1. According to the measurement principle

It is divided into speed water meter and volumetric water meter.

(1) Speed type water meter: it is installed in a closed pipe and is composed of a moving element, which is directly powered by the speed of water flow.

Typical speed water meters include rotary wing water meter and screw wing water meter. Rotor type water meters also include single beam water meters and multi beam water meters.

(2) Positive displacement water meter: installed in the pipeline, it is composed of some chambers with known volume that are filled and discharged with fluid step by step and the mechanism driven by fluid, or simply referred to as quantitative discharge water meter.

Displacement water meters generally adopt piston type structure.

2. Classification by measurement level

According to the old standard, it can be divided into class a table, class B table, class C table and class D table.

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 table, B-level table, C-level table and d-level table, and its measurement performance meets the corresponding requirements of measurement levels a, B, C and D specified in the national standard.

After the release of the new standard, the measurement grade classification method has become quite complex, which is mainly determined by various parameters such as flow value and range ratio. In short, the larger the range, the higher the measurement level.

3. By nominal diameter

It is divided into large caliber water meter and small caliber water meter.

According to the nominal diameter, it is usually divided into small-diameter water meters and large-diameter water meters.

Water meters with a nominal diameter of 50mm or less are usually called small-diameter water meters, and water meters with a nominal diameter of 50mm or more are called large-diameter water meters. These two kinds of water meters are sometimes called civil water meters and industrial water meters. At the same time, this division can also be distinguished from the connection form of the meter shell. Water meters with a nominal diameter of 50mm or less are connected with threads, and water meters with a nominal diameter of 50mm or more are connected with flanges. However, some special types of water meters also have 40mm flange connections.

4. By purpose

It is divided into civil water meters and industrial water meters.

5. According to the installation direction

Speed type water meters can be divided into horizontal mounted water meters and vertical mounted water meters.

According to the installation direction, it is usually divided into horizontal water meter and vertical water meter (also known as vertical meter), which refers to the water meter whose flow direction is parallel or perpendicular to the horizontal plane during installation. On the scale plate of the water meter, "H" represents horizontal installation and "V" represents vertical installation. The positive displacement water meter can be installed at any position without affecting the accuracy.

6. According to the temperature of the medium

It is divided into cold water meter and hot water meter.

According to the medium temperature, it can be divided into cold water meter and hot water meter, and the water temperature of 30 ℃ is the dividing line.

(1) Cold water meter: water meter with lower limit temperature of 0 ℃ and upper limit temperature of 30 ℃.

(2) Hot water meter: water meter with lower limit of 30 ℃ and upper limit of 90 ℃, 130 ℃ or 180 ℃.

The requirements of various countries are slightly different. The upper limit of cold water meters in some countries can reach 50 degrees Celsius.

7. According to the pressure of the medium

It is divided into ordinary water meter and high-pressure water meter.

According to the pressure used, it can be divided into ordinary water meter and high-pressure water meter. In China, the nominal pressure of ordinary water meters is generally 1MPa. High pressure water meters are all kinds of water meters with a maximum operating pressure of more than 1MPa, which are mainly used for the measurement of oilfield underground water injection and other industrial water flowing through the pipeline.

8. Classification of water meters

According to whether the counter is immersed in water, it can be divided into wet water meter, dry water meter and liquid sealed water meter.

(1) Wet water meter: the glass of a water meter whose counter is immersed in water bears the water pressure, and the transmission of the sensor and the counter is gear linkage. After a period of use, the quality of water will affect the clarity of the reading of the water meter.

(2) Dry water meter: a water meter whose counter is not immersed in water. Structurally, the sensor is 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 made of magnetic steel.

(3) Liquid sealed water meter: the digital wheel or the whole counter used for meter reading are all liquid sealed water meters prepared with a certain concentration of glycerin. The clarity in 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. 9. Divide according to the indication form of the counter

It is divided into analog type, digital type and analog digital combined type. 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 form is divided into analog device, digital device, analog and digital combined device.

10. According to the number of flow bundles driving the impeller

Rotor type water meters are divided into multi beam water meters and single beam water meters (referred to as single flow meters) according to the number of flow beams driving the impeller.

11. Classification of remote water meter

The remote water meter is usually a water meter with an ordinary water meter as the base meter and equipped with a remote output device. The remote output device can be placed in the water meter body or the indicating device, or can be configured externally. At present, there are two types of signals for remote water meters. One type includes switching value signals, pulse signals, digital signals, etc. representing real-time flow. Sensors generally use reed or Hall elements, and the other type represents digital signals and encoded other electrical signals of cumulative flow. Remote transmission output methods include wired and wireless.

12. Prepaid water meter

Prepaid water meter is a kind of water meter with preset function, which is composed of ordinary water meter as the base meter and equipped with controller and electric control valve. Typical ones are IC card cold water meter, TM card water meter and code prepaid water meter. Quantitative water meter also adopts a preset control technology.

(1) IC card water meter is a prepaid water meter with IC card as the media. According to the form of IC card and external data transmission, there are contact IC card and non-contact (also known as RF induction) IC card. The contact of contact IC card can contact with the outside world; The contactless IC card is equipped with RF transceiver circuit and related circuits, and does not lead out contacts.

(2) TM card water meter is a non-contact intelligent prepaid water meter. TM card is a touch memory card with IC card function.

(3) Code data exchange water meter uses a group of deformed data codes to transmit and exchange prepaid water purchase data. It is an intelligent prepaid water meter using this data control technology.

(4) The quantitative water meter adopts electrical control or numerical control mode, and sets and controls the water meter of water consumption within a certain range. This is the same type of meter before the successful development of IC card prepayment meter, which is used in industrial production processes (such as chemical production, concrete mixing in construction projects, etc.) and coin injection water intake occasions.