SPX Cooling Technologies 1000, 1200 specifications Enclosures, Sound Control, System Cleanliness

Marley / Sigma 1000/1200 CoolingTower / Engineering Data: Environmental

13

Enclosures

Occasionally, cooling towers are located inside architectural enclosures for aesthetic reasons. Although Sigma towers adapt well to enclosures, a poorly designed enclosure can impair proper operation. An effective design includes gener- ous air inlet paths, with the tower’s fan cylinder discharge at or above the top of the enclosure. See Marley Technical Report #H-004, “External Influences on Cooling Tower Perfor- mance”, for design recommendations.

It may also be advisable to increase your design wet-bulb temperature by 1°F to compensate for potential recirculation initiated by the enclosure. You’ll benefit from discussing your project with your Marley sales representative.

Sound Control

A Sigma tower operating in an unobstructed environment will meet all but the most restrictive noise limitations – and will react favorably to natural attenuation. Where the tower will operate within an enclosure, the enclosure itself will usually have a damping effect on sound. Distance will also reduce sound – by about 5 dBA each time the distance is doubled. 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:

Noise concerns are often limited to nighttime, when ambi- ent 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 configuration; and operating the fans at reduced speed without cycling “after hours”.This relatively inexpensive solution pays for itself quickly in reduced energy costs.

Where the problem can exist at all times (such as near a hospital), the best solution is to oversize the tower so it can operate continuously at reduced (1200 or 900 RPM) motor speed. Typical sound reductions are 7 dB at 2/3 fan speed or 10 dB at 1/2 fan speed.

Extreme cases may require inlet and discharge sound at- tenuator sections; however, the static pressure loss imposed by attenuators may necessitate an increase in tower size.

This is the least desirable approach because of its significant cost impact – and because it obstructs normal maintenance procedures.

Your Marley sales representative can help you meet your sound requirements.

System Cleanliness

Cooling towers are very effective air washers. Atmospheric dust able to pass through the relatively small louver openings will enter the circulating water system. Increased concentra- tions can intensify system maintenance by clogging screens and strainers; and smaller particulates can coat system heat transfer surfaces. In areas of low flow velocity (such as the cold water basin), sedimentary deposits can provide a breed- ing ground for bacteria.

In areas prone to dust and sedimentation, you should con- sider installing some means for keeping the cold water basin clean. Typical devices include side stream filters and a variety of filtration media.

You should also plan ahead to develop a consistent, ef- fective program of water treatment. A good water treatment program will help to assure long service life, while keeping your tower free of potentially harmful biological growths.

CAUTION

The cooling tower must be located at such distance and direction to avoid the possibility of contaminated discharge air being drawn into building fresh air intake ducts.The purchaser should obtain the services of a Licensed professional Engineer or Registered Architect to certify that the location of the cooling tower is in compliance with applicable air pollution, fire and clean air codes.