FST (Flexible Single Tube) +44 (0)1204 594941

FST (Flexible Single Tube)


This Class I igniter is located in a tilting tangentially fired boiler adjacent to the main fuel nozzle.

As an oil igniter, the unique rear atomizer results in a single tube extending to the one piece tip. This design eliminates the need for atomizer maintenance.

As a gas igniter, the gas is directed to the tip through the single flexible tube. Stabilization is maintained by a 7.5 inch swirler which creates a low pressure zone just down stream of the nozzle. Combustion air is provided from the windbox.

Forney’s Flexible Single Tube (FST) Igniter provides multi-fuel, stable and reliable ignition for tangential burners utilizing a flexible design for optimal ignition with tilting nozzles.

Fuel Types

Light - Medium Oil

Markets Served

Corner fired Utility boiler

• Class 1 warm up and ignition
• Capacity up to 11Mw
• Air atomised
• Designed for tilting burners
• Low opacity
• Patented protected combustion zone
• Flame detection with UV scanner
• High energy ignition as standard
• Complete stainless steel construction
• Available in any length
• Diameters from 50mm
• Near maintenance-free operation
• Up to 99% reliable ignition 
Fuel: No. 2 Oil or Natural Gas
BTU Rating: Oil: 10 – 37 MBTU/hr
Gas: 10 – 20 MBTU/hr
Fuel Pressure: Oil: 60 – 125 psig
Gas: 12 – 25 psig
Cooling/Combustion Air: Flow: 40 SCFM
Pressure: 6 WC
Guide Tube OD: 2.38”
Mount Tube OD: 2.88”
Length: As Required, up to 8.5’
Atomizing Pressure: 20 psig (Differential over oil pressure)
Material of Construction: Guide Tube and Mount Tube, Carbon Steel; 
Guide Tube Tip and Pilot Area, 304 SST
Retract Cylinder Air Pressure:
(HESI/oil gun)
60 to 100 psig

HESI Specifications

Input Voltage: 120 to 240 VAC, 50/60 Hz
Input Power: 120 VAC @ 1.5 A (2-A fuse); 240 VAC @ 0.75A (1-A fuse)
Output Voltage: 2000 VDC
Output Energy: 12 joules per spark
Spark Rate: 3 per second (approximately)
Duty Cycle: 50% at temp 0°F to 135°F (-18°C to 57°C) Ambient