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Sizing of the Spirelf Devices
For each insert size, there are two limits of flow velocites:
- a lower limit: the beginning of the vibrations (Mark A)
- an upper limit: the stretching point from which the spring is
overstretched (Mark C)
Spirelf devices introduce an extra pressure drop determined by the type
of insert and the flow velocity. The system is usually applied to retrofit
equipment, and this extra pressure drop has to be considered. This constraint
involves a smaller range of utilization for each sizing (Mark B).
The relative importance of the mechanical effect and the turbulent effect
depends on the position of the device in relation to the tube wall, i.e.
on the ratio (d/di) between the outlet diameter of the stretched
spring and the inlet tube diameter (Mark D).
At high ratio (d/di), the device is positioned near the wall
and primarily the turbulent effect is effective, whereas at low ratio the mechanical
effect is more important.
The final sizing of the devices can result in a compromise between
these factors to obtain the optimal result for any given application.
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