Multiple ammonia sensors fail calibration test resulting in evacuation of occupants from building

Incident overview

During season end maintenance at an ice arena facility, an ammonia sensor failed a calibration test. A detector sensor was relocated from another piece of equipment in the system to be used as a temporary replacement. This second sensor also failed and caused an ammonia alarm to be activated.

Regulated industry sector

Boiler, Pressure Vessel and Refrigeration

Location

Peace River Region

Investigation conclusions

Site, system and components

The ammonia sensors are routinely function tested to ensure accurate detection of ammonia leakage in the refrigeration system. This sensor upon detecting an ammonia leak causes an alarm to be activated in order to evacuate occupants from the building.

Failure scenario(s)

• Ammonia sensors failed after previously functioning in service

Facts and evidence

• Ammonia sensors failed calibration test by licensed contractor
• A check of the refrigeration equipment by qualified staff resulted in no actual ammonia leak in the refrigeration system
• A written procedure by staff for ammonia detector function testing indicates to conduct the sensor function test using an ammonia cleaner or actual test gas
• An ammonia cleaning product was reported as being used instead of test gas

Causes and contributing factors

• The person in charge confirmed that staff had been using an ammonia cleaning product to function test the leak detector sensors which may have contributed in the failure of the ammonia sensors.

Impact

• Injury
  • Qty injuries: None
  • Injury description: None
  • Injury rating: None
• Damage
  • Damage description: None
  • Damage rating: None

Incident rating

Minor