For metal bellows to perform properly, the open ends must usually be attached to some type of adapter fitting(s). Fulton Bellows creates leak tight joints between bellows and other metal parts by soldering, brazing, welding (resistance, GTAW, or laser), and adhesive bonding. Once attached to fittings, the bellows are used for such applications as pressure motors, flexible couplings, and pack-less valves. Pressure motors are devices where the bellows changes in length corresponding to changes in differential pressure. Flexible couplings and pack-less valves function similarly; the bellows provide a hermetic seal between two fittings that need to move relative to one another, whether it be axially, radial, or angularly.
Charged Bellows Assemblies
In other cases, the bellows are used for assemblies that respond to changes in pressure and/or temperature. By evacuating the bellows to a high vacuum and sealing, an aneroid can be created that will change in length with changes in atmospheric or system pressure. By filling the bellows with a fluid and sealing, a thermostatic actuator can be created that will change in length with changes in the surrounding temperature. By attaching a length of transmission tubing and a bulb, a thermostatic actuator can be created that will react to changes in temperature in some remote location. If the bulb is replaced with another bellows assembly, it becomes a remote motion or power transmitter. Other bellows assemblies may be charged with a gas or vapor to perform either the thermostatic or pressure sensing function or both.
