OS - Open Spring Mountings - Standard Range

Sizes OSB, OSS, OS25 & OS50

This unique range of Open Spring Mountings uses integral rubber end fixing of the springs which set them apart from all other designs. Loose springs and plates are now history and high frequency noise attenuation is provided regardless of whether a rubber seating pad is used or not.

Originally designed for use with Type IPF Inertia Pouring Frames, the OS Mountings are now widely used to isolate vibration from every conceivable type of rotating and reciprocating machine. Where control of transient motion is required Open Spring Mountings can be used in conjunction with our Viscous Dampers Type SFD.

Design Features:
  • Unique expanding rubber end fixing of springs (Patent applied for) which also provides high frequency attenuation.
  • Nominal 20, 25 & 50 mm deflection colour coded helical steel springs to BS1726 Class B with 50% overload capacity and O/D equal to at least 85% of working height.
  • Can be bolted to supporting structure or free standing on 6 mm thick ribbed rubber pad (3 mm on OSS).
  • Fully height adjustable (OS25 & OS50).
  • Zinc plated metals.
  • No snubbing gives maximum efficiency.
Typical Applications:
  • Axial and Centrifugal Fans.
  • Air Handling Units.
  • Low level pipework.
  • With Inertia bases type IPF for pumps, generating sets and compressors etc.
Application Notes:
  • Isolation Efficiency at Typical Machine Speeds:

    MACHINE SPEEDS (rpm) EFFICIENCY %
    15 mm DEFL. 25 mm DEFL. 50 mm DEFL.
    300 DO NOT USE 34.0 75.2
    500 68.7 83.3 92.3
    750 88.1 93.2 96.7
    1000 93.7 96.3 98.2
    1200 95.7 97.4 98.7
    1500 97.3 98.4 99.2
    1750 98.0 98.8 99.4
    2000 98.5 99.1 99.5


    The above figures are theoretical values only based on the vertical natural frequency of the sprung system assuming infinitely stiff structural supports.

    The effects of high frequency spring coil resonances on low frequency performance are also ignored.

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OS - Open Spring Mountings All Variants