With a staff of 2,350, Grand River Hospital (GRH) in Kitchner-Waterloo, Ontario, is the largest medical center in this area of 420,000 people, about an hour’s drive southwest of Toronto. For hospitals like GRH, where infections can mean the difference between life and death for those in fragile health, it is critical to maintain humidity within the 30- to 50-percent range recommended by the Centers for Disease Control. In 1998, the hospital switched from a 10-year-old steam system to a high-pressure fog humidification system on nine of its air-handling units (AHUs). This change eliminated the health risk of additive chemicals in boiler feed water entering the airstream, one of the drawbacks of the direct-steam method. But rather than proving to be a costly improvement to offer patients cleaner air, it turned out to be a cost-saving initiative. A fogging system uses 1.5 horsepower to atomize 1,000 pounds of water. This is about 3 percent of the electrical energy that compressed air or ultrasonic water atomizer uses, and 1 percent of the amount required by a steam humidification system
The GRH system incorporates a FM-700-B1050 main pump unit with a 5 hp Variable Frequency Drive motor to provide 1,000 PSI to the fogging units in all the AHUs. Rather than using a Programmable Logic Controller (PLC) to run the hospital’s humidification system, it was tied directly into GRH’s existing Energy Management Control System. Sensors were installed to measure the humidity in each zone of the hospital being serviced, as well as the humidity of the air returning to the AHU. High-pressure fog system by MEE Industries Inc., Monrovia, CA.