Basic Knowledge Training Manual on Water Meters

Basic Knowledge Training Manual on Water Meters

What is a Water Meter?  A water meter is a measuring instrument used under specific conditions to continuously measure, record, and display the volume of water flowing through a measurement sensor. In simple terms, a water meter measures water usage and serves as a fair and reasonable trade settlement tool between water suppliers and users.

1. Types and Classifications of Water Meters

Water meters can be classified in various ways, primarily based on measurement principles, structural design, measured medium, pipe diameter, usage, and display method.

1.1 By Measurement Principle

• Velocity-type water meters: Includes rotary vane and turbine types. Installed in closed pipelines, these meters have moving components driven directly by water flow velocity.

• Volumetric water meters: Feature a piston-type structure with chambers of known volume that are sequentially filled and emptied. These are also installed in closed pipelines and operate via fluid-driven mechanisms.

1.2 By Nominal Diameter

• Small-caliber meters: Diameter less than 40mm, typically connected via threaded joints.

• Large-caliber meters: Diameter 50mm or more, usually connected via flanges.

1.3 By Usage

• Residential water meters: Used for household water billing.

• Industrial water meters: Used for all other purposes, typically large-caliber.

1.4 By Installation Orientation

• Horizontal installation: Marked with “H” on the dial.

• Vertical installation: Marked with “V” on the dial.

• If unmarked, the meter is generally for horizontal installation. Volumetric meters can be installed either horizontally or vertically.

1.5 By Medium Temperature

• Cold water meters: For water temperatures from 0.1°C to 40°C.

• Hot water meters: For temperatures from 0.1°C to 90°C or above.

• If unmarked, the meter is typically for cold water.

1.6 By Medium Pressure

• Standard pressure meters: Nominal pressure of 1 MPa.

• High-pressure meters: For pressures exceeding 1 MPa.

• If unmarked, the nominal pressure is assumed to be 1 MPa.

1.7 By Counter Immersion

• Wet-type meters: Counter is immersed in water; the glass bears water pressure, and transmission is via gear linkage. Water quality may affect readability over time.

• Dry-type meters: Counter is isolated from water; the glass does not bear pressure, and transmission is typically via magnetic coupling.

• Liquid-sealed meters: Counter or number wheels are sealed with a glycerin-based liquid. Readability is unaffected by external water quality. Partial sealing is referred to as semi-liquid or small-liquid seal.

1.8 By Counter Display Type

• Type C: Pointer or analog display.

• Type E: Number wheel or hybrid analog-digital display.

1.9 By Number of Water Flow Jets Driving the Impeller

• Multi-jet meters

• Single-jet meters (commonly referred to as single-jet meters)

1.10 By Accuracy Class

• Class 1 and Class 2 meters:

• Low flow zone (Q1 to Q2, excluding Q2): ±5%

• High flow zone (Q2 to Q4, including Q2 and Q4): ±2%

• Most domestic meters are Class 2.

• Maximum permissible error:

• Applies to both cold and hot water meters.