The importance of peripheral speed



Peripheral speed is the speed at the periphery of a circular part due to its rotation.
It has both magnitude and direction (circular) and should be more aptly referred to
as
peripheral velocity, but the term peripheral speed has been more widely used.
It is calculated using the equation:


S  =  [ D x N ]  /  229

where:

S - peripheral speed (or peripheral velocity), feet per second (FPS)
D - outer diameter of part under consideration, inches
N - rotational speed, revolutions per minute (RPM)


Example:

What is the peripheral speed of a 10-inch diameter impeller rotating at 3560 RPM?

Answer:

S
 =  [ 10 x 3560 ]  /  229  = 155 FPS


The design, operation, or performance of some rotating pump parts are affected
by their peripheral speeds so it is important that their magnitudes are known:

  • impeller outer diameter - It determines the head it develops, and affects its
    material selection. Slurry service requires low peripheral speed, etc.

  • impeller eye diameter - It determines the pump NPSHR, and affects the
    onset of suction flow recirculation, etc.

  • anti-friction (ball) bearings - They have limited speed and, typically, are not
    used in high speed pumps.

  • sleeve, or journal, bearing - It determines the type of bearing to be used,
    and its type of lubrication system - the amount of lubrication, heat transfer,
    etc.

  • mechanical seal - It affects the required amount of cooling and lubrication.

  • impeller wear ring - Its peripheral speed affects the manner of mounting,
    or securing, the wear ring into the impeller shrouds.


More information is available on the full length version of this article.
Read more.


R: 0210-PESP
C: design, operation
F: speed peripheral


"Make it simple"
Related topic

maximum peripheral speed of cast iron impeller
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