HyQuest Solutions HS40C, User Manual, Page: 31 / 37

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Appendices
Basically the closed system will give good results subject to gradual changes of water temperature being experienced
and the system being completely gas tight.
A full discussion of this principle in given in “Low Cost Stream Height Recorders” - Unisearch (N.S.W) publication.
9.3 Appendix C HS40 Compact-DO (Dual Orifice)
Features of Dual Orifice
The Model HS40 Compact-DO comes with a dual orifice application. It consists of 2 orifices located at different heights
from the river bed. Under normal conditions the bottom orifice is active and the top orifice is inactive. The dual orifice
application become beneficial in a situation where severe siltation appears and causes the blockage of the bottom
orifice at which instance the valve of the bottom orifice (1) is closed and the valve of the inactive (top) orifice (2) is
opened to keep the bubbler system operating.
Another application for the dual orifice system is where higher accuracy is required over a large head, by splitting the
head into 2 smaller ranges – and using a transducer with lower range and higher resolution.
Note : Only one orifice can operate at a time. If the level of the second orifice exceeds the range of the transducer; the
transducer level can be set again at the second orifice.
9.4 Appendix D Gas Chamber Orifice Assembly GC01P/SS
Step 1:
Secure Socket/Locknut to the 2” BSP pipe