135
Descriptions
Oxygen ratio control - S-ORC
Oxygen ratio control - S-ORC
To ensure an O
2
concentration greater than 21% by
volume in the fresh gas, the anaesthetic workstation has
an O
2
ratio control system (S-ORC =
S
ensitive
O
xygen
R
atio
C
ontroller).
S-ORC limits the N
2
O flow as a function of O
2
flow.
Up to an O
2
flow of 200 mL/min, N
2
O is cut off. N
2
O is
slowly released as from an O
2
flow of 200 mL/min.
For O
2
flows greater than 300 mL/min, N
2
O can be
added, and the S-ORC prevents the O
2
concentration
falling below 21% O
2
by volume.
The graph shows the range of adjustable O
2
/N
2
O ratios.
S-ORC is not an oxygen-specific monitoring system.
By adding anaesthetic vapours (e.g. Desflurane up to
18% by volume), the O
2
concentration in the fresh gas
is reduced.
Therefore:
Monitor the O
2
concentration with the breathing gas
monitor.
100/0
Concentration ratio
O
2
/N
2
O
Minimum O
2
concentration
90/10
80/20
70/30
60/40
50/50
40/60
30/70
20/80
10/90
0/100
0
200
400
600
O
2
-Flow [mL/min]
800
1000
3000
4000
100/0
O
2
/N
2
O
90/10
80/20
70/30
60/40
50/50
40/60
30/70
20/80
10/90
0/100
O
2
/N
2
O ratios which can be set
with the delivery valves on the bank
of measuring tubes
Delivery valves
O
2
N
2
O
O
2
N
2
O
Control
diaphragms
N
2
O-
shutoff
valve
Flow restrictors
Flow tubes
in the bank of
measuring tubes
ORC
08728971
08828971