Spacelabs BleaseSirius - 5.2 Mechanical Hypoxic Guard Block

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5.2 Mechanical Hypoxic Guard Block
5.2.1 Introduction
The hypoxic guard prevents the operator from administering a mixture of gases
that contain less than 21% oxygen. To achieve this, the oxygen and nitrous
oxide control valves are linked via a set of gears. Any attempt to reduce the fl ow
of oxygen or to increase the nitrous oxide fl ow to a level which would result in
a oxygen concentration below 21%, results in the nitrous oxide valve closing or
the oxygen valve opening to maintain the 21% minimum oxygen concentration.
The fl ow meter has a minimum oxygen fl ow “Basal Flow”
which is only turned off via the main system ON/OFF switch.
• The hypoxic guard is factory-set and requires only routine calibration
checks.
• If any of the calibration results are found to be out of specifi cation during
routine checking, you can make some adjustment.This adjustment is
described later in this section and should be done with extreme caution.
• If it is deemed necessary to replace the hypoxic guard valve block due to
damage or wear, you can order a calibrated unit which will be supplied
with a test sheet. This sheet lists the regulator output pressures required
for correct setting.
• Do not dismantle the fl ow control valve cartridges. They are gas specifi c
and require no servicing. The cartridges cannot be repaired.
Detailed Repair Procedures