Valve with built-in orifice, and pressure-type flow rate control device

A valve with a built-in orifice, internally having an orifice, comprising:

• a base section having a top-opening housing recess, a first gas flow passage opening to a wall surface of the housing recess, and a second gas flow passage opening to a bottom surface of the housing recess;
• a valve seat body having an annular valve seat and a through-hole formed on an inner side of the valve seat;
• an inner disc for holding and securing the valve seat body;
• a valve element configured to capable of coming in and out of contact with the valve seat;
• and
• an orifice body having a through-hole including the orifice, wherein
• the housing recess is a stepped recess having a wide-diameter section and a narrow-diameter section opening to a bottom surface of the wide-diameter section, the wide-diameter section includes a valve chamber defined by the valve seat body, the inner disc, and the valve element, and the narrow-diameter section has inserted therein the orifice body;
• the valve seat body is mounted on the orifice body, and is pressed by the inner disc and thereby held and secured on top of the orifice body;
• and
• the first gas flow passage communicates with the valve chamber through a space between a wall surface of the narrow-diameter section and the orifice body, and the second gas flow passage communicates with the valve chamber through the through-hole of the orifice body and the through-hole of the valve seat body.