Description Of Normal Operation Dv5Hh - DeVilbiss IntelliPAP DV54 Service Manual

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12. Description of Normal Operation DV5HH

The heated humidifi er connects mechanically and electrically to a DV5X series PAP be-
tween the air stream going from the PAP to the patient. The keypad on the PAP controls
the heated humidifi er's output and ON/OFF functions. Before operation, the humidifi er
chamber is fi lled with water to a predefi ned and visible water-fi ll level with the patient
tubing and patient interface attached to the outlet port on the heated humidifi er system.
During operation, the DV5X series PAP device routes AC electrical power (100 – 240
VAC 50/60 Hz) to the heated humidifi er's drive circuitry, which is contained within the
PAP device. The drive circuitry directs the AC power to the heating element on the
heated humidifi er's heater plate. A thermistor on the heater plate provides continuous
feedback back to the control circuitry so that the temperature of the heater plate is con-
sistent with the setting selected via the PAP's keyboard. The PAP's internal switch-mode
power supply routes DC electrical power to the heater's low-voltage circuitry.
The heated humidifi er's heater plate transmits heat to the chamber, and then to the
water, through a heat transfer plate located on the bottom of the humidifi er chamber. As
the water is heated, its evaporation effi ciency increases. Air fl owing into the humidifi er
chamber from the PAP device is humidifi ed by the evaporation and is then transmitted to
the patient through the patient tubing and interface.
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