In 2009, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) commissioned a study through the University of Pittsburgh Department of Civil and Environmental Engineering. The two parties collectively established a protocol to test non-chemical water treatment systems and evaluate their efficacy at controlling biological fouling in cooling water systems.
After an eight-month comprehensive evaluation, it was concluded that none of the five different chemical-free systems showed any ability to control sessile or planktonic microbial growth rates compared with the control.
During a controlled investigation, two identical pilot-scale cooling towers were operated simultaneously under similar operating conditions. The model cooling tower systems were used to closely simulate realistic field conditions, including heat load, evaporative cooling, blowdown system, and water make-up. The cooling towers were operated to encourage the formation of surface occurring biofilm (sessile bio-mass) in the tower.
One tower (T1) acted as a control system throughout the study, and this tower received no treatment. The second tower (T2) received treatment from the Flow-Tech device throughout the course of the testing period. The test duration was just under two months. Biofilm coupon samples were pulled and sent to a Special Pathogens Laboratory for culture and counts. The Flow-Tech system reduced sessile bacterial growth by between 1-3 log. On average, sessile heterotrophic plate count concentrations were approximately 50 times higher in T1 (Control) than in T2 (Device), meaning the Flow-Tech treated tower realized a 98% reduction is biofilm growth.
California, 400 Ton Cooling Tower:
Due to 23 grain per gallon (GPG) hard water, this customer was experiencing substantial scale accumulation. The customer also recorded high bacteria counts and had higher than acceptable corrosion rates. Flow-Tech was installed, and using the chemical-free technology, new scale formation was prevented, and previous scale was softened, making for easy removal. Bacteria rates were reduced by 77%, and coupon rack tests indicated that the corrosion rate had been controlled. With scale formation resolved and energy efficiency increased, the customer achieved the improved water usage, bacteria control, better corrosion rates, and energy savings they wanted.
Washington, 1.5 Ton Closed Loop:
Bacteria counts in this closed loop system exceeded 13,000 CFU/mL. Instead of choosing a chemical dosing program, the customer elected to install a Flow-Tech chemical-free system to address the problem. With no plumbing modifications for installation, after four months of treatment, the bacteria count was reduced to 20 CFU/mL, a 99.85% reduction, meeting the CDC drinking water standards of <500 CFU/mL. After following up with the client two years after installation, the system was still showing low bacteria counts and operating efficiently.
California, 60 Ton Fluid Cooler:
This customer had been using chemicals, but was unhappy with the efficiency that led to high water usage. The Flow-Tech system was able to restore heat transfer efficiency. Increasing this efficiency resulted in less water needed by the evaporative condenser. In comparison to previous years, Flow-Tech was able to save 740,520 gallons of water in a three-month period, thus giving the customer the water usage reduction they wanted.
California, Brine Heat Exchangers:
Brine solution has high Total Dissolved Solids (TDS), which can be up to 300,000 ppm. For this customer, a 24” header supplied the brine to four large plate and frame heat exchangers. Before Flow-Tech installation, the heat exchangers had to be flushed for one hour twice a day to remove the mineral deposits. Upon installation, the customer realized a 93% savings by decreasing the frequency of cleanings from twice a day to once a week. They experienced an increase in heat transfer, reduction in labor, and a rapid ROI. Due to the results, the customer has installed Flow-Tech on many of their other applications, such as their distribution lines and pumps.
Arizona, Cooling Tower and Chiller:
This customer had tried three chemical-free water treatment systems on their cooling tower and chiller with varying degree of success. Two of the chemical treatments left the customer with scale, biofilm, high corrosion rates, decreased heat transfer, and high head pressure, causing the system to shut down. Flow-Tech was installed, and even with extremely challenging and varying water quality, the system has not turned off due to high head pressure. Other chemical-free treatments had left biofilm in the system, and Flow-Tech was able to remove the biofilm and prevent new formation. Corrosion rates improved, water usage was optimized, and scale in the tower chiller system is no longer present. With two seasons of results, Flow-Tech succeeded where other chemical-free systems failed, and it continues to protect the system.