Warmer temperatures herald the imminent arrival of the cooling season. Is your cooling tower ready to perform?
Now is a great time to tackle your annual to-do list for cooling tower maintenance. Make sure you adequately address both preventive maintenance needs: keeping Legionella from growing out of control and ensuring the tower’s continued physical integrity.
Ensure Good Legionella Control
Your spring startup will depend on your existing disinfection practices and whether you drained your cooling tower during shutdown. If you’re using a submersible UV lamp, it should be changed every year, notes microbiologist Dr. Robert Scheir, president of germicidal UVC provider Steril-Aire.
If you’re coming up on 12 months since the last time you changed the lamp, be sure to put in a new one – they lose output over time, Scheir notes.
As you replace the lamp, check to make sure it and the rest of the tower can function properly. Because Legionella can cost you so much money and bad PR, it’s paramount to make sure the bacteria are never allowed to grow out of control in the first place. This can be difficult because Legionella occurs naturally and isn’t a one-time problem that can be solved, Scheir explains.
Did you shut down your system long-term over the winter? If so, you should have drained the tower and other components, such as piping and heat exchangers, according to ASHRAE Guideline 12, which lays out a step-by-step startup process that minimizes Legionella risks.
If this is the case at your facility, clean any leaves, dirt, or other debris from the tower and fill the system with water. Before you operate the pumps, ASHRAE recommends that you use one of two approved biocidal treatments – either the biocide you were using before shutdown or sodium hypochlorite.
However, if the system is undrained and full of stagnant water, Guideline 12 recommends that you perform pretreatment directly in the cooling tower sump or remote storage tank.
Make absolutely sure that any biocides you’re using are registered with the EPA, as demonstrated by a label that includes a registration number and specific guidelines for use, notes William McCoy, chief technology officer for water management and testing firm Phigenics and the chair of ASHRAE’s committee for Standard 188P, which also addresses Legionella control.