PURPOSE: To shorten a fluid staying period by forming a section of a fluid passageway reducing in a direction of a flow of fluid in the passageway disposed on a fluid passageway of an annular body and an opposed surface of a lower member and an upper member as a boundary.

CONSTITUTION: A conduit 5 is opened with a circumferential wall of a body 1 and has a first part 5a threaded to communicate with a fluid supply passageway having a conjugate threaded member and a second part 5b of a smaller section opened within a recess 2. A bore 6a of an upper part of a large diameter is opened with a position of an assembling face 4a of a member 4, and a bore 6b of a lower part of a conjugate diameter with the diameter of the formed film is opened with a position of a lower surface of the member 4. A groove 7 is continued to the part 5b of the conduit 5 of the body 1 at the time of inserting the member 4 into the recess 2 of the body 1. And, an upper member 3 has an upper part 3b of a cylindrical shape to be forcibly inserted into the recess 2 of the body 1. Thus, a fluid staying period is shortened.