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Ignition position monitoring (SIL 2, PL d)

The ignition capacity of the burner during the start-up procedure until the operating signal of the automatic burner control unit is received must be limited.

Requirement as per EN 746-2


Pressure surge caused by exceeding the start fuel flow rate

Determining the required SIL pursuant to IEC 62061

Frequency & exposure duration Fr: < 1 per h to ≥ 1 per day; > 10 min → 5 points

Probability Pr: as the safety time safely limits the pilot gas volume (SIL 3, PL e), the probability that a hazardous event occurs is rather low. → 2 points

Avoidance Av: as the pilot gas volume is limited by a fixed orifice, it is probable that the hazard is avoided. → 1 point

Effects: death, loss of an eye or arm

Determining the required PL pursuant to ISO 13849-1

Severity of injury S: severe (usually irreversible injury including death) → S2

Frequency and/or duration of hazard exposure F: frequent to continuous and/or long exposure to hazard → F2

Possibility of avoiding hazard or limiting harm P: possible under certain conditions → P1


Enter details


Enter the calculated values in the adjacent “app” to determine the required safety level.

App: Determining the required SIL, PL




Select products








The required SIL and PL can be achieved with these products. The calculation (see below) provides verification of this.

Sensor and logic: Gasfeuerungsautomat PFU (Bei dieser Art der Zündmengenbegrenzung ist ein separater Sensor nicht erforderlich.)

Actuator: solenoid valve for gas VAS














The flowchart shows how the products are integrated into the application to achieve the required safely level.


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