NOTES:
1.Values are for a 2° F pressure drop at 125 F (51.7 C) saturated discharge tem- perature, 120 F (48.9 C) saturated condensing temperature, and 105 F (40.6 C) liquid refrigerant temperature.
2.Size each circuit separately.
Fig. 9 Ð R-134a Liquid Line Sizing, 30HXA Units
Table 3 Ð Liquid Line 2 F (1.1 C) Drop in
Saturated Temperature Example
SATURATED | | PRESSURE | | |
| LIQUID | | | | | |
| TEMP | R-134a | | R-22 |
F | | C | Psig | kPa | Psig | | kPa |
100 | | 37.7 | 124.3 | 857 | 195.9 | | 1351 |
98 | | 36.7 | 120.1 | 828 | 190.2 | | 1311 |
D PRESSURE | 4.2 | 29 | 5.7 | | 40 |
| | | | | | | |
Discharge lines should be looped above the compressors to avoid having charge ¯owing back to the oil separator and compressor during unit shutdown. Wrap back-pressure valve when brazing discharge line to avoid damaging the valve.
It is recommended that ®eld-supplied pressure relief valves be installed in each discharge line. Most local codes require that the relief valves be vented directly to the outdoors. The vent must not be smaller than the relief valve outlet, and the pressure setting should be 320 psig (2205 kPa).
Run a ®eld-supplied 1¤4-in. (6.4 mm) copper line between the back-pressure valve on the oil separator (bottom pres- sure vessel) to the ®tting on the refrigerant line entering the economizer port of the compressor to measure oil pressure differential. See Fig. 11. The back-pressure valve and the ®t- ting on the refrigerant line have a 1¤4-in. ¯are ®tting for mak- ing this connection. The ¯are nut is ®eld supplied.
IMPORTANT: There is a Schrader-type ®tting in each of the two 1¤4-in. ®ttings. These Schrader-type ®ttings MUST BE REMOVED before running the line.
The 30HXA units are shipped from the factory with a hold- ing charge of R-134a. Before opening the refrigerant sys- tem, relieve system pressure and recover system refrigerant through the charging valve on the cooler.
30HXC CONDENSER CONNECTIONS Ð The inlet fluid connection is always the lower of the 2 condenser con- nections. It is recommended that a screen strainer with a minimum of 20 mesh be installed ahead of the condenser inlet to prevent debris from damaging the internal condenser tubes.
The outlet water connection is the upper connection of the 2 connections. The condenser has weld couplings to connect ®eld-supplied piping. Plan the piping arrangement in accordance with good piping practices and so that the pip- ing does not cross in front of the condenser head. Use ¯ex- ible connections on the condenser piping to reduce vibration transmission. Offset the piping to permit condenser head re- moval for maintenance purposes. Install pipe hangers where needed. Make sure no weight or stress is placed on the water nozzle.
