Working Principle and common fault analysis of elliptical gear flowmeter
Elliptical gear flowmeter is a light volumetric flow meter with pointer display, word wheel cumulative counting device and zero return device. With the progress of technology, there are also product types of electronic digital display, and can do the measurement of the signal to 4-
The standard power signal output of 20mA has been widely used in liquid flow control in various industrial fields and is suitable for various types of liquid measurement, such as crude oil, diesel oil, gasoline, etc. It has large measuring range and high precision, it is convenient to use and maintain, and different manufacturing materials can be selected to meet the liquid flow measurement in various fields such as petroleum, chemical industry, medicine, food, metallurgy, electric power, transportation, etc.
It is widely used in trade settlement of industrial raw materials.
Elliptical gear flowmeter has a series of preparatory work to be done before it is put into use. Specifically, the following points must be paid attention to and implemented by users: when the instrument is in use, the meter should be filled with liquid.
Gas should not be mixed in the liquid to be measured, otherwise the mixed volume of gas and liquid should be measured to make the measurement inaccurate. When gas is mixed in the liquid, a gas separator must be installed upstream of the instrument.
The flow rate in the pipeline should not increase or decrease sharply, and phenomena such as pipeline vibration, hydraulic impact and sharp pressure fluctuation should be avoided, otherwise the normal operation of the instrument will be affected.
Because when measuring high viscosity liquid, the liquid is generally heated to reduce the viscosity, and then circulated in the pipeline (With insulation jacket type flowmeter).
When the instrument is disabled, the liquid filled in the instrument becomes sticky due to cooling. If it is to be activated again, it must be heated outside the surface by steam or other methods to reduce the viscosity of the liquid, it can only be used after the viscosity of the liquid in the instrument is reduced.
Otherwise, the mucus will bite the drive parts, causing the instrument to be damaged.
The temperature of the liquid to be measured should not be higher than the specified value, otherwise, the instrument cannot work normally, or even get stuck, and the counter part is easy to be damaged at high temperature.
Changes in liquid temperature can also cause additional errors in viscosity effects.
When the flow rate exceeds the specified large flow rate, the wear of elliptical gear flowmeter increases with the increase of rotating speed and the pressure loss increases sharply, so it should be avoided.
Lower than the small flow, although it can still be measured, but the error increases.
The starting flow rate of the flowmeter is about 2% of the large flow rate, and the normal working flow rate is preferably 70% of the large flow rate-80%.
Before the installation of the instrument, the pipeline must be thoroughly cleaned. In the whole pipeline system, if there is no strict filter device, a filter should be installed in front of the instrument to prevent impurities from entering the meter.
The instrument shall be installed at the outlet end of the pump, and the flow regulating valve shall be installed downstream of the instrument.
When in use, open the upstream stop valve first, and then slowly open the downstream flow regulating valve or stop valve. It is strictly forbidden to open or close suddenly.
When each instrument leaves the factory, it is calibrated with No. 0 diesel oil at room temperature. At normal temperature, the viscosity of the oil is about 3mpa. S.
If the viscosity of the liquid used by the user differs greatly from this, the gear ratio or flow coefficient shall be adjusted.