Compound water meter

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Compound water meter

Compound water meters are measuring devices in which two water meters with different nominal loads are combined. Depending on the flow rate, the water is fed through a switching device either through the smaller water meter or through both water meters.

function

The compound water meter consists of a main meter ( bulk water meter ) and a smaller secondary meter. When the flow rate is low, the main meter is closed by a tightly closing switchover flap, the water then only flows through the small secondary meter. When the load is higher, the switchover flap opens and enables the main meter. Now both counters run in parallel. To determine the amount of water that has flowed through, both meters must always be read and the amounts displayed must be added.

In older versions, the main meter, switchover unit and secondary meter (with secondary lines) are screwed together as individual elements. Here the secondary meter can be arranged on the left or right (in the direction of flow) depending on the installation situation. More modern compound water meters have a compact housing in which the main meter with switchover flap and a standard measuring capsule (mostly Q n = 2.5 m³ / h) are located.

Types and designs

  • WPV: The turbine axis of the main meter runs parallel to the pipe axis, i.e. horizontally.
  • WPV-Inline: Compact housing with WP main meter and multi-jet or rotary piston meter as secondary meter.
  • Models with approval for cold and hot water
  • Operating pressures according to DIN 2401
  • Connection dimensions according to DIN 19625 or DIN ISO 4064
  • Flange connection according to DIN 2501 or 2533
  • Carbide wheel bearings
  • Protection class IP 68
  • Contactor options for remote reading devices (reed contact, optical, inductive)
  • M-BUS option for remote data transmission according to EN 1434

Applications

Water supply for large consumers such as industry, hotels, swimming and sports centers, shopping centers, schools, etc.

  • for measuring high and strongly fluctuating flow rates
  • for measuring the smallest flow rates and for leak detection
  • Use in buildings with fire extinguishing systems (large flows required)

Laws and Regulations

Compound water meters may only be installed by trained specialists.

Calibration validity

Compound water meters that are used in business transactions must be calibrated and comply with the PTB guidelines . The calibration period is 6 years as for simple cold water meters. This period has also proven itself as a maintenance interval for uncalibrated meters. However, depending on the water quality and operating conditions, a shorter period may be required. Compound water meters can only be calibrated as a whole. If one of the two counters is exchanged, the calibration expires.

source

  • European Water Framework Directive 2000/60 / EC
  • Martin Bantel: Measuring device practice - functions and use of measuring devices . September 2004, Hanser Fachbuchverlag
  • Karl Walter Bonfig: Technical flow measurement with special consideration of novel flow measurement methods , 3rd edition, Vulkan-Verlag GmbH, Essen, 2002

See also

Individual evidence

  1. ↑ PTB guidelines (PDF; 208 kB)