Refrigerant Piping Design Guide - inspectapedia.com

1 Application Guide AG 31-011 Engineered for flexibility and performance. Refrigerant Piping Design Guide TX Valve Mounted in Vertical LineSolenoid ValveFilter-DrierLiquid LineSuction LineSight GlassBulbExternal Equalization LineSlope In Direction Of Refrigerant FlowDistributor2 Application Guide AG 31-011 Contents Audience ..3 Using This Refrigerant Piping ..4 Refrigerant Piping Design Check List ..5 Typical Refrigerant Piping Layouts ..6 Piping Design Basics ..9 Liquid Lines ..10 Suction Lines ..12 Discharge Lines ..13 Multiple Refrigeration Circuits ..16 Sizing Refrigerant Lines.

2 18 Refrigerant Capacity Tables ..18 Equivalent Length for Refrigerant Lines ..18 Refrigerant Oil ..22 Suction Line Oil Return in Suction and Discharge Risers ..23 Thermal Expansion Valves ..33 Hot Gas Hot Gas Bypass Valves ..36 Installation Details ..40 Pump Down ..40 Piping Insulation ..40 Refrigerant Line Installation ..41 Low Ambient Operation ..42 Fan Cycling and Fan Speed Control ..42 Condenser Flood Back Safety and the Appendix 1 - Glossary ..45 Appendix 2 Refrigerant Piping Tables (Inch-Pound) ..49 Appendix 3 Refrigerant Piping Tables (SI) ..70 THE INFORMATION CONTAINED WITHIN THIS Guide REPRESENTS THE OPINIONS AND SUGGESTIONS OF McQUAY INTERNATIONAL.

3 EQUIPMENT, AND THE APPLICATION OF THE EQUIPMENT AND SYSTEM SUGGESTIONS ARE OFFERED BY McQUAY INTERNATIONAL AS SUGGESTIONS AND GUIDELINES ONLY, AND McQUAY INTERNATIONAL DOES NOT ASSUME RESPONSIBILITY FOR THE PERFORMANCE OF ANY SYSTEM AS A RESULT OF THESE SUGGESTIONS. THE SYSTEM ENGINEER IS RESPONSIBLE FOR SYSTEM Design AND PERFORMANCE. Application Guide AG 31-011 3 Introduction Audience This Application Guide was created for Design engineers and service technicians to demonstrate how to size Refrigerant Piping . Using This Guide This Guide covers R-22, R-407C, R-410A, and R-134a used in commercial air conditioning systems.

4 It does not apply to industrial refrigeration and/or Variable Refrigerant Volume (VRV) systems. Illustrations and figures are not to scale. Examples showing how to perform an analysis appear in shaded outlined boxes. How to Determine Equivalent Length Calculate the equivalent length of the liquid line for the following condensing unit with DX air-handling unit. The liquid line is composed of the following elements: 30 ft ( m) of 1-3/8 inch (35 mm) Piping 4 long radius elbows 1 filter drier 1 sight glass 1 globe type isolating valve To determine the equivalent length for the Refrigerant accessories use Table 4 and Table 5 (page 50).

5 Item Quantity Dimension (ft) Total (ft) Long radius elbow 4 ( ) ( ) Filter drier 1 35 ( ) 35 ( ) Sight glass 1 ( ) ( ) Globe valve 1 38 ( ) 38 ( ) Piping 1 30 ( ) 30 ( ) Total ( ) 4 Application Guide AG 31-011 Refrigerant Piping Several HVAC systems require field refrigeration Piping to be designed and installed on-site. Examples include: Condensing units Direct expansion (DX) coil in air handlers Remote evaporators with air-cooled chillers (Figure 1) Chiller with a remote air-cooled condensers Figure 1 - Typical Field Piping Application The information contained in this Application Guide is based on Chapter 2 of ASHRAE's Refrigeration Handbook and McQuay's experience with this type of equipment.

6 A properly designed and installed Refrigerant Piping system should: Provide adequate Refrigerant flow to the evaporators, using practical Refrigerant line sizes that limit pressure drop Avoid trapping excessive oil so that the compressor has enough oil to operate properly at all times Avoid liquid Refrigerant slugging Be clean and dry Application Guide AG 31-011 5 Refrigerant Piping Design Check List The first step in Refrigerant Piping Design is to gather product and jobsite information. A checklist for each is provided below. How this information is used will be explained throughout the rest of this Guide .

7 Product Information Model number of unit components (condensing section, evaporator, etc.) Maximum capacity per refrigeration circuit Minimum capacity per refrigeration circuit Unit operating charge Unit pump down capacity Refrigerant type Unit options (Hot Gas Bypass, etc.) Does equipment include isolation valves and charging ports Does the unit have pump down? Jobsite Information Sketch of how Piping will be run, including: o Distances o Elevation changes o Equipment layout o Fittings o Specific details for evaporator Piping connections Ambient conditions where Piping will be run Ambient operating range (will the system operate during the winter?)

8 Type of cooling load (comfort or process) Unit isolation (spring isolators, rubber-in-shear, etc.) Tip: Use this list to gather the information required to Design your Refrigerant Piping system 6 Application Guide AG 31-011 Typical Refrigerant Piping Layouts This section shows several typical Refrigerant Piping layouts for commercial air conditioning. They will be used throughout this Guide to illustrate Piping Design requirements. Figure 2 shows a condensing unit mounted on grade connected to a DX coil installed in a roof-mounted air-handling unit. 1. A liquid line supplies liquid Refrigerant from the condenser to a thermal expansion (TX) valve adjacent to the coil.

9 2. A suction line provides Refrigerant gas to the suction connection of the compressor. Figure 2 Condensing Unit with DX Air Handling Unit DX Air Handling Unit Filter-Drier Suction Riser Inverted Trap Not Required With Pumpdown Liquid Line Suction Line Air Cooled Condensing Unit TX Valve Sight Glass Solenoid Valve Application Guide AG 31-011 7 Figure 3 shows a roof-mounted air-cooled chiller with a remote evaporator inside the building. 1. There are two refrigeration circuits, each with a liquid line supplying liquid Refrigerant from the condenser to a TX valve adjacent to the evaporator, and a suction line returning Refrigerant gas from the evaporator to the suction connections of the compressor.

10 2. There is a double suction riser on one of the circuits. Double suction risers are covered in more detail in the Oil Return in Suction and Discharge Risers section of this Guide (page 123). Figure 3 - Air-cooled Chiller with Remote Evaporator Suction Line Riser Solenoid Valve Filter-Drier TX Valve Sight Glass Liquid Line Double Suction Riser Liquid Line Riser Air Cooled Chiller With Remote Evaporator Remote Evaporator 8 Application Guide AG 31-011 Figure 4 shows an indoor chiller with a remote air-cooled condenser on the roof. 1. The discharge gas line runs from the discharge side of the compressor to the inlet of the condenser.