Pneumatic check valve and method for making a pneumatic check valve

A method of manufacturing a check valve, comprising the steps of:

• machining a metallic, cylindrical member in an axial direction to form a first annular recess surrounding a cylindrical boss that is coaxial with the member and that projects toward a first axial extreme thereof;
• machining the member in a radial direction to form a second annular recess defining two opposing annular lands near the first axial extreme, the lands being coaxial with the boss;
• drilling a hole extending into the member from the cylindrical boss to provide a low-pressure channel;
• drilling a second hole extending into the member from the first annular recess to provide a high-pressure channel;
• inserting a circular diaphragm into the second annular recess so that an annular peripheral portion of the diaphragm is disposed between the opposing annular lands;
• and
• crimping the member onto the annular peripheral portion so that the diaphragm is captively retained by the member and cooperates therewith to form an annular chamber circumscribing the boss.