Inspect for Damage and Debris
No annual inspection is complete without a comprehensive examination of the tower’s physical condition.
Ideally, this starts in the fall with a thorough assessment to determine if the tower can last another year, explains Dan Glover, technical services group manager for Southland Industries, a national mechanical engineering, construction, and service firm.
However, it’s not uncommon to save this task for the spring, roughly a month or two before you plan to switch over to cooling. Common trouble spots include:
Basin: This is usually the first place you’ll spot major problems because the sediment will rust the metal parts, Glover notes.
“If you haven’t maintained that, you’ll have to replace the pan,” he adds. “Replacing the pan is almost as expensive as replacing the whole cooling tower.”
Fill: This plastic part is made to last about 10 years, but the stress of heat and cold exposure, constant moisture, and exposure to sunlight will break it down.
Nozzles: If you neglect them, clogs can become so bad that the nozzles themselves have to be replaced, Glover says.
Structural integrity: “Once the structure rusts out, it’s done,” Glover explains. “It’s best to keep it painted with a zinc paint.”
As you inspect, look for signs or potential causes of scale and corrosion, such as these red flags noted in the OSHA Technical Manual:
- Visible buildup of scale, sediment, or bio-fouling (accumulated biological material)
- Presence of rust or scale in the water, which could indicate infrequent use, corrosion, or biofilm formation
- Free residual chlorine above 1 part per million, which can corrode metals in the system, react with any organic substances in the water to form toxic byproducts, and damage any wood in the tower
- A pH above 8.0
Also look for damage from environmental causes, especially if your facility is in an urban area with polluted air, Glover recommends.
“Garbage in, garbage out. If you’ve got contaminated air, your cooling tower is breathing it, and that’s going to attack your tower,” Glover explains. “I once worked on a building with diesel trains sitting next to it. The diesel smoke got into the cooling tower and caused iron-reducing bacteria to grow and eat away at the piping – they thrive in environments that contain a lot of petroleum.”
The Bottom Line
It’s easy to overlook periodic maintenance if your water testing and physical examination both indicate a healthy cooling tower, but that attitude can be harmful to occupants and the tower itself.
Fortunately, with a watchful eye and routine preventive maintenance, you can keep your tower running efficiently and occupants healthy for years to come.
Keeping the tower in good shape and preventing Legionella are as simple as preventing food poisoning, McCoy adds. Effective practices are widely known, but you actually have to use them to avoid illness. The same attitude applies to maintaining the tower’s physical integrity.
“You can’t eliminate food poisoning – if you buy hamburger, leave it to sit for a couple of days, and then don’t cook it properly, you’re going to get sick. The only way to prevent disease is to handle the food properly,” McCoy says. “Handle the water properly and use a risk management system that is scientifically based and reliable.”
Janelle Penny firstname.lastname@example.org is associate editor of BUILDINGS.