Medivance Arctic Sun 2000, Руководство по обслуживанию

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The hydraulic system is composed of two major fluid circuits; the circulating circuit and the chiller
circuit (see Figure 2.1). The circulating circuit controls the flow of water to the pads. The chiller
circuit provides a constant source of cold water that is pumped, as needed, into the circulating
circuit.
Water in the circulating circuit is pulled from the Circulating Tank through the Inlet/Outlet Manifold
and out to the Energy Transfer Pads. Water then returns from the pads through the Inlet/Outlet
Manifold to the negative pressure side of the positive displacement Circulating Pump. Water
leaves the Circulating Pump under positive pressure then passes through a turbine flow meter
and heater before returning to the Circulating Tank. Water in the Main Tank replenishes the
circulating circuit.
The chiller circuit operates independent of the circulating circuit. Water in the Chiller Tank drains
into the centrifugal Chiller Pump where it then is pumped under positive pressure through the
Chillers’ evaporator. The evaporator is a heat exchanger with cold refrigerant on one side and
water on the other. Water then returns to the Chiller Tank to complete the cycle. The system
controls the temperature of the water in the Chiller Tank to 4
°
C by activating a valve on the
refrigerant side when additional cooling is no longer needed.
When the system determines water must be warmed, the heater is activated in the circulating
circuit. When the system determines water must be cooled, water is drawn out of the Circulating
Tank by the positive-displacement Mixing Pump and metered into the Chiller Tank. This causes
water to overflow the Chiller Tank and refill the Circulating Tank with cold water where it mixes,
cooling the circulating water.
The flow of water to the pads is controlled by regulating the Circulating Pump speed using
pressure sensor (P1). The pressure is regulated to -7 psi. This assures that the flow through
each pad is maintained regardless of how many pads are connected. Since water in the pads
and lines is at a negative pressure relative to ambient, any break causes air to enter the circuit
instead of water leaking out where it may contaminate the patient. This valuable feature can
make troubleshooting leaks more difficult.
The temperature of the water going out to the pads is controlled using a temperature sensor (T2)
and monitored by a temperature sensor (T1). Both sensors are located in the Circulating Tank.
Temperature sensor (T3) measures the temperature of water returning from the pads. The
difference between outlet and inlet water temperature along with the flow rate provides the control
algorithm real-time feedback on the current heat load for optimal temperature regulation.
Temperature sensor (T4) is used to regulate the cold water within the chiller circuit.
There are three valves installed in the Inlet/Outlet manifold to permit filling the system with water,
pre-conditioning the water to a desired temperature, and emptying the pads of water at the end of
a case. When the Fill mode is activated, water is drawn up through the Fill Tube, through the Fill
Valve (FV) by the Circulating pump. The water then enters the Circulating Tank and by gravity
passes to the Main Tank. Air, displaced by the water, exits the Main Tank through a small hole
in the top of the tank. It is important to note that pads cannot be connected during this operation.
The user may wish to pre-condition the temperature of the water prior to pads being connected.
The system will detect the absence of pads connected by feedback from the flow meter and
pressure sensor and will open the Bypass Valve (BV). Water is drawn out of the Main Tank
through the Bypass Line and is shunted past the Fluid Delivery Lines into the circulating circuit