Principle analysis of various types of flowmeters
(1) Principles of mechanics: Instruments belonging to such principles have differential pressure and rotor type using Bernoulli's theorem; impulse type and movable tube type using momentum theorem; direct mass type using Newton's second law; The target type of the momentum principle; the turbine type using the angular momentum theorem; the vortex type using the principle of fluid oscillation, the vortex type; the pitot tube type using the total static pressure difference; the volumetric type, the enthalpy, the trough type, and the like.
(2) Electrical principle: The instruments used for such principles are electromagnetic, differential capacitive, inductive, strain resistant, etc.
(3) Acoustic principle: Ultrasonic type, acoustic type (shock wave type), etc. are used for flow measurement using the acoustic principle.
(4) Thermal principle: The heat, direct thermal, indirect calorimetry, etc., which measure the flow using the thermal principle.
(5) Optical principle: laser type, photoelectric type, etc. are instruments belonging to such principles.
(6) Originally based on physical principles: nuclear magnetic resonance, nuclear radiation, etc. are instruments of this type.
(7) Other principles: Marking principle (trace principle, NMR principle), related principles, etc.
Corrosion resistance and wear resistance
Stainless steel: 0Crl8Nil2M02Ti is used for industrial water, domestic water, sewage and other weakly corrosive media. It is suitable for petroleum, chemical, steel and other industrial sectors as well as municipal, environmental protection and other fields.
Hastelloy B: has good corrosion resistance to hydrochloric acid at all concentrations below the boiling point, and is also resistant to corrosion by non-chlorinated acids, bases, non-oxidizing salts such as sulfuric acid, phosphoric acid, hydrofluoric acid, and organic acids.
Hastelloy C: resistant to non-oxidizing acids, such as nitric acid, mixed acid, or corrosion of mixed media of chromic acid and sulfuric acid, and also resistant to oxidizing salts such as Fe, ", Cu" or other oxidants, such as Corrosion of hypochlorite solution and seawater above normal temperature
Titanium: It is resistant to seawater, various chlorides and hypochlorites, oxidizing acids (including fuming sulfuric acid), organic acids and alkalis. It is not resistant to the corrosion of relatively pure reducing acids (such as sulfuric acid or hydrochloric acid), but if the acid contains an oxidizing agent (such as nitric acid, Fc++, Cu++), the corrosion is greatly reduced.
钽: Excellent corrosion resistance and glass are very similar. In addition to hydrofluoric acid, fuming sulfuric acid, alkali, it is almost resistant to the corrosion of chemical media (including boiling point of hydrochloric acid, nitric acid and sulfuric acid below 50 ° C). Antimony in alkali; corrosion resistant.
Almost resistant - cut chemical media, but not for aqua regia and ammonium salts.
Stainless steel coated tungsten carbide
For non-corrosive, strong abrasive media.
Note: Due to the wide variety of media, its corrosiveness is affected by complex factors such as temperature, concentration and flow rate, so this table is for reference only. The user should make his own choice according to the actual situation. If necessary, the corrosion resistance test of the material to be selected, such as the coupon test.
Second, the gas turbine flowmeter projection operation steps
1. Open the bypass shut-off valve;
2. Open the flow upstream shutoff valve;
3. Slowly open the downstream shutoff valve of the flowmeter;
4. Slowly close the bypass shutoff valve.
Third, the gas turbine flowmeter stop table operation steps
1. Open the bypass shut-off valve;
2. Turn off the downstream shutoff valve of the flowmeter;
3. Close the flow upstream shutoff valve;
Fourth, gas turbine flowmeter use precautions
1. The newly installed or repaired pipeline must be purged. When purging the metering line, the flow meter must be removed and the corresponding short section replaced the flow meter for purging.
2. When the gas turbine flowmeter pipeline is put into production, it should be slowly boosted and gradually increase the flow rate. When the production is stopped, it should be slowly depressurized.
3. Check the sound of the gas turbine flowmeter or the vibration of the casing during operation to determine whether the turbine blades and bearings are working properly. At low flow rates, attention should be paid to the change in sound, and the vibration of the casing is observed at high flow rates.