Technical Safety BC-led boiler investigation influences global standards
Have you ever waited a moment too long to light a barbecue and been surprised by the “whoosh” as built-up gas ignites? Safety professionals call this a “hard light-off” or delayed ignition and, if you are outside, the result is typically a yelp followed by jokes about singed eyebrows. But in many circumstances, it’s no laughing matter.
Several hard light-off incidents at commercial and industrial buildings around British Columbia were reported to Technical Safety BC between 2011 and 2015. Owners of specific models of gas-fired hot water boilers reported hearing a loud bang or pop during start-up or operation, often with associated damage to the boiler venting system.
“One of these delayed ignitions actually blew the venting off and the boiler continued to operate,” recalls Technical Safety BC's Jeff Coleman, Leader, Engineering and Incident Investigations. “It was no longer venting properly and the products of combustion, including carbon monoxide, were staying inside the building.”
Thanks to the data reported to Technical Safety BC through past incidents, a trend became apparent. “Each time was a little different but we noticed it was the same manufacturer and same boiler model series in all the cases,” Coleman says. After an incident at a public athletics centre in Burnaby in October 2015, Technical Safety BC kicked off an in-depth investigation to prevent future occurrences.
Technical Safety BC brought together the manufacturer of the affected boiler, the boiler certification body and the facility owner to collaborate on an investigation and possible improvements. Building trust and communication between the parties was key and Technical Safety BC worked hard to keep the emphasis on mutual co-operation, collaboration and public safety.
Technical Safety BC guided the team through a number of activities including a review of the past incidents; interviews with witnesses, operators and maintenance contractors; and an examination of the boiler installation, components, gas supply and venting systems.
“The investigation quickly identified some commonalities among all the boilers that had malfunctioned,” says Chris Jorgenson, Technical Safety BC's Administrator of Gas Equipment Approvals. The first was the presence of a “white-potted” igniter that functions as part of an igniter-injector assembly. A particular design feature of these older igniters caused the metal tip to snap or the ceramic tube to crack when heated. The location of the igniters also contributed to carbon deposit build-up, preventing a clean ignition every time.
Another issue involved the purge system, which is responsible for clearing out gas if lighting doesn’t happen immediately. The purge cycle was found to be too short and weak to clear gas out of longer chimneys. The damaged igniter tip, combined with a low blower speed during purge, likely caused the ignition of an increased amount of gas within the boiler, forcing gas through and damaging the venting system.
Under the Safety Standards Act, a provincial safety manager can issue a safety order to prevent, avoid or reduce risk of personal injury or damage to property. Technical Safety BC's Gas Safety Manager, Brad Wyatt, issued a safety order that mandated an adjustment to the purge cycle, upgrade of the igniter, and regular service and maintenance requirements for these types of boilers in BC. “It is so important that these types of gas-burning equipment are installed to the manufacturer’s requirements as well as regularly inspected, cleaned and maintained by qualified gas fitters,” reminds Wyatt.
The manufacturer also noted several instances of maintenance neglect believed to be related to the incidents. It issued an updated technical service bulletin to alert owners of the potential issue and how to remedy it. The manufacturer also facilitated repairs to the damaged boilers and the replacement of white-potted igniters with the safer black-potted ones. All boilers of this type installed in BC are now required to have the igniters and the equipment serviced and maintained annually by a qualified gas fitter.
The implications of this investigation extend beyond BC. Underwriters Laboratories Inc., the certification body that certifies equipment of this kind, is currently clarifying the technical standards for gas-assist ignition system design and certification. When implemented, these changes will affect boiler certification standards at an international level.
This is just one example of how incidents reported to Technical Safety BC are resulting in wide-reaching changes to industry that are improving safety in the province and beyond.
This article was originally published in the 2016 State of Safety.