Technical information
25
Venturi casing
Function
The gas mixer arranged between the air cleaner and the engine block draws gas into the
venturi throat at varying pressure up to about 1 mbar (i.e. pressure drop relative to air
cleaner internal pressure) in proportion to the air flow velocity in the area of the restriction
of the venturi.
In this annulus, gas and air are mixed. See also negative-pressure controlled gas meter-
ing in zero pressure regulator of gas regulating station.
With the throttle valve open (full load), the setting screw, (5), is used to limit the gas flow
according to the value of the gas and the maximum permissible engine output as well as
the desired air excess (lambda).
The setting screw is factory set during the test run of the engine in the maker’s works,
but the engine output has to be tuned up again by trained personnel at destination before
commissioning the set to allow for any differing operating conditions, especially with
respect to gas quality.
After this final setting, no changes should be made and a seal should be applied to pre-
vent unauthorized interference.
By no means must the maximum continuous engine rating permitted by the maker
(see applicable engine performance characteristic of E 2842 E) be exceeded due to
incorrect setting.
Any necessary readjustment of the gas flow, e.g. especially when a different gas quality
with a higher heat value is used, must only be entrusted to trained personnel.
Throttle valve casing
By adjusting the throttle valve and, thereby varying the gas/air mixture flow, it is possible
to set the desired engine speed as a function of the engine load.
To regulate the idling speed, the bypass gas flow is adjusted by turning the locked setting
screw (5), with the throttle valve closed.
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