For differential pressure applications, the Hex five valve blowdown manifold performs the block and equalizing functions of a standard three valve manifold and provides two additional block valves to be used for blowdown purposes. To blow down the impulse lines, the block valves on the manifold are closed, and the two blowdown valves are opened, allowing the impulse lines to be blown out through the ports on the lower side of the blowdown valves.
The design of the HM56 allows the user to install just one compact assembly that eliminates eight nipples, four tees, and two shutoff valves that are required for a conventional blowdown valve installation. In addition, the HM56 incorporates a single flange, which enables the installer to mount the transmitter directly to the mounting flange, thereby eliminating the installation of even more tubing and nipples.
The HM55 is identical to the HM56 except both the process and instrument connections are threaded for in-line installations.