Play it Safe with Interlock Testing

Play it Safe with Interlock Testing

Your boiler is a fired, pressured vessel – left unchecked, it could be a potential time bomb, so it’s important to perform regular maintenance and conduct periodic safety checks, including routine testing of your boiler’s interlocked safety devices.

Inside your boiler is a series of valves, piping, wires and switches which provide control over the combustion process. As long as this process is controlled, combustion takes place when you want it to and everything goes according to plan. 

Fuel trains regulate the gas pressure as it feeds into the burners and prevents gas from entering the combustion chamber when your boiler is shut off. Regulators, valves and vents also help manage this process and ensure any leakage is directed outside the building when the equipment is off. Flame sensing components, gas valve position switches and furnace pressure switches also work in conjunction to make sure the combustion process operates smoothly.

Imagine all of these various parts in your boiler are musicians in an orchestra. Just as the orchestra needs a conductor to direct the music and keeps things in the right tempo, the boiler relies on the BMS (burner management system) to run the show, as it is interlocked with all of the safety devices. The BMS monitors all of the various components and safety conditions; if a problem is detected, the BMS will close the fuel valves.

The law requires regular checking of these safety interlocks and switches, but corporate budget crunches often lead to these checks being delayed or, worse, overlooked. While a boiler may continue to operate even if some of the interlock components aren’t working, this could lead to a critical mass situation where even the malfunction of one of the smallest components creates a domino effect that puts the entire boiler in jeopardy. 

To ensure the safety of your employees, it is critical to be properly trained and conduct regular service and testing. Here are just a few items to keep a watchful eye on:

Water Treatment – To prevent corrosion and scaling that can lead to deformation, overheating, and carry over of the water. 

Combustion Equipment – If not properly maintained, will result in reduced efficiency and soot deposits, which can contaminate the tubes and cause the efficiency to drop, creating less heat transfer. 

Automatic Boiler Burners – An electric spark ignites a fine mist of light fuel oil. If the flame does not start, the oil mist must be shut down or a dangerous explosive mixture of fuel and air could result. A properly functioning safety interlock shuts down the burner when the flame fails to ignite.

Low Burner Air Flow – Should the forced draft fan not develop enough air flow, a dangerous situation arises as combustible gases will start to accumulate. Again, a functioning safety interlock shuts things down before they get out of hand.

Water Level Interlock – This is, perhaps, the most vital safety feature. Should water levels fall too low, boiler components exposed to the heat will not be cooled by the water. As temperatures rise, steel parts lose their strength. Like Superman, the safety interlock comes to the rescue and shuts things down to prevent further damage.

With so many valves, igniters, burners, fans and vents, this article only scratches the surface. Interlock testing is a complex and serious issue. If problems arise, the WARE boiler pros are here to help with highly trained service technicians. We also recommend budgeting for regular service and maintenance, as well as for potential repairs. When you consider the catastrophic loss of life and property that could result without it, it is always money well spent. 

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