Water meter: It is a measuring instrument used to record the amount of water flowing through tap water pipes. It is also called a measuring instrument.
A brief history of the development of water meters
The development of water meters has a history of nearly 200 years since the British engineer Crouse invented the balanced tank water meter with real instrument characteristics in 1825. During this period, water meter structures have appeared in the form of reciprocating single-piston water meters, rotating piston water meters, disc water meters, rotor-type water meters, and screw-wing water meters.
The working principle and basic structure of the above-mentioned water meters are still used by various water meter manufacturing companies today, but continuous advancements in design, technology, and material selection have improved the metering performance and reliability of water meters, and also reduced manufacturing costs.
Types and classifications of water meters
There are many classification principles for water meters. Classification according to measurement principle, measurement method and structural form, measurement purpose, measurement medium, measurement pipe diameter, indication value display method, etc. is the main method.
Water meter classification-according to the measurement principle
Speed water meter – a water meter that measures the velocity of water flow and indirectly measures the volume of water flowing through it;
Typical speed water meters include rotor water meters and propeller water meters. There are single-flow water meters and multi-stream water meters in rotor-type water meters.
Volumetric Water Meter – A water meter that measures the actual volume of water flowing through it, or simply a quantitative discharge meter.
Volumetric water meters are mainly used for pure water measurement.
Speed water meters can be divided into Single-beam water meters and multi-beam water meters.
Features of single-jet water meters: Water flows into the movement from one direction and impacts the rotation of the impeller, which easily causes eccentric wear of the impeller movement, shortens the service life of the water meter, and has low sensitivity.
Features of the multi-jet water meter: Water flows into the movement from all directions and impacts the rotation of the impeller, which will not cause eccentric wear of the impeller. High sensitivity, long service life, and other advantages.
Classification of water meters – according to water meter caliber
According to the caliber of water meters, they are usually divided into small caliber water meters and large caliber water meters. The diameters of water meters are 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 150, 200, and 300mm.
Water meters with a diameter of 40mm and below are usually called small-diameter water meters, and water meters with a diameter of 50mm and above are called large-diameter water meters. These two types of water meters are sometimes called residential water meters and industrial water meters.
Classification of water meters – by use
Residential Water Meter: Water meter used for residential water settlement
Industrial water meters: Except for residential water meters, they are all called industrial meters. Industrial water meters are generally large-diameter water meters.
Classification of water meters – According to the installation direction of the water meter
Horizontal installation water meter and vertical installation water meter (also called vertical water meter)
Note: “H” on the water meter dial represents horizontal installation; “V” represents vertical installation.
According to the temperature of the medium – cold water meter, the hot water meter
Cold water meters generally choose T30 or T50, whose maximum allowable operating temperatures are 30°C and 50°C respectively, and the lowest allowable operating temperature is 0.1°C.
Press whether the counter is immersed in water
Wet water meter (the watch glass directly bears water pressure)
Dry water meter (the watch glass does not withstand water pressure)
Liquid-sealed water meter (the watch glass directly bears water pressure, and glycerin is injected under the watch glass in a liquid-sealed manner)
So what is the difference between dry water meters and wet water meters?
Wet water meters and dry water meters are distinguished according to whether the main meter is filled with water, and whether water can be filled is determined by the internal movement. The two water meters have different characteristics and each has its advantages.
The biggest difference between the two is whether water can enter and the installation environment is different.
Wet water meter
The wet water meter has a wet movement, which is filled with water, and the counter is also in the water, allowing the water flow to drive the impeller through the water inlet, and relies on magnetic force to rotate the gear for counting.
Suitable for installation in areas with good water quality and suitable temperature
Advantages of wet water meters:
①No demagnetization will occur, stable performance and high accuracy
②Low manufacturing cost, mature research and development, simple structure
③At the same measurement level, the initial flow rate and smaller flow rate are better than dry-type water meters
Disadvantages of wet water meters:
①The counter of the wet water meter is immersed in water, and the transmission between the sensor and the counter is gear linkage. After a period of use, the dial is prone to yellowing and blackening, which affects reading;
②The surface glass of the water meter is subject to water pressure. If the surface glass of the water meter is broken, water will overflow.
③When the temperature difference between the inside and outside of the watch is large, fog and water droplets are likely to form on the glass, which affects reading;
④When the weather is cold, the water in the surface glass of the water meter will freeze, which will make the water meter unable to work and directly damage the water meter. The above phenomenon mostly occurs in the northern part of my country, and has almost no impact in the south.
Dry water meter
A dry water meter has a dry movement. The main meter does not come into direct contact with water. The sensor is isolated from the chamber of the counter and is generally rotated by magnets.
Advantages of dry water meter:
①If you do not come into contact with water, it will not be affected by water quality. You don’t have to worry about the water meter being damaged due to water quality.
②Does not come into contact with water and will not be affected by temperature. It has a wider range of applications and is safer.
③Dry-type water meters, because their counting mechanism is isolated from the water being measured, are not affected by suspended impurities in the water, ensuring the normal operation of the counting mechanism and clear readings;
④At the same time, unlike wet water meters, the temperature difference between the inside and outside of the meter will not cause fogging or condensation under the glass, which will affect the reading of the water meter;
⑤Even if the glass is accidentally broken during use, water will not overflow and it is safe.
However, due to its relatively complex structure, dry-type water meters require higher production technology and assembly processes from manufacturers, so their costs are higher than wet-type water meters.
Liquid-sealed water meters can be divided into two types: Fully liquid-sealed water meters and semi-liquid-sealed wet water meters.
Fully liquid-sealed water meters are characterized by high costs and complex processes.
Semi-liquid-sealed wet-type water meters are characterized by low cost, easy maintenance, and the ability to maintain clear water meter readings for a long time.
