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., ; SECTION IV - SYSTEM DESIGN UL EX3470 ULC EX3470 Page 4-4 REV.7 7-1-09 Transition Protection I Transitions are protected at a point in the transition where the The 1/2N nozzle(Part No.419334)must be centered 10 to 26 in. perimeter or the diameter is equal to or less than the maximum (25 to 66 cm)below the precipitator and aimed to discharge at the size duct that can be protected.The nozzle(s) must be located in center of each precipitator cell.However,it it is physically impossi- the center of the area at that point, or center of the module pro- ble to mount the noule at 10 to 26 in.(25 to 66 cm)due to pre- tected when more than one duct noule is required.Note:Nozzles cipitator placement,the noule may be mounted closer than 10 in. to protect ducts with a transition that Is more than 4 ft(1.2 m) (25 cm).See Figure 5. in height,will be required to be positioned in the opening of the transition from the hood 2 to 8 In.(5.1 to 20.3 cm)Into the opening using standard duct noule destgn parameters. See .Figure 4. DUCT SEE DUCT FOR NOZZLE � TRANSITION � OUCT PROTECTION '�. _L TRANSITION � ► ��' PRECIPITATOR �� i� i � 4� 10•28 IN' (12 m) MAX. I (25-88 cm) � ( NOZZLE FOR ( PRECIPITATOR PROTECTION 'IF PHYSICALLY IMPOSSIBLE AT 10 TO 2B IN.(25 TO 68 cm),NOaLE MAY BE FIGURE 4 MOUNTED CLOSER THAN 10 IN.(25 cm). °0°"� FIGURE 5 Electrostatic Precipitator Protectlon 00°1B� ► Note:For protection of Pollution Control Units(PCUs)or air scrub- Some restaurant ventilating ducts have an electrostatic precipita- ►bers with or without ESPs, contact Ansul Technical Services for ►tor installed at or near the base.These precipitators are generaliy ►non-UL listed recommended application. ►small and are used to aid in the cleaning of exhaust air. Ducts with precipitators located at or near the base can be pro- tected using duct nozzle(s) above the precipitator and 1/2N noz- zle(s)(Part No.419334)for the precipitator.One 1/2N nozzle must be used for each cell being protected.This nozzle tip is stamped with 1/2N,indicating that it is a 1/2-flow nozzle and must be count- ed as 1/2 flow number. When protecting ducts equipped with precipitators,the duct noz- zle(s) must be installed above the precipitator and aimed to dis- charge downstream.If the area above the precipitator is a duct,the nozzle(s) must be positioned according to duct protection guide- lines.If the area above the precipitator is a transition,the transition guidelines must be followed. I