RST Instruments VW2100, Instruction Manual, Page: 13 / 34

VW2100 Vibrating Wire Piezometer
Instruction Manual
ELM0005P RST Instruments Ltd. Page 13
Example for a 350 kPa Range Piezometer
A = - 4.1484E-07 kPa/(B-Unit
2
)
B = - 0.10991 kPa/B-Unit
C = 996.58 kPa
L = 7200 B-Unit
T
K
= -0.03413 kPa/ºC
T
0
= 22.9 ºC
T = 5.0 ºC
F = 0.1 kPa/mbar
S
0
= 1003.1 mbar
S = 995 mbar
P = [(-4.1484 E-07) x (7200)
2
] + [-0.10991 x 7200] + [996.58]
+ [-0.03413 x (5.0 - 22.9)] - [0.1 x (995 - 1003.1)]
= [-21.51] + [-791.35] + [996.58] + [0.61] - [-0.81]
= 185.14 kPa
5 I
NSTALLATION
Vibrating wire piezometers can be installed in various ways to suit the individual
application. Specific guidelines for piezometer installation have been developed by
various agencies and technical specialists. Appendix F provides a list of references.
The following instructions summarize the generally accepted practice for:
•
Filter saturation;
•
Cable identification;
•
Piezometers installed in clay fill, granular material, or boreholes;
•
Cable routing.
It is not recommended that vibrating wire piezometers be installed in wells or
standpipes where an electrical pump and/or a power supply cable is present or
nearby. Electrical interference from these sources can cause unstable readings.
Ground fault currents from this type of equipment can easily damage the sensitive
low voltage vibrating wire piezometers. Additional steps must be performed on site to
ensure complete isolation and adequate grounding of the instrumentation circuits if