Safety and Cooling Towers
Cooling towers are classed as "specified as high risk plant" and as such have the following areas of safety that must be considered.
- Air and water borne diseases
- Working at heights
- Confined space
- Rigging / dogging
- Falls from Heights
- Falling Objects
- Working around cranes
What is the needed ratio of water treatment chemicals to that of debris load inside the cooling tower to ensure cooling tower safety?" Although the question is obvious, the answer isn't. Organic debris is drawn into cooling towers in different concentrations depending upon location and time of year. Every type of debris places a different demand upon the biocides and scale inhibitors being dosed into the water; therefore, there is no known ratio that will hold constant for every cooling tower. However, it is safe to say that if you don't deploy diligent maintenance procedures that specifically call for the prevention of organic debris from getting into the cooling tower or its periodic removal, more water treatment chemicals will be required to keep it safe. Some may say, "Load the tower up with chemicals to ensure safety", however, federal and state EPA guidelines place restrictions on the amount and type of chemicals that can be used, therefore the use of chemical treatment alone is not the solution. Furthermore, adding chemicals to offset poor maintenance practices is a shortcut that will do little to prevent fouling and clogging of the fill, strainers, blow down valves, chiller and heat exchangers and could eventually lead to health and safety problems and a reduction in equipment performance. Although the answer to the chemical ratio to debris question isn't apparent, the answer to how to keep a safe cooling tower is crystal stated - "Keep the cooling tower free of debris and deploy a good water treatment program and your cooling tower will operate safely and efficiently." This may sound like an over simplification, but in reality if you keep the debris out of the cooling tower, you will break the bacteria supporting food chain. Additionally, when you chemically treat the water you create an environment non-conducive to bacteria habitation. In short, when you eliminate food and shelter for bacteria it won't take-up residence in your cooling tower!
How to Keep a Safe Cooling Tower
In recent years Government bodies and AIRAH has established excellent recommendations for cooling tower maintenance. In addition to recommending maintenance activities, it also calls for establishing procedures that are measurable. Although AIRAH guidelines are excellent, companies must ultimately weigh the operational and economic realities of any maintenance procedure they deploy. As the old saying goes "There's more than one way to skin a cat". If on the one hand maintenance procedures are too frequent, cumbersome or complex, it commonly results in more downtime, lost productivity and higher maintenance costs. Furthermore, the natural human tendency is to take shortcuts to quickly complete an unpleasant job - often times with unsatisfactory results. Conversely, if the intervals between maintenance are too long, it may be more cost effective, but the condition of the cooling tower at each interval may be less than desirable and potentially place maintenance workers, employees, tenants and the public at risk. So the answer largely lies somewhere in the middle where water treatment and managing debris in the tower come together. Today, companies have many options available to them for managing debris; they include a variety of water based filtration technologies and air intake filtration technology. Water filtration can help manage waterborne and other debris after it gets into the cooling water while Air intake filtration technology is highly effective at stopping airborne debris from getting into the tower by filtering the air as it enters the system. . Furthermore, air intake filtration can be used in glycol based cooling systems and on other air-cooled condenser systems to keep airborne debris out of the coils, enabling optimal cooling efficiency. When determining what maintenance and debris management technology to use, it is important to first determine what the source of debris is. If the source of debris is waterborne (e.g.; sediment, algae from pond or river, or water with high dissolved solids content), water filtration in combination with a good water treatment program is typically the best solution and will protect the chiller and heat exchanger from scaling and fouling. If on the other hand, the source of debris is airborne related (cottonwood seed, insects, leaves, pine needles, paper, birds & droppings, harvest chaff, construction debris, etc), then water filtration systems will not stop the debris from getting into the cooling tower (especially the fill). For airborne debris related problems, the best solution is to prevent the debris from getting into the system by using air intake filtration technology that filters the air as it enters the system. Air intake filtration in combination with a good water treatment program is highly effective in stopping the kind of debris that clogs strainers, blow down valves, fill, chillers and heat exchangers - In short, air intake filtration effectively protects the entire system. In extreme cases where both waterborne and airborne debris is problematic, both air intake filtration and water filtration in combination with a good water treatment program may be required in order to keep the cooling tower safe and operating efficiently.
No matter what procedures are adopted in maintaining cooling towers, personal safety precautions must be integral to the maintenance procedures. Best practices require workers to wear respirators, gloves and protective clothing to help prevent exposure to bacteria, especially Legionella. Important Note: cooling water doesn't have to look dirty to be dangerous - just because the water is clear doesn't mean it's clean or free of bacteria - Every cooling tower can harbor bacteria. Always, always take precautions because unless the water is routinely tested for Legionella and other bacteria, the bacteria will never announce its presence until it's too late.
Consider the Costs of a Sick Tower
Companies that don't take appropriate precautions and insist upon diligent cooling tower maintenance procedures put not only their employee's health and safety at risk, but also their business and reputation. Consider the cost of a single cooling tower related Legionella incident:
- Reduced employee moral and productivity due to an unsafe work environment.
- Negative customer perceptions of the company and their willingness to buy goods & services should a Legionella outbreak become public. (especially risky for food and related processors)
- Loss of income to families when a loved one becomes ill or dies from Legionella.
- High cost for litigation which can follow.
- Higher company insurance costs when claims due to job related sickness or death occur. In comparison to the cost of a proactive maintenance initiative, the incidents listed above when considered individually or collectively carry staggering cost.