As you prepare to perform a functional test, there are several precautions and preparations that need to be considered to protect personnel and equipment. Precautions for the industrial building environment have been included in Section 17 Supplemental Information.
These discussions do not represent a comprehensive list of issues and safety concerns associated with working around machinery and performing functional testing. Thus, PIER, LBNL, and PECI assume no responsibility for how they are applied beyond the teaching purposes of this guide. It is up to the commissioning practitioner to assess each project for its own specific risks and liabilities and to plan their testing process and site visit protocols accordingly.
Personnel safety will continue to be discussed throughout this guide. Sometimes, you won’t realize that a certain procedure has risk until you actually start performing it. If you can’t do something safely or are not comfortable with an evolving situation, then stop and reevaluate. You may need to develop a better approach or may need to be assisted by someone with more experience in a particular area prior to proceeding.
Working safely on a commercial construction site is usually a matter of complying with the existing safety requirements, including a hard hat and eye protection, and steering clear of hazardous work areas. As a commissioning provider on larger projects, you may be contractually obligated to attend a safety training session prior to being allowed to work on the site. In addition, you may be required to attend regular project safety meetings. It is important to assess this requirement when you are preparing your bid or proposal for the commissioning work and budget for it accordingly.
Working safely on an industrial site can be more complicated than a typical commercial construction site. For information on industrial personnel safety practices, refer to Section 17 Supplemental Information.
Equipment safety is an underlying theme in many commissioning test plans. By their nature, some of the functional tests that you will perform will place the systems at risk. One of the major goals of this guide it to help commissioning providers assess specific test situations and understand:
1 Risks to the system in normal operation.
2 Safety measures to adequately protect the system from those risks.
3 Tests that ensure that safety measures function properly.
Generally, this information is presented in the Functional Testing Benefits table in each chapter under Other Benefits and the Functional Testing Field Tips table in each chapter under Precautions. The test writer should evaluate this information with other project specific information, and then develop their test plan accordingly. When exposing a system to a potential risk through a functional test, structure the test to minimize that risk and be ready to respond if a problem does occur. The key question is what level of risk is appropriate for the benefit gained.
For example, one of the most difficult things for a large HVAC system to do is to simply come online and stabilize. The start can be a simple scheduled start or it can be a recovery from a power failure or fire alarm. The start-up event places a step change into the system that impacts most of its control loops and can ripple out to the supporting utility systems. If there is instability in any one of the loops, a restart is one of the situations under which this instability will likely show up. If the system has not been tuned to dampen these upsets, then they can quickly escalate out of hand. On large systems, the pressure and flow surges associated with a restart can trip safety systems and ultimately can become destructive if left unchecked. So, for some large systems, a restart from a shutdown places the system at risk for a failure. As a result, you might consider a simple test to shut down the system, perhaps under near design climate conditions, and then restart it. Is this test worth the potential risk of disruption of service or potential damage? In almost all situations the answer will be “yes” for the following reasons:
1 In a real operating environment, most systems will have to deal with a restart, even if they are intended to run 24 hours per day, 7 days per week. At some point in time, there will be a power failure, a fire alarm, or an equipment failure that will knock the system off-line. If you don’t do the test, then “mother nature” will, probably in the middle of an ice storm with record low temperatures on Christmas Eve. At that point, any failure will be unanticipated and there will be limited resources available to deal with it.
2 If problems are discovered, you and the test team will be there to observe the response, use the information to formulate a solution, and abort the test before any damage occurs. In addition, since the test was a scheduled event, any problems or failures will be less of a surprise to the test team and the building occupants.
All tests may not be worth the risk. For example, verifying that the system’s pressure relief doors will blow open by forcing the discharge smoke damper to slam closed has the potential for causing more problems than the benefit of such a direct test would provide. If the pressure relief doors did work flawlessly, then you would have absolute assurance of their functionality in a real event. On the other hand, if a problem occurred and the doors failed to function properly, then considerable damage could occur including rupturing of the air handling unit casing or duct system and distortion of the smoke dampers due to air hammer effects. As a result, you might choose a less rigorous test approach that provided nearly the same degree of certainty of the damper functionality. One option might be to use a duct testing machine and a specially fabricated test boot to subject only the door to its rated release pressure and verify that it opens. Another might be to use a spring scale to exert the force that correlates to the doors release pressure on the door and verify that it opens.
The preceding example shows that commissioning providers need to carefully evaluate all aspects of a system’s test requirements and match the needs of the system with the limits of time, budget, risk, and benefit. Items to consider when developing and executing the test procedures include:
· Risk: What level of testing rigor is appropriate for the risk? How dangerous will the test be and how dangerous will the system be if not tested for a particular situation?
Contractually, it is important that the Owner and/or contractor approve of the testing plan. A well-designed test will not put a system at risk in any manner that it would not normally encounter at some point in its operating life. However, tests are often targeted at verifying the stability of the system and the performance of interlocks and failure functions, which can put the system at risk. Since it is the Owner’s or the Contractor’s system, they need to formally acknowledge and accept those risks.
In understanding the risks imposed on the system by the test, the commissioning provider should understand the problems that could occur in the event that the system fails the test. If the risks of damage to the system are high, it may be good to have a plan of action in place for different scenarios. The plan should include:
1 A specific decision point that when reached will result in the test being aborted without question.
2 A plan of action that will be used to shut down the test including specific assignments for responsibilities and actions associated with the test shut down.
3 A recovery plan if the premature shut down of the test places the system in a mode that will cause significant disruption at the loads or pose other operational problems.
· Degree Of Certainty Required: How much assurance do you need that the outcome predicted by the test will be the actual outcome in the real time operating environment? Life safety functions typically require a high degree of certainty and are generally tested rigorously via a code enforced testing regime. Efficiency functions, while economically important, have more tolerance for failure. Problems that do occur can typically be identified by alarms, utility monitoring and continuous commissioning processes and corrected without performing tests process that might subject the system to damage. Testing processes for efficiency functions should prove that the process should work and then supplement the testing with trending to verify the process.
· Clear Understanding of the Limits of the System and Test: The test writer and the technicians performing the test should have a clear understanding of the limits of the system and the test. It is highly desirable to document this information somewhere in the test procedure for ready reference. Building occupants should also be informed of any tests that may affect their environmental conditions. Laboratory, process, and health care environments are particularly intolerant of unannounced environmental swings.
· Chain of Command: Frequently, contractual requirements, labor regulations, work rules, and Owner operating protocols may dictate that someone other than the commissioning provider actually run the test. In these situations, the commissioning provider becomes more of a planner, consultant, and observer of the test. It is essential that the commissioning provider clearly communicate the test procedure to whomever will be running the test. This person needs to understands the test and be committed to performing it. If they do not agree with the plan, then it is usually better to negotiate to a test plan that is satisfactory to them rather than attempting a test that they disagree with.
· Dry Run: For complex tests or tests with critical failure modes, rehearsing the test steps, including what will happen if something goes wrong, can go a long way towards verifying the understanding of the test process among the team members. In addition, this process often will uncover weak points in the test plan, allowing the plan to be modified and improved.
Obviously, not every test will require a high level of planning and consideration. The commissioning provider should assess which tests merit this level of effort and then plan the testing accordingly.