For the protection layer proxy and viewing component and method of project, such as gold-plated jewelry, it is used to form such protection.

摘要

A combined pressure reduction valve and over-pressure relief valve comprises a piston 61 reciprocatable within a cylinder and having a central pressure-reduction valve 602, 67 opened by engagement of a rod 69 with an abutment 73 on the cylinder when the pressure on the downstream side of the pressure-reduction valve falls below a first predetermined pressure, and an overpressure valve 70 which is also carried by the piston and opens when the pressure on the downstream side of the pressure-reduction valve rises above a second predetermined pressure which is above the said first pressure. The valve may be connected to a pressure vessel having a circumferentially-grooved neck by a mounting comprising a wall (27, Figs. 2, 3) having a notch (29) to receive the neck, a seat (41) to receive the portion of the neck outboard of the groove, and means (31,22) for drawing the wall and the seat towards one another. IMAGE