A water meter is a measuring instrument used by water supply enterprises to settle trade with users, and is the main basis for water supply enterprises to collect water fees from users. Deviation in water meter measurement will have a negative impact on water supply companies in increasing water fee recovery rates and reducing production and sales differentials, and can easily lead to disputes between water supply companies and users.The reasons and solutions for errors in water meters are as follows:

1、 Reasons for measurement deviation

01Quality issues with the water meter itself

(1) The water meter is not produced by a legitimate manufacturer, and the accessories of the water meter are not qualified;

(2) Not calibrated at the factory, or not corrected if the calibration is not qualified, or if the calibration device itself is also unqualified;

(3) The accuracy of old-fashioned watches is insufficient. This inevitably leads to deviations in water meter measurement.

02、The problem of overdue water meters：The water meter should be regularly calibrated and replaced upon expiration.

(1) When the water meter is in use, the impeller rotates frequently and rubs against the upper side, which is an important component supporting the rotation of the impeller inside the water meter, causing wear and tear. Firstly, this increases the frictional resistance between the impeller and the water meter, resulting in a negative measurement; Secondly, the position of the impeller decreases, the distance between the impeller and the impeller box increases, the resistance decreases, and the water meter measurement is biased;

(2) When using a water meter, due to the uneven distribution of water inside the meter, the flow rate through the inclined inlet side of the impeller box is greater than the inlet flow rate on the outlet side of the water meter,One is that it leads to frequent friction between the middle part and the impeller shaft sleeveThe impeller tilts towards the outlet side of the water meter, causing the edge of the impeller to become close to the inner wall of the impeller box, increasing resistance. At the same time, the diameter of the impeller is reduced, reducing the impact torque of water on the impeller and resulting in a negative measurement of the water meter;Secondly, the upper central axis of the impeller and the upper clamp sleeve are inclined towards the water meter outletThe upper clamp shaft sleeve is frequently rubbed and ground into an elliptical shape, causing the impeller axis to shift and wear between the impeller shaft and the gearbox, resulting in increased resistance and negative water meter readings.

03、The issue of water meter selection

When selecting the diameter of the water meter,Not selecting the appropriate water meter model based on the changing patterns of user water usage and without hydraulic calculationsAs a result, some models of water meters installed have a larger diameter, causing the water flow rate to be lower than the small flow rate specified by the water meter during low water usage periods, resulting in a negative measurement of the water meter; Some water meter models have a smaller diameter, and during most of the water usage, the water flow rate exceeds the rated flow rate specified by the water meter. Long term operation can cause mechanical wear and tear on the water meter components, resulting in inaccurate measurement.

04、Design and installation issues

(1) According to the verification regulations, the water meter must be installed on the straight line of the pipeline. The length of the straight pipe section on the inlet side of the water meter shall not be less than 10 times the diameter of the water meter, and the length of the straight pipe on the outlet side shall not be less than 5 times the diameter of the water meter. Otherwise, it is easy to generate rapids and eddies, causing measurement deviations in water meters.

(2) The installation of the water meter is tilted, causing an increase in resistance between the impeller shaft and the upper clamp bushing, impeller bushing, gear shaft and clamp, and sometimes accompanied by gear meshing, resulting in a negative measurement of the water meter.

(3) The water meter is installed on a vibrating belt. If the water meter is installed in places with strong vibrations such as sidewalks and motor vehicle lanes, it may be damaged or the water meter gears may become loose or misaligned, thereby affecting the measurement accuracy.

05、Water quality issues in the pipeline network

(1) Causing the water meter to run too fast:If the quality of the pipe is poor and there are debris, debris left during installation, or problems with the water quality itself, when debris blocks part of the inlet, when the flow rate is constant, the water flow rate through the water meter increases and the water meter measurement is biased.

(2) Causing slow water meter operation:When debris passes through the filter screen of the water meter, it is easy to cause the impeller of the water meter to be tangled and squeezed, resulting in separation or jamming of the impeller and gear, and the water meter measurement to be negative.

06、The influence of water and air

After pipeline maintenance, there is often air mixed in. On the one hand, most of the air remaining in the water meter is trapped in the upper part. When it is discharged outside the water meter with water, the capacity indicated by the water meter pointer is often greater than the actual drainage volume; in additionThe residual air can also weaken the function of the water meter adjusterThe rebound effect of the regulator on water is significantly weakened, and the water meter measurement is biased.

07、The problem with the valve in front of the table

When using the water meter, the valve in front of the meter is not fully opened, and sometimes the flow rate of the water meter is adjusted using the valve in front of the meter, resulting in a deviation in the reading measurement of the water meter.

IISolution measures

01、Regarding the existing water meter

Establish records and cards, strengthen inspections, conduct periodic checks, and replace upon expiration.

02、For newly purchased water meters

Use water meters from legitimate manufacturers, and ensure that both certificates (quality certificate and water meter calibration certificate) are complete. Eliminate * meters and explore the use of new types of meters with accurate measurement.

03、Requirements for verification

Strengthen the daily maintenance of calibration devices and provide technical training and responsibility education to water meter calibration personnel.

04、Design Selection

(1) Accurately estimate the water volume to avoid a mismatch between the diameter of the water meter and the water flow rate,Choose a water meter with a rated flow rate similar to the water consumption；

(2) For users and residents with significant changes in water usage, they should chooseHorizontal rotor water meter；

(3) For users with large water consumption and little change in water usage, they should chooseHorizontal spiral wing water meter with low head loss and high water carrying capacityIts high flow performance is superior to rotor type water meters;

(4) For places with significant changes in water usage, generallyCompound water meter；

(5) For areas where the water supply network is yet to be determined, if the actual flow inside the pipeline is greater than 30% of the nominal flow of the horizontal spiral wing water meter, then it can be selectedHorizontal wing water meter；

(6) For places that are prone to flooding and have a lot of dust, dry water meters should not be usedWet water meter.

05、When designing and installing

(1) Water meterMust be installed on the straight section of the pipelineThe length of the straight pipe section on the inlet side of the water meter shall not be less than 10 times the diameter of the water meter, and the length of the straight pipe section on the outlet side shall not be less than 5 times the diameter of the water meter;

(2) Strive to improve the water meterHorizontal or vertical installation；

(3) Water meters should not be installed in areas with strong vibration or water hammer, and should be installed as much as possibleAvoid designing and installing water meters in soft areas；

(4) Can beInstall a small "water hammer" eliminator on the pipelineTo avoid "water hammer" caused by the opening and closing of valves or water;

(5) After pipeline installation, the water meter should be installed firstRinse the debris inside the pipeline clean；

(6) After installing the water meter or repairing the pipeline, it should*Open the valve in front of the meterEvacuate the air inside the pipeline through the exhaust valve;

(7) Should try as much as possibleChoose smooth inner wall, inner wall coating and hydraulicPipes with good conditionsReduce the phenomenon of scaling on the inner wall.