Unregulated ORO/ORD system operation

Unregulated'ORO pressure control valve and ORD differential pressure valve to offer the most cost-effective system refrigerant side of the head-pressure control. As ORI/ORD simplified system of this type of control, ORO/ORD system offers the possibility for accommodation condenser and receiver on the same level (see Fig. 11-36). By making these two valves, either individually or brazed together, there is added flexibility in the piping layout. Operation ORO/ORD system is such that almost constant receiver pressure is maintained for normal operation. As the temperature ORO element is reduced, the pressure is reduced accordingly. However, running bypassed hot gas through'ORO element temperature is adequately maintained so ORO/ORD system works well for ambient temperatures 40F (40C) and below. This is the third connection on'ORO also eliminates the need ti compounds in liquid drain line.

Please note that in Fig. 11-36'ORO is set in the liquid drain line between the condenser and receiver, while ORD is " the hot line of the gas pipeline bypass capacitor. Other than the fact that ORO acts in response to its outlet pressure (pressure in the receiver), ORO/ORD works in the same basic way as ORI/ORD system explained earlier.

Head-Pressure Control Valve Service

There are several possible causes of malfunction of the system with refrigerant sideЂќ head pressure control. It can be difficult to isolate from each other. As in any other system Troubleshooting, you need to know about the existing operating temperatures and pressures up to system problems can be determined. After fault is established, it is easier to pinpoint the cause, and then take the appropriate measures. Table 11-5 shows the most common problems, possible causes and remedies.

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