HYDROLOGICAL SERVICES PTY LTD
_______________________________________________________________________________________
Fig.8 - water seals off air and at this point system pressure is still atmosphere.
Fig. 9 - system operating under head conditions.
As the water rises, the system pressure increases to the equivalent of the head H minus the
amount the water rises within the bulb.
This amount x, is non-linear and therefore cannot be completely compensated for by simple
calibration.
Provided the head H does not fall below say 300 mm, error from this cause is minimal.
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.
Gas Purge Compressor
Issue 7:
16/12/03
© Copyright
HS55 110-020
