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Installation and structure of elliptical gear flowmeter

Feb 25, 2017

Flow meter installation

1,  the installation should be thoroughly cleaned before the pipeline, and  in the flowmeter before the installation of filters to prevent debris  into the flow meter. When the liquid to be measured contains gas, an air separator should be installed.

2,  it should be noted that the oval gear shaft of the flowmeter must be  placed in a horizontal position, that is, the dial is perpendicular to  the ground plane. Adjust the flow and start, close the valve should be installed separately at the inlet and outlet of the flowmeter.

3, the flowmeter shell on the arrow pointing should be installed with the pipeline in the same direction of liquid flow.

4,  the continuous flow of the pipeline, the installation of the flow meter  level pipeline should be equipped with bypass valve, in order to  regular cleaning, maintenance. The flowmeter on the vertical pipe should be installed in the bypass pipe to prevent the debris from falling into the meter.

5, the flow meter in the correct installation conditions, in order to  facilitate the reading, according to the need to rotate the counter 180o  or 90o installation requirements

Second, the use of Note:

1. Do not test water flow with water. 2.  When starting or stopping, the opening and closing valves should be  slow to prevent sudden shock and should prevent backflow. 3. When the flowmeter is overhauled, do not remove the rear cover so as to avoid the accuracy change when the reload is applied.

10, error calculation and adjustment

(A) the basic error of the flow meter, by the test flow point of the  measured values were calculated according to the following formula:  (volume method)

E = Vm-V / V x 100%

E-flow meter error (generally refers to the cumulative error) to take two significant figures.

Vm - Flowmeter measured value (ie indication)

V- After correction, the measured value of the flowmeter standard  device (ie, the actual value) is calculated from the basic error. When  Vm> V, the basic error of the flowmeter is "+", indicating that the  flowmeter is running faster.

Vm <V, the basic error of the flowmeter is "-", indicating that the flowmeter is slow.

In order to make the flowmeter error within the basic error limit, often need to be error. That is, by changing the pair of adjustment gears (adjustment teeth)  installed in the counter to change the mechanical transmission ratio, so  that the flow meter to adjust the value.

Error adjustment can not change the flow characteristics of the  flowmeter, so that the characteristic curve is artificially in the new  coordinate system.

In general, the basic error range of the maximum and minimum flow  check points within the specified (or actual) flow range is not greater  than the basic error limit of the specified accuracy, and the basic  error of the flowmeter can be adjusted by error adjustment.

Has been used flow meter, generally with the original adjustment gear  set for error verification, and then according to the specific error  situation and then adjust the error.

Working principle and structure:
The  flowmeter is composed of a metering box and a pair of oval gears in the  metering box. The upper and lower covers form a sealed early moon  cavity (which is not absolutely sealed due to the rotation of the gear)  as a unit of calculation for the displacement. When  the measured liquid into the flowmeter through the pipeline, due to the  pressure generated at the inlet and outlet to promote a pair of gears  continuous rotation, constantly by the early moon-shaped cavity of the  liquid after the delivery to the exit, the number of oval gear and The product of four times the secondary displacement is the total amount of the measured liquid flow