Industry new

Need to pay attention to the problem introduction when selecting the electromagnetic flowmeter

The selection of the electromagnetic flowmeter is very important, it determines whether it can work normally and reliably at the user's site. Although there are many articles in this area, there are always some generalities. Here we will talk about the selection of electromagnetic flowmeters.
◆ On-site process parameters to be provided by the user
Since the electromagnetic flowmeter is a field instrument, the process parameters on site are the basics of electromagnetic flowmeter selection. The data in this area is generally provided by the user, and the parameters required to be provided must be accurate and reliable.
(1) The type of liquid to be tested (including the specific composition and concentration);
(2) The usual flow rate, maximum and minimum flow rate of the liquid to be tested;
(3) On-site process pipe diameter, and the material of the pipe (whether metal pipe or non-metal pipe or metal pipe with lining, etc.);
(4) the temperature of the liquid to be tested;
(5) the pressure inside the pipeline;
(6) Conductivity of the fluid to be measured (provided by the user)
(7) It is also best to provide the installation position of the electromagnetic flowmeter (conditions, etc.)
(8) If it is to replace the old electromagnetic flowmeter, it is best to provide the flange standard and connection form of the original electromagnetic flowmeter, as well as the length of the original electromagnetic flowmeter. Otherwise, the newly purchased instrument may not be installed at the site.
◆Users provide other requirements
(1) Structure form: Is it a split type or an integrated type? If it is a split type, it is necessary to provide the distance between the sensor and the converter so that the manufacturer can provide an accurate communication cable;
(2) Degree of protection: Due to the installation location factor, the user must provide an accurate level of protection so that the electromagnetic flowmeter can fully adapt to the site environment;
(3) Communication method: There are a variety of communication methods for electromagnetic flowmeters, and users can make reasonable choices according to their own needs.
(4) Whether it is explosion-proof;
(5) Accessories requirements: Supporting flanges and fasteners are essential accessories for on-site installation of electromagnetic flowmeters. If the instrument is replaced, it can be omitted, otherwise it must be ordered in the order.
(6) For the special requirements of other users, the manufacturer's salesperson must be accurately informed and detailed in the remarks in the order form.
◆ User selection or manufacturer business personnel selection
(1) Determine whether the electromagnetic flowmeter can be used according to the characteristics of the measured medium to be tested;
Note: Electromagnetic flowmeters can only measure the flow of conductive liquids, while gases, oils and most organic liquids are generally non-conductive or have low electrical conductivity.
(2) determining the electrode material according to the characteristics of the liquid to be tested;
Note: Which kind of electrode should be used according to the nature of the medium to check the relevant information manual or consult the business personnel and technical personnel of the production enterprise, absolutely must not blindly choose, it is easy to lead to the selection error, causing problems in use.
(3) Determine which lining to use based on the temperature of the medium that is known;
Note: The temperature resistance of rubber should not exceed 80 °C; the temperature of PTFE is generally 130-150 °C; the PFA can be below 180 °C. Generally, the rubber lining is standard with stainless steel electrode, and the user can also use some sort of lining.
(4) Select the body flange specification according to the known medium pressure;
Note: The flange standard for electromagnetic flowmeters is usually GB9119-2010 (≤4.0MPa) and GB9119-2010 (>4.0MPa). For other standard flanges, the implementation standard must be clearly indicated in the remarks. Grade and seal form.
(5) determining the conductivity of the medium;
Note: (1) The conductivity of the electromagnetic flowmeter must not be less than 5uS/cm.
(2) The conductivity of tap water is about tens to hundreds of uS/cm. Generally, boiler soft water (deionized water) conducts electricity, and pure water (highly distilled water) does not conduct electricity.
(3) The conductivity of gases, oils and most organic liquids is much lower than 5 uS/cm, and the non-conductivity or conductivity exceeds the requirements of electromagnetic flowmeters.
(4) Selection: Combine all the above conditions to determine the model specifications of the electromagnetic flowmeter. In the selection of the type must be more communication and communication, can not rely on subjective judgment, to seek truth from facts, in order to correctly select the most suitable electromagnetic flowmeter for field use.

PREVIOUS：Introduction to the correct selection and useNEXT：The application of the flowmeter, you think o