Choosing the Best Gas Detector - Ease of Use and Alarm Set Points
Choosing the Best Gas Detector - Ease of Use and Alarm Set Points
Datalogging vs. Non-datalogging
Datalogging AND Event Logging standard with G450 and G850 detectors
Make sure you have the needed accessories !
Charger?
Calibration gas and regulator?
Sample draw kit?
Datalogging kit?
Carrying case?
Warranty
Make sure to verify coverage before purchasing an instrument!
In the attached warranty:
Limited lifetime warranty on complete instrument applies to components and assemblies that are not consumed or degraded in normal operation
Sensors have separately identified warranty period: 3-year warranty on O2, LEL, CO, H2S and COSH sensors
One-year warranty on rechargeable NiMH battery pack and filters
Ease-of-operation!
Basic instruments should be simple to operate
A good sign is when the manufacturer can summarize normal day-to-day procedures on a single "Quick Reference" card
Alarm Setpoints and Take Action Criteria
Alarm settings must be sufficiently conservative to allow self-rescue
Workers must have enough time to get to a position of safety before conditions become so hazardous that the ability to self-rescue is impaired!
Alarm Setpoints
Should be determined as function of :
Potential hazards
Nature of job being performed
Environment being monitored
Regulatory requirements
Use "factory default" settings only if appropriate!
Example of typical default setpoints
OSHA 1910.146 specifies 10% LEL as the concentration at which the atmosphere is hazardous
Most manufacturers use 10% LEL as the "default" alarm setting
This is actually the maximum concentration to which the alarm may be permissibly set
Watch out for jobs and environments which require a more conservative alarm setting
If there is the slightest doubt use a more conservative setting!
Alarm Settings Under "Alternate" Entry Procedures
In the Preamble to 1910.146 "Permit Confined Spaces" the "safe for entry" level is 50% of the flammable or toxic substance that would otherwise constitute a hazardous atmosphere
LEL = 5%
Toxic gas = 1/2 PEL
Alarm Setpoints
Take action criteria should be subject to modification as function of job, circumstances, and/or other special conditions
Be alert to changes in the job or environment which may require changes in monitoring procedures!
Regulatory Requirements
OSHA 1910.146 "Permit-required confined spaces"
OSHA CPL 2.100 "Application of the PermitRequired Confined Spaces (PRCS) Standards, 29 CFR 1910.146"
1915 Subpart b "Confined and Enclosed Spaces and Other Dangerous Atmospheres in Shipyard Employment"
