Base Mounted Pumps

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.

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.