| 摘要 |
<p>Disclosed is an improved device (10) for preventing back flow of possibly-contaminated water into a potable water system. The device (10) includes first, second and third nozzles (33, 35, 37) in series flow relationship, and an air gap (49) between the first and second nozzles (33, 35). In the improvement, the air gap (49) is a primary air gap and the device (10) includes a secondary air gap (19) fixed with respect to the second nozzle (35). In a more specific aspect of the new device (10), the second and third nozzles (35, 37) are in a tubular housing (41) and the device (10) includes a containment bowl (21) around the housing (41). The secondary air gap (19) includes an aperture (53) in the housing wall (55) and such aperture (53) opens to the containment bowl (21). Other aspects of the new device (10 involve particular nozzle configurations and relationships and a restrictor (103) inhibiting back flow. <IMAGE></p> |
