2
®
O 38 mm
120 mm
A
FLANGED MOUNTING TUBE
MOUNTING TUBE FOR WELDING
3 x O 7 mm
O 52 mm
O 64 mm
120°
6 mm
~ 25 mm
2. OPERATION PRINCIPLE AND TECHNICAL SPECIFICATION
Unit construction provides a stable flame, ignition repeatability. No moving parts ensure long, trouble-free operation
with low maintenance costs.
SureFire II™
Pilot
SP-32-
NG/PG-
ND
can operate as an intermittent (light-off), or as a continuous gas pilot.
Main parts of
SP-32-ND
pilot are: air tube (pos. 4 on Fig. 1) with combustion-cooling air inlets covered by sliding
adjusting sleeve (pos. 5) secured by locking thumb screw and gas part assembly including gas head (pos. 3) with gas
inlet (1/2” BSP) and igniter rod hole (1/2”BSP) with igniter rod holding gland (pos. 7) together with the fixed gas
tube (pos. 2). The orifice-stabilizer assembly (pos. 1) is fixed at the end of gas tube. Orifice-stabilizer assembly
consists of nipple with main and bleeding orifices, mounting bracket and stabilizer. Gas part assembly is mounted in
the air tube by means of the thread joint with mounting ring (pos. 6).
Note that gas supply line should be equipped with an effective strainer unit to prevent the orifices from clogging.
In many applications
SP-32
pilots are mounted on the main burner in the mounting tube (see p. 3).
The source of ignition is an electrical high energy spark igniter (HESI) or high tension arc igniter (HTI) for safe or
hazardous area (depending on the application) equipped with the ignition rods of outer diameter up to 16 mm and
co-axial electrode arrangement.
The ignition rod is mounted in the gas head and goes through air tube to the mounting bracket of orifice-stabilizer
assembly. The rod tip end should be placed as on drawing Fig. 1 (depending on the kind of ignition device), to
provide a successful ignition of air-gas mixture.
Gas pilot
SP-32-NG/PG-ND
can be supplied together with electrical ignition device selected depending on the
application. Ignition device is not in gas pilot scope of supply, and should be ordered separately.
SP-32-NG/PG-ND
gas pilot principle of use: gas is supplied through the inlet 1/2 " BSP to the gas head and to the
gas tube and orifice-stabilizer assembly. Gas exits the main orifice to the primary combustion zone. At the same
time a small amount of gas leaves the bleed orifice before the stabilizer plate passing into the zone where it mixes
with air to form a combustible mixture. Air flow is adjusted by the sleeve which is fixed by a thumb screw.
Orifice-stabilizer assembly is optimized for Natural gas or Propane gas/LPG. In case of other Fuel gas type or other
capacity needed contact Fireye as this may need the pilot construction changes - see p. 11 for Special Pilots.
Ignition is initiated by a spark or an electric arc generated at the tip of the igniter rod before stabilizer. The pilot
flame stabilizes at stabilizer plate with holes while the main flame stabilizes in the primary combustion zone, at the
outlet of the air tube.
Thanks to this principle of design, the pilot combustion zone is protected, the main combustion zone is outside the
igniter, and hence the air tube does not overheat and there is no need for retraction of the ignition rod.
Pilot has to be mounted on main burner such that no part of pilot shall be in the main burner flame and cannot
project beyond the heater lining or a burner throat. The distance of the tip of pilot air tube from the main burner
flame should not be smaller than 150 mm – see Appendix 2.
The flame length is
0.3 - 0.5 m depending
on the kind of gas
, gas pressure versus the pressure in combustion
chamber and environmental conditions outside boiler/heater.
In addition,
using Fireye high tension igniter type
HTSS
in the
Spark & Sense
version
, the center electrode of
igniter rod is also an ionization rod extended into the primary combustion zone and specially designed to work with
SureFire II™
Pilots
.
The HT igniter initially creates the electric arc to ignite the gas, and then the circuit switches the operating mode for
ionization detection, confirming the presence of the igniter flame
FIGURE 2.
Pilot mounting tubes: for welding and flanged
