Communication Key to Ensure Uptime in Mission-Critical Data Centers

Ask anyone involved with mission-critical facilities to list steps that can be taken to increase reliability, and the answers are likely to involve technology: uninterruptible power supply systems, generators, redundant chillers and so on. But hardware is only part of the story. Soft skills also are important. And perhaps no soft skill is more essential than communication. That’s because miscommunication can wreak as much havoc as a utility power outage.

Consider the following examples of what can happen when there is a failure to communicate in the mission-critical environment. These examples, drawn from the realm of commissioning, show that it’s crucial to have consistency and clarity of vocabulary. But the lesson for facility managers is broader than commissioning: It’s essential to ensure that everyone involved in a mission-critical facility project or operation uses words the same way.

Consider the word “redundancy.” Designers have used that term to fulfill requirements for high reliability since the early days of the engineering profession. Broadly speaking, redundancy has taken many forms over the years. Sometimes, it exists as an inherent aspect of a design, such as a safety factor applied to a structure. In other cases, a system must undergo a mode or state change in response to an external condition for a redundant component like a back-up generator to activate. Either way, redundancy has existed for so long that we have grown comfortable — perhaps too comfortable — assuming that everyone understands what it means.

Recently, however, the question “What does redundancy really mean?” arose in a real-world way that threatened to hold up the integration testing of a major central plant project. The problem appeared during functional performance testing of centrifugal chillers. The plant repeatedly could not deliver sufficient differential pressure to the chillers’ evaporator sections at full load, even though the balancing report indicated routine settings and flows. After verifying the chillers’ pressure sensing, checking valve status, reviewing the pump curves, and ruling everything else out, it was determined that balancing had to be involved.

At nearly midnight, a sudden insight occurred to one of the team members. The four-chiller design called for N+1 redundancy, he noted, so “how did the balancer reflect that requirement?” As it happened, the balancer had adjusted the chilled water pumps assuming that all five would operate at full load. Rebalancing on a one-pump-to-one-chiller basis the next morning solved the problem.

Was this a basic mistake? Perhaps. The fact remains that the balancer misunderstood the meaning of “N+1 redundant” as applied at the hands-on level where it counts.

The plant owner had to deliver on a firm “go live” date, which made a tight schedule tighter and increased the owner’s schedule risk. Still, the team went on to complete the commissioning on time, and the owner has achieved high operational reliability since.

Defining “Factory Tested”

Designers, buyers, construction managers and owners have long looked to factory-witness testing for multiple useful purposes. For designers, it offers an opportunity to hold a manufacturer to a tough spec and, if there’s a problem, address it early on. For construction managers and buyers, it can satisfy auditors that funds are being released for equipment that meets specifications and, barring installation issues, will operate as designed.

For the commissioning team, factory tests provide opportunities to simulate faults, adjust settings, and learn how the equipment really works — beyond what’s documented by the manufacturer. The team can then use the results to either validate their commissioning plan or adjust it, based on what they observe.

Maintenance and operations personnel stand to benefit as well. Factory testing offers a head start on learning the equipment’s operating characteristics and working with abnormal modes they may not encounter for years once the project goes live.

Like redundancy, factory testing is one of those concepts that have become routine — so much so that we rarely revisit what we mean when we say “factory test.”

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