Dräger Medical Zeus Technical Documentation Manual page 42

Function Description
Figure 17 Metering module gas flow diagram
34
When the metering module is connected and locked in place, the closure
valves (25) and (72) are mechanically opened. The module detector (38)
detects the connected and locked metering module. The pressure sensor
(21) measures the input pressure of the propellant gas.
The storage tank (17) for the anaesthetic is fitted with a capacitive level
gauge (18) and a safety valve (64). The safety valve (64) opens at 1.5 bar. It
activates only if the metering module is overheated, e.g. by being exposed to
direct sunlight, and the vapour pressure rises. In operation, the pressure of
the storage tank (17) can be relieved by solenoids (15, 22 and 23 or 15, 22
and 31) via the anesthetic gas scavenging line, so that storage tank can be
safely filled at any time with no risk of anesthetic vapor escaping.
When the tank outlet valve (16) is opened, the anaesthetic in the storage tank
(17) flows by gravity into the pump tank (14). At the same time, the open tank
vent valve (15) vents the space above the fluid level in the pump tank into the
storage tank, as otherwise the pump tank cannot be filled.
When the pump tank is full the tank outlet valve (16) and the tank vent valve
(15) close. The supply pressure valve (22) opens. Propellant gas flows out of
the supply module through the non-return valve (25), the supply pressure
valve (22) and the buffer volume (19) to the pump tank (14) and pushes the
liquid anaesthetic through the open top-up valve (13) into the metering tank.
The metering tank (12) is fitted with a capacitive level gauge (10) and a pres-
sure sensor (11). At approx. 1.3-1.6 bar the top-up valve (13) and the supply
valve (24) close. To enable the pump tank to be filled by gravity alone, the
line must be vented from the pump tank through the buffer volume (19), the
supply pressure valve (22) and the relief valve (23) into the anaesthetic gas
scavenging system (3.1). The buffer volume (19) artificially extends the sys-
tem so that no anaesthetic enters the anaesthetic gas scavenging system
(3.1). This reduces anaesthetic consumption.
Zeus
5133.001