The accuracy of water meter （1）

The accuracy of water meter

There are many types of water meters. In principle, the water meters used for residential use are generally rotary-wing water meters, which are one of the speed-type water meters. According to the type of counter indication, there are pointer type and word wheel type.The counter of some water meters is immersed in water, which is called a wet water meter; the counter of some water meters is not immersed in water, and the dial is dry, which is called a dry water meter in the industry. Residential water meters are mostly wet water meters.

The caliber of residential water meters is generally 15mm to 40mm, with 15mm caliber being the most common. The accuracy of the water meter is 2% in the common measurement range and 5% in the smaller flow. The levels of water meters are divided into A, B and C, and their accuracy is the same, but the measurement range is different. The measurement range of A is narrower, and the measurement range of C is larger than that of both A and B. For example, the measurement range of a 15mm caliber A-class water meter is from 45 liters/hour to 1500 liters/hour, while the measurement range of a C-class water meter is from 15 liters/hour to 1500 liters/hour. For a Class C water meter, when the flow rate is lower than 15 liters/hour but higher than 4 liters/hour, the character wheel or pointer should be able to rotate, but there is no requirement for the accuracy of the water meter at this time，just proceed is okay.

Experts pointed out that there are many factors that affect the accuracy of water meters. People often pay considerable attention to the accuracy of the water meter product itself, but often ignore other links. Installation does not meet the requirements, improper use, air in the water, poor water quality, use beyond the verification period, etc., will affect the accuracy of the water meter.

Experts pointed out that there are many factors that affect the accuracy of water meters. People often pay considerable attention to the accuracy of the water meter product itself, but often ignore other links. Installation does not meet the requirements, improper use, air in the water, poor water quality, use beyond the verification period, etc., will affect the accuracy of the water meter

Improper installation has a great impact on the measurement accuracy. According to the regulations, the water meter should be installed and used horizontally. If the water meter is installed obliquely or even vertically, it will not only affect the measurement accuracy of the water meter, but also shorten the service life of the water meter. Some data show that for a water meter with a diameter of 15mm, under the condition of 1000 liters/hour, if the horizontal inclination is 45 degrees, the error will increase by 1%, and if the longitudinal inclination is 45 degrees, the error will increase by 3% at most; Under the circumstance, if the horizontal inclination is 45 degrees, the error will increase by more than 5%, and if the vertical inclination is 45 degrees, the maximum error will increase by 20% or more.

In addition, the water meter also has requirements on the length of the upstream straight pipe section and the downstream straight pipe section length. Taking a water meter with a diameter of 15mm as an example, there should be at least a 150mm straight pipe section upstream and a 75mm straight pipe section downstream, otherwise, it will affect the Metering accuracy.

To be continued...