Datex-Ohmeda Aestiva 7900 SmartVent, Service Manual

Page: 25 / 181

2/Theory of Operation
1503-0151-000 3/27/97 2-7
Figure 2-9
MOBO (Mechanical Over pressure Bleed Off)
The Mechanical Over pressure Bleed Off Valve is a mechanical valve operating
even if there is no electrical power. The MOBO has two functions. First, it serves
as a third level of redundancy to the ventilator's pressure limit control functions,
providing pressure relief at approximately 110 cmH
2
O. Second, the MOBO serves
as a backup in the event of a complete blockage of the exhalation valve system,
relieving circuit pressure at approximately 30 cmH
2
O under such failure conditions.
Mechanical
Overpressure
Bleed Off
(MOBO)
Drive Gas Check Valve
(DGCV)
Supply
Gas
Hose
Manifold
Pressure
Transducer
Flow
Valve
Pressure
Regulator
Inlet
Filter
Gas
Inlet
Valve
(GIV)
25 psi
25 mm port 17 mm port
Exhaust
to Scavenging
System
Exhaust to
Ambient
Exhalation Manifold
35 - 100 psi
Supply inlet