Nortec Humidifies a World of Butterflies

An Adiabatic Humidifier Solution

Located within the Milwaukee Public Museum is the remarkable Butterfly Vivarium exhibit. It is rated as one of the two best butterfly exhibits in North America
and has been constructed as an open walk-through experience that allows visitors to
interact with the butterflies as they pass through the 75 feet long simulated tropical rain
forest environment. In this enclosure a wide variety of butterfly species, indigenous to
the Central and South American jungles, fly freely amongst their guests and sometimes
even alight on them, although they are not permitted to leave with them!

In order for the butterflies to continue to thrive in this northern outpost where nature
has created seasonal temperatures that range from about 100º F to minus 20º F, the
architects and environmental engineers had to devise a system that could ignore
whatever was going on outside.

They not only had to maintain the air temperature at a steady 80 degrees F., night and day, they also had to keep the humidity level throughout the entire area at a constant 80%, even as exterior conditions impacted on the humidity in the air being pumped into the building from outside. And the air inside the exhibit had to be recirculated completely every 15 to 20 minutes without creating any discernible breeze. The butterflies only live in their flying state for a few weeks and they require optimum living conditions to thrive and procreate their species. Just like Goldilocks’ Three Bears, they don’t like it to be too cold or too hot, or too moist or too dry, they want it to be “just right!”

And then there was also the FDA, who has strict regulations pertaining to plants and
creatures that are indigenous to exotic regions and have been brought into the U.S.
They must be confined securely in areas where they cannot contaminate American
livestock or vegetation. The butterflies had to stay in their artificial rain forest and not
be able to get out!

A design was decided upon that satisfied all these environmental and regulatory challenges. It also enabled the museum to use the Vivarium as a showcase window into the museum for passers-by outside on busy Wells Street, in the middle of downtown.
Essentially the structure is a sealed three sided, double glass walled and roofed rectangle with interior dimensions about 75 feet long and 20 feet deep. There is a space between the inner and outer glass walls of about 2 feet that contain automatic, electronically controlled mechanical shades that respond to changes in solar intensity. This space is maintained with forced air at a temperature of 80 degrees F., creating an insulating blanket against changes in the exterior environment, no matter whether it gets too hot or too cold outside. This effectively isolates the interior from all exterior climatic influences and eliminates both icing and condensation on exterior and interior glass surfaces. With the interior effectively cocooned, attention was now focussed on the heating, air-conditioning and humidification systems that would control and maintain the interior air at the appropriate levels. This equipment would have to be thoroughly reliable and sensitive to every subtle change in demand, delivering humidity accurately and efficiently year-round.

A Nortec atomizing humidification system supplying and controlling 16 strategically placed nozzles was installed in the facility. Each nozzle is individually set to maintain fogging patterns that provide even humidity throughout the entire enclosure. Machined from 316 stainless steel, the nozzles have self-cleaning pins to minimize maintenance. The timer for the cleaning pin is adjustable to match the quality of the water supply. The mist from the nozzles also creates the ambiance of a rain forest for museum visitors. The butterflies are prevented from leaving the area by maintaining a negative interior air pressure that blows them back from each entry and exit door if they are too close when the doors are opened. Also a fine mesh filter is fitted over all the air supply and exhaust fittings.

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