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Need help with cooling tower evaluations? You’ve come to the right place.

CleanAir Engineering is the leading independent test agency for cooling tower performance evaluations and is licensed by the Cooling Technology Institute (CTI) for all third-party CTI test programs including: thermal performance, drift emissions, sound and thermal certification.

Thermal Performance Testing

New Cooling Towers

Large field-erected cooling towers are a substantial investment and impactful to the performance of associated equipment. In order to ensure that you “got-what-you-paid-for”, many cooling tower contracts include a final milestone payment tied to demonstration of guaranteed performance through independent testing. CleanAir performs these performance tests as a CTI licensed test agent under the guidelines of ATC-105. An ATC-105 test is a rigorous test that translates performance from off-design conditions to equivalent performance when the tested tower is operated at design water flow rate, heat load, inlet wet bulb temperature, and fan motor power.


Old Cooling Towers

Cooling tower thermal performance typically degrades slowly over time hiding the negative impact to plant and process efficiencies. Often other equipment such as turbines, boilers and chillers attract more day-to-day focus, but cooling towers maintain a vital role in fulfilling production and efficiency objectives. A cooling tower thermal performance test can separate the cooling tower from other components in the heat rejection cycle and provide necessary data to conduct the economic evaluations to evaluate the potential financial impacts of cooling tower modifications.

Drift Emissions Testing

Cooling towers emit drift – which is a small fraction of their circulating water. The evaporation of cooling tower drift leads to PM emissions that cause downwind corrosion, icing, transmit legionella, and present other safety concerns. The US EPA considers cooling towers to be a source of particulate matter (PM) emissions so drift is often regulated by local air permits. Federal emissions factors as published in AP-42 are grossly conservative. This means facilities using AP-42 factors are “over-reporting” the amount of drift and associated PM from their cooling towers. We can accurately test your cooling tower drift emissions per industry standards so that you can report realistic drift and PM numbers.

Particle Size Testing

The size of the particles generated by the evaporation of the drift from a cooling tower is a function of the size distribution of the drift as well as the water chemistry. We can also measure the size of the droplets exiting the tower (7 to 4000 microns) and determine PM size fractions (PM10 and PM2.5). To do this, CleanAir has adapted a laser technology to measure the size distribution of cooling tower drift – Oxford Laser’s VisiSize D30.

With this technology, we can measure the portion of the drift droplet between 10 and 50 microns. Analyzing this part of the spectrum improves our ability to measure PM size distributions. It is also critical for getting PM10 and PM2.5 fractions. 


We deploy our laser-based system above cooling tower fan stacks. The camera and the laser are mounted so that we can adjust where we measure. The specific number of measurement points and sampling time lengths can vary by application, but each of our system contains:

  • A pulsed class 4 laser
  • Video camera with adjustable magnification (2x, 4x, and 7x) and 30 fps frame rate
  • Image processing software – used to determine the particle size distribution

Sound Testing

One of the most common workplace injuries is hearing loss, and cooling towers can be a significant source of noise emissions. Like our clients, we are continuously working to eliminate hazards and use engineering controls to reduce our employees’ exposure to dangerous environments. CleanAir can perform sound testing in accordance with CTI ATC-128 or other test codes to measure near field and worker exposure to noise from your cooling towers. Taking this first step helps you determine the most effective ways to reduce cooling tower noise emissions.

Thermal Certification

CleanAir does not sell cooling towers, but offers evaluations that help make sure your cooling towers are working as expected. Purchasing a CTI certified unit will ensure that a new cooling tower or fluid cooler works as specified. The CTI Thermal Certification Program certifies the published thermal ratings for factory assembled towers through rigorous review and validation in accordance with the STD-201 standard.

STD-201 Testing

The STD-201 standard requires both an initial qualifying test and annual reverification test for each line of towers. CleanAir is licensed by CTI to conduct this testing and our experienced test agents are often complimented by new applicants on their knowledge and helpfulness during the initial qualifying tests.

Plume-Abatement Testing

Plume-abated cooling towers are designed to minimize the amount and density of the visible plume that condenses at the cooling tower exhaust. These towers may be required by local authorities when the visible plume is a safety hazard or nuisance. Common settings include airports, locations adjacent to highways and urban settings. CleanAir evaluations are conducted in accordance ATC-150 to determine if plume-abatement performance guarantees have been met.