Most aspects seem to have been touched upon; still there seems to be a vagueness about the difference between balancing arriving air/gas pressures on one hand AND AFTERWARDS doing the dispensing of the gases.
In a traditional T–type mixer, the handregulated secondary airflap has
2 functions combined:
Reducing the intake air pressure to the same as the arriving gasline pressure.
Dispensing the same airflow as the arriving gasflow.
The obvious can be said as:
Create THE SAME FLOW RESISTANCE for air,
as the arriving gas has to OVERCOME.
With the membrane you can ONLY provide EQUAL PRESSURES
in the air– and gasline
BEFORE ANY DISPENSING and subsequent MIXING.
The dispensing happens with ganged TWIN flaps in TWIN throats...
Max, the repeating machine...