CCG Facilities Integration

Innovating Mission Critical Systems

Research & Whitepapers

Vibration and Alignment Testing – Hidden PUE and OpEX Savings

12.21.2012

Authored by:  
Thomas J. King, PE, CxA, CEM, LEED AP BD+C   
Director of Commissioning 



Summary
All rotating machines produce a vibration during normal operation.  The amount of normal vibration produced during equipment operation is unique to each type of equipment.  Factors such as equipment manufacturing, installation, duty, and nearby environmental conditions contribute to equipment vibration during operation.   Identifying and correcting abnormal vibrations from newly installed equipment is critical to any project, particularly those projects whose infrastructure equipment serve to support a critical business mission.   

The process by which project equipment is assessed for abnormal vibration should be defined and implemented during the execution of a mission critical project.  Project specifications must be developed to define the minimum level of vibration performance for rotating equipment.   The project’s commissioning plan should also be developed to track and coordinate the project’s equipment vibration testing requirements with equipment prefunctional testing, equipment startup, and functional performance testing.  

Without the establishment of vibration performance requirements for project equipment, optimal baseline equipment performance and energy efficiency cannot be accurately established.  Other 
consequences of omitting vibration testing during the project equipment commissioning process includes compromising the operational longevity and service reliability of the mechanical and electrical systems equipment.  

Specification Development and the Equipment Vibration Testing Process

During the Design Phase of a project, the Owner, Engineer of Record (EOR), Commissioning Authority (CxA), Equipment Vendors Representatives (EVR), and Representatives of the Construction Team should work together to understand the baseline project vibration test program.   The program should detail the project equipment identified for vibration testing and the process for vibration testing during the project construction and acceptance phases.  Inclusion of vibration testing performance and acceptable remediation processes greatly assists the CxA during the Acceptance Phase of the project.


With product performance resource support from the project’s EVR, the EOR should detail baseline vibration testing program requirements in the Part 3 - Execution section of all equipment specifications.  Vibration testing requirements should ideally detail the following:

  • Testing personnel requirements, including certifications or contractor affiliation (3rd party requirements)

  • Test equipment and associated calibration requirements

  • Test setup requirements, including equipment test isolation requirements

  • Vibration performance criteria, including maximum displacement (peak), velocity (in/sec), and acceleration (in/sec2)

  • Test witnessing requirements by the project EOR and / or CxA.

  • Test results report requirements, including report contents and recommendations.

  • Acceptable equipment vibration remediation solutions.

If the project specifications do not detail equipment vibration testing requirements, the project procurement process may not include this work scope in the project budget or schedule.   Inclusion of a vibration test program into a project after budget approval and contract document procurement can be difficult if not impossible.

Commissioning Plan Development and the Equipment Vibration Testing Process
Development of the project Commissioning Plan (CxP) ideally begins at the inception of the project or immediately following the deployment of a CxA on a project.  Among many of the coordination activities conducted between the EOR team and the CxA team during the development of the CxP is accounting for all specified prefunctional, startup, and functional tests as prescribed in the construction documents (CDs).   It is the responsibility of the CxA to coordinate the EOR specified testing with the Cx testing for a project in an integrated manner to maximize acceptance testing efficiency and completeness.   Equipment vibration testing is one key process that must be integrated into both the CDs and CxP.

Since equipment vibration performance testing is critical to verifying day one peak performance of rotating equipment, the CxA has an opportunity during the Design Phase of a project to assist the EOR in including vibration testing program performance in the respective equipment specifications.   The CxP can then cross-reference the specified performance requirements for vibration testing in the CxP as well as the prefunctional and functional test procedures. 

In instances where the CxA is procured on a project with 100% construction documents that lack vibration testing and performance specification criteria, the CxA should evaluate all opportunities where equipment vibration testing and performance can be installed into the project’s commissioning process.  Where possible, the CxP and the Cx procedures should attempt to include certain minimum levels of vibration testing to support necessary corrective actions without major consequence to the project budget or schedule. 

