Electronic Gas Mixer (Details); Electronic Gas Mixer - GE Datex-Ohmeda Aisys Carestation Reference Manual

Aisys
2.9.1 Electronic
Gas Mixer
(details)
Summary
2-26
The function of the Electronic Gas Mixer is to deliver a combination of Oxygen and a
Balance Gas (N O or Air) at a set percentage and flow rate as set by the user.
2
Total flow range for the system is 0.20 to 15 l/min of O
is greater than or equal to 25%. The system can flow Air only. The minimum flow though
any single flow channel must be greater than or equal to 0.1 l/min.
• O flow range is zero or 0.1 to 15 l/min
2
• N O flow range is zero or 0.1 to 12 l/min
2
• Air flow range is zero or 0.1 to 15 l/min
The flow accuracy of the Electronic Gas Mixer is +/- 20 ml/min or 5% of setting.
Diameter specific tubing (N
brings supply gasses O , Air, N
2
The Electronic Gas Mixer contains 6 solenoid valves.
Electronics located on the Electronic Gas Mixer board and flow sensor assembly
control and monitor the flow of gas delivered to the Electronic Gas Mixer output
connection.
The Electronic Gas Mixer receives 12.5 VDC Accessory power from several of the 10VA
power modules located on the Anesthesia Control Board Bd. Circuitry on the
Electronic Gas Mixer board further generates internal voltages required for systems
local to the Electronic Gas Mixer board. These voltages include: 3.3VDC and 5.5 VDC.
The Electronic Gas Mixer also controls the pan fan speed (Hi/Low). All these voltages
can be viewed in the service screens.
The microcontroller on the Electronic Gas Mixer has seven activity indicators. They are
failcode, Mixer Code, CPU, XMIT, and RCV. Under normal operation, the CPU Activity
LED will flash a 2 Hz (once per second) rate. The Red Fail LED should not be lit and the
XMIT and RCV LEDs should flash briefly and randomly to indicate communication with
the Anesthesia Control Board.
Two additional LEDs (Valve 1 and Valve 2) light to indicate when Channel 1 (O
Channel) or Channel 2 (Balance Gas Channel) Mixer Proportional Valves are opened.
Control of the Channel 1 and Channel 2 Proportional Valves is provided by circuitry on
the Electronic Gas Mixer. Closed loop feedback for these valves is provided by the Hot-
Wire Anemometers located on the flow sensor assembly (part of the Electronic Gas
Mixer).
Three pressure transducers; located at distal of the O
the Balance Gas Proportional Valve (P2), and proximal of the Outlet Check Valve, are
used to verify the accuracy of the flow in the gas channel. Hot-Wire Anemometer
Selector Valves (O , N O, and Air) are controlled by signals that originate on the
2 2
Anesthesia Control Board.
Shortly after Power-Up, the Anesthesia Control Board will generate fourteen
independent 10 VA Power Circuits, two of which will be used to power the Electronic
Gas Mixer.
The Electronic Gas Mixer will generate two local voltages: 5.5 VDC and 3 VDC.
The CPU LED will flash at a 2 Hz rate and the XMIT and RCV LEDs will flash randomly
indicating communication with the Anesthesia Control Board.
O = 4mm; O = 6mm; Air = 8mm; Mixed Gas = 1/4 inch)
2 2
O to the Electronic Gas Mixer control manifold.
2
2
or mixed O concentration that
2 2
2
Proportional Valve (P1), distal of
04/08 M1046983