We analyze the importance of structural strength in this class of special equipment for large projects.
By Alfredo Sotolongo*
The most economical energy to produce is the one that is saved!
In the previous writing I mentioned that I want to refer to other equipment, which although they do not contribute directly to the conservation of energy, offer you a more complete idea of what we have available in the air conditioning industry.
In this letter I want to refer to cooling towers. We all know that when they are correctly selected and their thermal capacity is certified by the corresponding institutions, they can contribute significantly to energy conservation and offer the lowest level of sound in the industry.
Its structural strength is as important a part of the design as its thermal capacity. The losses suffered by property insurance companies, as a result of the damage caused by hurricanes in recent years in the Caribbean, the southern United States and the Gulf of Mexico, have resulted in these companies significantly increasing the already high premiums.
The mechanical equipment that due to its size offers the greatest resistance to hurricane winds is the cooling tower and is, in addition, the equipment that when it is not properly designed structurally suffers and causes the greatest damage.
In several of our countries, it has been taken very seriously to solve this problem. The new standards that dictate the guidelines for both the structures of buildings and the mechanical equipment that is installed in such buildings, present a challenge for manufacturers of cooling towers. Structural engineers have been applied in the study of internal and external structures of cooling towers, analyzing even the smallest detail using computer programs specialized in these types of structures.
Prior to these new standards, it was only recommended that cooling towers be installed following the manufacturers' instructions. This was never enough to withstand the onslaught of hurricane-force winds, resulting in heavy losses for insurance companies and often for building owners as many insurance policies excluded certain types of equipment because of their location. The disproportionate increase in policy premiums also represents an additional cost for homeowners.
Originally, structural engineers only ensured that the anchorage of the cooling tower resisted the stresses of the pressure created by wind speed, both in compression and tension. However, the structural integrity of the full body of the cooling tower was not considered. In some cases, even if the anchors resisted the onslaught of the winds, the tower could separate from the anchors and fly into pieces causing damage to other parts of the building structure or adjacent structures.
The new standards require anchors to withstand stress and that the structural integrity of the body of cooling towers be maintained when the pressures exerted on them are the product of wind speeds of up to 146 miles per hour (235 km/hr) in gusts of at least 3 seconds duration.
What does all this mean? Simply put, prior to these changes, structural engineers only had to ensure that the anchors resisted in such a way that hurricane-force winds did not separate the cooling towers from their anchors, regardless of whether the cooling tower body disintegrated. After this change, structural engineers must ensure that structural integrity is maintained when pressures from wind speed are exerted.
Having lived all my life in hurricane-susceptible areas, it has always been our company's policy to supply products that minimize property loss while also contributing to keeping building costs within budget. For this reason, we have devoted special attention and considerable economic resources to carry out the most detailed structural analyses to ensure that Protec cooling towers provide structural and mechanical engineers with a reliable and durable product.
It is advisable to request from the manufacturers of cooling towers, evidence and certification of the structural integrity of the same by an engineer who has the necessary credentials to issue such certification. In this way, engineers and architects who design projects can be sure that they offer their client the optimal available in the industry.
* President of Protec, Inc., is certified as a professional engineer in Puerto Rico and the state of Florida; has more than 40 years of experience in the application and sale of systems and equipment for energy conservation. He is a member of ASME (American Society of Mechanical Engineers), AEE (Association of Energy Engineers), ASHRAE and was president of the Miami chapter of that association.
