4 Safety THE TECHNOLOGY BEHIND THE ION SCIENCE TIGER XT
Photoionisation Detector (PID) PID is the abbreviation for “Photo-Ionisation Detector”. A PID is a hand-held, personal, or fi xed wall-mounted detector that measures a broad range of volatile organic compounds (VOCs) and some inorganic compounds in the parts-per-million (ppm) to parts-per-billion (ppb) range. It gives a continuous read-out and can alarm when concentrations exceed user-defi ned set-points. It can also log data, calculate Time-Weighted Average (TWA) and Short-Term Exposure Limit (STEL), and alarm above these hygiene values.
What PID is used in the ION Science Tiger XT?
The ION Science Tiger XT incorporates their own PID sensor, known as the MiniPID 2. This sensor consists of a high energy output, ultraviolet lamp and three electrodes. MiniPID 2 has been independently verifi ed as best performing on the market for speed, accuracy, resistance to humidity and contamination.
What makes the MiniPID 2 sensor diff erent to other PID sensors?
Standard photoionisation sensors do have issues, if the sensor chamber becomes contaminated with airborne dirt, ambient humidity can be absorbed by the contamination, creating a conductive path between the electrodes. This conductive path creates an artifi cial signal that varies with humidity. Airborne dirt can also coat the lamp window which over time, reduces sensitivity. To combat these effects of contamination, ION Science have a unique patented fence electrode and an anti-contamination system. The anti-contamination system consists of a fi ne, PTFE membrane that covers the entrance of the sensor chamber. It not only blocks the path to larger particulates, but it also retains ozone, that is naturally generated in the sensor chamber. Ozone cleans the sensor chamber and lamp window, helping the sensor to maintain optimum performance. Even the ION Science sensor chamber may become contaminated, the ION Science fence electrode blocks the path between the two main electrodes. This practically eliminates the effects of humidity. All ION Science PID sensors have a fence electrode and an anti- contamination system.
Tiger XT Response Factors The response factor (RF) relates the sensitivity of PID to a particular compound against the sensitivity to the standard calibration gas isobutylene. The RF is inversely proportional, so the lower the RF, the higher the sensitivity, and vice versa.
Ideally, the PID response to a compound would be calibrated using similar conditions to the end application. For example, calibrating the PID to the compound in the concentration range of interest. However, this is often not practical. Due to its safety, cost, and availability, Isobutylene is often used to calibrate PID, and a RF used to convert the isobutylene calibrated measurement to a measurement of the target volatile:
Concentration of target chemical = isobutylene calibrated measurement x RF
For example, the RF of anisole is 0.59 with a 10.6 eV lamp. That means 0.59 ppm anisole delivers the same PID response as 1 ppm isobutylene. A 10 ppm response to anisole, from an isobutylene-calibrated unit would indicate:
Concentration of anisole = 10 ppm x 0.59 = 5.9 ppm
ION Science are continually running research and development programs into PID. As such, the RFs of many chemicals have been measured against different PID variants, and lamps of various photon energy and intensity.
When calibrating, for the greatest accuracy, ION Science recommends calibrating against the target gas at the concentration of desired measurement. However, where this is not practical, over 1000 RFs are available in technical article ‘TA-02’.
Download here:
https://ionscience.com/en/gas-and- leak-detectors/customer-support/support-documents/ technical-application-articles/
Author Contact Details Rhys Redrup, Instrumentation Marketing Specialist • Ion Science Ltd
• The Hive, Butts Lane, Fowlmere, Royston, SG8 7SL, UK • Tel: +44 (0) 1763 208503 • Email:
info@ionscience.com • Web:
www.ionscience.com
PIN ANNUAL BUYERS’ GUIDE 2024
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88
