Methods of Detection Copy

Methods of Detection

  3. NOSE

Which one is most reliable? Why?

The API-55 recommends that monitors be calibrated at least once a month. They should be calibrated after each use with a Cal-Gas up to 50% of the maximum scale of the instrument. A 10% variance is allowed.


  1. Not Reliable
  2. Olfactory Accommodation/Paralysis Occurs About 50-100 ppm.

Personal Monitors

Personal Monitor Limitations

The battery and sensor are sensitive.
They work from a chemical reaction.
The reaction uses the chemical up.
When the chemical is used-up, the battery or sensor dies.
When the alarm sounds, leave the area to a safe zone and not return until the area is SAFE.

Contingency Plan

Evacuate in an upwind / uphill direction.  Report to briefing area immediately.  Do not return to the area until someone using proper detection equipment has re-evaluated the area and approved it safe to re-enter.


When approaching the job site, take precautions to ensure a safe entry.

  1. Observe condition signs & audiovisual alarms.
  2. Check for wind direction.
  3. Look for personnel & their activity.
  4. Enter the job site slowly.

H2S Signs

Do not be misled by signs reading caution H2S or warning H2S.

Because of the characteristics of the gas.  It has the ability to accumulate in levels above IDLH (100ppm).

H2S Location Entry Warning Sign

Typical Entry Warning Sign used on H2S Locations.

A colored flag may be placed in the corner of the sign to indicate current danger status.

Condition Green

Possible Danger – No Alarms.

All personnel on location must have a current one year H2S certificate from a formal H2S course.
Beards & sideburns must be trimmed as necessary to assure the seal
on the SCBA face piece will be free of hair.
Upon arrival at well site, report to supervisor to receive H2S briefing.

  1. Familiarize yourself with the site’s Contingency Plan.
  2. NO SMOKING except in specifically designated areas.
  3. Inspect & practice putting on your specific breathing apparatus.
  4. Know the location of the “Safe Briefing & Assembly Areas.”
  5. Remain “Wind Conscious” at all times. Be prepared to move across and “Upwind” in the event of an emergency involving an H2S release.

Condition Yellow

Moderate Danger – Intermittent Audible Alarm and Yellow Flashing Light.  10 – 50 ppm H2S

Go to “UPWIND” Safe Briefing Area if you are not specifically designated to control the well.
Be alert for change in weather conditions.
Check your safety equipment for readiness.
During an emergency, use the ”BUDDY SYSTEM” to prevent anyone from entering or being left alone in a contaminated area.
Report any indications of H2S to a supervisor.
Extinguish ALL SOURCES OF IGNITION after an alarm has been activated.

Condition RED

 Extreme Danger – Continuous Audible Alarm and Red Flashing Light.  > 50 ppm H2S

  1. Same precautions as in Condition “Yellow.”
  2. Don your SCBA.
  3. Remain in Safe Briefing Area or Assembly Area and await instructions for evacuation.
  4. Provide assistance to anyone who may be injured by toxic gases.
  5. Personnel shall ensure that their breathing apparatus is properly fitted and operational before entering an H2S contaminated area.