TROLL 9500 Operator's Manual - Geotech Environmental Equipment

Section 7: Monitoring Pressure (Water Level)4. In the Barometric Correction window, select the type of correctionto be performed:• None• Value: Enter a barometric pressure value to be subtracted fromall data points in the test file. Units are selectable, and yourentry is checked for validity. For example, in inches of mercurythe valid range is 14.3 to 33.5 (covering altitudes from the Alpsto the Dead Sea). You may not leave this entry blank, becausea fixed value will be needed even with a reference file (next option,see below) in case the time stamps in the two files do notcompletely overlap.• File: Select a test of barometric pressure data collected by aBaroTROLL or other PSIA instrument. This becomes the Referencefile from which barometric pressure corrections will bederived. If the time stamps in the files do not overlap completely,the fixed value will be applied.5. To save the corrected data in a new file that will be automaticallynamed, check the create new file checkbox.6. Click OK. The correction is performed immediately and the correctedfile is displayed.Recalibration RecommendationsPressure sensor accuracy can be adversely affected by improper careand handling, lightning strikes and similar surges, exceeding operatingtemperature and pressure limits, physical damage or abuse, as wellas normal drift in the device’s electronic components. Aside from damageto the sensor, the need for factory recalibration is dependent uponthe amount of drift a customer is willing to tolerate. Factory calibrationevery 12-18 months is recommended. Contact In-Situ Customer Servicefor information on the factory maintenance and calibration plan.Calculations of the accuracy drift of the MP TROLL 9500 over time arecontained in the Appendix of this manual. Contact In-Situ CustomerService for information on periodic check-ups and re cal ibration.A single fixed correction is appliedto the entire PSIA test file4The content of a reference file ofbarometric pressure data is usedto correct the PSIA test fileWith a check here, the correcteddata is saved in a separate,automatically named fileTROLL 9500 Operator’s Manual 530095110 rev. 007 01/09