Hello everyone, today I’m here to talk about the installation requirements and precautions for oval gear flowmeters. I hope this information can be helpful to you when installing gear flowmeters in the future.
Composition of elliptical gear flowmeter .
An elliptical gear flowmeter consists of a metering tank, a pair of elliptical gears housed within the metering tank, and upper and lower cover plates, forming a sealed crescent-shaped cavity (not absolutely sealed due to gear rotation) as the unit for calculating the primary displacement. When the measured liquid enters the flowmeter through a pipeline, the pressure difference generated at the inlet and outlet drives the pair of gears to rotate continuously, conveying the liquid, which has been metered through the crescent-shaped cavity, to the outlet. The product of the number of revolutions of the elliptical gears and four times the displacement per revolution is the total flow rate of the measured liquid. So, what should be considered when installing a gear flowmeter?What are the installation requirements for gear flowmeters
What are the installation requirements for elliptical gear flowmeters
1. The direction of instrument installation should ensure that the arrow direction indicated on the instrument housing aligns with the direction of liquid flow*. The installation location should be chosen to facilitate reading.
2. The instrument should be installed in a room with normal temperature as much as possible, rather than in a room with harmful gases and strong heat radiation, to prevent damage to the counter part of the instrument.
3. The elliptical gear shaft in the instrument should be installed in a horizontal position as much as possible, and the dial should be installed in a vertical position (with the “0” scale mark on top), in order to reduce the friction between the elliptical gear and the housing and minimize the wear of parts. Due to different installation positions, the counter (meter head) can be rotated by 90amp;deg; or 180amp;deg; for ease of reading;.
4. Before installing the instrument, the pipeline must be thoroughly cleaned. In the entire pipeline system, if there is no strict filtering device, a filter should be installed before the instrument to prevent impurities from entering the instrument.
5. The instrument should be installed at the outlet end of the pump, and the flow regulating valve should be installed downstream of the instrument. When using, first open the upstream stop valve, and then slowly open the downstream flow regulating valve or stop valve. Sudden opening or closing is strictly prohibited.
6. When using the instrument, the meter should be filled with liquid. The measured liquid should not contain any gas, otherwise the measured volume will be the mixture of gas and liquid, leading to inaccurate measurement. If the liquid contains gas, a gas separator must be installed upstream of the instrument.
7. The flow rate in the pipeline should not increase or decrease rapidly, and phenomena such as pipeline vibration, hydraulic shock, and sharp pressure fluctuations should be avoided, otherwise it will affect the normal operation of the instruments.
8. When the flow rate exceeds the specified maximum flow rate, the elliptical gear experiences increased wear as the rotational speed increases, and the pressure loss rises sharply, making it unsuitable for use. If the flow rate is below the minimum flow rate, although metering is still possible, the error increases. The starting flow rate of the flowmeter is approximately 2% of the maximum flow rate, and the normal operating flow rate is preferably 70%-80% of the maximum flow rate.
9. When measuring high-viscosity liquids, the liquid is generally heated to reduce its viscosity before circulating through the pipeline. After the instrument is deactivated, the liquid filled inside the instrument becomes viscous due to cooling. If it is to be reactivated, steam or other methods must be used to heat the exterior of the instrument body, thereby reducing the viscosity of the liquid. The instrument can only be used after the viscosity of the liquid inside the instrument is reduced. Otherwise, the viscous liquid will seize the transmission parts, causing damage to the instrument.
10. The temperature of the measured liquid should not exceed the specified value; otherwise, the instrument may malfunction or even become stuck. Changes in liquid temperature can also introduce additional errors due to viscosity effects. Additionally, an increase in temperature leads to an increase in the volume of the crescent-shaped space, causing the instrument to “run slowly”. When the measuring chamber is made of cast iron and the elliptical gear is made of cast aluminum, the additional error is +0.14% per 100℃
11. Each instrument is calibrated with No. 7 machine oil at room temperature before leaving the factory. At room temperature, the oil viscosity is approximately 10 mPa·s. If the viscosity of the liquid used by the user differs significantly from this value, the double-layer gear can be replaced.
Okay, that concludes our discussion on the installation requirements and precautions for the oval gear flowmeter today. If you have any further questions, please feel free to contact us. We will respond to you as soon as possible after receiving them.
