Experts teach you how to install tap water meter

A water meter is a kind of flow meter, which is a measuring instrument that correctly measures and reasonably allocates water resources. Wang Dongwei, director of the traffic office of the China Academy of Metrology, and associate researcher, pointed out in an interview with reporters recently that in order to ensure the accuracy of water meters, they have implemented strong inspections and enhanced supervision and management of water meter products on the market, and they have also responded to the installation and use of water meters. Attention is given to such links.

In recent years, China's tap water business and water meter production have developed rapidly. According to incomplete statistics, there are more than 100 water meter production plants in the country, and IC card water meters, remote transmission water meters, numerical control water meters, and heat meters for hot water heat metering have been introduced in the decoration market. According to experts, there are many kinds of water meters. In principle, the water meters used for civilian use are generally rotor-type water meters, which are one of the speed-type water meters. According to the counter indication type, there are pointer type and word wheel type. Some meter counters are immersed in water and are called wet-type water meters; some water meter counters are not submerged in water and the dial is dry. The industry calls it a dry-type water meter. The civilian water meters are mostly wet water meters.

The caliber of civilian water meters is generally 15mm to 40mm, with 15mm caliber being more. The water meter has an accuracy of 2% in the commonly used measurement range and an accuracy of 5% at the smaller flow rate. The water level is divided into Level A, Level B, and Level C. Their accuracy is the same, but the measurement range is not the same. The measurement range of Level A is narrow, and the measurement range of Level C is higher than that of Level A and Level B. All wide. For example, the measurement range of a 15MM A-class water meter is from 45L/hour to 1500L/hour, while the measurement range of a C-class water meter is from 15L/hour to 1500L/hour. For Class C water meters, the flow rate Below 15 litres/hour but above 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, as long as the word “walks”.

Experts pointed out that there are many factors that affect the accuracy of water meters. People often pay considerable attention to the accuracy of water meter products themselves, and often overlook other aspects. Installation does not meet the requirements, improper use, water in the water, poor water quality, use over the verification period, etc., will affect the accuracy of the water meter.

The non-standard installation has a great influence on the measurement accuracy. According to the provisions of the water meter should be installed and used horizontally. If the water meter is inclined to install or even install vertically, it will not only affect the metering accuracy of the water meter, but also shorten the service life of the meter. Data shows that for a water gauge with a caliber of 15 mm, if the lateral tilt is 45 degrees, the error will increase by 1%. If the vertical tilt is 45 degrees, the error will increase by 3% at the maximum; at 180 liters/hour In this case, if the lateral tilt is 45 degrees, the error will increase by more than 5%. If the vertical tilt is 45 degrees, the error will increase by 20% or more.

In addition, when the water meter is installed, there are also requirements for the length of the upstream straight pipe and the length of the downstream straight pipe. Taking a water meter with a caliber of 15 mm as an example, there should be at least 150 mm of straight pipe upstream, and at least 75 mm of straight pipe downstream, otherwise it will affect Measurement accuracy.

Water in the water can also affect the metering accuracy. Air mixed with water often stagnates in the upper regulator of the water meter and other higher spaces, directly causing the water meter to count more. Not only that, these air hidden inside the water meter will also weaken the counter-attack effect of the regulator on water, and further increase the amount of water indicated by the water meter.

In addition, the accuracy of water metering is guaranteed and there are requirements for water sources. The ideal source of water should be clean. If there is more debris in the water, when the water flows through the water meter, the dirt will adhere to the impeller of the water meter or the wall surface of the water meter, causing the impeller to rotate inflexibly or the flow rate in the metering area to become faster. Inaccurate, and damage the water meter. Sometimes, the water source is clean, but the inner wall of the water pipeline is dirty, and eventually it causes a drop in water quality.

For the correct use of water meters, experts recommend that, in addition to the correct installation of water meters, frequent switching of valves should also be avoided. Frequent opening and closing of the valve during use will cause the pressure in the pipeline to change frequently. There is no problem when the valve is opened. However, when the valve is closed, a "water hammer" phenomenon will occur. The faster the valve closes, the more obvious the "water hammer" phenomenon will be. This is because water is an incompressible fluid. The inertial force of the water flow causes the water to exert tremendous pressure on the valve, the pipeline and the water meter in an instant. The lighter one reduces the service life of the valve and the water meter. In severe cases, the valve may be damaged, the pipeline may be broken, or the water meter Core deformation. Even if the valve is not closed quickly each time, frequent switching will reduce the accuracy of metering. Therefore, the correct method of use is to lightly turn off the tap and minimize the number of switches.

Water meter installation and use should grasp "six links":

(1) Ensure that the front and rear of the water meter have long enough straight sections. The installation location of the water meter should not be too close to the wall. This is especially important for horizontal-wing type water meters. There should be no less than 10 times the length of the water meter in front of the table. After the watch, it should be no less than 5 times the length of the straight line of the water meter. If the valve before the water meter is directly connected with the water meter, the influence of the opening of the valve on the error of water indication is extremely obvious. The distance between the water meter housing and the wall surface is lo~30mm.

(2) The installation of the water meter should avoid direct sun rays and the erosion of harmful gases and liquids, and should be well protected against freezing.

(3) The installation environment of the water meter should be tidy, easy to check meter readings and dismantle the water meter, and should be far away from the road where the heavy vehicles pass. Water meters must be removed from the pipeline before installation.

(4) The water meter installation direction, the case arrow direction and the direction of the water flow in the pipe should be the same.

(5) Newly installed pipelines should first remove impurities such as stones, silt, and hemp in the pipeline. Filters should be installed in front of the water meter with poor water quality. Filters should be regularly cleaned.

(6) During the use of the water meter, wear, corrosion, and other wearing parts of the parts must be promptly inspected and regularly checked by the technical supervision department. According to China's water meter verification regulations, the water meter verification period is generally two years.

Note: Install the water meter before and after the pipe section and the center line of the water meter to be concentric, to avoid forced connection. The water meter front and rear pipe section and the water meter are not concentric and forced to connect. The connection port will be subject to a large shear stress. With the increase of time, leakage will occur at the interface, and it is very easy to cause damage to the water meter. Especially in the evening when the water consumption of the pipe network is low and the water pressure is high, breakage may occur. In addition, the connection between the pipe section before and after the water meter and the water meter will also affect the accuracy of the water indication value.

When installing the water meter, you must first adjust the front and rear pipe sections to make them concentric, and then install the water meter so that the center of the water meter and the front and rear pipes are kept on the same center line. Under normal circumstances, when the front of the water meter is adjusted, first hand to twist the two ends of the water meter joints 2 to 3 deduction, the left and right sides must be simultaneously operated, and then check it again, and other water meters in a completely natural state, and then tighten the two ends Union thread.