Multiport Plug Valves:

Multiport valves are particularly advantageous on transfer lines and for diverting services. A single multiport valve might be installed in lieu of three or four gate valves or other categories of shutoff valve. A drawback is in which several multiport valve configurations do not fully shut off flow.

In many cases, one flowpath is always open. Those valves are intended to divert the flow of one line although shutting off flow from the other lines. It is essential that a style of multiport valve be used which allows this if complete shutoff of flow is a requirement, or a secondary valve should be installed on the basic line ahead of the multiport valve to allow complete shutoff of flow.

In a few multiport configurations, concurrent flow to more than one port is also possible. Huge care should be taken in specifying the particular port arrangement needs to guarantee which proper operation will be possible.