2
®
Main parts of
SP-48-FD
pilot are: air tube (pos. 4 on Fig. 1) with combustion-cooling air inlet (3/4”BSP) and gas
part assembly including gas head (pos. 3) with gas inlet (1/2” BSP), ignition rod hole (1/2”BSP) with igniter rod
holding gland (pos. 6) and sight port hole (1/2” BSP) with stop plug mounted. It includes also the gas tube
(pos. 2) mounted in gas head. The orifice-stabilizer assembly (pos. 1) is fixed at the end of gas tube. It consist of a
gas divider with main and bleed orifices, gas tube and swirler-stabilizer. Gas part assembly is mounted in the air
tube by means of the thread joint with mounting ring (pos. 5).
Note that gas supply line should be equipped with an effective strainer unit to prevent the orifices from clogging.
In many applications
SP-48
pilots are mounted on the main burner using the mounting tube (see p. 3).
The source of ignition is an electric 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 of 16 mm and
coaxial electrode arrangement – see Fig. 3.
The ignition rod is mounted in the gas head and goes through air tube to the orifice-stabilizer assembly. The rod tip
end should be placed as on drawing Fig. 1, to provide a successful ignition of air-gas mixture.
Gas pilot
SP-48
can be supplied together with electric ignition device selected depending on the application
.
Ignition device is not in gas pilot scope of supply and should be ordered separately.
SP-48-FD
pilot principle of use: gas is supplied through the inlet 1/2“BSP to the gas head and to the gas tube and
further to the orifice-stabilizer assembly. A small amount of gas leaves through the bleed orifice mounted in the gas
divider, into the zone before the swirler-stabilizer plate, where it mixes with air to form a combustible mixture.
It is
ignited in that zone by a spark or an electric arc generated at the tip of the
electrical
igniter rod.
This pilot
flame
stabilizes at swirler-stabilizer plate. Further it ignites the main stream of gas which exits the main nozzle at the outlet
of the air tube. The main flame then stabilizes in the primary combustion zone at the outlet of the air tube. The
swirler-stabilizer plate and holes in air tube provide an adequate shape and stability of the flame.
The 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.
Thanks to this principle of design, the pilot combustion zone is protected, the main combustion zone is outside the
pilot, hence the air tube does not overheat and there is no need for retraction of the ignition device 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
0.6 – 0.8
m depending on the kind of
gas, gas pressure and pressure in combustion chamber.
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 electric circuit
switches the operating mode for ionization detection, confirming the presence of the igniter flame.
3. MOUNTING TUBES
FIGURE 2.
Pilot mounting tubes: for welding and flanged
For fixing the pilot burner to a burner plate there are two types of mounting tubes available (material: carbon steel),
offered as an optional accessory and to be ordered separately (see Fig. 2):
- a flanged mounting tube allowing the fixing of a gas pilot without the use of welding, to be fixed with bolts to
the burner plate. After inserting the pilot into the mounting tube its position is determined and secured with a
clamping ring located at the end of the tube assembly. This ring also provides the necessary sealing for the
connection,
A
O 55
mm
O 90
mm
3 x O 9 mm
O 73
mm
120 mm
FLANGED MOUNTING TUBE
MOUNTING TUBE FOR WELDING
120°
6 mm
~ 34 mm
