Base-mounted pumps normally require a concrete inertia base. Selection and sizing of the base should ensure that the range of motion is limited and provide the appropriate vibration isolation for the system. Housekeeping pad depth and size, exposure to extreme events, pump type, horsepower, rpm, size, location in the building, and weight distribution are contributing factors in selecting the appropriate isolators.

CIB - Concrete Inertia Bases provide vibration and start-up torque damping by adding mass to and lowering the center of gravity of the mechanical equipment it is installed under. Fans 50HP and up recommended to use Concrete Inertia Bases

SFS - Seismic Free Spring series provide vibration isolation for base mounted pumps. The isolator has a seismic restraint housing for greater lateral and vertical support.

FS - Free Spring series provide vibration isolation for base mounted that installed on floor or base. These open spring isolators compress on neoprene cups and absorb low and high frequency vibrations.

FLEX - Flex Connectors are applied to piping connections with vertical inline pumps to isolate the connecting piping and reduce structure-borne noise.

Slab on Grade Design Considerations

Structure-Borne Vibration

Problem: Pumps are a major source of vibration. If this vibration is transferred to the structure, it can create serious noise problems in many different areas. Vibration can travel through the structure as well as through the connecting piping.

Solution: Isolate Equipment Inertia base with spring type isolators – The addition of mass to the bottom of the pump helps lower the center of gravity which reduces vibration. Spring isolators are required to prevent vibration transfer. Proper selection is required based on pump size and surrounding space considerations.

Solution: Isolate Connecting Piping Spring hangers are recommended on the inlet and discharge piping before the drop and until the vibration is dissipated. Depending on pipe size, this set-up usually requires 3 to 5 hangers on either side. Proper calculations should be performed for quantity and locations of the hangers.

Flexible connectors are required to isolate the connecting piping from the vibration source.

Uneven Weight Distribution

Problem: Water and pipe weights increase force on springs under pump side of unit.

Solution: Proper selection of isolators is required with safety factor to avoid bottoming out springs or not providing adequate deflection.

Seismic Requirements

Problem: Forces are determined by a number of factors including: project location, site class, risk category, component importance factor and equipment location equipment relative to the overall height of the building.

Solution: Certified anchorage calculations must be submitted to verify loading conditions are met for each piece of equipment.

Problem: Horizontal and vertical seismic forces are applied at the center of gravity of the unit. The resulting overturning moment creates tension and shear forces that can be very large.

Solution: All connections of the restrained spring isolators must be designed for these loads. For concrete attachments, this requires ICC-ES certified anchors.

Problem: Reinforcement and doweling in of the housekeeping pad to the structure is often overlooked.


Solution:
The load path must be accounted for from the center of gravity of the unit to the structure. Problem: Poor installation of concrete anchors.

Solution: IBC 2015 requires ICC-ES approved anchors for cracked concrete and Omega Naught Factor (Horizontal forces multiplied by 2.5).

Problem: Differential motion up to 2” in a 20’ story height.

Solution: Flexible connectors are required to reduce equipment nozzle loads.

Base-mounted pumps normally require a concrete inertia base. Selection and sizing of the base should ensure that the range of motion is limited and provide the appropriate vibration isolation for the system. Housekeeping pad depth and size, exposure to extreme events, pump type, horsepower, rpm, size, location in the building, and weight distribution are contributing factors in selecting the appropriate isolators.

CIB - Concrete Inertia Bases provide vibration and start-up torque damping by adding mass to and lowering the center of gravity of the mechanical equipment it is installed under. Fans 50HP and up recommended to use Concrete Inertia Bases

SFS - Seismic Free Spring series provide vibration isolation for base mounted pumps. The isolator has a seismic restraint housing for greater lateral and vertical support.

FS - Free Spring series provide vibration isolation for base mounted that installed on floor or base. These open spring isolators compress on neoprene cups and absorb low and high frequency vibrations.

FLEX - Flex Connectors are applied to piping connections with vertical inline pumps to isolate the connecting piping and reduce structure-borne noise.

Upper Floor Design Considerations

Structure-Borne Vibration

Problem: Pumps are a major source of vibration. If this vibration is transferred to the structure, it can create serious noise problems in many different areas. Vibration can travel through the structure as well as through the connecting piping.

Solution: Isolate Equipment Inertia base with spring type isolators – The addition of mass to the bottom of the pump helps lower the center of gravity which reduces vibration. Spring isolators are required to prevent vibration transfer. Proper selection is required based on pump size and surrounding space considerations.

Solution: Isolate Connecting Piping Spring hangers are recommended on the inlet and discharge piping before the drop and until the vibration is dissipated. Depending on pipe size, this set-up usually requires 3 to 5 hangers on either side. Proper calculations should be performed for quantity and locations of the hangers.

Flexible connectors are required to isolate the connecting piping from the vibration source. They Reduce energy at blade passage frequency traveling through water column. They also provide discontinuity in metal piping to reduce motor caused vibrations.

Problem: Increased floor spans tend to increase deflections.

Solution: Proper location of equipment relative to column supports can control beam deflection and therefore reduce vibration in structure.

Uneven Weight Distribution

Problem: Water and pipe weights increase force on springs under pump side of unit.

Solution: Proper selection of isolators is required with safety factor to avoid bottoming out springs or not providing adequate deflection.

Problem: Addition of inertia base weight must be factored into structural design for dead and seismic forces.

Solution: Increased Edge distance and/or thicker housekeeping pads may be required. Larger structural beams may be needed.

Seismic Requirements

Problem: Forces are determined by a number of factors including: project location, site class, risk category, component importance factor and equipment location equipment relative to the overall height of the building.

Solution: Certified anchorage calculations must be submitted to verify loading conditions are met for each piece of equipment.

Problem: Horizontal and vertical seismic forces are applied at the center of gravity of the unit. The resulting overturning moment creates tension and shear forces that can be very large.

Solution: All connections of the restrained spring isolators to the structure must be designed for these loads. For concrete attachments, this requires ICC-ES certified anchors.

Problem: Reinforcement and doweling in of the housekeeping pad to the structure is often overlooked.

Solution: The load path must be accounted for from the center of gravity of the unit to the structure.

Problem: Poor installation of concrete anchors.

Solution: IBC 2015 requires ICC-ES approved anchors for cracked concrete and Omega Naught Factor (Horizontal forces multiplied by 2.5).

Problem: Differential motion up to 2” in a 20’ story height.

Solution: Flexible connectors are required to reduce equipment nozzle loads.

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