Dräger Narkomed 2B Operator's Instruction Manual page 30

Section 2
General Description
Scavenger
Interface for
Passive Systems
2-18
The scavenger interface for passive systems is used with
nonrecirculating HVAC systems (also called exhaust systems). This
scavenger is a "closed" system, using a spring-loaded valve for positive
pressure relief.
WARNING: Do not use this device with a waste gas disposal system
capable of applying a negative pressure to the scavenger
interface (a suction or vacuum waste gas disposal system).
WASTE GAS
INPUT PORT,
19MM HOSE
TERMINAL
INPUT
PORT CAP
OP76131
SAFETY RELIEF
VALVE, SHOWN
CLOSED
WASTE GAS
INPUT PORT,
19MM HOSE
TERMINAL
WASTE GAS EXHAUST PORT,
19MM HOSE TERMINAL