Glossary
Shut-off needle
Definition
Spring-loaded needle inside the atomizer that closes the orifice when the burner stops.
A shut-off needle is a spring-loaded needle that seats against the orifice from inside the atomizer. When the fuel pressure drops at burner stop, the needle closes the bore, so no fuel can drip into the hot combustion chamber.
Without a needle the sealing function must be provided elsewhere in the oil train — typically by the burner lance, by a solenoid valve or by the pump valve. Whether a needle is required therefore follows from the safety concept of the burner, not from the nozzle alone.
Fluid Control Instruments Ltd supplies TYPE 9 spill-back atomizers without a needle, TYPE 12 with or without, and TYPE 32 with a needle; the disc and air/steam atomizers are available in both versions. The lances H, EH and HA all carry a needle shut-off and are certified with original Fi atomizers as safety shut-off devices per DIN EN ISO 23553-1:2022.