Application Considerations

Figure A-1 — Typical Steam Supply Piping

1. Steam Supply Valve (Detail "B")

2. Strainer

3. Union or Flanged Connection

4. Gate Valve

5. Drip Leg

6. Float & Thermostatic Trap

7. Pressure Gauge, Vent and Shut-off Valves (Detail "A")

8. Pressure Reducing Valve

9. Pressure Gauge

10. Relief Valve

Note: Nominal steam valve is selected for a pressure drop of 5 psig. If steam supply pressure exceeds the selected valve pressure drop, a pressure reducing valve (Item 8) may be needed.

Detail "B"

General

Trane Horizon™ two-stage absorption chillers are designed for use in air conditioning and process applications requiring a continuous and reliable supply of chilled water in the range of 40 F to 60 F. The Horizon two-stage model range is 380 tons through 1150 tons. Two-stage machines are most often used where an economic evaluation of refrigeration equipment justifies a higher first cost to obtain a lower operating cost.

Catalog application data is based on ARI 560-92. All selections are based on a fouling factor of .00025 on the interior of all tube surfaces. Selections based on the use of fluids other than water, or with other fouling factors, can be obtained by contacting a local Trane sales engineer.

In planning an absorption refrigeration installation, consideration must be given to providing the following:

• structural support

• service access

• tube pull space

• piping access for tube maintenance

• condensate handling

• steam supply control

• condenser water temperature control

• chilled water flow control

• chilled and condenser water flow limit

• generator hot water application

In a properly installed and maintained installation, the Trane two-stage absorption chiller offers a high degree of reliability.

Operating Limits

Trane two-stage absorption chillers operate with steam pressure up to 115 psig. In all applications, superheat should be limited so steam temperature does not exceed 400 F. Hot water machines can use up to 370 F hot water.

Water flows within the limits indicated on the appropriate selection charts will insure tube water velocities not exceeding 10 feet per second in copper tubes and 11 feet per second in cupronickel tubes. Changes in chilled water flow or condenser water temperature should not exceed 3 percent of chilled water flow per minute or a 1 degree condenser water temperature change per minute.

Steam Supply

The steam supply piping should be designed in accordance with good design practice, providing strainers, unions and gate valves for ease of operation and maintenance. A properly sized steam modulating valve, based on design flow and pressure drop requirements, is provided factory mounted by the Trane Company.

A hand valve in the steam supply piping is recommended when the machine will be out of operation for an extended period. The modulating steam valve may experience a small amount of leakage during shutdown. This leakage may result in heating of the equipment room unless the machine is properly valved off with a hand valve.

In all applications, it is recommended that the steam supply pressure to the control valve inlet not exceed design to assure proper valve close off. If steam supply pressures exceed design, a pressure reducing station should be used to control the steam pressure to the valve.

Figure A-1 illustrates a typical steam supply piping illustration that includes the appropriate hardware. Steam Supply