
BHS41X-16 common type device to prevent backflow check valve in series two. But it is a seal broken; another had a role sealed to prevent reflux. But two valve seal destroyed, it will have lost only to function, its safety and reliability relative badly working principle is simple. BHS41-16A Safe in the backflow prevention device on the basis of the ordinary-middle drainage device, Even though the two valve seal destroyed, can also prevent the return of the role of pollution. A normal supply: a. urban living clean water from the first grade through the drainage valve on the second level of the check valve to export water users. first-class high-pressure valve imports by the high-pressure water hose into the drainage divide with superior vena, and divide cavity and the first export-check valve (the second check valve imports), so that its existence as a pressure difference, promoting lower flap valve, drainage for the closure of backflow prevention device normal water supply; b. When the pipeline after the valve without the users, static water. If the pressure of imports remained unchanged after its existence pressure, drainage devices are still closed; C. If the import pressure drop before and after its pressure dropped to a certain value, the flap valve spring to promote progressive, open drainage pressure relief device, Relief and imported pressure to restore the margin, were closed for drainage. 2. Seal failure: backflow prevention device after increased pressure on the network, more than before the import pressure valve, If the second check valve seal intact no leakage, high-pressure water will not turn the clock back, the next drainage divide for pressure maintenance, closed drainage device, pressure relief. When the second-valve damage have sealed leaks, the second valve before increasing the pressure, caused drainage divide with the pressure difference decreased to open drainage, drainage venting; At this time, If the first-class check valve while sealing, the second-valve back to the high-pressure water has been venting decompression, Hence, it will not turn the clock back to the first-class check valve. 3. If the process of water pressure drop of water, drainage divide with the upper pressure drop Drainage Control safety spring to promote spool open drainage for drainage. When the pressure of imports dropped to zero, or negative pressure, drainage devices are fully opened, water discharges, air entered the drainage from the vacuum chamber, thereby preventing backflow siphon phenomenon.