KST – KROMSCHRÖDER SYSTEM TECHNOLOGY
The main flame and, if applicable, the pilot burner flame, shall be supervised by means of an automatic burner control system.1) Exceptions are only permitted when equipment safety is not compromised (e.g. see 22.214.171.124 and 126.96.36.199).
Automatic burner control systems shall comply with EN 298 or EN 125, if technically applicable. If necessary for process reasons, the characteristics of the system shall differ from the requirements specified in EN 298 or EN 125 providing the levels of safety and reliability are not reduced.
For systems where the pilot burner remains in use during main burner operation, separate flame detector device to supervise the pilot and main flames shall be fitted. The main flame detector device shall be so positioned that it cannot in any circumstances detect the pilot flame. In the case that the pilot burner ignites under all circumstances the main flame, it is sufficient to supervise only the pilot flame providing the flow rate of that pilot burner is checked by a protective System according to 5.7.2 and 5.7.3 (e.g. minimum gas pressure switch).2)
Where the pilot burner and the main burner are each provided with their own flame detector device the ignition flame shall not influence the response of the main flame sensor.
For systems where the pilot flame is extinguished during main burner operation a single flame detector device may suffice.
Where fitted, flame sensors shall be unresponsive to unintended radiation.
Where a burner is required to fire continuously for periods in excess of 24 h, the automatic burner control system shall be designed for permanent operation.3)
The detection of a flame when there should not be a flame or a defect of the automatic burner control system or the protective system (according to 5.7.2 and 5.7.3) shall result into lock-out (see 3.48).
Where manual checking of the automatic burner control system is carried out, the instruction handbook shall specify the procedures to be followed in the event of a malfunction.
The following chapters are printed with the permission of the DIN Deutsches Institut für Normung e.V. (German Institute for Standardization). For the implementation of the DIN Standard, the version with the most recent issue date is deemed authoritative. This is available from Beuth Verlag GmbH, Burggrafenstrasse 6, 10787 Berlin, Germany.
Our note on this Standard:
1) In the case of combined pilot and main burners, both pilot burner and main burner must be supervised with an automatic burner control unit.
2) We always recommend combined pilot and main burner control if ignition of the main burner cannot be guaranteed under all operating conditions.
3) In this instance, the requirements of the Standard are more stringent than those of the predecessor version. A “once per week” test interval is no longer permitted.