27 EN2R-9004 0606R20-NE
SOFTLITE
Some burners function well using a fast opening valve with the
pressure build up as shown in fig. 15. However, other burner/
appliance combinations need a means of improving their
ignition characteristics by providing quieter ignition and
reducing flame roll-out. The
SOFTLITE mechanism achieves
this by changing the profile of the outlet pressure curve as
shown in fig. 15.
An extra diaphragm and spring are inserted below the main
diaphragm. When the electric servo operator valve is opened,
working gas enters the
SOFTLITE chamber via the inlet orifice,
and is fed into the space between the diaphragms. Working
gas pressure rapidly increases to a preset level, partially
opening the main valve ( fig. 16 .).
As soon as it reaches the start level it overcomes the
SOFTLITE
spring pressure. The resultant move of the
SOFTLITE
diaphragm inhibits the increase of working gas pressure on
the main valve diaphragm. Only when the
SOFTLITE spring has
been totally compressed does the working gas pressure
increase rapidly once again until the regulator set point
pressure is reached.
Fig. 15. Opening characteristics
SOFTLITE adjustment
The adjustable
SOFTLITE feature allows for individual SOFTLITE
setting from the rated min. setting upwards and for switching
over from natural gas to LP gas pressures.
An example is given in fig. 18.
Fig. 16. Servo pressure regulation
SOFTLITE models
SOFTLITE
Fast open
time (s)
02
SOFTLITE ON position,
SOFTLITE gas only, main valve partially open
SOFTLITE ON position, main valve open
Safety valve open
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