The following were questions and answers submitted to “Ask the Expert” columnist at the Cooling Water Institute’s CTI Journal – used by permission here:
Q: I am trying to educate a customer on Legionella. From a water treatment perspective, what do you suggest regarding biocides?
A: The CTI Legionella White Paper and ASHRAE Guideline 12-2000, “Minimizing the Risk of Legionellosis Associated with Building Water Systems” are excellent documents. They discuss use of oxidizing and non-oxidizing biocides. Go to the CTI website for a free download.
Q: How can you maintain the approach temperature in a cooling tower?
A: It’s recommended that, to maintain the approach temperature, the cooling tower be in proper working order. This means fans set to proper pitch to draw in the proper amount of air, fill is in good condition, correct water flow to each cell is properly distributed and wet bulb temperature is not exceeded.
Q: What are general CTI prescriptions for building/selecting gearboxes? Are CTI standards applicable for couplings as well as gearboxes?
A: CTI Standard 111 and Chapter 10 of the Cooling Tower Manual address cooling tower gear drives and Chapter 10 addresses requirements for couplings.
Q: What is the average life cycle of cooling towers?
A: There is no set answer since it varies tremendously with the water quality, water treatment and air quality around the cooling tower. In general, however, the normal range is between 15 and 25 years. There are many cooling towers in industrial plants that are older than 25 years but have good water treatment plans and periodic inspections of the cooling tower.
