13
Eclipse ThermJet Design Guide No. 205, 3/5/07
Modulating gas with fixed-air control
A burner system with modulating control gives an input that
is in proportion with the demands of the process. ANY input
between high and low fire is possible.
Air
The amount of air to the burner is fixed.
Gas
The control valve
1
is in the gas line. It can modulate to any
position between low and high fire.
Note:
Use of a ratio regulator
2
in a fixed-air system is optional
on a single burner system only. However, eliminating the
ratio regulator will adversely affect the ignition reliability at
inputs greater than 40% of maximum.
1.
2.
Step 2:
Control Methodology
(continued)
Multiple burners
Automatic shut-off at the burner
Multiple burners
Automatic shut-off by zone
Single burner
Figure 3.2:
Modulating gas with fixed-air control
Optional IF flame monitoring system controls the main gas shut-off
valve train AND ignition above 40% of maximum is NOT required.
NC
Automatic
shut-off by
zone
NC
Automatic
shut-off at
the burner
P
to other Zones
to other Burners
Main gas
shut-off
valve train
to other Burners
➊
➋
to other Zones
P
to other Zones
to other Zones
Main gas
shut-off
valve train
to other Burners
to other Burners
➊
➋
P
NC
➊
Main gas
shut-off
valve train
➋
(optional)
