ITT Barton Model 224, 224C differential pressure unit

A bellows assembly consists of two opposing internally connected bellows. Linear movement of the bellows which actuates a chart recorder or pressure gauge is caused by a change in differential pressure. DPI offers a line of Stainless Steel and Alloy 625 bellows assemblies for this line of Differential Pressure Units.  

 You have many choices when it comes to materials and safe working pressures. The Cryogenic industry prefers Forged Brass differential pressure unit and the Energy, Oil and Gas industries often opt for the Stainless Steel DPU's for their oil and gas field equipment . The U.S. Navy prefers Cupro Nickel (CuNi) material for shipboard applications. Bellows material choices are Stainless Steel or Inconel 625. 

The torque tube in the differential pressure unit converts the linear travel of the bellows to a rotational motion and transmits this to the micrometer movement via a drive arm and linkage in the pressure gauge . The Torque Tube is a critical element of the instrument, because it allows the required rotation to exit the liquid filled DPU while maintaining the pressure boundary. Manufactured from high quality materials and uses a precision ruby jeweled bearing for reduced friction.  

Torque Tube - eliminates possibility
of leakage and need for lubrication.
The needle bearing (inboard end) and
ball bearing (on follower drive arm)

operate with a minimum of friction — resulting in a high degree of

sensitivity over the life of unit. To get a closer look, click the Spin button.