subject: A Guide To Choosing Electromagnetic Flow Meters [print this page] Electromagnetic Flow meters are among the commonly used flow meters for quantifying fluid flow. These flow meters come in many designs, with models available for a wide range of operational specifications. The choice of the flow meter depends on the fluid and the medium in which flow is to be measured. Before purchasing a flow meter it is important to have precise information about operational pressures, temperatures and composition of the fluid, even if there is no scope for variation in these parameters.
The principle of working of the Magnetic Flow meter
Flow measurement employing magnetic fields have been in use for quite some time now. Measurement is done by calculating the potential difference created when a magnetic field is applied to the metering tube. The potential difference is proportional to the fluid velocity which in turn is perpendicular to the magnetic flux. To put it simply, a magnetic field is applied horizontally and when a conducting fluid interrupts the field, it causes a potential difference which is measured. This principle works best for liquids. The flow of gases is not measured using this kind of measurement device. The inner surface of the pipe carrying the liquid should be insulated. Usually metal pipes are rubber lined on the inside if magmeters are to be used. To produce a magnetic field an electromagnet is better suited when compared to a permanent magnet. Electrochemical effects at the electrodes can affect the potential difference warranting the use of alternating magnetic fields which can only be produced by electromagnets.
Choosing the magnetic flow meter
The nature of fluid and measurement determines the choice of flow meter. There are many kinds of meters, differing in measurement principle. Among those which work on electromagnetic technology, the choice of a device is determined by the operating conditions, electrical conductivity of the fluid and the type of installation preferred. Flow meters can be battery operated and remote controlled through GPRS and CDMA. If there are space constraints owing to the small diameter of the pipe, insertion type devices can be used. You can also choose devices with removable electrodes. Such devices are ideal for low cost operation as replacement of electrodes is inexpensive compared to replacing the whole meter in case of damage.
Buy from reputed manufacturer
Electromagnetic Flow Meters should be purchased from manufacturers known for their after sales service. The devices should be power efficient, highly accurate, and easy to install. They should work with a wide range of fluids and under varying conditions. It goes without saying that low cost devices which are not expensive to maintain, should be preferred.
