5. The vessel shall display an ASME nameplate that shows the pressure and temperature data and the “U” stamp for ASME Section VIII, Division 1. A re-seating pressure relief valve(s) shall be installed on each heat exchanger. If a non-reseating type is used, a backup reseating type shall be installed in series.
6. Waterboxes shall have vents, drains, and covers to permit tube cleaning within the space shown on the drawings. A thermistor type temperature sensor with quick connects shall be factory-installed in each water nozzle.
7. Cooler shall be designed to prevent liquid refrigerant from entering the compressor. Devices that introduce pressure losses (such as mist eliminators) shall not be acceptable because they are subject to structural failures that can result in extensive compressor damage.
8. Tubes shall be individually replaceable from either end of the heat exchanger without affecting the strength and durability of the tube sheet and without causing leakage in adjacent tubes.
9. The condenser shell shall include a FLASC (Flash Subcooler) which cools the condensed liquid refrigerant to a reduced temperature, thereby increasing the refrigeration cycle efficiency.
F. Refrigerant Flow Control:
To improve part-load efficiency, liquid refrigerant shall be metered from the condenser to the cooler using a float-type metering valve to maintain the proper liquid level of refrigerant in the heat exchangers under both full and part load operating conditions. By maintaining a liquid seal at the float valve, bypassed hot gas from the condenser to the cooler is eliminated.
G. Controls, Safeties, and Diagnostics:
a. The chiller shall be provided with a factory-installed and factory-wired microprocessor control center. The control center shall include a 16-line by 40-character liquid crystal display, 4 function keys, stop button, and alarm light. Other languages are available using the international language translator software.
b. All chiller and motor control monitoring shall be displayed at the chiller control panel.
c. The controls shall make use of non-volatile memory.
d. The chiller control system shall have the ability to interface and communicate directly to the building control system.
e. The default standard display screen shall simultaneously indicate the following minimum information:
1) Date and time of day
2) 24-character primary system status message
3) 24-character secondary status message
4) Chiller operating hours
5) Entering chilled water temperature
6) Leaving chilled water temperature
7) Evaporator refrigerant temperature
8) Entering condenser water temperature
9) Leaving condenser water temperature
10) Condenser refrigerant temperature
11) Oil supply pressure
12) Oil sump temperature
13) Percent motor rated load amps (RLA)
f. In addition to the default screen, status screens shall be accessible to view the status of every point monitored by the control center including:
1) Evaporator pressure
2) Condenser pressure
3) Compressor speed
4) Bearing oil supply temperature