tailieunhanh - HVAC and Dehumidifying Systems_5

Tham khảo tài liệu 'hvac and dehumidifying systems_5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | MIL-HDBK-1003 3 Simpo PDF Merge and Split Unregistered Version - http Reprinted by permission of ASHRAE from ASHRAE Handbook Fundamentals. Figure 13 Friction Loss for Water in Plastic Pipe Schedule 80 a Hot Water Piping to Coil. Water coils will not perform if there is air in the piping. Ensure that the piping from the main to the coil and to the return main is appropriately sloped up and vented to eliminate entrained air that can air lock the flow. b Hot Water Coil Selection. Consult the manufacturer s catalog data to decide the best selection number of rows parallel or counter flow turbulators or serpentines and other selection information. Using the appropriate type make the coil selection 1 Capacity required 2 Water temperature in and out 3 Air temperature in and out 4 Airflow 5 Water flow 6 Air pressure drop 72 Simpo PDF Merge and Split UnregisteredVersion- http 7 Water pressure drop 8 Coil face velocity 9 Any special requirements After the coil selection has been made and documented in the design analysis be sure to provide the above data in the coil schedule on drawings. This will ensure a good bidding climate with equipment manufacturers knowing what to bid and what to submit in the shop drawings phase. Expansion Tanks and Air Separator a Expansion Tanks General. When water in a hot water heating system is heated water expands and occupies more volume. System pressure control is needed to 1 Limit pressure in all parts of the system to the allowable working pressure. 2 Maintain minimum pressure in the system to prevent pump cavitation and to prevent boiling of system water. 3 Minimize addition of makeup water. b Expansion Tank With Air Separator. An expansion tank with an air separator performs these system pressure control functions. Since this section does not address medium temperature hot water system 250 to 350 degrees F or high temperature hot water system above 350 degrees F discussion will be limited to the .