Welch Allyn Duet CO2 Module - User Manual - Manual (Page 48)

Duet CO
2
Module OEM Implementation Manual
Page 48 Confidential Welch Allyn OEM Technologies
Total Inlet Occlusion
A kinked or occluded sample line, a fully saturated Water trap or an occluded secondary shutoff pellet
typically causes a total inlet occlusion. In the event that this condition occurs, the Pneumatic System
ramps up the pump speed to achieve a high clearing vacuum (HCV) for 5 seconds. If the occlusion is
cleared by this action, the pump returns to normal operation.
If the occlusion is not cleared after 5 seconds, the automatically reverts to a hold, or low clearing
vacuum (LCV) state, for up to 15 seconds. During this condition, the module responds to status
requests with a Water trap or Sample Line Occlusion response. If the occlusion is not
removed after 15 minutes of LCV, the module reverts to the standby mode and a new measurement of
auto run mode command must be issued to start CO
2
waveform and breath data packet transmission.
NOTE Inducing a total inlet occlusion can be useful to check for internal pneumatic leaks. When the
module goes into the LCV state, typical pump operation remains relatively stable in holding
the vacuum.
NOTE However, if there are leaks within the overall system, the pump ramps up and cycles often to
maintain LCV. The module may possibly toggle between the normal and inlet occluded state
depending on the magnitude of the leak. A specific connection may also be tested by
blocking locations in the pneumatics.
Partial Inlet Occlusion
A partial blockage of the inlet tubing, or partial inlet occlusion, is typically caused by a partially occluded
sample line. In the event that this condition occurs, the Pneumatic System ramps up the pump speed
sufficiently to sustain the set flow rate. The module responds to status requests with a Status
OK response.
A condition of unstable operation may be evident when a partial blockage approaches the occlusion
threshold limits, causing the module to toggle between normal and occlusion states. If the blockage
increases enough to completely occlude the inlet tubing, the module reverts to the total inlet occlusion
state.
Total Exhaust Occlusion
An obstructed external exhaust port or clogged internal muffler typically causes a total blockage of the
exhaust tubing or total exhaust occlusion. In the event that this condition occurs, the Pneumatic System
ramps up the pump speed and remains in a high speed/no flow state indefinitely. During this condition,
the module responds to status requests with a Exhaust Occlusion or Pneumatic Leak
response.
WARNING The module remains indefinitely in the total exhaust occlusion state if not commanded
by the host.
Partial Exhaust Occlusion
In the event of a partial blockage of the exhaust tubing, the Pneumatic System ramps up the pump
speed enough to maintain set flow rates. During this condition, the module responds to status requests
with a Status OK response.
A condition of unstable operation may be evident when a partial blockage approaches the occlusion
threshold limits, causing the module to toggle between the normal and occlusion states. If the blockage
increases enough to completely occlude the exhaust tubing, the module reverts to the total exhaust
occlusion state.