Data Aire LCS Installation, Operation And Maintenance Manual

Also see for DAFC 06: Installation, operation and maintenance manual Installation, operation and maintenance manual Installation, operating and maintenance manual

Data Aire LCS Installation, Operation And Maintenance Manual Manual pdf 9 page image

92.0 PIPING2.1 Split Air Cooled Unit PipingRefer to the attached line sizing chart on page 31 for a guideline for sizing refrigerant lines. Theultimate responsibility for line size selection is that of the installing contractor or project engineer.Data Aire does not assume this responsibility. The chart covers distances up to 200 equivalent feet.For installations greater than this distance, consult ASHRAE or similar references.Standard piping practice must be used to ensure proper oil return and efficient operation.The interconnecting lines to the remote air cooled condenser or condensing unit mustbe installed by a qualified refrigeration mechanic.2.1.1 Discharge LinesDischarge lines, also called hot gas lines, should be trapped at the top (inverted) and bottom, as wellas every 20 feet of vertical rise. Discharge line check valves are recommended on all installations,especially those where there are long pipe runs or cold climate. Check valves should be installed noless than six feet from the compressor. The discharge, suction and liquid lines need to be refrigerantgrade copper and in accordance with local code. All refrigeration piping should be installed withhigh temperature brazed joints. When brazing, a supply of nitrogen gas needs to be fed through therefrigerant lines. Be sure to open the other end of the refrigerant line to allow the nitrogen to bleedoff and not pressurize the piping. Prevailing good refrigeration practices should be employed forpiping support, leak testing, dehydration and charging of the refrigerant circuits. During the installationthe lines should be capped off and filled with dry nitrogen at the end of each day’s work or until thesystem is completed and sealed.Data Aire recommends a silver/phosphorus/copper alloy with 5 to 15% silver be used to braze therefrigerant line sets to the indoor and outdoor units. Nitrogen needs to be flowing through the lines toeliminate carbon deposit buildup on the inside of the joints. Carbon could contaminate the refrigerantand restrict the metering device.Piping must be supported within 18” of the inlet and outlet connections. The inlet connection is locatedon the top header of all units. The discharge outlet is located at the bottom of the header.Discharge line pressure drop should not exceed 6 PSI for R-407c and 9 PSI for R-410a. Recommendedgas velocity for proper oil return is 1,000 FPM. Slope horizontal lines downward in the direction ofrefrigerant flow, 1/2” for every ten feet of line length. Discharge lines do not require insulation butdue to the high temperatures of the refrigerant inside the line, the pipes may be insulated to protectagainst burns to individuals near or around the lines.2.1.2 Liquid LinesLiquid line size is determined by pressure drop and velocity. The liquid line pressure drop for R-407cshould not exceed 5 PSI or 9 PSI for R-410a. The recommended velocity should be between 200and 300 FPM. To avoid excessive liquid line pressure drop, the air cooled condenser should belocated above or at the same level as the evaporator. Condenser installation more than ten feetbelow the evaporator is not recommended. Insulation of liquid lines is not required but can be usefulin preventing condensation from forming and to avoid flashing on long pipe runs.2.1.3 Suction LinesSome applications call for the compressor(s) to be mounted as part of the condenser, more commonlyreferred to as a condensing unit. Such cases require field piping of liquid and suction lines. Suctionlines are trapped similarly to discharge lines. Common practice for suction line selection andinstallation should be followed. Suction lines should always be insulated.