How to make preliminary selection of flowmeter? Posted by : admin / Posted on : Oct 19， 2020

(1) According to the name and nature of the measured medium, determine whether to use electromagnetic flowmeter (determined by salesman)
Note: The electromagnetic flowmeter can only measure the flow of conductive liquids, and gas, oil and most organic liquids are not examples of general conductive liquids.
(2) Determine the electrode material according to the learned properties of the substrate
Note: The company generally provides four types of electrodes, such as stainless steel, Hastelloy, titanium and tantalum. Which electrode should be used should be checked according to the nature of the medium.
(2) Determine whether to use rubber or PTFE lining according to the learned medium temperature (determined by the salesperson)
Note: The temperature resistance of rubber shall not exceed 80C;
PTFE temperature resistance 150C, instantaneous resistance 180C;
City sewage generally can use rubber lining and stainless steel electrodes
(3) According to the learned medium pressure, select the flange specification of the meter body (determined by the salesperson)
Note: The electromagnetic flange specification is usually when the diameter is from DN10 to 250, the flange rated pressure is ≤1.6Mpa;
When the caliber is DN250-1000, the flange rated pressure is ≤1.0Mpa;
When the actual pressure of the medium is higher than the corresponding range of pipe diameter-pressure, it is a special order, but the maximum pressure shall not exceed 6.4Mpa
(4) Determine the conductivity of the medium
Note: (1) The conductivity of the electromagnetic flowmeter shall not be lower than 5uS/cm
(2) The conductivity of tap water is about tens to hundreds of uS/cm. Generally, boiler soft water (deionized water) is conductive, while pure water (highly distilled water) is not.
(3) The electrical conductivity of gas, oil and most organic liquids is much lower than 5uS/cm, so they are not conductive.
3. Understand user requirements
(1) Know whether it is a combined local display or a split remote display (provided by the user)
Note: Please understand the maximum distance when displaying split remote transmission, the maximum separation distance is 100 meters
(2) Know whether other additional functions are needed (provided by the user)
Note: 1. The electromagnetic flowmeter itself has the upper and lower limit flow alarm, frequency and current output functions, no special order is required
2. There are two types of electromagnetic flowmeter casing sealing protection grades: IP65 and IP68. When the submersible type IP68 is selected, it is a special order
3. When the electromagnetic flowmeter is to be connected to the computer, the RS-485 communication port needs to be added, which is a special order
4. Model selection: After passing the above steps, the model and specifications of the electromagnetic flowmeter can be finally determined.