VW 量水堰-DGSI

VW Weir Monitor

Model:52612402

Contents

Introduction (1)

Installation Procedure (3)

Taking Readings (4)

Data Reduction (8)

Introduction The measurement of free current flow in open canals is widely used in the environmental and geotechnical sectors.

This measurement is obtained making a section of known cross area inside the canal where the water flows.

INSTRUMENT DESCRIPTION

The purpose of the weir is to transform the instantaneous flow values into the pressure/level measurement by a specific measuring equipment.

For reliable measurements, the canal upstream should have a fair slope (1-3%) and a known upstream section for a length of at least 10L (where L=width of canal).

A level difference in the section downstream prevents turbulent motion which could affect the level upstream and, hence, the flow measurement. The possibility of solid materials being drawn by

the current and deposited upstream of the measuring equipment should be kept in mind. Accumulated sediments may affect the reliability

of measurements: sediments should therefore be cleared regularly.

Specifications Range: 150mm, 300mm, 600mm

Resolution: 0.02% F.S

Accuracy: ±0.1% F.S.

Temperature Range: -30 to +80℃

Cable: 4-Conductor, 22 gage PU Poly_urethane

Installation Procedure

Part of the system may be preassembled before final installation. Proceed as follows:

1. realize an open channel on site. The stilling

basin and the sedimentation tank made in concrete or better in stainless steel o others material. The measurement canal bottom should have a 1-3% slope towards the weir edge. Any joints should be sealed by means of welding or resins, depending on the materials used. The basin should be adequately anchored; any holes should be sealed by suitable resins;

2. Fix the weir to the measurement canal and seal

any joints. The weir must be perfectly vertical and normal in relation to the canal axis;

3. Make a transition section after the weir to join

the measuring canal and the current flow. This section’s dimensions will be similar to those of the measurement canal, with a 5% slop;

4. Place the pressure transmitter in a suitable

housing fixed to the measurement canal bottom, which will have been previously part-filled with

water. Handle the transducer carefully in order to avoid shock. The transducer should not be immersed beyond its full scale value.

5. The PVC slotted tubing has a bottom plug at its lower end, which can now be cemented in place using PVC cement. (It is left loose in case the PVC pipe needs to be shortened a little due to space limitations). Use the four 3/8-16 bolts provided to bolt the stilling well to the wall of the weir box using the pipe-strap and spacer bars.

6. Check the zero reading. Carefully attach the weight to the eyebolt on the base of the sensor and lower the assembly into the stilling well until the pipe cap sits firmly on top of the pipe.

The Black vented readout cable can now be extended to a local readout location where an optional terminal box can be used to enclose the end of the black vented cable and the vent line moisture trap.