Product selection of intelligent electromagnetic flowmeter

Selection of Caliber and Range
The diameter of the transmitter is usually chosen to be the same as that of the pipeline system. If the distribution system needs to be designed, the diameter can be selected based on the range and flow rate of the manifold. For electromagnetic flow meters, a flow rate of 2-4m/s is more suitable. In the situation If there are solid particles in the liquid, considering the wear situation, the commonly used flow velocity can be ≤ 3m/s. For fluids that are prone to adhering to the pipe wall, the flow velocity can be ≤ 2m/s. After the flow velocity is determined, the transmitter diameter can be determined based on it.
The range of the transmitter can be selected based on two principles: one is that the instrument's full range is greater than the expected high current value, and the other is that the normal current address is greater than 50% of the instrument's full range to ensure a certain measurement accuracy.
Lining selection
Correct selection method of lining material for electromagnetic flowmeter
The lining material should be selected based on the corrosiveness, wear resistance, and temperature of the tested medium:
1、 Natural rubber (soft rubber)
1. Good elasticity, wear resistance, and tensile strength
2. Resistant to corrosion from general weak acids and bases
3. Water and sewage measurement
2、 Acid resistant rubber (hard rubber)
Can withstand corrosion from hydrochloric acid, acetic acid, oxalic acid, ammonia water, phosphoric acid, and 50% sulfuric acid and potassium hydroxide at room temperature, but not resistant to corrosion from strong oxidants
Measure general acid, alkali, and salt solutions
3、 Neoprene rubber
1. Good elasticity, high tensile strength, and wear resistance
2. Resistant to corrosion from low concentration acid-base and salt solutions, but not resistant to corrosion from oxidizing media
<80℃；
Measure water, sewage, mud and slurry
4、 Polyurethane rubber
1. Wear resistance of *
2. Poor acid and alkaline resistance
<40℃
Coal slurry, mud, and slurry for measuring neutral and strong wear
5、 Polytetrafluoroethylene (PTFE)
1. Boiling resistant hydrochloric acid, sulfuric acid, nitric acid, aqua regia, concentrated alkali, and various organic solvents
2. Good wear resistance, poor adhesion performance
-80～+180℃；
Measurement of concentration, strong corrosive solutions with concentrated alkali, and sanitary media
Application site selection
1. Understand the process parameters
(1) Understand the name of the tested liquid (provided by the user)
(2) Understand the high flow rate, common flow rate, and low flow rate of the tested liquid (provided by the user)
(3) Understand the process pipe diameter (provided by the user)
(4) Understand the temperature of the medium (provided by the user)
(5) Understand the pressure of the medium (provided by the user)
(6) Understand the conductivity of the tested fluid (provided by the user)
(7) Understand whether there is negative pressure (provided by the user)
2. Preliminary selection
(1) Determine whether to use an electromagnetic flowmeter based on the name and properties of the measured medium (to be determined by the salesperson)
Attention: Electromagnetic flow meters can only measure the flow rate of conductive liquids, while gases, oils, and the vast majority of organic liquids are not included in the general category of conductive liquids
(2) Determine the electrode material based on the properties of the dielectric material learned
Attention The company generally provides four types of electrodes: stainless steel, Hastelloy, titanium, and tantalum. The selection of which electrode should be based on the properties of the medium and relevant information manuals
(2) Determine whether to use rubber or PTFE lining based on the temperature of the medium learned (to be determined by the marketer)
Attention: The temperature resistance of rubber should not exceed 80C;
PTFE can withstand a temperature of 150C and can instantly withstand 180C;
Urban sewage can generally be treated with rubber lining and stainless steel electrodes
(3) Based on the learned medium pressure, select the flange specification for the body (to be determined by the marketer)
Attention: The specification of electromagnetic flanges is usually that when the diameter ranges from DN10 to 250, the rated pressure of the flange is ≤ 1.6Mpa;
When the diameter ranges from DN250 to 1000, the rated pressure of the flange is ≤ 1.0Mpa;
When the actual pressure of the medium is higher than the corresponding range of pipe diameter pressure mentioned above, it is considered as an order, but the high pressure shall not exceed 6.4Mpa
(4) Determine the conductivity of the medium
Attention: (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 non-conductive
(3) The conductivity of gases, oils, and the vast majority of organic liquids is much lower than 5uS/cm, making them non-conductive.
3. Understand user requirements
(1) Understand whether it is a combination type on-site display or a split type remote transmission display (provided by the user)
Attention: When displaying for split remote transmission, please be aware of the large distance, which is 100 meters apart
(2) Understand if additional features are needed (provided by the user)
Attention: 1. The electromagnetic flowmeter itself has upper and lower limit flow alarm, frequency and current output functions, and does not require additional ordering
2. The sealing protection level of the electromagnetic flowmeter housing is IP65 and IP68. When choosing the submersible IP68, it is considered as an order
3. When the electromagnetic flowmeter needs to be connected to a computer, an RS-485 communication port needs to be added, which belongs to ordering
4. Selection: After the above steps, the model and specifications of the electromagnetic flowmeter can be determined later.