Technical Information Document

Part-filled permanently installed flow metering system

Calibrated measuring channel for flow metering in pipes and ducts for waste water and rain water.

April 2014– Subject to change 2

Why should waste water flows be measured

by the permanently installed flow metering

system from STEBATEC AG?

Usage-based accounting is making inroads also in measuring waste water flows. As the requirements on the precision of measuring and control hardware increase,

the STEBATEC «permanently installed» measuring system offers major advantages:

Advantages in action

• Guaranteed and controllable measuring accuracy – in calibrated measuring section

• Reliable, very difficult to tamper with or be affected e.g., by solid material, deposits or external factors

• Also works in backwater situations (reservations)

• Easy to maintain, maintenance outside the manhole, device open on top for cleaning

• Backlog-safe, emergency overflow port

• Long life – no parts subject to wear

Advantages of the design

• Fits most available building structures – no modifications required

• Wide measuring range due to individually adapted gutter shape

• Installation possible without diverting the water flow

• Installation completed in 1 day (reservations)

Applications

• Flow metering in municipal waste water systems

• Waste water discharge monitoring for waste water producing factories

• Drainage water measurement

• Pit and process water measurement in mining and tunnel construction

• Suitable cost accounting measurement

• Suitable external water measurement

• Suitable rainwater measurement

April 2014– Subject to change 3

The 3 principles

«Permanently installed» the flow metering system with guaranteed and controllable precision based on three principles:

Controlability

The part-filled permanently installed flow metering system is open on top; the measuring accuracy is easy to check manually by dipstick and Q/H curve. The actual accuracy check is made with the in-house hydraulic test facility in which all systems are tested and calibrated by a reference measuring system under practical conditions. The actual measuring accuracy of the measuring and control system is defined at the installation site and is guaranteed. We even undertake to supply results suitable for accounting purposes.

Reliability

Calibrated measuring sections and channels do not depend on local conditions such as hydraulics, channel roughness or channel gradient. Optimum measuring conditions are created in combination with sensors which are very hard to manipulate by solids or deposits. This makes the measuring systems very reliable.

Ease of maintenance

Long life and precision of the system depend on the level of maintenance. Easy maintenance is therefore an important aspect of the system. Layout and arrangement are planned together with the customer and adapted to his needs and technical equipment.

STEBATEC hydraulic test system

April 2014– Subject to change 4

Ultrasonic runtime difference as measuring principle

Ultrasonic flow meters measure the flow rate of the fluid medium by means of sound waves. Imagine two boats crossing a river on the same diagonal line, one boat in the direction of flow, the other boat in the opposite direction. The boat moving with the water flow needs much less time to cross the river than the other boat. Sound waves behave the same way. The sound waves travel much faster in the direction in which the medium flows than the sound wave propagating in the opposite direction.

The propagation of the waves is measured continuously. Thus the difference in the runtime of the two ultrasonic waves is directly proportional to the mean flow rate. The flow volume per unit of time is the result of the mean flow rate multiplied by the diameter of the pipe or channel.

Sonic flow measurement has several advantages over other methods. The measurement is largely independent of the properties of the medium measured, such as electric conductivity, specific gravity, temperature or viscosity. There are no moving parts, so the system does not require much maintenance and there will be no pressure loss due to restriction of cross section. A wide measuring range is another positive feature of this method.

Gutter shape, measuring very small volumes and wide measuring range

Flow meters are often unable to measure low water levels. Therefore, the exact measurement of very small volumes of waste water is generally considered a challenge among flow metering experts. The purpose of the adaptive gutter shape from STEBATEC is to provide a device by which flows in part-filled (open) stretches (e.g., gutters) can be measured as much as this can be done in closed structures, e.g., in pipes even when the discharge is very small. The ”dry weather gutter“ at the part-filled permanently installed flow metering system is able artificially to maintain the water level and the flow rate at a level that can be measured.

April 2014– Subject to change 5

Adaption/integration in available buildings

The part-filled permanently installed flow metering system has been designed for integration in available building structures. In the way the gutter is adapted to the expected water volume; different adapters are available for connecting the infrastructure.

Example: Connection of a closed pipeline (dry construction type with maintenance opening)

Example: Integration in a manhole structure

Example: Connection in the rectangular duct installation / removal

April 2014– Subject to change 6

Dimensioning guide

The devices are dimensioned on the basis of main hydraulic data – the size of the duct system is not relevant and is a restricting factor only for larger nominal diameters.

Basis of calculation:

Qmin (H > 3cm) = Width of the dry weather gutter (A) Qtwmax x1.2 = Height of dry weather gutter (B) Qregen = Rain pipe volume (C)

April 2014– Subject to change 7

Standard version specifications

Pipe wall materials: Polypropylene (PP) Protection class: IP 68 ATEX certification: ATEX ll 2GD EEX de, wired EEx e Seals: EPDM Temperature range: 0 – 80°C pH: pH 6 – 9