(1) rotor type. It represents a variety of elliptical gear type, waist wheel, egg wheels, screw type. The rotor type is the main variety of volumetric flow meters, and there are many forms of form, which can be used for the measurement of various media of liquids and gases. The flowmeter diameter DN6 ~ 500mm, flow (0.2 * 10-3 ~ 3000) m3 / h, viscosity 0.3 ~ 2000 MPa.s. Measurement (0.5 ~ 0.2)% R.
1) Elliptical gear flow meter. The flow portion of the elliptical gear flow is mainly composed of two mutually engaged elliptical gears and their housing (metering chambers). Two elliptical gears have a special shape that is rolled with each other. The P1 and P2 represent the inlet pressure and outlet pressure, obviously P1> P2, and the lower gear is rotated in the case of the pressure difference in both sides, which is a main wheel; the upper gear is equal to the pressure of both sides, and does not generate rotational moments. It is a driven wheel, which is driven by the lower gear, and rotates clockwise.
The measurement of the measurement mass extension in the elliptical gear is 4 times that of the half month, and the volumetric flow QV of the elliptic gear flow is
QV = 4Nυ = 2πn (R2-AB) δ
In the formula, n is the number of times the rotation of the gear; A, B is the long half shaft of the elliptical gear, short half shaft: δ is the thickness of the elliptical gear; the volume of the half-moon portion.
Thus, under the condition of the elliptical gear flow meter, the flow rate of the medium is detected as long as the rotation speed n of the elliptical gear is measured.
The display of the elliptical gear flow meter flow signal (i.e., the rotational speed n of the elliptic gear), there is two types of display and remote transmission. On the spot, the rotation of the gear is displayed directly through a series of deceleration and adjusting the speed ratio mechanism, and is directly connected to the indicator of the instrument panel, and the total amount of display is performed through the mechanical counter. The remote transmission is mainly rotated by a gear after deceleration, so that the contacts of the spring relay are synchronously closing or disconnected in synchronization with the same rotation frequency as * magnet, thereby emitting an electrical pulse to another display meter.
The characteristics of the elliptic gear flow meter: 1 flow measurement is independent of the flow state of the fluid, because the elliptical gear flow meter is measured by pressing the head of the test medium to rotate the elliptical gear. 2 The harma of the viscosity, the smaller the leakage from the gear and the metering space gap. 3 Elliptical gear flow meter is not suitable for fluid containing solid particles (solid particles will die, so that traffic cannot be measured). If a gas is mixed in a liquid medium, a measurement error is also caused.
2) Waistone volume flow meter. Waist wheel volumetric flowmeter is also known as Roots type volume flow meter. The working principle and working process of this flowmeter is basically the same as the elliptical gear type, which is also in progress, and the outlet fluid pressure difference produces motion, and each rotation is discharged from four "metering space" fluid volume. The difference is that there is no teeth on the waist wheel, which is not directly engaged, but is driven by the drive gear set mounted outside the housing.
The waist wheel is composed of a pair of waist and housing. The two waves are rotors that are interacting with the conjugate curve, that is, the Roots wheel, the drive gear is attached to the waist wheel, and the measured flow is driven Rotate, the rotor is driven by the drive gear, the waist wheel, the meter case housing is generally made of cast iron, cast steel or stainless steel, and the temperature is selected according to fluid corrosion and its working pressure. The metering room is also made separately, separated from the instrument housing so that the metering room does not withstand the static pressure, no static pressure causes an additional error.
(2) Scraper type. The fluid pushes the blade and the rotor rotation, and the blade is radially retreated along a particular track. When the distance between the two opposite squeegee end faces is a certain value, when the scraper is continuously rotated, two adjacent scrapers, rotor, housing lumen, and upper and lower cover plates form a fixed metering chamber, rotor One turn, discharges four (or six) metering chamber volume, namely the cycle volume. The non-contact of the blade and the cavity can be divided into two types of elastic squeegee and rigid squeegee. The front end of the elastic squeegee is elastic contact with the cavity wall. It is suitable for measuring a liquid containing impurities such as sand; the front end of the rigid squeegee is maintained with the cavity wall There is a fixed minor gap for cleaning or having a liquid having fine powder impurities. The structure of the rigid squeegee can be divided into concave type (British Avery Hardoll) and a cam type (Mei SMITH).
Scraping type working vibration and noise can be used to use liquids with fine particulate impurities, especially the elastic squeegee, suitable for measuring a dirty flow containing a particle impurity, used in well port metering of the oil field. Measuring the gas of the Gas, CON-Stant Volume Meter, CVM, has the advantage of running non-pulsating and noise compared to the gas waist flowmeter.
(3) Rotating the piston. Insert the annular piston into the housing of the two-layer cylindrical cylinders, constitutes the form of rotating with the flow cyclic piston of the liquid in the housing, and the flow rate diameter DN 20 to 100 mm, the measurement is 0.5% R. Can be used for the measurement of oil and food.
(4) Rehabilitation. The piston is pushed under fluid, reciprocating in the cylinder, measuring volumetric flow, typically the gas station, the gas station is such type, with a flow rate of 60 l / min, and the measurement is ± (0.15 ~ 0.3)% R.
(5) Disc type. Also known as the Nutating Flowmeter, a disk with a central ball in the metering chamber and the nutation, the entry and discharge fluid, which is poor than other PDF, and the viscosity is more affected. Big. my country has produced production to measure petroleum products, and there is less application. More useful in North America for water meters and industrial water meters.
(6) Turker. Also known as wet gas meter is used to measure the total amount of gas. There is about one half sealing liquid (water or oil) in the flowmeter housing, and half of the drum is immersed in the sealing liquid, and the gas flows into the formation, and its sealing is no leakage. The range width is 20: 1, the performance is stable, and the higher level can be obtained under careful operation, ± (0.2 ~ 0.5)% R, mostly in laboratory, usual value value transfer table or standard table.
(7) Membrane. Also known as dry gases, the free telescopic portion (metering volume) A, B, C, D, and a sliding valve associated with it in the gas table by the dish type diaphragm. Since the film's telescopic and split valves are continuously sent from the inlet to the outlet, the number of cycles of this action can be measured. The membrane gas flow meter is widely used in household gas (gas) consumption measurements, so it is used to referred to as a household gas table. The series of large-scale instruments are used in the factory and industrial production process. Flow range 1.6 * 10-5 ~ 1000m3 / h, range wide to 100: 1, medium measurement, sloppy ± (2 ~ 3)% R.
Editor in charge: WV
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