Readouts

The Data Recorder lets you read thermistors (now Slope Indicator’s standard) and RTDs. At the “type:” prompt, you must choose either RTD or thermistor. A reading such as the one you are getting is typical of reading a thermistor as an RTD. Make sure the type is set to thermistor and your readings will probably be normal.

You probably have the standby timer set for 10 or 15 minutes. If you don’t press any keys for that length of time, the Recorder goes into low power standby mode to save battery power. To wake it up, press the Change key. If you want to change your standby timer setting, connect the Recorder to your computer and run the Manager program. Choose Edit Settings – Standby Timer, then enter a standby delay of days, hours, or minutes.

The following formula is valid only with the microstrain reading displayed by the VW Data Recorder. It is not a general purpose formula for converting microstrain to Hz.

F = sqrt ( (microstrain reading + 2030.1) / 0.0007576).

F is the microstrain reading converted to Hz.

Try these diagnostic steps.

1.  Make sure the internal tank has adequate pressure and the tank control valve is ON.
2. With no piezometer attached, set the supply pressure regulator to 100 psi.
3. Turn the flow control valve ON, and open the flow rate valve until the digital gauge reaches 100 psi.
4. Turn the flow control valve OFF. The digital gauge should settle around 100 psi. (Supply regulated pressure).
5.  If the the pressure drops below 100 psi, there is indeed a problem with the indicator. If the pressure is maintained at 100 psi, there is probably a problem with the piezometer connection, the piezometer tubing, or the piezometer itself.

Short Instructions for Reading Twin-Tube Piezometer

1. Before leaving office, check that the indicator has enough gas.
2. At the site, turn flow control valve to Vent and zero the pressure gauge.
3. Turn flow control valve Off.
4. Wipe off all dirt and moisture from the transducer tubing and connectors.
5. Connect the quick connect plug to Transducer socket and vent tube to the return flow indicator.
6. Turn tank control valve On, then turn the regulator knob clockwise until pressure reaches the rating of the gauge. 7. Turn flow control valve On.
7. Adjust the flow rate knob so that the pressure reading on the main gauge rises at about 1 PSI per second.
8. Wait until ball in return flow indicator shows a return flow of gas from the transducer, then turn flow control valve Off.
9. Wait until pressure reading stabilizes, then tap gauge and write down reading.
10. To verify, briefly turn flow control valve to Vent, then return to On. This changes the pressure reading. Now take a second, verification reading.