The OSHA Technical Manual (TED 01-00-015) — intended to provide technical information about workplace hazards and controls to the Occupational Safety and Administration’s compliance safety and health officers — provides a wealth of information about industrial hazards. Chapters address sampling, measuring methods and instruments, health and safety hazards including Legionnaires’ disease exposure, equipment-related hazards such as pressure vessel guidelines, and personal protective equipment. (You can review the full manual at https://www.osha.gov/dts/osta/otm/).
Recognizing, investigating and controlling Legionnaires’ disease is the focus of Section III, Chapter 7. As one might expect, especially in light of the outbreaks that plagued New York in the summer of 2015 and the subsequent development an ASHRAE Legionellosis standard, cooling towers and evaporative condensers are covered thoroughly. As the manual notes, cooling towers should be cleaned and disinfected at least twice a year. A natural time to complete this biannual task is before initial startup for the cooling season and after shutdown in the fall.
Once the system is clean, another important step is to treat the tower components to prevent corrosion. In “Protecting Cooling Systems from Corrosion during Winter Layup,” Casey Heurung and Julie Holmquist of Cortec Corp., St. Paul, Minn., explain how vapor-phase corrosion inhibitors can be used instead of alternatives such as nitrogen blanketing, dry-air systems or contact-type corrosion inhibitors.
Cooling tower preventive maintenance also is the focus of “4 Tips for Ensuring Top Cooling Tower Performance.” The engineering team at SPX Cooling Technologies, Overland Park, Kan., points out that good cooling tower performance begins before the tower ever arrives at the plant — on the drawing table. Factor in sizing, construction material requirements, necessary redundancy and serviceability.
If your cooling-water system uses water drawn from a river, lake or ocean, also remember to engineer the tower’s cooling water intake to protect aquatic life, says Nigel R. Rogers of Salt Lake City-based Ovivo USA. Process facilities have ample incentive to minimize the impingement of fish: Doing so reduces disposal costs and the potential for process disruptions due to the loss of cooling water following massive inundations of schooling species.