Water Metering

SM250Product Specification

METROLOGICAL CHARACTERISTICS

Nominal Pipe Diameter DN mm 20

Permanent Flow Q3 m3/h 4.0

Measuring Range Q3/Q1 200 160

Minimum Flow Q1 l/h 20 25

Transitional Flow Q2 l/h 32 40

Overload Flow Q4 m3/h 5.0

Accuracy Class 2

TECHNICAL CHARACTERISTICS

Typical pressure loss at Q3 bar <0.63

Pressure rating (working) bar 16

Max. pressure rating bar 20

Ambient operating temp. °C -10 to +85

Ambient storage temp. °C -10 to +70

Temperature class T30

Electromagnetic class E1

Environmental class B & C

Nominal diameter DN mm 20

Thread size in G 1”

Lay-length mm 190 +0/-2

Weight kg 1.9

Indicating range m3 999,999

Display resolution m3 0.001

Typical battery Life years 15

Ingress protection IP 68

OperationThe SM250 is a fluidic oscillator type, cold water meter. Water enters

the fluidic oscillator through a nozzle that creates a jet. When the

jet enters the flow chamber, it will initially be drawn to one of the two

diffuser walls and will travel along the wall through the principle of

the Coandã effect and then exit the flow chamber. Due to the local

pressure being lower by the opposite diffuser wall, the jet will move

towards the other wall and therefore starts to oscillate between

one diffuser wall and the other. Carefully optimized features within

the flow chamber provide oscillation across a greater flow range.

This oscillation between the diffuser walls continues while flow is present where each oscillation represents a precise volume that has passed through the meter. The oscillation is monitored by electrodes placed next to each diffuser wall, in which an electrical current is induced in the jet by a pair of powerful permanent magnets. Sensing electronics capture when the oscillations occur and totalize the volume passed displaying the registered volume on a liquid crystal display. When no fluid present i.e. air, no signal is present and no volume measured.

ApplicationThe meter is for use only with potable cold

water up to 50ºC and an overload pressure

up to 20 bar. The meter will register between

98% and 102% accurate throughout the

normal operating range and between 95%

and 105% at the low flow for accuracy class

2, T30 temperature class meters, as stated

within OIML R49-1:2006. No adjustment

is required before or after installation and

the in-service accuracy errors can be up

to twice that of the rated accuracy class.

MATERIALS

Main case Copper alloy

Bottom plate options Copper alloy

Bottom plate o-rings Neoprene

Bottom plate gasket EPDM

Connection liner Glass reinforced nylon

Measuring chamber PPS

Sensor electrodes Hastelloy

Conditioning plate Acetal

Strainer Acetal

Non-Return Valve Acetal

Register Acetal

Register lens Polycarbonate

Lockshroud and Lid Acetal

Battery Lithium Thionyl Chloride

For more informationwww.elstermetering.com

Elster Water Metering Ltd 130 Camford Way

Sundon Park, Luton

Bedfordshire, LU3 3AN

United Kingdom

T +44 1582 846400

F +44 1582 564728

water.metering@elster.com

All rights reserved. The company’s policy is one of continuous product improvement and the right is reserved to modify the specifications contained herein without notice. These products have been manufactured with current technology and in accordance with the applicable referenced standards.

Rev.1 SM250 Specsheet 11/18 Lit Ref: 8518D93221© 2018 Honeywell International Inc.

REGISTERThe register is contained within an advanced engineered polymer casing which is completely potted to eliminate air and any potential condensation. To assure easy reading, the totalizer LCD digits are large and the dial face is colour coded to identify billing units and verification units. The applicable flow range, type approval and registration units are printed on the dial face.

The LCD includes a low-flow indicator that provides visual indication of plumbing leaks. The register contains a removable Lithium Thionyl Chloride battery pack that has a typical 15 year battery life under normal operating conditions.

READING THE METERThe reading is displayed on the electronic register of the meter under the protective lid. The display digits before the decimal point, surrounded by a black or both a black and white border on the facia, represent whole cubic metres (m3) and the digits after the decimal point, surrounded by a red border, represent fractions of a cubic metre.

Billing units Decimal fraction

Standard billing unit = 1 cubic metre

m35/8"NSF®-61-G

Q700

m3

When water is flowing, a flashing square icon appears to the lower right of the display, but when the flow has stopped this indicator will be extinguished. To read the meter using a remote reading system, refer to the manufacturer’s instructions.

CONSTRUCTIONThe construction of the SM250 meters comply with requirements of the OIML R49-1: 2006 and WRAS specifications. The meter consists of a straight through-flow main case with the connections lined with polymer, a single piece fluidic oscillator measuring chamber with no moving parts, and an electronic register assembly that is mounted onto the measuring chamber. The main case is cast from a high copper content alloy and has markings designating the model type and direction of flow. The fluidic oscillator measuring chamber uses patented magnet sensing with inset moulded sensor electrodes to monitor flow. The register assembly includes a sealed battery compartment and a clear lens for viewing the LCD display. The register is secured from tamper with a register lockshroud assembly and wire security seal.

AMR EXTENDED DATA FEATURES

FEATURE DESCRIPTION

Leak count Event triggered and count incremented when the meter detects continuous flow at or above Q1 for a factory set duration

No-flow count Event triggered and count incremented when the meter detects no continuous flow at or above Q1 or no water present for a factory set duration

Dry count Event triggered and count incremented when the meter detects air by volume present in the water flow

Tamper count Event triggered and count incremented when the meter electrical power is disrupted by. Meter periodically stores the most significant 8 digits of the latest volume recorded for display on re-powering

Battery status Battery Low event triggered when a maximum 12 months of expected battery life remains, subject to typical flow rate, AMR read rate and regional temperatures. Battery Low is also indicated by the LCD display flashing On and Off every second

Note: Extended data features not available for all communication modes

AMR/AMI CONNECTIVITYThe SM250 meter is supplied AMR ready with a communication port that is factory set to support the following output mode:

• Encoder output that uses standard ASCII serial protocols

• Pulse output with default setting 1 pulse per litre

Suitable connector cable accessories can be supplied for connection to Elster compatible devices.

APPROVALSMeter manufacture and performance specification

• MID 2004/22/EC

• OIML R49

• IS04064

• WRAS (UK)