By Dr. Marcus Allhands
Thousands of people visit the Jewish Museum in Manhattan each year. For over 100 years it has displayed past and present Jewish culture, both secular and religious, to the world. Special care must be taken in protecting over 26,000 paintings, sculptures, works on paper, photographs, ethnographic material, archaeological artifacts, numismatics, ceremonial objects and broadcast media materials. This care begins with proper environmental conditions that rely on a dependable HVAC system.
A reliable and economical means of removing suspended solids from the twin cooling towers was sought to protect heat exchangers in the 150 ton chiller system. This maintains the museum’s temperature and humidity at precise set-points. The selected equipment was an ORG-020-LE automatic self-cleaning screen filter from ORIVAL, Inc.
The filter was set up as a side-stream system with about 20% of the full flow passing through it. This reduces total suspended solids to a level that protects the heat exchangers from experiencing deposit buildup that would impact the efficiency of the HVAC system.
As solids encounter the stainless steel weave-wire screen element inside the filter, all particles larger than the 100 micron openings are immediately blocked from passing. As these particles accumulate, a filter cake develops. The pore spaces between these 100+ micron particles are smaller than 100 microns so this filter cake becomes a screening element of its own. It can capture smaller and smaller particles, possibly as low as 10 microns.
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As the filter cake thickens, a pressure drop develops across the screen element until a 7 psi threshold is met. At this point, a differential pressure switch makes contact and sends a signal to the filter controller to initiate a rinse cycle to automatically clean the filter cake off the screen. Nozzles open to atmospheric pressure move across the screen surface, vacuuming solids off the screen and discharging them to a drain. The entire cleaning process takes only 8-10 seconds. A timer built into the controller can also be used to initiate rinse cycles at pre-set times.
Nick Silenko is an engineer for the Jewish Museum and project leader for the filter installation. He states that, “prior to the installation of the filtration system, the cooling tower basins had to be manually cleaned at least every six months. Inspection of the cooling tower basins after three months of filtration showed a noticeable improvement in tower cleanliness.”
At its installation, the filter experienced rinse cycles every three to four hours. The rate of solids accumulation on the screen began to decrease over time as the filter removed more and more solids from the system. Rinse cycles are now every 24 to 36 hours. Heat exchangers are maintained at high efficiency levels, providing a reliable HVAC system to precisely control environmental conditions in the museum.
Dr. Marcus Allhands, PhD, PE, is with Orival. This article appears in ES&E Magazine’s August 2016 issue.
Interesting article. To protect artifacts, books and art objects, it is necessary to maintain certain parameters of the internal microclimate: temperature and humidity. Such parameters can be achieved only if HVAC systems are configured correctly. I have a country house with a small collection of old books. For their best protection, I built a separate room, in which I needed to maintain a certain temperature and humidity. To do this, it was necessary to install a ventilation system and adjust its work. Since I did not have a necessary knowledge, I started looking for suitable contractors. After this, my books are protected much better. Therefore, a correct work of HVAC systems can help protect artifacts in the museum.