Armfield Instruction Manual
12
connector. When it is required to drain water from the sand tank the flexible tube is
connected to one of the quick-release connectors (5) on the side of the sump tank,
allowing the water to return to the sump tank. The flow of water can be varied using
the in-line valves (32). When it is required to admit water to the sand tank the flexible
tube is connected to one of the water feeds via the quick-release connector (15).
A deep cut-out (31) at the left-hand end of the sand tank allows water (and
transported sediment) to leave the sand tank. This cut-out incorporates side slots that
locate stop-logs (rectangular strips of plastic) that create a rectangular weir. Adding
or subtracting stop-logs of different sizes can vary the height of the weir. A weir
chute/diffuser (26), fabricated from clear acrylic, is bolted to the end wall of the sand
tank adjacent to the cut-out. The weir chute/diffuser allows the water and sand exiting
the sand tank to fall into the outlet collecting tank (28) with minimal disturbance to the
surface of the water or any collected sediment in the outlet collecting tank (described
below). A clear polythene skirt with slits is attached to the bottom of the weir
chute/diffuser, using a rubber band, to minimise splashing as the water and sand fall
into the collecting tank.
Outlet Collecting Tank
Water and sediment exiting the sand tank via the weir chute/diffuser is deposited into
the outlet collecting tank (28) that is designed to measure the flow of water and
collect any sediment washed from the sand tank. This tank is fabricated from clear
acrylic and incorporates the following features:
The water and sediment fall into the open area of the tank. A vertical mesh screen
(30), supported by perforated plates on either side, ensures that sediment is retained
in the tank. The water flows through the mesh, along a stilling channel then over a
narrow rectangular notch (31) before discharging into a funnel (29) that returns the
water to the sump tank for re-use. The flowrate of the water is determined from the
height of the water upstream of the notch using an inclined manometer that
incorporates a scale calibrated directly in litres/min. The manometer is mounted
directly on the side of the outlet collecting tank.
Sediment falling into the tank is deposited in the bottom of the tank. The sand can be
removed by lifting the tank clear from its support. If it is required to collect the sand
for quantitative measurements then a piece of fine cloth or a small strainer can be
positioned beneath the weir chute/diffuser to collect the sediment. If this is changed
at regular intervals then the rate of accumulation of the sediment can be determined.
When version S12-MKII-50 has been supplied, additional instrumentation and a USB
interface is included that can be used to measure both the water flow and the
accumulation of sediment continuously using a PC.
S12-MKII-50 (S12-MKII Including Data Logging and Educational
Software)
Note:
This option can only be supplied at the time of ordering the equipment and
cannot be fitted to en existing S12-MKII.
This system works by measuring the height of the water and the combined weight of
the sand and water collected in the outlet tank (28). The water flow rate is calculated
from the height over the outlet weir (27) and the sediment flow rate is calculated from
the rate of change of the weight. The system comes with educational software
incorporating help texts, graph plotting, etc. and requires a user provided PC with an
Summary of Contents for S12-MKII
Page 1: ...Advanced Environmental Hydrology System Instruction Manual S12 MKII ISSUE 21 February 2014...
Page 4: ......
Page 8: ...4 Equipment Diagrams Figure 1 Front View of S12 MKII Hydrology System...
Page 9: ...Equipment Diagrams 5 Figure 2 Plan View of S12 MKII Hydrology System...
Page 10: ...Armfield Instruction Manual 6 Figure 3 End View of S12 MKII Hydrology System...
