The High Accuracy Volume Change Device (HAVCD)
provides a simple, high resolution, high accuracy alternative to
traditional volume change devices. The device is used to measure
volume change along a pressure line. The most common application for
the use of the HAVCD is during unsaturated testing where accurate
measurement of both small and large pore volume change is critical.
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specification datasheet as
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What are its
uses
The basic principle of the HAVCD is to record the change in the
height of the water column inside a vertically orientated tube
connected to the drainage line. The pressure head in the
tube is measured using a low range, high-accuracy differential
pressure transducer.
The water volume change is equal to the change in the water level
multiplied by the cross section of the tube. The accuracy and
resolution of the water volume indicator depends on the
cross-section area of the tube connecting to the drainage line.
Three tubes with inner cross-sectional areas of 28sq mm, 63sq mm and
196sq mm are installed as standard in the apparatus (see Fig. 1).
Through a series of valves, the user can choose one or two of the
three tubes according to the expected water volume change.
