Modular Restraint/Isolator | Model FMS
Patent No. 7,028,969
Designed for the latest building codes, the Model FMS Seismically Rated Restraint/Vibration Isolator can be used as a restraint device or as a seismically rated vibration isolator assembly. The unit is comprised of a restraint module and an optional vibration isolation module. This modular design allows the engineer to design for seismic or wind forces independent of the load and deflection requirements of the vibration isolator. The vibration isolation module uses laterally stable springs compliant with industry guidelines.
The FMS restraint modules are available in a wide range of capacities. The vibration isolation modules are available in a full complement of coil capacities through 4 in. (100 mm) deflection. The ability to select the restraint module independent of the vibration isolator load and deflection requirements ensures a custom, no-compromise fit for restraint and vibration control. This modular feature allows the FMS to be optimized for a wide range of applications. In addition, the isolator can be used in applications requiring constant free and operating height.
The unique design of the FMS restraint module minimizes the seismic loads transmitted into the anchors or other attachment hardware. As a result, considerably higher seismic ratings are possible versus conventional designs using similar sized connection hardware.
The FMS vibration isolation module offers an open spring design where the spring is completely visible for inspection and totally accessible for adjustment. The top adjustment nut can be accessed with a ratchet or power impact-type tool in addition to conventional open end wrenches, reducing field installation time. The pendulum suspension feature lowers the center of gravity of the applied load and increases the isolator stability. This application is somewhat different on cooling tower installations.
Restraint components are available in 8 sizes with horizontal force capacity ratings ranging to 70,000 lb. Standard isolation elements are available to 4 in. deflection with support capacities ranging to 23,000 lb.
Because of the extreme design flexibility of the modular concept, Model FMS Seismic Restraint/ Vibration Isolators can be used effectively for large, heavy pieces of equipment in highly active seismic or wind prone areas as well as for more common applications in less active areas without financial consequence. The FMS is ideal for equipment mounted on structural frame or concrete inertia bases. As with any seismic restraint or vibration isolation device, direct mounting to light pieces of equipment may not be possible without an intermediate frame.
Because of the minimal vertical travel and near constant operating height, the FMS isolator is excellent for use on cooling towers, chillers, boilers or other equipment where the potential for wide weight variations during service is anticipated.
With 4 in. (100 mm) deflection coils, these isolators are ideal for the isolation of sensitive equipment or for use in protecting long span flexible structures from induced vibrations.
Typical restraint element showing optional coil configurations.
In a similar fashion, coils with 1-, 2-, and 4-in. deflection can be fitted to the same restraint element, or different restraint elements can be substituted.
Model FMS Installation Options
Spring isolators shall be comprised of two interfacing but independent elements; a coil spring element and a seismically rated housing. The spring coil element shall be comprised of one or more coil assemblies having all of the characteristics of freestanding coil spring isolators as specified in the vibration isolation portion of the specification. The seismically rated housing shall be sized to meet or exceed the force requirements applicable to the project and have the capability of accepting coils of various sizes, capacities, and deflections as required to meet the desired isolation criteria.
All spring forces will be contained within the coil/housing assembly and under no seismic load condition shall the restraint anchoring hardware be exposed to spring – generated forces.
The restraint element shall incorporate a steel housing with elastomeric elements at all dynamic contact points. The restraint will allow 1/4 in. (25 mm) motion in any direction from the neutral position. All elastomeric elements shall be replaceable.
To ensure the optimum anchorage capacity, the restraint will have an overturning factor (the ratio of the effective lateral snubber height to the short axis anchor spacing) of 0.33 or less.
The leveling nut or screw shall be accessible for adjustment with the use of a pneumatic or electric impact wrench.
The spring element shall be replaceable without having to lift or otherwise remove the supported equipment.