Chester Co. lab will take part in first ever full-scale hail storm testing

Business EditorFebruary 17, 2013 

If all goes according to plan, two years of research by Tanya Brown of Rock Hill and others will be blasted from the ceiling of a Richburg lab Wednesday and shown live on national television on the “Today Show.”

There will be the appropriate oohs, ahs and wows you come to expect from the lab run by the Insurance Institute for Business & Home Safety.

After all, this is the place where man creates weather – indoors. There have been full-scale tests on houses and commercial buildings inside the lab. Structures have been destroyed by hurricanes, burned by swirling, wind-borne embers and crumbled by tornadoes.

This time it’s hail, in the first full-scale test of a hailstorm. Artificial hailstones of varying sizes will be blasted from cannons installed in the catwalks of the lab. The enormous fans will be cranked up to create tornado-strength winds.

Over a four-minute span, 8,000 hailstones will smash into a house built with a variety of materials, pelt an almost-new Toyota Camry sedan and crash into lawn furniture. A few children’s toys have also been scattered about to see what happens.

After all the news crews depart, Brown and other lab researchers will start measuring the impact of the hail on the vinyl siding, the shingles, on the standing-seam metal room, two different skylights – one rated to withstand a hurricane – and on the aluminium gutters and downspouts.

They will also measure how badly the Toyota is pitted and the damage to the lawn furniture.

The goal – as it has been with other tests at the lab – is to understand how severe weather affects the places where we live and work, and to develop new building materials and construction standards that can lessen that damage.

Creating artificial hail fell to Brown, who holds a bachelor’s degree in meteorology, a master’s in engineering and a doctorate in wind science engineering. Early in her studies she realized she wanted to understand the impact of weather “rather than reporting the highs and lows.”

To replicate hail, Brown first looked at what others had done before her. Science told her how hail forms. It starts when moisture tumbles in tornadic winds. With each updraft the hail collects more moisture and freezes, growing bigger to the point that it eventually falls out of the updraft. The cycles gives hail a distinct set of rings, much like growth rings on a tree, Brown said.

Science also told her the velocity of the falling hail, which depends on its size.

And data from her own institute showed her the severity of the problem. There are between 10,000 and 12,000 hailstorms annually, causing about $1 billion in damage, according to the institute.

Brown and others even went storm chasing, traveling just behind hailstorms. They periodically stopped to measure patches of hail along the road for density and size.

At the Richburg lab, Brown and her team set out to learn how to make artificial hail and develop a lifelike test that would yield measurable results and could be replicated.

All previous hail testing has used either steel balls or ice balls shot at a section of roofing or siding.

Brown and other researchers wanted an artificial hail that came as close to the density of real hail as possible.

They tried using a machine to crush ice and then press the shavings into a ball.

They tried an ice-cream maker, hoping that a sorbet setting would produce the texture of hail.

They turned to a staple of comedy – seltzer water – thinking the bubbles in the water would give them the density they sought. When a mixture of seltzer water and regular water yielded promising results, they experimented with different ratios of the two liquids. They settled on an 80:20 ratio of seltzer water to regular water.

They have been making hail since January, injecting the mixture into form blocks and then freezing the blocks for 12 to 24 hours. The bigger the stone, the longer it takes to freeze. They make hail every afternoon at 3:30 p.m., and on the weekend the security guards pitch in.

Eight freezers in the lab are filled with the stones. On Wednesday the stones will be loaded into cannons above the test house.

The cannons will shoot the hail at the house. The 1-inch, quarter-sized hail will be shot at 53 mph. The 1 1/2-inch, ping-pong-ball-sized hail will be shot at 63 mph and the 2-inch hail, which is larger than a golf ball, is fired at 76 mph.

While Brown acknowledges that Wednesday’s test probably won’t be as dramatic as the hurricane test – that test scattered parts of a house across the Chester County countryside – she is optimistic that the results will be as important scientifically.

After all, it’s never been done this way before.

Don Worthington •  803-329-4066, •  dworthington@heraldlonline.com

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