Hollis Explorer User Manual - page 50
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The TPM contains 5 Thermostats arranged longitudinally through the
canister absorption path. The readings from these 5 thermistors are logged
and analyzed by the system. In this manual, it is not appropriate to explain
this data analysis in detail. However, it is appropriate to describe some of
the limitations of the device.
The CO
2
absorbent produces heat when CO
2
is absorbed. However, there
is also a temperature rise even when incomplete absorption of the CO
2
in
the breathing gas is achieved. This is a potentially dangerous situation, as
the system appears to be working correctly as there is still a measurable
temperature rise and wavefront in the system. The human body is tolerant
to only approximately 5 to 10mBar of CO
2
(ref CE standards for a life sup-
port system). A well-packed fresh Absorbent Filter absorbs all the exhaled
CO
2
for a period of time until an amount of CO
2
starts to creep through.
When this level reaches 5mb it is assumed there is no life left in the filter.
However even at 5mb there is still considerable thermal activity within the
filter.
DANGER: So be aware that a well packed and well maintained
Absorbent Filter is key in achieving a life-support system. The
CDM is not a substitute for good system maintenance and Pre-
Dive checks. Always use your training and discipline to ensure
the sub-systems in the EXPLORER are operating correctly.
Critical components and potential failures are:
• The filter seal around the Absorbent filter
• A poorly packed (user pack only) filter
• Used or out of date absorbent material
!