Differece Between Variable And Constant Spring Hangers.

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• Variable Spring hangers are used to support piping subject to vertical movement where Constant Supports are not required. The inherent characteristic of a Variable Spring is such that its supporting force varies with spring deflection and spring scale.

Therefore, vertical expansion of the piping causes a corresponding extension or compression of the spring and will cause a change in the actual supporting effect of the hanger. The variation in supporting force is equal to the product of the amount of vertical expansion and the spring scale of the hanger. Since the pipe weight is the same during any condition, cold or operating, the variation in supporting force results in pipe weight transfer to equipment and adjacent hangers and consequently additional stresses in the piping system. When variable spring hangers are used, the effect of this variation must be considered.

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• Constant support hangers provide constant supporting force for piping throughout its full range of vertical expansion and contraction. This is accomplished through the use of a helical coil spring working in conjunction with a bell crank lever in such a way that the spring force times its distance to the lever pivot is always equal to the pipe load times its distance to the lever pivot.

Because of its constancy in supporting effect, the Constant Support hanger is used where it is desirable to prevent pipe weight load transfer to connected equipment or adjacent hangers. Consequently, they are used generally for the support of critical piping systems.

The function of constant load hanger is the same function of counter weight when used to support a piping system which provide constant supporting force for piping throughout its full range of vertical expansion and contraction.

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