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FM Frequency: What Is Your Weakest Link?

Written by Retired Columnist. Posted in Columnists, FM Frequency, Magazine, Retired Columnists


Published on June 02, 2003 with No Comments

By Jeff Crane, P.E., LEED® AP
Published in the June 2003 issue of Today’s Facility Manager

Replacing obsolete equipment or making staff changes can beef up weak links. But another, less direct approach might include asking the question “What if something bad happens to….” Well prepared facility professionals will not only know if a solution is in place, but they will also test to see if it’s a good solution before something goes wrong! This type of questioning can help quantify exposure to risk (security, downtime, and other related issues) and determine which budget items are most important. Facility professionals that have addressed their “weakest link issues” should be able to request funds from the CFO based on realistic ROIs that are hard to dispute.

Since I’m most passionate (some might even say “obsessed”) about my mechanical systems, I’ll share some of the details about one of my “weak links” that recently snapped. My building consists of four floors with three major HVAC zones per floor. In each of these 12 zones, we have a large, water-cooled air conditioner (about 80 tons) with multiple internal compressors. The manufacturer calls these big boys “self contained units” (SCUs) and they are critical to our operation as an international corporate headquarters.

We have a pretty conservative mechanical design that includes redundant cooling tower pumps and fans, independent refrigeration circuits in each SCU, multiple zone variable air volume (VAV) control, and a reliable source of tower make up water from the City of Charleston. These features allow for most preventive (and reactive) maintenance to be done without paying overtime charges or sacrificing the productivity of about 750 staff members and over 100 tenants on the hottest days of the South Carolina summer.

Unfortunately, there is only one belt driven supply air fan in each of the 12 SCUs. So if a fan motor, belt, bearing, or variable speed drive (VSD) fails, we immediately lose cooling to 1/3 of a floor! Needless to say, I have struggled with the best proactive way to prepare for the failure of this link.

Just last week, a VSD overheated and brought an 80-ton SCU beast to its knees in a matter of seconds. (It’s amazing how a tiny set of bearings on a $15 component can cripple a gigantic marvel of engineering worth tens of thousands of dollars!) In response to that particular failure, I carried a box fan and an extension cord up to the mechanical room, opened the VSD cabinet, and just like cranking up an old Model T, proceeded to cool off the VSD manually with the box fan.

That got the SCU started and I was back in business! Very few people in the affected area even noticed the temperature drift.

I will confess this wasn’t my first VSD failure. Last summer, I lost one, immediately purchased a new unit (to the tune of about $12,000), and had it shipped overnight.

That might seem like an expensive repair for an internal capacitor failure, but my only other options were to pull the bad unit for repairs (possibly taking more than a week) or find a starter to crank the fan motor manually and run it at full speed. First, I contemplated the riots that would ensue if the building went without air conditioning for a week. Then I imagined the exploding ductwork above the ceiling if the fan had to be run at full throttle. It wasn’t all that difficult to pull the trigger on the new VSD.

The decision served a dual purpose. It not only provided next day repair on the down SCU, but it also gave me the chance to get the broken VSD fixed and placed on the shelf as a very expensive spare part. Last week that investment paid off. The expense was justified when my service technician modified the spare VSD for the smaller motor and swapped it out in about an hour! Now if all of the building’s SCUs were identical, I could simply keep a collection of spare parts that could be swapped out when something breaks.

Belts and bearings are pretty cheap, but unfortunately, the 12 SCUs feature several different size fan motors. This makes the economics of spare parts a little more challenging, yet the concept is definitely worth considering.

It’s a good preventive maintenance exercise to ponder these things once in a while and figure out how to create redundancies and backups with equipment, security, and staff functions before emergencies strike. And when performing what I call “the autopsy” on an incident, it’s usually a smart time to invest in improvements while problems are fresh in the boss’ mind and ROI justifications have additional merit. Indeed, it can be tough to justify contingency investments when creative problem solving and a successful status quo make the hard work of your department invisible to most people (including the folks with the money). In order to make the most compelling case, facility professionals must frame budget justifications in terms of a “weak link analysis” when failures are still fresh in everyone’s mind.

Crane is a mechanical engineer and regional property manager with Childress Klein Properties, a leading real estate developer and property management services provider in the Southeast.


About Retired Columnist

This expert formerly served as regular contributor to Today’s Facility Manager magazine. His vast knowledge of the facility management profession continues to provide a rich resource for facility managers by way of this online archive.

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