Flow Valve Calibration (Vhome Trim) - CareFusion LTV 1200 Service Manual

Flow Valve Calibration (VHome Trim)

The flow valve should not normally require recalibration from its factory set values. However,
some circumstances, such as mechanical shock, may cause the flow valve calibration to
change from its factory-set condition. This flow valve calibration procedure can be used to
adjust the flow valve calibration setting to compensate for improper flows measured during
the Performance Checkout procedure.
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LTV software includes an adjustable VHOME option to allow for field calibration of the flow
valve. Specifically, the location of the flow valve HOME position Flag can be set relative to
the position sensor.
Proper ventilator flow performance depends on several conditions, such as transducer
calibration and lack of leaks in the airway passages, in addition to flow valve calibration.
Flow valve recalibration should only be performed after all other factors affecting flow
performance are verified to be correct. This procedure is designed so that it checks the
other factors contributing to flow performance before adjusting the flow valve calibration. For
this reason, it is important to follow this flow valve calibration procedure completely, and in
the stated order.
CAUTION
Recalibration of the flow valve - When recalibrating the flow valve this procedure must be
followed completely, and in the listed order of events.
Calibration of the valve differential (see page 6-14) and stepper motor (see page 6-20) must
be performed prior to performing flow valve calibration.
1) Determine the current configuration of the flow valve.

Turn the Set Value knob to the VENT OP menu and push the Select button.

Turn the Set Value knob to the VHOME XXX display and record the value.
2) Allow the vent to warm up by operating at nominal settings for 1 hour, or warm up to
102° – 105° F in SERVO mode with a suggested setting of 20 Lpm and 6000 rpm
(maximum rpm settings), before beginning the flow valve calibration.
3) To put the ventilator into SERVO mode, turn on the LTV
Clear the REMOVE PTNT alarm and press Select when VENT MTNCE is displayed.
Press Select when SERVO is displayed and navigate to SERVO ON, then press
Select. Use the Insp. Time window to set Lpm and the High Pres. Limit/Low
Pressure windows to set turbine rpm value.
4) Once the vent is warmed up, return the flow to 10 Lpm and the turbine speed to 4000
rpm.
5) Connect the patient outlet port of the ventilator to a flow meter using a 22mm flexible
hose (P/N 10983, Optional).
6) Press the Manual Breath button. Allow the ventilator to run for a minimum of 1 minute
to stabilize.
Page 6-26
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LTV 1200, 1150, and 1100 Ventilator Service Manual
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in the VENT MTNCE mode.
p/n 18603-001, Rev. J