Welch Allyn LC101 CO2 Module - User Manual - Manual (Page 48)

LC101 CO
2
Module OEM Implementation Manual
Page 48 Confidential Welch Allyn OEM Technologies
Pneumatic Events
Pneumatic events which may occur include
• total inlet occlusion
• partial inlet occlusion
• total exhaust occlusion
• partial exhaust occlusion
• barometric pressure out of range
• unexpected reverse flow
• unexpected forward flow
Total Inlet Occlusion
A total blockage in some region of the inlet tubing, or a total inlet occlusion, is typically caused by
a kinked or occluded sample line, a fully saturated watertrap or an occluded secondary shutoff
pellet. 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 Module automatically reverts to a hold, or low
clearing vacuum (LCV) state, for up to 15 minutes. During this condition, the Module responds to
status requests with a Watertrap or Cannula 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 specific 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.