An electromagnetic flow meter is often a common choice for continuous measurement for water, effluent, sludge, slurries, pulp, pastes, beverages; and highly corrosive liquids (ie acids). It does not have any moving parts and is ideal for water and wastewater applications with conductive medium and low-pressure drop.
An electromagnetic flow meter detect flow by using Faraday’s Law of induction. Inside an electromagnetic flow meter, there is an electromagnetic coil that generates a magnetic field, and electrodes that measure voltage induced by liquid flows.
In order to obtain consistent and accurate flow measurement, it is important to understand and meet the installation requirements. Here are some installation requirements and guidelines:
Pipe requirements:
- Flow meter should always be filled with the medium all the time.
- Direction of the medium is the same as direction of the flow meter.
- Straight pipe length requirements: Min 5X upstream, min 3X downstream.
Horizontal Mounting:
- Flow meter must not be mounted at the highest point of the pipe system or in free outlets, where gravity could empty or partially empty the pipe.
Vertical Mounting:
- When flow meter is mounted vertically, the flow direction should always be upwards. This will ensure pipe is always full and reduce bubbles significantly.
- Flow direction for vertically mounted flow meter should not be downwards or in front of a free outlet, where gravity could partially empty the pipe.
- In case the liquid is carrying particles (ie sludge, slurry, sewage, etc), vertical mounting reduces clogging and noise interference caused by the sediment.
Bending Pipe:
- Flow meter must not be mounted at the highest point of the pipe system or in free outlets, where gravity could empty or partially empty the pipe.
Long pipe system:
- In a longer pipe system, a pump should be installed at the upstream of the flow meter; A cut off valve should be installed at the downstream of the flow meter.
Bypass line:
- It is recommended to install a bypass line to facilitate maintenance and zero adjustment.
