WRM Gas Roots Flowmeter with Mechanical Counter

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 Overview

WR series gas Roots flowmeter is a kind of positive displacement measuring instrument with high precision, strong reliability and wide range, which is mainly used for accurate measurement of gas flow in closed pipelines. The flowmeter can automatically track and compensate the pressure and temperature of the measured gas, and directly display the total volume of the gas under the standard state. It can be used to measure natural gas, city gas, propane, air, nitrogen, carbon dioxide, industrial inert gas and other non-corrosive gases. Widely used in catering, hotels and other industries of gas commercial settlement, transmission and distribution network gas, gas pressure regulation, industrial and civil boiler gas metering.

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 Characteristics

1. Wide flow range (>100:1), the starting flow rate is low, the pressure loss is small, suitable for the occasion of large flow load change.

2. High measurement accuracy, strong reliability, not affected by pressure and flow changes.

3. High precision machining and repeated positioning technology, so that the parts have good versatility and interchangeability, so that the flowmeter has good repeatability, long working life.

4. The flowmeter does not require a straight pipe section and can be installed in a narrow space.

5. High precision digital temperature sensor and digital pressure sensor, and the digital pressure sensor with temperature compensation correction function, high pressure detection accuracy, good long-term stability, small temperature drift.

6. It can automatically detect the temperature and pressure value of the medium, and modify the temperature, pressure and compression factor, and convert the volume flow and total volume flow under the working condition to the standard state.

7. Using advanced micro-power high technology, low power consumption, long-term power supply with internal battery.

8. Using large capacity data memory, with data tamper-proof function, automatically record key data modification and historical data.

9. With real-time data storage function to prevent data loss during battery replacement or power failure, internal parameters can be permanently saved in case of power failure.

10. It can be embedded with wireless modules such as 4G or NB, and can be composed of various forms of wireless meter reading system, which is powered by the built-in battery to achieve wireless transmission of limited times (once a day), no external power supply, easy to use. Or an external power supply to achieve unlimited data transmission.

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 Operating Principle

Gas Roots flowmeter is a kind of high precision volumetric flow measuring instrument. It is mainly composed of a fixed metering chamber between the housing, two Roots wheels and the cover plate. When the gas enters the flowmeter, the pressure difference between the inlet and outlet is generated (P_in>P_out), acting on the Roots wheel, through two high precision machining synchronous gears (linked to the Roots wheel) drive the Roots wheel always maintain the correct relative position rotation. The constant gap between the Roots wheel, between the Roots wheel and the housing, and between the Roots wheel and the cover plate is maintained to realize continuous contactless rotation. For each revolution of the Roots wheel, four times the gas of the metering chamber is discharged (a rotating volume), and the number of revolutions of the Roots wheel is proportional to the volume of gas passing through the flowmeter.

• Drive the mechanical counter through the mechanical structure.

• According to the principle of electromagnetic induction, the magnetic sensor is used to induce a pulse signal proportional to the volume flow rate of the fluid from the synchronous rotation of the signal plate. The signal is sent to the volume correction instrument, and the temperature, pressure and other signals are processed together, and are separately displayed on the display screen.

• The working principle of its measurement process is shown in FIG.1 (only a quarter period is represented in the figure).The structure of  Roots flowmeter is shown in FIG.2.

FIG.1  Working principle diagram

FIG.2  Structure diagram of gas Roots flowmeter

| Design Advantages

• The instrument core component is the whole extraction type, easy to install, easy to maintain and clean. It can realize online maintenance without disassembling the instrument.

FIG.3  Instrument core component diagram

• Single cavity refueling design, the instrument body is shorter, the strength of the instrument body is stronger, the installation stress is not sensitive, the installation space is saved, and the installation can be mounted against the wall. The oil injection port and oil window are on the front end face, and are used for vertical and horizontal installation. Easy refueling operation and observation.

FIG.4  Single-side end-face refueling structure diagram

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 Technical Performance Index

• Accuracy level:

1. The accuracy of the flowmeter is level 1.0 and level 1.5 within its specified flow range and  under operating conditions:

   Level  1.0: 0.2Q_max～Q_max: ±1.0%; Q_min～0.2Q_max: ±2.0%

   Level  1.5: 0.2Q_max～Q_max: ±1.5%; Q_min～0.2Q_max: ±3.0%

2. Temperature indication error: ≤±0.5℃

3. Pressure indication error: ≤±0.2%

• Mechanical performance index:

Table 1  Basic parameter

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 Overall Dimensions and Installation

The dimensions of the flowmeter are shown in the figure below. The dimensions are listed in Table 2. The flowmeter adopts a flange connection mode, and the size of the flowmeter complies with GB/T9119-2010 standard.

FIG.5  External dimensions

Table 2  Dimensions data

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 Ordering Instructions

• Before ordering products, please read this manual carefully, should be based on the pipeline nominal diameter, nominal pressure, flow range, medium maximum pressure, medium temperature range and environmental conditions to select the appropriate specifications.

• The front end of the flowmeter is strongly recommended to install a filter, the flowmeter and filter can be ordered.

• Please fill in the code form correctly when ordering. WR series gas Roots flowmeter code table is as follows:

FIG.6  Ordering information