Execution and Acceptance Testing and the Equipment Vibration Testing Process
Inclusion of the vibration testing process into the Cx t
est schedule and test procedures further ensures that vibration testing is executed and results are reviewed by the entire project team. Prefunctional tests can be developed to verify equipment alignment work is completed, proper vibration isolation fixtures are installed, prescribed equipment assembly processes are followed, and various other construction activities are followed to minimize abnormal equipment vibration during operation.

During functional testing of equipment, particularly equipment with onboard vibration metering, assessment of normal equipment operation under various loads should include assessment of equipment vibration.   If abnormal vibration conditions are observed, project specifications, which detail the performance requirements for equipment vibration, will greatly support the CxA in assessing equipment operation, operational control setpoint and alarm setup, and Owner acceptance. 

Following the project commissioning process, the CxA assembles a Project Systems Manual (PSM) for the Owner and Facility Operators.   The CxA should include all initial vibration reports in the PSM to support future facility maintenance.   The CxA should recommend to Facilities Operations representatives that all rotating equipment be retested for vibration performance annually.   Changes in equipment vibration as compared to baseline performance recorded during the project build-out can provide valuable information that can be used to pinpoint the source for equipment performance deficiencies, energy use increases, or upcoming equipment component failures. 

Case Study - Retro Cx and Energy Audit of a Cooling Tower 
CCG recently completed the commissioning of a data center project, which utilizes a water-cooled chiller plant to serve the HVAC systems.   Due to project construction delays and the project’s fast-track schedule, the General Contractor (GC) evaluated every aspect of the project delivery process to recover time.  Elimination of vibration and alignment testing was one opportunity the GC offered to the owner and project team as a way to regain lost workdays. 




Acting as the project’s Engineer of Record and CxA, CCG recommended to the Owner that the vibration testing of critical system equipment remain a part of the project Acceptance Phase process.  As a result, the plan for deploying a vibration testing firm to assess new chiller plant equipment was retained.  
 

During the course of the vibration testing, abnormal vibration signatures were observed for the plant cooling towers.  Cooling tower fan motors were measured to be using 31 amps at 460 volts / 3 phase (approximately 24.7 kW) at 60 Hz.  Following realignment of the cooling tower fan motor and drive shaft as well as work to correct the equipment level, motor amperage was reduced to 26.7 amps at 460 volts / 3 phase (21.1 kW) at 60 Hz.   This represents a 15% reduction in the tower motor load which would have been forfeited had vibration testing been eliminated to improve the project schedule. 


Facility PUE Reductions
In addition to the energy use reductions obtained from the cooling tower equipment alignment work detailed above, a consequential reduction in the facility’s Power Usage Effectiveness (PUE) was accomplished.   PUE is the ratio of total amount of power required to operate the data center facility to the power required by the data center computing equipment. 

The PUE for the data center facility discussed above was originally estimated to be 1.6.  This estimate was based on the equipment schedule information detailed in the design documents.  This ratio was calculated by taking the total power required to operate the facility (8,000 kW) and dividing it by the critical power required to operate the facilities’ IT equipment (5,000 kW).  If all of the mechanical plant equipment (less chillers) required 15% more power to operate, the actual total power required to operate the data center facility could be as high as 9,000 kW.  As a result, the actual facility PUE could be as high as 1.8.   This is an 11% increase between the originally designed facility PUE performance and the actual facility PUE performance.  

OpEx Energy Cost Savings 
Assuming a $0.15 / kWh utility electric rate and a 8,760 hr/yr operational schedule, the vibration test and associated corrective measures reduced the annual operating energy costs for this cooling tower by $4,730.  Over the estimated useful life of the cooling tower (up to 25 years per ASHRAE Equipment and Systems) and holding energy costs constant, the total energy use savings could be as high as $118,250.