YUMA PROVING GROUND, Ariz.-- Soldiers are accustomed to facing insidious enemies, but rely on testers at U.S. Army Yuma Proving Ground (YPG) to keep them safe from one that can't be dispatched with weaponry: the ravages of extreme conditions on equipment.

YPG specializes in extreme environmental testing of military equipment, with jurisdiction over test centers in the arctic, tropics, and desert. Among testing activities performed by the Metrology and Simulation Division at YPG's Yuma Test Center is one that can create rain and dust storms on demand, any time of the year.

The rain facility can accommodate virtually any piece of equipment normally tested at YPG, including ammunition. If necessary, testers can bring in a large fan to simulate wind-driven rains of up to 50 miles per hour and can vary the speeds to mimic gusts of winds of different velocities and intensities.

"We can rain on anything, but the rain facility is primarily used for vehicles," said Frank Aguilar, engineering technician.

Comprised of over 500 adjustable nozzles on three stationary and two portable walls, the rain chamber can deliver highly pressurized water to simulate a fierce monsoon or a slow, steady, misting rain. Testers can simulate either over the entire item, or concentrate the spray on one part of it.

"We can close off walls and hit the test item from any angle the customer wants," said Aguilar. "One program wanted only their vehicle's turret hit at a 45 degree angle, so we adapted the nozzles to do that."

Two pumps push the pressurized water from a 10,000 gallon tank outside the facility's test bay through nozzles inside. The rate of spray hitting the item is entered onto a control panel, and is confirmed by a rain gauge inside. Drains in the test bay floor send the water to two sump pits. When the test is completed, the collected water, which could possibly contain oil or grease residue, is transferred to tanker trucks, which transport it for disposal in an environmentally friendly way.

Exterior cameras monitor the test item's experience inside the facility, and occasionally video is taken from inside a vehicle during the mock storms. A wet vehicle compartment caused by inadequate seals would be more than just uncomfortable for Soldiers in theater: it could be potentially life-threatening if the water shorts out important electrical equipment inside, a threat that YPG testers keep close watch for during evaluations.

"If there is substantial leakage, we'll measure by weight the amount of water that intruded into the vehicle," explained Aguilar.

Rain is a potential menace for equipment in a desert environment, but the ravages of dust is a daily reality that must be planned for in places where American Soldiers are currently deployed. Though YPG has both in abundance, test items are subjected to controlled and sustained exposure in a separate steel chamber that is part of the same complex as the rain facility. The items inside endure potent concentrations of blowing silica powder for six hours at a stretch, and are often put through their paces on the test range as soon as the punishing dust blasting is completed.

The Metrology and Simulation Division has a wide range of facilities, including hot and cold climactic chambers, vibration tables to test the effects of intense shaking on munitions, and a lightweight shock testing machine that evaluates a piece of equipment's ability to withstand sudden shock such as that caused by underwater explosions encountered in naval combat.