Combustion safety switches on boilers & furnaces

April 25, 2011

Low gas pressure supervisory pressure switch on a boiler

When was the last time you consciously looked at and inspected the supervisory switches on your boilers and furnaces? When I visit a facility, I try to look at them whenever I walk by them. Sometimes, more times than I should, I find that the low pressure supervisory switch and the high pressure supervisory switch on the natural gas combustion train are pegged to the minimum position on the low pressure switch, and maximum position on the high-pressure switch. Occasionally I will also note other controls, such as the high-pressure cutout switch which is designed to shut the boiler down if the pressure exceeds safe pressure limits is not properly set.

Chances are that the boiler being protected by this switch with this setting will never shut down if the gas pressure falls below safe limits.

During normal operations, your fired equipment (your boiler or furnace) will operate normally for long periods of time, sometimes many months. During these times of smooth operation operators may become lax and may not perform the checks they should be doing on a regular basis. The disabling of safety devices, such as the high and low gas pressure supervisory switches, may lead to catastrophic results. Safety devices and combustion controls are installed for your safety and the safety of your employees. These devices are required because history has proven that they are needed, they can prevent catastrophic events, and they can save lives.

I urge you to implement a combustion safety program at your facility, and perform safety checks and calibrations of all safety devices on at least an annual basis.

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Dry Standpipe System Inlet

April 17, 2011

Dry Standpipe inlet for Fire Department use

Dry standpipes are an economical method to provide water supplies to areas which fire engines cannot access. This Dry Standpipe is located at the parking garage of an airport. A fire engine will pump water into the inlet fittings. The swing-clapper type  check valve allows the water to enter into the piping and prevents it from draining out when the hoses are removed. A low point drain prevents water from standing in the pipes and freezing in the winter. Fire departments should have a written operating procedures for using these systems.


Hydrant flushing should be performed annually

April 13, 2011

Yard hydrants should be operated annually and flowed until all foreign material has cleared.

This is a yard hydrant which had not been flushed for many years. This hydrant has been flowing for 3 to 4 minutes when this picture was taken, and the water is still brown. Yard hydrants should be operated and flushed on an annual basis. Each hydrant in your fire system should be opened fully and flowed until all foreign material has cleared, but for not less than one minute. A good flushing to remove silt and particulate matter should be performed annually to clear the underground pipes of debris.