Blinding Light EN298

Blinding Relays on Burners Systems

Burner control boxes for both package burners (EN676) and industrial burners (UP12/EN746) are built to EN298. The boxes are designed to follow a logic of checking interlocks and sequencing the burner through purge to ignition.

Industrial burners are typically designed to scan across the flame, whereas package burners and smaller nozzle mix burners scan down through the flame.

This is not a problem when applying burners to air heaters, boilers or thermal fluid heaters, but when they are wrongly applied to high temperature equipment there is a risk they will detect ‘stray UV’ from either the process or another burner.

EN298 states; during start up, the system shall check for a flame signal. If detected the system shall not proceed to the next step in the sequence or proceed to a lockout. EN746 states; detection of a flame where there should not be a flame shall result in lockout.

To overcome this there is an accepted practice of either physically blinding the UV or by using a relay to blind the signal prior to the control box, up to start-up.

Which means not only does the burner (if EN676) burner not comply with the relevant standards for industrial application but the control system is also compromised.

It may not seem a big problem, but this essentially removes the safety circuit from controlling the burner.

A compromise which not only lowers the level of safety but can create a very dangerous situation and should be avoided.

Let me word this a different way if you have to introduce components into a hard wired safety circuit to make burner work, then you have to ask is the product fit for purpose?

If you are concerned your equipment does not meet standards or is unsafe, you should immediately report the issue to either Gas Safe or OFTEC.

Alternatively if you need advice or support contact us via the website www.duomo.co.uk