Since bellows are a critical factor in valve reliability, MKS incorporates formed bellows into the 150/160 valves. The first major advantage of using formed bellows is consistency. Since formed bellows do not have welds joining each membrane, there is no stress concentration and fatigue failure from non-uniform welds. The second advantage is that the bellows convolutions never touch completely in the compressed position. Many vacuum processes, like chemical vapor or thin film deposition contain particulate contamination. If small particles fall between formed bellows, they have no effect. If similar particles fall between welded, nested bellows, they deform the membranes, cause stress concentration, and lead to early bellows failure.

MKS vacuum valves may be installed in any position, with either the bellows or the nosepiece facing the pump. In systems with condensable materials, it is advantageous to install the valve with the nosepiece toward the chamber. The electropneumatic valve has a solenoid valve attached to the cylinder with a nipple. The cap screws fixing the cylinder to the body may be removed and the cylinder indexed at 90° increments for valves of sizes .75'' to 1.5'', and 60° increments for valves with port sizes 2'' to 6''. If necessary, the solenoid valve can be removed and located remotely.