SERVICE MANUAL
Medi-Therm II
THEORY OF OPERATION
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aymar
.com P/N 10187-000 7/98
The Gaymar Medi-Therm II machine provides a means of regulating patient
temperature by supplying temperature-controlled water through a connector
hose to a Gaymar Hyper/Hypothermia blanket. The blanket provides an interface
for heating or cooling the patient. A patient probe senses patient temperature,
which is displayed on the control panel. (See figure 3, p. 8.)
The Medi-Therm II machine controls output water temperature by mixing hot
and cold water from two reservoirs using hot and cold solenoid valves under
microprocessor control. The feedback for control purposes is dependent on the
machine’s operating mode. A circulating pump, heater and refrigeration unit (all
under microprocessor control) are also utilized.
Bimetallic thermostats and associated backup circuitry limit output water
temperature independent of the microprocessor.
OPERATING MODES
The Medi-Therm II machine may be operated in one of three operating modes:
In
MANUAL
mode, the operator must observe patient temperature and
manually adjust the blanket water set point temperature. An inline blanket
water probe senses the temperature of the water pumped to the blanket and
provides feedback for control purposes to the microprocessor. The patient
temperature may be monitored by use of a patient probe.
In
AUTO
mode, the operator sets the desired patient temperature. The
patient’s temperature (as sensed by the patient probe) is automatically
regulated to this set point. The patient probe input provides feedback to the
microprocessor so it can adjust water temperature accordingly.
In
MONITOR
mode, the operator can monitor patient temperature through
the patient probe. No patient therapy is provided. The pump, heater, and hot
and cold solenoid valves are de-energized.
WATER RESERVOIRS
The hot water reservoir contains a small reserve of water. When the blanket
water requires heating, a cartridge heater under microprocessor control quickly
heats the water.
The cold water reservoir maintains approximately 10 quarts (9
1
/
2
liters) of water
at approximately 39.2°F (4°C). A cold water reservoir probe provides
temperature feedback to the microprocessor which then cycles a refrigeration
compressor to control the reservoir temperature.
6.0
THEORY OF
OPERATION, SYSTEM
6.1
THEORY OF
OPERATION,
MEDI-THERM II
MACHINE
9
