3
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DESCRIPTION (continued)
Guide Tube Assembly
The guide tube assembly contains the working parts of the igniter and houses the gas transport tube,
baffle, and HEI spark rod.
Gas is transported down the guide tube through the gas transport tube and is distributed to the pri-
mary combustion zone. A small orifice upstream of the baffle releases a small amount of gas to mix
with the cooling/combustion air.
Cooling/combustion air is transported down the guide tube and mixes with the gas at the baffle plate
to form a combustible mixture.
Ignition first occurs at the spark tip and then spreads to the gas transport tube opening at the tip end
of the igniter. Combustion is completed 2 to 3 feet into the furnace.
Mounting Tube (optional)
The mounting tube (Figure 4) is welded to the burner front plate in most cases, and supports the
igniter assembly. The igniter guide tube slides into the mounting tube and is secured in place by a
split clamping ring (squeeze collar), which is bolted to the mounting tube. The squeeze collar also
acts as a packing gland follower.
High Energy Igniter (HEI)
The HEI spark rod provides a 12-joule spark, which ignites the gas/air mixture. The HEI consists of
a fouling-resistant surface gap spark tip connected to a positioning rod, power unit, and cable. (See
HEI bulletin for details.)
View Port
An integral view port is provided on the head of the SureFire™ igniter.
SPECIFICATIONS
SUREFIRE 20
Fuel
Natural gas/propane
Guide Tube OD
1.88”
Mounting Tube OD
2.13”
Capacity Rating (MBTU/hr.)
1.0
Fuel Supply Requirements (psig)
10 psig
Cooling/Combustion Air Supply
12 SCFM@3”> windbox
Cooling/Combustion Air Pressure
(inches w.c. measured at the sight port)
0.5
Cooling/Combustion Air Connection
3/4” NPT, female
Cooling/Combustion Air Pressure
Measurement Port
1/8” NPT, female
Material of Construction
304 Stainless Steel (except for gas transport tube and HEI Rod).
Ignition Method
High Energy Igniter (HEI), 12 joule
NFPA Class
1, 2, or 3
Recommended Gas Hose Size
3/4”
Gas Hose Connection
1/2” NPT, female
Gas Line Strainer (FNPT)
0.33”
Summary of Contents for SureFire 20
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