Oval gear flow meter

working principle

The measuring part of the oval gear flow meter is mainly composed of two intermeshing elliptic gears and its outer casing (metering chamber). The measured medium volume per revolution of the elliptical gear is 4 times of the half moon volume, and then the elliptical gear is passed through. The flow rate Q of the meteor meter is:

Q=4nÏ…0

In the formula:

N—rotation frequency of the elliptical gear (r/s);

Ï… 0 - The volume of the half moon (Bay).

In this way, the flow rate of the medium to be measured can be known by measuring the rotation speed n of the elliptic gear under the condition that the half-moon volume 椭圆0 of the oval gear flow meter is constant. The display of the flow signal of the oval gear flowmeter (ie, the rotation speed of the oval gear n) can be displayed in two ways: local display and remote display. After the gears have been rotated through a series of deceleration and speed ratio adjustment mechanisms, they are directly connected to the indicating pin on the instrument panel and displayed on the mechanical counter. The remote transmission display mainly drives the rotation of the permanent magnet through the decelerated gear, so that the contact of the spring relay is synchronously closed or opened at the same rotation frequency as the permanent magnet, so that one electric pulse is transmitted far away to another display instrument.

Features

The flow measurement is independent of the flow state of the fluid, because the oval gear flow meter is metered by relying on the indenter of the measured medium to drive the rotation of the oval gear. The larger the viscosity of the medium, the smaller the leakage of leakage from the gear and the metering space gap, so the larger the sticky skin of the verification medium and the smaller the leakage error, the better the measurement is. Oval gear flowmeters have a high measurement accuracy and are suitable for measuring high-viscosity media flows, but are not suitable for fluids containing solid particles (solid particles will jam the gears, making it impossible to measure flow). If the measured liquid medium contains gas, it will also cause measurement error.

Oval gear flowmeters should clean the pipeline before installation. If the liquid contains solid particles, a filter must be installed upstream of the pipeline; if the gas is contained, the exhaust device should be installed. Oval gear flowmeters do not have certain requirements for front and rear straight sections. It can be installed horizontally or vertically. When installing, make the ellipse gear axis of the flowmeter parallel to the ground.

use

In accordance with the requirements of the correct installation of the elliptical gear flow meter, when used to ensure adequate accuracy, the cumulative accuracy of the cumulative accuracy of up to 0.5, is a more accurate flow metering instrument. However, if the flow rate of the measured medium is too small, the instrument's leakage error will be prominent and sufficient measurement accuracy cannot be guaranteed. Therefore, the elliptic gear flowmeters of different model specifications have a permissible value for the minimum use flow rate. Only when the actual measured flow rate is greater than the lower limit flow allowable value, the measurement accuracy can be guaranteed.

Second, the use of oval gear flowmeter should pay attention to the measured medium temperature can not be too high, otherwise it will not only increase the measurement error, but also make the gear stuck. For this reason, oval gear flowmeters are used within the specified operating temperature range of the instrument. After long-term use of the oval gear flowmeter, the internal gears will be corroded and worn, which will affect the measurement accuracy. Therefore, always pay attention to observation and remove it regularly for inspection. If conditions permit, it is better to perform calibration on a regular basis.