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APECS 4™ OPERATIONAL
INSTRUCTIONS (v.)
Avoiding the dreaded voltage limited sensor:
Most eCCR’s rebreathers share a common voting system called “Sample data
control”. All rebreathers should have 3 sensors, as the saying goes, 1 is none, 2
is 1 and 3 is two. With 3 sensors you have an odd number system that can “Vote”
the odd man out or bad sensor in this case, but it can also vote the good sensor
out.
Since the sensors are the eyes of the rebreather, they send millivolts (Voltage)
down wires to the electronics, and the electronics via calibration make sense of
what the output is from the sensors, and the diver understands that as PO2
displayed on the handset.
If a sensor is somehow compromised such as being too old, it will not put out the
proper level of millivolts and in fact it will be too low and if it is a single failing
sensor it will be voted out and removed from oxygen addition system that
controls the solenoid. The other two sensors will then average the PO2 and send
signals to the solenoid to add oxygen when required.
The dreaded mV limited sensor is when two sensors go bad or all three go bad
and average the millivolts from the sensors and they cannot reach the required
mV to achieve a set point above 1.0 or higher, and they keep injecting oxygen to
try to reach the required mV output. But what happens is the diver thinks they are
breathing a PO2 of 1.3, but in reality a 2.0 or 4.0 PO2! And suffer an O2 hit as a
result.
HOW TO AVOID! CHANGE THE SENSORS YEARLY!!! USE ONLY ISC
SENSORS!!! As of 12 March 15, ISC has had a 0.03% failure of ISC sensors.
A near perfect performance.
DIVING SIGNS OF mV LIMITED SENSORS!
• A Sensor gets voted out and stays voted out.
• Sensors that are acting slow.
• Solenoid keeps injecting or you are constantly adding oxygen manually, and
you are not ascending.
• You know you have old sensors or you know you are diving the wrong ones!
Bailout if you have doubt! If there is any doubt then there is doubt and
bailout!
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Revision a
APECS 4™
58 of 63
Date: 01 Nov 14