe across the  two connecting flange, the cathodic protection current between the  sensors isolation.

Sometimes  after the stray current is too large, such as electrolytic cell leakage  current along the electrolyte affect the EMF normal measurement, you  can take flow sensor connected with the process of electrical isolation  between the methods. This method can also be used when cathodic protection currents affect  the EMF measurement on cathodically protected pipelines as well.

Second, the converter and its accessories installation specification

1,  the converter and the signal cable between the sensor can not be  greater than 50M, and the signal cable must be worn with galvanized pipe  wear. Such as galvanized pipe in the air, should be galvanized pipe with a  reliable grounding, grounding resistance is less than 10 ohms

2, the power supply 220v unidirectional AC, in the instrument box  inside the installation of air switches, lightning arrester and air  switch connected in parallel, the wire from the air switch out followed  by a three-outlet

3, lightning arrester grounding

Lightning  arrester grounding wire length can not exceed 1M, cross-sectional area  of more than 6MM square multi-strand copper insulated wire. If  there is no ground network near the lightning arrester should be made  near a simple network, as follows: with three 1.5M length of flat steel  or angle steel, according to the triangle into the ground into the top,  flat steel with three flat steel welded together , In which a corner of the welding bolts, and then the lightning  arrester grounding wire can be connected to ground 220V AC lightning  protection ground-level installation panel.