SPX Cooling Technologies 1200, 1000 Specifications, Specification Value, Low Noise Tower

Marley / Sigma 1000/1200 CoolingTower / Specifications: Options

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Specifications

Low Noise Tower:

1.1Add the following at the end of this paragraph: The cooling tower shall be quiet operating, and shall produce an overall level of sound no higher than ____

dBA at the critical location indicated on the Plans.

Specification Value

■Sound produced by a Sigma Steel tower operating in an unob- structed environment will meet all but the most restrictive noise limitations – and will react favorably to natural attenuation.

Where the tower has been sized to operate within an enclosure, the enclosure itself will have a damping effect on sound. Sound also declines with distance – by about 5 or 6 dBA each time the distance doubles. Where noise at a critical point is likely to exceed an acceptable limit, you have several options – listed below in ascending order of cost impact:

•Where only a slight reduction in noise will satisfy — and the source of concern is in a particular direction — merely turning the tower may be the answer. Less sound emanates from the cased face of the tower than does from the air intake face.

•In many cases, noise concerns are limited to nighttime, when ambient noise levels are lower and neighbors are trying to sleep. You can usually resolve these situations by using two- speed motors in either 1800/900 or 1800/1200 RPM configura- tion; and operating the fans at reduced speed without cycling “after hours”. (The natural nighttime reduction in wet-bulb tem- perature makes this a very feasible solution in most areas of the world, but the need to avoid cycling may cause the cold water temperature to vary significantly.)

•Variable speed drives automatically minimize the tower's noise level during periods of reduced load and/or reduced ambient without sacrificing the system's ability to maintain a constant cold water temperature. This is a relatively inexpensive solution, and can pay for itself quickly in reduced energy costs.

•Where noise is a concern at all times (for example, near a hos- pital), the best solution is to oversize the tower so it can operate continuously at reduced (1200 or 900 RPM) motor speed even at the highest design wet-bulb temperature. Typical sound reduc- tions are 7 dBA at 2/3 fan speed or 10 dBA at 1/2 fan speed, but larger reductions are often possible.

•Extreme cases may require inlet and discharge sound attenu- ator sections; however, the static pressure loss imposed by attenuators may necessitate an increase in tower size. This is the least desirable approach because of the significant cost impact – and because of the obstruction to normal maintenance procedures.

Your Marley representative can help you meet your sound requirements.