iAIRE, LLC
iAIRE
OM manual
76
LINE SIZING
In sizing refrigerant lines, cost considerations favor keeping
the line size as small as possible. However, suction and
discharge line pressure drops cause loss of compressor
capacity and increased power usage.
Excessive liquid line pressure drops can cause the liquid
refrigerant to flash, resulting in faulty expansion valve
operation. Refrigeration systems are designed so that
friction pressure losses do not exceed a pressure differential
equivalent to a corresponding change in the saturation
boiling temperature.
The primary measure for determining pressure drop is
a change in saturation temperature. Pressure drop in a
refrigerant line causes a reduction in system efficiency.
Correct sizing must be based on minimizing cost and
maximizing efficiency.
Pressure drop calculations are determined as normal
pressure loss associated with a change in saturation
temperature of the refrigerant. Typically, the refrigeration
system will be sized for pressure losses of 2°F differential or
less for each segment of the discharge, suction, and liquid
lines. An HFC refrigerant liquid line is sized for pressure
losses of 1° differential or less.
IMPORTANT:
The information above is intended for general
information on refrigerant piping only. Reference specific
AHU and condensing units manuals for specific piping
details.
REFRIGERANT PIPING GUIDELINES
IMPORTANT:
The information below is intended for general
information on refrigerant piping only. Reference specific
AHU and condensing units manuals for specific piping
details.
The design of a refrigerant piping system should:
Ensure proper refrigerant feed to evaporators; Provide
practical refrigerant line sizes without excessive pressure
drop; Prevent excessive amounts of lubricating oil from being
trapped in any part of the system; Protect the compressor at
all times from loss of lubricating oil; Prevent liquid refrigerant
or oil slugs from entering the compressor during operating
and idle time; and Maintain a clean and dry system.
REFRIGERANT LINE VELOCITIES
Economics, pressure drop, noise, and oil entrapment
establish feasible design velocities in refrigerant lines. These
are:
Suction line - 700 to 4,000 fpm
Discharge line - 500 to 3,500 fpm
Condenser drain line - 100 fpm or less
Liquid line - 125 to 450 fpm
Higher gas velocities are sometimes found in relatively short
suction lines on comfort air conditioning or other applications
where the operating time is only 2,000 to 4,000 hrs per year
and where the low initial cost of the system may be more
significant than low operating cost.
Industrial or commercial refrigeration applications, where
equipment runs almost continuously, should be designed with
low refrigerant velocities for the most efficient compressor
performance and low equipment operating cost.
The liquid line from the condenser to the receivers should
be sized for 100 fpm or less to ensure positive gravity flow
without incurring a backup of liquid flow. Liquid lines from
the receivers to the evaporator should be sized to maintain
velocities below 300 fpm, thus minimizing or preventing
liquid hammer when solenoids or other electrically operated
valves are used.
Minimum Discharge- Line Velocities
Refrigerant Velocity, fpm
Nominal Pipe
Size, in.
Riser
Horizontal
7/8
375
285
1-1/8
430
325
1-3/8
480
360
1-5/8
520
390
2-1/8
600
450
Summary of Contents for ultraDRY
Page 1: ...O M manual PD 02 22 2020 v 5 71 ultraDRY outside air solutions ...
Page 51: ...iAIRE OM manual iAIRE LLC 51 ...
Page 70: ...iAIRE LLC iAIRE OM manual 70 ...
Page 71: ...iAIRE OM manual iAIRE LLC 71 ...
Page 78: ...iAIRE LLC iAIRE OM manual 78 APPENDIX A CAPACITY CONTROL DEVICE ...
Page 79: ...iAIRE OM manual iAIRE LLC 79 ...
Page 80: ...iAIRE LLC iAIRE OM manual 80 ...
Page 81: ...iAIRE OM manual iAIRE LLC 81 CALL US TODAY 800 231 3112 TO DISCUSS YOUR APPLICATION ...
Page 84: ...iAIRE LLC iAIRE OM manual 84 APPENDIX B VFD ...
Page 85: ...iAIRE OM manual iAIRE LLC 85 Operating Instructions SMVector Frequency Inverter ...
Page 129: ...iAIRE OM manual iAIRE LLC 129 APPENDIX C ICM LOW AMBIENT CONTROL ...
Page 131: ...iAIRE OM manual iAIRE LLC 131 APPENDIX D SPACE SENSOR ...
Page 138: ...iAIRE LLC iAIRE OM manual 138 APPENDIX E SPLIT SYSTEM PIPING REQUIREMENTS ...
Page 139: ...iAIRE OM manual iAIRE LLC 139 iAIRE SPLIT SYSTEM PIPING CHART ...
Page 153: ...iAIRE OM manual iAIRE LLC 153 Page 2 of 4 ...
Page 154: ...iAIRE LLC iAIRE OM manual 154 Page 3 of 4 ...
Page 155: ...iAIRE OM manual iAIRE LLC 155 Page 4 of 4 ...
Page 156: ...iAIRE LLC iAIRE OM manual 156 APPENDIX F SPLIT SYSTEM DAT SENSOR INSTALLATION ...
Page 158: ...iAIRE LLC iAIRE OM manual 158 APPENDIX G MODULATING GAS VALVE ...
Page 159: ...iAIRE OM manual iAIRE LLC 159 ...
Page 161: ...iAIRE OM manual iAIRE LLC 161 ...
Page 164: ...iAIRE LLC iAIRE OM manual 164 Mod Gas Heat Install I O M manual PD 03 25 2019 v 1 2 ...
Page 165: ...iAIRE OM manual iAIRE LLC 165 APPENDIX H SMOKE SENSOR ...
Page 172: ...iAIRE LLC iAIRE OM manual 172 APPENDIX J 24 7 TIMER ...
Page 173: ...iAIRE OM manual iAIRE LLC 173 ...
Page 174: ...iAIRE LLC iAIRE OM manual 174 ...
Page 175: ...iAIRE OM manual iAIRE LLC 175 ...
Page 176: ...iAIRE LLC iAIRE OM manual 176 ...
Page 177: ...iAIRE OM manual iAIRE LLC 177 ...
Page 178: ...iAIRE LLC iAIRE OM manual 178 ...
Page 179: ...iAIRE OM manual iAIRE LLC 179 ...
Page 180: ...iAIRE LLC iAIRE OM manual 180 ...
Page 181: ...iAIRE OM manual iAIRE LLC 181 ...
Page 182: ...iAIRE LLC iAIRE OM manual 182 ...
Page 183: ...iAIRE OM manual iAIRE LLC 183 APPENDIX K HIGH HEAT BOX ...
Page 188: ...iAIRE LLC iAIRE OM manual 188 ...
Page 191: ...iAIRE OM manual iAIRE LLC 191 ...
Page 197: ...iAIRE OM manual iAIRE LLC 197 ...
Page 198: ...iAIRE LLC iAIRE OM manual 198 15 APPENDIX B Heatco Application Guide ...
Page 200: ...iAIRE LLC iAIRE OM manual 200 ...
Page 201: ...iAIRE OM manual iAIRE LLC 201 ...
Page 202: ...iAIRE LLC iAIRE OM manual 202 ...
Page 203: ...iAIRE OM manual iAIRE LLC 203 ...
Page 208: ...iAIRE LLC iAIRE OM manual 208 ...
Page 209: ...iAIRE OM manual iAIRE LLC 209 ...
Page 215: ...iAIRE OM manual iAIRE LLC 215 APPENDIX L UPC BACNET INSTALLATION ...
Page 236: ...iAIRE LLC iAIRE OM manual 236 APPENDIX M BACNET TROUBLESHOOTING GUIDE ...