The composition of the water meter:
The main components of an ordinary water meter include: case, movement, counter, watch glass, watch cover, copper pipe and other accessories.
Movement: All water meter movements are made of ABS engineering plastic.
Reason: Because ABS engineering plastic has good stability, high strength and is not easy to deform. The hot water meter movement is also made of ABS engineering plastic, but temperature-resistant materials are added to it to improve the temperature-resistant value of the plastic.
Case: At present, all the company’s water meters are made of ductile cast iron cases. According to the new national standards, all parts of water meters that come into contact with water should be made of materials that are generally considered to be non-toxic, non-polluting, and non-biologically active, and comply with relevant technical standards.
According to the new standard water meters, the current gray iron case will be eliminated. From 2011, all water meters will be made of ductile iron. Small-diameter water meters on the market are made of aluminum alloy materials, nanotechnology synthetic plastics, ABS engineering plastics, copper materials, stainless steel, etc.
Water meter installation requirements and maintenance:
1. Before installing the water meter, the sediment in the pipe must be drained to prevent the water meter from being blocked;
2. Check the water flow direction of the water meter clearly to prevent it from being installed backwards;
3. During installation, the length of the straight pipe at the water inlet end of the water meter shall not be less than 10 times the diameter of the water meter, and the length of the straight pipe at the outlet end shall not be less than 5 times the length of the water meter diameter; (for example: the length of the straight pipe at the water meter inlet end shall be 15 mm That is 15X10=150mm)
4. The installation location should be considered to avoid corrosive places and places with poor drainage.
5. A check valve should be added behind the installed water meter to prevent water in the pipes behind the meter from flowing back, causing damage to the water meter or contamination of the water supply pipe network.
6. When installing, you should also consider installing expansion joints and filters; locate the water meter reasonably, build the meter well, and reserve a reasonable space for maintenance to prevent freezing and flooding;
7. After the water meter is installed, it should not be subject to excessive stress caused by pipes and fittings;
8. After the water meter is installed, seal it in time;
Common problems with basic meters (mainly mechanical water meters, gas meters, electricity meters, etc.) include inaccurate measurement, dial fogging, water or air leakage, unclear readings, meter failure, wear and aging, etc. These problems will affect the normal use of users and the accuracy of billing.
The following is a detailed list of these common problems, their causes and corresponding solutions:
Inaccurate measurement
Reason:
– After long-term use, internal parts wear and tear, resulting in increased friction and affecting the flexibility of rotation.
– Internal sensors or gear components are aged or damaged, causing measurement errors.
– External environmental influences, such as temperature changes, magnetic field interference, etc., will also affect the measurement accuracy of the base meter.
– There are impurities, sediments or bubbles in the pipeline, which affects the measurement accuracy.
Solution:
– Calibrate the base meter regularly to ensure that the measurement accuracy is within a reasonable range.
– Where water quality is poor or gas quality is unstable, install filtration devices to reduce the impact of impurities.
– Avoid installing the base meter in a place with large temperature changes or strong magnetic field interference.
– For base meters that have been used for many years, regular replacement or repair should be considered.
The dial is foggy
Reason:
– Insufficient sealing of the base watch, causing moisture to enter the interior of the dial.
– The ambient humidity is high, and the temperature difference between the inside of the water meter and the external environment is large, causing water vapor to condense.
Solution:
– Choose a base surface with good waterproof properties and sealing properties.
– Optimize the installation environment of the base surface and avoid installation in places with humidity and large temperature differences.
– If fogging occurs, waterproof sealing treatment can be adopted, or moisture-proof devices can be installed during installation.
Water or air leakage
Reason:
– The base surface interface is not tightly sealed or aged, resulting in water or air leakage.
– There are cracks or damage to the base meter casing or internal piping.
– Improper connection between the pipeline and the base surface during installation, resulting in loose joints or water and air leakage.
Solution:
– Regularly check the sealing performance of the base table. If the sealing ring is found to be aging, replace it in time.
– When installing, make sure all connections are tight and use suitable sealing materials.
– Regularly inspect and maintain the base surface and its connecting pipes, and promptly repair or replace damaged parts.
Unclear reading
Reason:
– There is dirt or water stains on the dial surface, which affects the clarity of readings.
– The numbers and scales on the dial are faded or corroded.
– Long-term exposure to sunlight or chemical corrosion will cause the dial to age.
Solution:
– Clean the dial regularly to keep its surface clean and free of impurities.
-Choose a high-quality base watch to ensure that the dial is corrosion-resistant and anti-aging.
– During installation, try to avoid direct sunlight or environments with corrosive gases.
Failure to stop the watch
Reason:
– The internal mechanical parts are stuck or damaged, causing the base meter to not work properly.
– The battery is exhausted (for electronic water meters or smart meters) and there is no power supply.
– The watch is stopped due to external physical impact or man-made damage.
Solution:
– Regularly inspect the internal components of the base meter to ensure its normal operation.
– For smart meters or electronic water meters, batteries should be replaced regularly or the power system should be checked.
– Avoid external impact or human damage to the base surface, and pay attention to protection during installation.
Wear and aging
Reason:
– Long-term use causes mechanical parts to wear out, affecting metering and operation.
– The casing or seals have aged after being exposed to harsh environments for a long time.
Solution:
– For base meters with a long service life, periodic replacement is recommended.
– During installation, select a base table that meets environmental conditions and perform regular inspection and maintenance.
The base meter will inevitably encounter various problems during long-term use. Regular inspection and maintenance are the key to ensuring the normal operation of the base meter. For different problems, targeted preventive measures and solutions should be taken to extend the service life of the base meter, improve the accuracy of measurement, and reduce user troubles and losses.
