When it is worthwhile to provide a spring hanger and allow the pipeline to change its height mainly during expansion and contraction, constant force and variable spring hangers will be used. In this discussion, we will look at the special reasons and factors to choose the spring hangers, whether we use the constant force or the variable spring hanger. First of all, we will consider why we call these devices called variable or constant force spring hangers, and consider the meaning of the word effort.
Variable spring support hanger
The meaning of the word effort means that the pipe is supported by the force produced by the spring. In rigid supports and hangers, a fixed length hanger or a base carries a pipeline. However, it is hard to imagine that the rigid element is exerting a upward force on the location of the pipe with the same gravity direction but the same size. Newton is the first person to define the motion of the solid and determines the phenomenon of gravity. His work shows that every action has an opposite function for every action, so a thing experiences continuous movement in one direction unless it is acted by another force.
Imagine a kitchen scale, you put a kilogram of sugar or rice in the disk, and the disk will drop fixed a few mm until the pointer in the 1kg tag. When more materials are placed in a dish, the plate will drop lower.
The difference between the variable spring hanger and the pointer is the same way to respond to external force. The only difference is that we precompressed the spring on the test bench to balance the weight of the pipeline. In doing so, we have removed the uncertainty in the installation process. When the variable spring support hanger is installed, the weight of the pipe is transferred to the spring, and the spring will have little or no longer compression or extension.
When the spring is unlocked, it is still at its preset height until the pipe starts to move, and then the force of the spring decreases or increases as the pipeline moves up and down. So the force of the hanger is variable according to the deformation of the spring.
Constant force spring support hanger
Unlike a variable spring support hanger, the constant force spring hanger has a mechanical device that changes the characteristics of the spring and makes it different. The two arm crank type constant force spring hanger is used to use a rotating double arm crank, which is connected to the spring, and is connected to the pipe.
The double arm crank analogy is considered to be a seesaw. The spring is pressed on one side of the fulcrum, and the pipe is placed on the other side of the pivot. When the displacement of the pipe is far from the pivot, if the seesaw must be balanced, the weight of the seesaw must be reduced. The further analogy of a constant force spring hanger is a frictionless pulley with one side bearing the pipe and a block with the same weight of the pipe on the other. The tension on both sides of the rope is the same, so that if the pipe is displaced downward, the weight block moves up to 0 or the rope tension does not change.
The purpose is to allow the pipeline so you can move down, change and no force, rather than have to overcome branch hanger internal friction when the hanger is installed, the locking device can be removed, and because we have to design the device calibration load accurately, perfect balance will reach (very well a near perfect balance) Constant effort phrase literally means: the entire range of travel boom tension can be accommodated in the hanger remained constant.