Kroeschell, Inc.

Scope Of Work

A newly constructed medical facility planned to offer patients corneal refractive (Lasik) surgery; however, shortly after the facility was completed, surgical procedures were suspended abruptly.

Challenge

The existing HVAC system serving the surgical procedure room couldn’t deliver the required temperature and humidity necessary for optimal surgical outcomes.

Studies have shown that successful refractive surgeries demand exacting environments. That means no more than a ± 1 F° swing in temperature and a ± 2% change in relative humidity (rh) over a 10-min period. If the room doesn’t hold conditions, surgery cannot be performed. As a result, the new surgical suite was temporarily unusable, and surgical procedures had to be performed offsite.

Solution

Kroeschell was chosen to evaluate and make recommendations to correct the problem.

An investigation performed by Kroeschell found that the existing chilled-water coil temperature did not allow for the discharge air temperature to be any lower than 50° F. This would not allow the space to achieve much below 50% rh. This was unacceptable since required optimal conditions are between 68° F and 72° F and 40% and 45% rh. There was an existing supplemental fan coil installed above the ceiling in the room, but even that unit could not effectively lower the relative humidity to acceptable levels.

It was determined that mechanical dehumidification was a required addition to the system to achieve the temperature and humidity criteria requested. Also, highly accurate sensing instruments were to be included in the design.

Kroeschell recommended a Munters HCD Series desiccant dehumidifier as a standalone solution to the problem. This unit incorporates Munters’ HoneyCombe wheel that is capable of collecting and releasing water six times every hour, 24/7. In addition to the desiccant wheel, the unit includes filtration, a supply fan, and a reactivation heater and discharge fan for the wheel.

Results

The project was a success, with surgical procedures commencing immediately and continuing on schedule without interruption. Medical personnel report the system is maintaining humidity with a deviation of only ±0.6% rh, a tolerance they believe is virtually unprecedented in other Lasik surgery facilities in the country.