Honeywell vk41 series Handbook page 27

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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
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
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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
spring pressure. The resultant move of the
diaphragm inhibits the increase of working gas pressure on
the main valve diaphragm. Only when the
been totally compressed does the working gas pressure
increase rapidly once again until the regulator set point
pressure is reached.
ON position,
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gas only, main valve partially open
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mechanism achieves
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chamber via the inlet orifice,
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spring has
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Fig. 16. Servo pressure regulation
0 2
Fig. 15. Opening characteristics
adjustment
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The adjustable
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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.
Safety valve open
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27
Fast open
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time (s)
feature allows for individual
ON position, main valve open
models
EN2R-9004 0606R20-NE
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