 |
 |
 |
|
Abstract and Manuscript Management System - Abstract Detail |
|
| Main Menu | Abstracts | |
| Speaker: | Mike Johnson |
| Title: | Improving Humidity Measurements For Field Calibration |
| Topic Group: | Humidity |
| E-mail: | mike.johnson@vaisala.com |
| Co-Authors: | |
| Abstract: |
Improving Humidity Measurements for Field Calibration Mike Johnson Vaisala Improving humidity measurements for field calibration relies on the hand-held instruments ability to hold its calibration curve over its established interval period. One of the most common causes of instruments drifting is due to chemical interference. As a hand-held instrument is used in a variety of applications and processes the susceptibility of the sensor element absorbing chemicals that could alter the calibration pose a serious risk. Eliminating the chemical interference from the sensor element is crucial to maintaining the performance of the instrument. Unknown Issues for Field Calibration The varieties of conditions hand-held instruments are exposed to are limitless. In most cases the user is not even aware of potential chemical interference. Preventing exposure is impossible in all cases so the key is to develop a way of eliminating the effect of the interference. Technology Challenges Eliminating the chemical from the sensor surface is the objective for improving performance. The need to develop a method in which sensors could be purged of chemicals without affecting the functionality is the main objective. How is it done? Using a specially modified sensor element and software controls, the sensor is able to eliminate chemical interference from the sensor surface. The sensor element is heated to a high temperature initiated and controlled by the hand-held indicator. The process for what is called the “chemical purge” takes only a few minutes. The feature can be activated at any time thus the control is in the hands of the operator. Results from Chemical Purge Tests have been conducted by exposing the sensor of a hand-held device to chemicals that are adhesive based. Data was recorded throughout the range for both before and after chemical exposure. A comparison was made to determine the calibration shift and the magnitude of the drift. The “chemical purge” feature was activated and the data was recorded once again. What does this mean? Users of hand-held devices can now feel more confident in the measurement they are taken. Calibration intervals may be increased based on the analysis of data from calibration results. Improvements of measurements will benefit the overall processes, with increased product performance and reduced operational costs. |
|
NCSL International © 1996-2008 All Content. May 16, 2008 10:21 AM |