Sierra Monitor Corporation TR-002 user manual

Summary of the content on the page No. 1

Technical Reprint TR-002

Gas Risk Management – A Safer Approach to
Monitoring for Hazardous Gases

Monitoring for gas leaks has historically consisted of the use of dosimeters, or fixed detectors. Little has been done to
use these measurement methods within a system’s concept; and, collectively, these technologies do not encompass all
the ingredients required to comprehensively manage the risk of personnel or equipment exposure to gas leaks.

Essential to the goal of protecting people

Summary of the content on the page No. 2

Technical Reprint TR-002 For some gases, excursions are permitted where the gas concentration may increase above the TLV for a limited period of time, i.e. the allowable excursion duration. The ceiling limit is the maximum concentration of a contaminant allowed without regard to duration. For example, in California, Hydrogen Sulfide has a TLV of 10 ppm with an excursion limit of 20 ppm for minutes in an 8-hour period. Its ceiling limit is 50 ppm. Oxygen Deficiency. Where purging or pro

Summary of the content on the page No. 3

Gas Risk Management – A Safer Approach to Monitoring for Hazardous Gases numbers of sensors, it may be economical to apply the calibration gas automatically. A method to check sensor span voltage versus acceptable tolerance should be available either through calculation or as a system report. Advanced systems can prompt “calibration due” according to a user configured calibration frequency. Response To Alarms. Response to alarms begins with preplanning – in plant and outside the pla

Summary of the content on the page No. 4

Technical Reprint TR-002 Typical Hydrogen gas sensor locations in a semiconductor manufacturing facility include: • Hydrogen storage areas • Valves in Hydrogen pipelines • Furnace area – inlet, outlet, internal tubing • Off gas ducts • Return room air ducts • Cavity between dropped ceiling and the roof (or floor above) In this plant there are sixteen sensors located within four rooms. Sensors are a catalytic bead type. There are two beads in each sensor element, one of which is a