Classification of water meters

Classification of water meters

There are many classification principles of flowmeters, which are mainly classified according to measurement principle, measurement method and structural form, measurement purpose, measurement medium, measurement pipe diameter, indication value display mode, etc.

1. According to the measurement principle
 By measurement principle is a major classification method. Generally, it can be divided into velocity water meters and volumetric water meters.
 (1) Speed-type water meter: It is installed in a closed pipe, consists of a moving element, and is directly obtained by the speed of the water flow to obtain the power speed.

 Typical speed-type water meters include rotary-wing water meters and screw-wing water meters. There are single-flow water meters and multi-flow water meters in the rotor-type water meter.

 (2) Volumetric water meter: It is installed in the pipeline and consists of some chambers of known volume that are successively filled and discharged with fluid and a water meter composed of a fluid-driven mechanism, or a quantitative discharge water meter for short.
 Volumetric water meters generally use a piston-type structure.

2. According to the measurement level
 The metering grade reflects the working flow range of the water meter, especially the metering performance under small flow. According to the order from low to high, it is generally divided into A-level meters, B-level meters, C-level meters, and D-level meters. . Common small-diameter water meters: the flow ratios of measurement grades A and B are 50:1 and 100:1 respectively; large-diameter screw-wing water meters: the flow ratios of measurement grades A and B are 25:1 and 67:1, respectively .
 Note: The large-diameter water meters (such as turbine water meters or duplex water meters) in some European countries have a particularly wide working flow range (can reach more than 200:1), and also mark the segmentation error limit and mark B, C grade symbols, However, the specific meaning and characteristic flow value of the metering grade symbols of this type of table are different from those specified in the international standard ISO 4064.

3. According to the nominal diameter
 According to the nominal diameter, it is usually divided into small diameter water meters and large diameter water meters.
 A water meter with a nominal diameter of 40mm and below is usually called a small-caliber water meter, and a water meter with a nominal diameter of 50mm and above is called a large-caliber water meter. These two types of water meters are sometimes called civil water meters and industrial water meters. At the same time, this method can also be distinguished from the connection form of the water meter's case. blue connection.

4. According to the purpose
 It is usually divided into civil water meter and industrial water meter according to the purpose. Residential water meters only refer to water meters used for residential water settlement, and other uses can be classified as industrial water meters. Industrial water meters are generally large-diameter water meters.

5. According to the installation direction
 According to the installation direction, it is usually divided into horizontally installed water meters and vertically installed water meters (also known as vertical meters), which refers to the water meters whose flow direction is parallel or perpendicular to the horizontal line during installation. Use "V" for vertical installation.
 Note: When the name of the water meter is not specified, the water meter is generally installed horizontally. There is no requirement for a positive displacement water meter to be installed horizontally or not. Some large-diameter water meters with dynamic balance treatment in Europe can also be installed in a horizontal, vertical or inclined way, but the metering performance obtained by different installations is different. To downgrade.

6. According to the temperature of the medium
 According to the temperature of the medium, it can be divided into cold water meter and hot water meter, and the water temperature is 30 ℃.
 (1) Cold water water meter: a water meter with a medium lower limit temperature of 0°C and an upper limit temperature of 30°C.
 (2) Hot water water meter: a water meter with a lower limit temperature of 30°C and an upper limit of 90°C or 130°C or 180°C.
 Note: When not specified, general water meters refer to cold water meters.

7. According to the pressure of the medium
 The nominal pressure (or maximum allowable working pressure) of ordinary water meters in my country is generally 1MPa. High-pressure water meters refer to various types of water meters with a maximum operating pressure of more than 1MPa, which are mainly used for the measurement of underground water injection in oil fields and other industrial water flowing through pipelines.
 Note: When not specified, the nominal pressure of the water meter is 1MPa. The nominal pressure of water meters in some European countries is 16bar (1.6MPa).

8. Press whether the counter is immersed in water
 According to whether the counter of the water meter is immersed in water, it is divided into wet water meter, dry water meter and liquid-sealed water meter. The typical performance difference is whether the watch glass of the water meter can withstand water pressure, and whether the transmission between the mechanical sensor of the water meter and the counter is a direct gear linkage or a magnetic steel transmission.
 (1) Wet water meter: a water meter with a counter immersed in water, the glass of the watch is subjected to water pressure, and the transmission between the sensor and the counter is a gear linkage. After a period of use, the quality of the water quality will affect the clarity of the water meter reading.
 (2) Dry water meter: a water meter in which the counter is not immersed in water. The sensor is structurally isolated from the chamber of the counter. The glass of the water meter is not subject to water pressure. The transmission between the sensor and the counter is generally driven by magnetic steel.
 (3) Liquid-sealed water meter: The meter wheel used for meter reading or the entire counter is completely sealed with liquid. The clarity of the sealed and isolated counter is not affected by the external water quality, and the rest of the structural performance is the same as that of the wet water meter.
 Note: In the industry, small liquid seals and large liquid seals are sometimes used to distinguish whether the counter is a partial liquid seal of the character wheel or a liquid seal of the entire counter.

9. According to the instruction form of the counter
 According to the indication form of the counter, it can be divided into pointer type, word wheel type (or digital type or E-type table) and pointer word wheel combination type. In the national standard GB/T 778-1996, the indication forms are divided into analog devices, digital devices, and combination devices of analog and digital.
 Description: In the industry, the pointer type watch is often called the C-type watch, and the combination type of the word wheel type and the pointer word wheel is called the E-type watch or the digital type.

10. According to the number of water jets driving the impeller
 Rotor-type water meters are divided into multi-beam water meters and single-flow water meters (referred to as single-flow meters) according to the number of water beams driving the impeller.
 
11. Classification of remote water meters
 The remote water meter is usually a water meter with an ordinary water meter as the base meter and a remote transmission output device installed. The remote transmission output device can be placed in the water meter body or the indicating device, or it can be configured outside.
 At present, there are two types of signals of remote water meters. One is switch signal, pulse signal, digital signal, etc. that represent real-time flow. The sensor generally uses reed switch or Hall element, and the other is digital signal and Other encoded electrical signals, etc. The methods of remote transmission include wired and wireless.

12. Prepaid water meter
 The prepaid water meter is a water meter with a preset function, which is composed of an ordinary water meter as the base meter, and is equipped with a controller and an electric control valve. Typical ones include IC card cold water meter, TM card water meter, etc. The quantitative water meter also adopts a preset control technology.
 (1) IC card water meter: prepaid water meter with IC card as the medium. According to the form of IC card and external data transmission, there are two types of IC cards: contact type IC cards and non-contact type (also known as radio frequency induction type) IC cards. The contacts of the contact IC card can be in contact with the outside world; the non-contact IC card has a radio frequency transceiver circuit and its related circuits, and does not lead out contacts.
 (2) TM card water meter: It is also a non-contact smart prepaid water meter. TM card is a touch memory card with IC card function.
 (3) Code data exchange type water meter: a set of deformed data codes are used to transmit and exchange the prepaid water purchase data, and the intelligent prepaid water meter adopts this data control technology.
 (4) Quantitative water meter: a water meter that uses electrical control or numerical control to set and control water consumption within a certain range. This is the same type of meter before the IC card type prepaid meter was successfully developed. It is used in industrial production processes (such as chemical production, concrete mixing in construction projects, etc.) and coin-operated water intake occasions.


13. Standard water meter for inspection
 The standard water meter used for inspection is generally a well-manufactured volumetric water meter or flowmeter, and the accuracy can reach 0.5% within a certain flow range. This type of standard water meter is also called an online water meter calibrator. (Reprinted information is for reference only)