Nibp Pneumatics Description - Welch Allyn PROPAQ CS Service Manual

116 Technical overview

NIBP pneumatics description

The NIBP (cuff) system:
• inflates the cuff to a target cuff pressure
• converts the cuff air pressure to an electrical signal using a pressure transducer
• deflates the cuff in a controlled manner while the monitoring electronics determines
blood pressure
• protects the patient from cuff over-inflation
The NIBP air system consists of the pump, air valves, transducers, and the cuff. Except for
the primary transducer and cuff, all NIBP pneumatic components are located on the
Recharger Board.
The pump inflates the cuff only when the bleed and dump valves are closed. These two
valves are normally open to ensure the NIBP tubing does not remain pressurized when
the valves are not energized. The linear valve's programmable iris determines the cuff
inflation and deflation (bleed) rate.
Two transducers provide redundancy in pressure monitoring to ensure accurate readings
and to ensure cuff deflation in an over-pressure condition. If the cuff pressure reaches the
maximum allowable pressure for the patient class (adult, pede, or neonate), the dump
valve opens to quickly deflate the cuff.
The figures on the following pages illustrate the pressure conditions during a typical NIBP
measurement process.
pneumatics system diagramp
CUFF
TO DAP A-D
CONVERTER
PRIMARY
TRANSDUCER
SERVO
(LINEAR)
VALVE
(N.C.)
DUMP
VALVE
(N.O.)
SECONDARY
TRANSDUCER
TO DCP A-D
CONVERTER
Welch Allyn Propaq CS Vital Signs Monitor
BLEED
VALVE
(N.O.)
PUMP
0696-61