6.2 Attaching Vibrating Wire Transducers (VWT)

Tools and accessories required: 11/16" (18 mm) and 5/8" (16 mm) wrenches.

Figure 6-5 Tools and Accessories Required

Each one of the VWT's cables has been cut to the length requested in the original order. This length also includes an additional 10% contingency. The total cable length is labeled on the cable's end.

Match the serial number on the VWT body with the labeled cable end, and its corresponding "Vibrating Wire Transducer Calibration Report" provided in the shipment (see Appendix II).



Match the serial number on the body of the VWT with the label at the end of the cable.


Figure 6-6 Presoaking the Vibrating Wire Transducers


Soak all of the VWTs for about 30 minutes, in either the borehole, or in a bucket of water at the same temperature as the borehole water. Once the VWT has stabilized, lift the VWT just out of the water and record the measured transducer temperature and vibration reading. Record this value on the Installation Log as the VWT's 'zero value'.

Compare this 'zero value' to the 'Factory Zero Reading' on the Calibration Report. These values should not differ by more than 0.1% of full scale. Remember that pressure varies with elevation (your site vs. factory calibration location), temperature, and barometric pressure.

The 'zero value' is used to subtract from all future pressure/head readings to calculate final depth to water measurements. See Appendix III for a sample depth to water calculation.

Uncoil the VWT's cable out to its full length. Push the 3/8" SS compression fitting with attached VWT onto the Port Stem. Using the 11/16" and 5/8" wrenches, tighten the two compression fitting nuts onto the Port Stem by 1 and 1/4 turns.


Figure 6-7 Vibrating Wire Transducer



Record the VWT 'zero value' on the Installation Log. It is needed to benchmark against all future readings.


Figure 6-8


Figure 6-9