Oval gear flowmeters (also known as displacement flowmeters, gear flowmeters) are a type of volumetric flowmeter, which is a type of high accuracy in flow meters. It uses a mechanical measuring element to continuously divide the fluid into a single known volume part, and measures the total volume of the flow according to the number of times the metering chamber fills and discharges the fluid in the volume one by one. Oval gear flowmeters can be made of different materials (cast iron, cast steel, 304 stainless steel, 316 stainless steel), and are suitable for flow measurement in industrial sectors such as chemical, petroleum, pharmaceutical, power, metallurgy, and food.
The flow meter consists of a measuring box and a pair of elliptical gears installed in the measuring box, and an upper and lower cover plate forming a sealed lunar-shaped cavity (not completely sealed due to the rotation of the gear) as a unit for calculating the displacement. When the measured liquid enters the flowmeter through the pipeline, a pair of gears are continuously rotated due to the pressure difference generated at the inlet and the outlet, and the liquid measured by the initial moon-shaped cavity is continuously delivered to the outlet. The product of four times the secondary displacement is the total amount of liquid measured (see the figure for the principle). The flow meter is mainly composed of a housing, a counter, an oval gear, and a coupling (a magnetic coupling and an axial coupling).
As a kind of precision flowmeter, elliptical gear flowmeter must be installed very carefully. To ensure these installation requirements, it is indispensable!
1. Before the installation of the oval gear flowmeter, the pipeline needs to be flushed. During the flushing, a straight pipe section (replaces the position of the oval gear flowmeter) is used to prevent welding slag and debris from entering the oval gear flowmeter.
2. Before installing the elliptical gear flowmeter, use a bamboo stick to push the gear several times from the outlet. If it is found to be stationary, you can soak it with gasoline (to avoid memory deposits after factory calibration)
3. Under the condition of correct installation of oval gear flowmeter, if it is not easy to read the reading, you can turn the counter to 180 ° or 90 °.
4. A matching filter should be installed in front of the flowmeter, and the outlet of the matching filter is immediately adjacent to the inlet of the flowmeter. The arrows on the two bodies point in the same direction as the flow of the liquid.
5. When the liquid to be measured contains gas, a degassing filter should be installed in front of the flowmeter.
6. Whether the pipeline is installed vertically or horizontally, the oval gear in the flow meter should be installed in a horizontal position (that is, the dial should be vertical to the ground).
7. Under the condition of correct installation of the flowmeter, if it is not easy to read the reading, you can turn the counter to 180 degrees or 90 degrees.
8. Before installing the new flowmeter, push the oval gear with a bamboo stick from the outlet several times before installation. If you find that it is not moving, you can soak it with diesel oil (to avoid deposits in the memory after factory inspection).
9. The flow control valve should be installed at the inlet of the flowmeter, and the opening and closing valve should be installed at the outlet. When using the opening and closing valve, start it slowly, and do not open it suddenly to prevent water hammer.
10. Before installing the flowmeter on the new pipeline, the pipeline needs to be flushed. During the flushing, a straight pipe section (instead of the flowmeter position) is used to prevent welding slag and debris from entering the flowmeter.
11. In the continuous use department, the bypass gear meter needs to be bypassed.
12. The flow rate of the flow meter in use must not exceed the technical requirements. The flow meter works at a high flow rate of 70-80%.
13. If the liquid to be tested is chemically corrosive, a stainless steel flowmeter should be used. The oval gear flowmeter can be installed and used correctly to ensure the measurement accuracy of the product.
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