减压区总成必须按照当地有关规定定期检查和测试，以确保这种装置内的止回阀能够正常运行。
　　Reduced Pressure Zone Assemblies must be inspected and tested periodically, in accordance with local codes, to ensure proper operation of check valves within the unit.
　　对于检测1，建议采用差压表，而不要采用流体压力表，理由在于差压表进行检测的时间最短。差压表避免关闭进口球阀，从而避免由于重新开启时可能会将管道结垢和外部物质冲刷下来，并将其带入防回流阀中。在检测时，只有少量的水"溢出"。水银压力表可能产生污染破坏.
　　A differential pressure gauge is recommended for Test No. 1 rather than a manometer for the following reasons: It utilizes minimum time to perform the test. It eliminates the necessity of closing the inlet ball valve which could release pipe scale and foreign matter into the backflow preventer. Only a slight amount of water is 'spilled' in test. A mercury manometer could cause a pollution hazard.

检测装置
Test Set Up

减压区总成
Reduced Pressure Zone Assembly

　　关闭检测组件上的阀门A, B和C。
　　将高端软管连接到测试旋塞2号上
　　将低端软管连接到测试旋塞3号上。关闭关断阀2号
　　开启测试旋塞2号和3号。
　　开启排气阀C。
　　开启'高'阀A，并且排放到大气里，直到所有空气排放出来为止。
　　关闭阀门A。开启'低'阀B，并且排放到大气里，直到所有空气排完为止。关闭'低'阀B。关闭'排气'阀C。
　　将排气软管连接到测试旋塞4号。
　　Close Valves A, B and C on Test Kit.
　　Connect high side hose to test cock #2
　　Connect low side hose to test cock #3. Close shutoff #2.
　　Open test cocks #2 and #3.
　　Open vent valve C.
　　Open 'high' valve A and bleed to atmosphere until all the air is expelled.
　　Close valve A. Open 'low' valve B and bleed to atmosphere until all air is expelled. Close 'low' valve B. Close 'vent' valve C.
　　Connect vent hose to test cock #4.

检测程序
Test Procedure

减压区总成
Reduced Pressure Zone Assembly

　　所需现场检测设备
　　减压区防回流阀检测组件
　　Field Test Equipment Required
　　Reduced Pressure Zone Backflow Preventer Test Kit

检测1
Test No. 1

　　目的：检测止回阀2号对于回流的紧固密封性。
　　Purpose: To test Check Valve No. 2 for tightness against reverse flow.
　　要求：在所有压差下，对于回流，阀门必须紧固密封。慢慢开启'高端'阀门A和'排气'阀C，'低端'阀门B保持在关闭状态。开启测试旋塞4号。只是压差将会有稍微的降低。如果压差持续降低(直到排气开启)，则说明止回阀2号'泄漏'。
　　Requirements: Valve must be tight against reverse flow under all pressure differentials. Slowly open the 'high' valve A and the 'vent' valve C, and keep the 'low' valve B closed. Open test cock #4. Indicated pressure differential will decrease slightly. If pressure differential continues to decrease (until the vent opens) check valve #2 is reported as 'leaking'.

检测2
Test No. 2

　　目的：检测关闭2号的紧固密封性。
　　Purpose: To test shutoff #2 for tightness.
　　要求：在通过检测1后，关闭测试旋塞2号，继续进行检测2。指示压差将会稍微降低。如果压差继续降低(接近"零")，则说明关闭阀2号"泄漏"。
　　Requirements: After passing Test No. 1, continue to Test No. 2 by closing test cock #2. The indicated pressure differential will decrease slightly. If pressure differential continues to decrease (approaching "zero"), shutoff #2 is reported to be "leaking".

检测3
Test No. 3

　　目的：检测止回阀1号的紧固密封性。
　　Purpose: To test Check Valve No. 1 for tightness.
　　要求：在所有压差下，对于回流，阀门必须紧固密封。关闭‘高’阀门A，并开启测试旋塞2号。关闭测试旋塞4号。将排气软管从测试旋塞4号上拆开。开启阀门B和C，排放到大气中。然后关闭阀门B，将系统恢复到正常静止状态下。观察压差表。如果只是的数值降低，说明止回阀1号有“泄漏”。
　　Requirements: Valve must be tight against reverse flow under all pressure differentials. Close 'high' valve A and open test cock #2. Close test cock #4. Disconnect vent hose at test cock #4. Open valves B and C, bleeding to atmosphere. Then closing valve B restores the system to a normal static condition. Observe the pressure differential gauge. If there is a decrease in the indicated value, Check Valve No. 1 is reported as "leaking".

检测4
Test No. 4

　　目的：检测压差安全阀的运行。
　　Purpose: To test operation of pressure differential relief valve.
　　要求：压差安全阀必须起到这样的作用，即能够保持两个止回阀之间的“区”的压力比主供应管道的压力至少低2 psi。关闭‘排气’阀门C。开启‘高’阀门A。非常缓慢地开启‘低’阀门B直到差压表指针开始下降为止。把握住这个点上的阀门，当安全阀出现第一次排放时，观察表上的读数。当开启安全阀的压差时，进行记录。
　　Requirements: The pressure differential relief valve must operate to maintain the "zone" between the two check valves at least 2psi less than the supply pressure. Close 'vent' valve C. Open 'high' valve A. Open the 'low' valve B very slowly until the differential gauge needle starts to drop. Hold the valve at this position and observe the gauge reading at the moment the first discharge is noted from the relief valve. Record this as the opening differential pressure of the relief valve.

　　注：重要的是差压表的指针要缓慢下降。关闭测试旋塞2号和3号。通过开启阀门A, B和C，采用‘排气’软管从检测组件内释放压力。拆卸所有检测设备，并开启关断阀2号。
　　Note: It is important that the differential gauge needle drops slowly. Close test cocks #2 and #3. Use 'vent' hose to relieve pressure from test kit by opening valves A, B and C. Remove all test equipment and open shutoff #2.

球型检测阀
Ball Type Test Valves