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emphasizcd that thc air gap funncl asscmbly will handle only thc occasional spitting <br /> and will not control flow in a continuous rclicf situation. <br /> K. Bccausc of thc naturc of a reduccd pressurc backt]ow prevcntcc fluctuating supply <br /> pressurc on an extreme low tlow or static Ilow condition may cause nuisancc <br /> dripping and cventual fouling of the assembly. In a static condition, (i.e., an RPBA <br /> on thc makcup water linc to a boilcr) the rcduced pressure zonc betw�een thc tirst and <br /> second check valves must be maintained at a 2.0 psi or grcater differential below the <br /> supply pressurc. Depcnding on Ihc dcgrcc of iluctuating supply pressurc, thc <br /> asscmbly may discharge watcr Gom timc to timc. This becomcs a nuisancc <br /> discharge and can eventually cause a fouling of thu firsl check val��e. It is good <br /> plumbing practice to rccommend a sofl scatcd chcxk valve immediatcly ahead of the <br /> RPBA �vhich would hold thc pressurc cons�ant to the val��e in timcs of tluctuating <br /> supply pressurc. <br /> L. Size the assembly hydraulically to a��oid excessive pressure loss. The head loss is <br /> not necessarily direcUy proportional to Ilow. Some assemblics have a high head loss <br /> at low tlows and a low hcad loss a high tlows. <br /> M. Good plumbing practicc rccommcnds a straincr wdh blow out tapping ahcad of thc <br /> assembly. <br /> N. Largcr sizc asscmblics (I'/z" anJ up) shall hacc support blocks to prcvcnt Ilangc <br /> damagc. <br /> O. TlIOROUGIiLY FLUSH THE LINES PRIOR TO INSTALLING THE RPBA: <br /> Gapericncc has sho�vn th�t a largc majority of "failurc of test' results in ncw <br /> installations arc duc to dchris fouling cithcr thc first or sccond chcck valvc scats. <br /> � <br /> ^�;� <br /> � <br /> " , I � '^ --?—�_ <br /> _ , o <br /> ���\ � i � I � �� � <br /> ��� ,� � � I <br /> ,,.----- .� _ <br /> �,� ;�,�;_— <br /> �--�—=,.;,r „i:• ; '�' <br /> ��.:�J--- � �- �.i� ✓.� <br /> �:. j' 1�_�: r�=����� t=�'—� <br /> �\ �= � � . a—, � <br /> N \ T <br /> I / T � _ � � I J �O?r <br /> / � 5�C?c <br /> � ` / � <br /> `J� � . _ .r.xv5:.•�tt:'FCti�.w�. <br /> i �:% � � � <br /> S � � <br /> b V�l <br /> \.J <br /> c� <br /> l` <br /> �in <br /> 5:\86ru�e\Backflow In:lallation Requirements 021i09 jm.da �' <br />