{"id":4262,"date":"2026-03-30T11:29:27","date_gmt":"2026-03-30T15:29:27","guid":{"rendered":"https:\/\/backflow-shop.com\/?p=4262"},"modified":"2026-03-31T10:30:03","modified_gmt":"2026-03-31T14:30:03","slug":"demystifying-the-double-check-valve-assembly-dcva","status":"publish","type":"post","link":"https:\/\/backflow-shop.com\/en\/demystifying-the-double-check-valve-assembly-dcva\/","title":{"rendered":"Demystifying the Double Check Valve Assembly (DCVA)"},"content":{"rendered":"

The Double Check Valve Assembly (DCVA) is, as its name\u00a0suggests, a device designed to protect against backflow. It is used in continuous pressure applications that may be subject to back pressure or siphoning1<\/sup>. It is primarily found in interconnexions presenting a low health hazard; it is intended for low-or moderate-risks installations2<\/sup>.<\/p>\n

COMPONENTS<\/strong><\/h4>\n

The DCVA is equipped with two simple spring-loaded check valves assembled in a single body. It is fitted with four test cocks that allow for testing of the device\u00a0and\u00a0two shut-off valves2<\/sup>.<\/p>\n

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Source\u00a0: https:\/\/www.rbq.gouv.qc.ca\/fileadmin\/medias\/pdf\/Publications\/francais\/guide-dar-protection-reseau-eau-potable.pdf<\/a>, Figure 55 (traduite en anglais par Atelier Backflo Shop)<\/h6>\n

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OPERATION<\/strong><\/h4>\n

Under normal flow conditions, the check valves open\u00a0with\u00a0the\u00a0supply pressure. They\u00a0close if water flows back towards the supply to prevent any\u00a0backflow3<\/sup>.<\/p>\n

In the event of\u00a0back pressure<\/strong><\/p>\n

Back pressure, i.e. backflow\u00a0caused by a higher pressure at the device outlet than in the supply network,\u00a0causes the second check valve to close, thus preventing any backflow. In case of leakage of the latter, the\u00a0first check valve also closes3<\/sup>.<\/p>\n

In the event of\u00a0siphoning<\/strong><\/p>\n

When\u00a0a\u00a0siphoning occurs, the pressure at the inlet\u00a0drops below the pressure downstream of the device. The\u00a0first\u00a0check valve\u00a0then\u00a0closes. If it is not perfectly\u00a0sealed, the second check valve\u00a0takes over and closes, thereby preventing any reversal of the flow direction3<\/sup>.<\/p>\n

GENERAL INFORMATION<\/strong><\/h4>\n

The DCVA must be\u00a0inspected at the installation, in case of cleaning, repair or refurbishment, after a relocation, once\u00a0a year and according to the instructions of the competent authority2<\/sup>.<\/p>\n

This device can be installed horizontally or vertically, subject to approval by a recognized agency. In compliance with the standards requirements CSA B64.10, it can be installed\u00a0below\u00a0ground level, in a pit or vault, provided that the valves are properly sealed4<\/sup>.<\/p>\n

The following moderate-risk devices are given as exemples2<\/sup>:<\/p>\n