Moveable chem-test modules:thinking outside the chamber

By Mr. Al C Vogel (ATEC)August 17, 2015

Ross Lang, an electronics technician with the Data Management Division
1 / 5 Show Caption + Hide Caption – Ross Lang, an electronics technician with the Data Management Division, discusses the electrical system of a Secondary Containment Module (SCM) with Matt McCarty, program manager with the Chemical Test Division. Delivered in December 2014, each SCM w... (Photo Credit: U.S. Army) VIEW ORIGINAL
Inflatable seal along edge ensures airtightness when closed
2 / 5 Show Caption + Hide Caption – Doors of each Secondary Containment Module (SCM) and its attached Support Module have an inflatable seal along their edge, to ensure airtightness when closed. A changing room and emergency decontamination shower are in the Support Module. Each of the... (Photo Credit: U.S. Army) VIEW ORIGINAL
A 36-foot Secondary Containment Module weighs 28,000 pounds
3 / 5 Show Caption + Hide Caption – A 36-foot Secondary Containment Module weighs 28,000 pounds. The air filtration system for its 33-foot chamber, atop the SCM, weighs 4,000 pounds. Eventually, with everything in place, it will weigh about 35,000 pounds. A 12-foot Support Module will ... (Photo Credit: U.S. Army) VIEW ORIGINAL
The interior of each 33-foot Secondary Containment Module
4 / 5 Show Caption + Hide Caption – The interior of each 33-foot Secondary Containment Module. Cable baskets across the ceiling eliminate floor entanglements. The upright ribs are slotted to temporarily accept cabinets, benches, instrumentation, etc. The floor is partly solid, for posi... (Photo Credit: U.S. Army) VIEW ORIGINAL
Viewing ports line the walls of each SCM chamber
5 / 5 Show Caption + Hide Caption – Viewing ports line the walls of each SCM chamber, but they may be readily replaced with a Penetration Panel, to provide cables for each test's specific needs. The upright rib next to the Penetration Panel can support benches, cabinets, instrumentatio... (Photo Credit: U.S. Army) VIEW ORIGINAL

U.S. ARMY DUGWAY PROVING GROUND, UTAH ---When completed in the late 1990s, the Materiel Test Facility at Dugway Proving Ground (DPG) boasted one of the world's largest chambers for testing defenses against chemical warfare agents.

Created to challenge large vehicles with chemical agent, simulant or toxic industrial chemicals, the Multipurpose Chamber's (MPC) floor and ceiling are 50 feet long and wide, with 30-foot walls. Smooth stainless steel covers all, to ease decontamination and resist corrosive decontaminants. The MPC can maintain temperatures and humidity to replicate most of the world's environments.

But aside from a 60-ton M1 Abrams tank in 2001, no vehicles were tested. Instead, it tested smaller items in gloveboxes and small chambers. One detector test used the MPC for 10 years; no equipment could be moved. While the detector test was important, chemical defense experts at DPG felt the MPC could be used more efficiently.

A variety of DPG professionals in chemical defense began sketching what would become two Secondary Containment Modules (SCM): large, moveable testing chambers that could be configured outside, then moved into the MPC for tests. Testing complete, each SCM could be moved out again, to be reconfigured for the next test. Each identical SCM is 36 feet long and 12 feet wide. With integral air filtration system, it's 14 feet high. Within each SCM is its test chamber: 33 feet long, 10-1/2 feet wide and about 8 feet high.

"We wanted to run more than one test at a time," said Matthew McCarty, project manager for the Chemical Test Division. "In order to do that, we needed two separate chambers with their own filtration unit and space."

In 2013 Standard Aero, a Houston-based international aeronautics company, designed and constructed the two SCMs for $3.7 million. Another $450,000 went into instruments, labor, and six gloveboxes: three in each SCM. Both SCMs are expected to be operational in spring, 2016.

Completed in December 2014, each 28,000-pound SCM was trucked from Texas on a trailer, then backed into the MPC. Integral screw jacks raised the SCM off the trailer, and the truck drove out from under. Industrial air bladders went under each SCM. The jacks were raised. Resting on the bladders, each SCM was pushed into place by snow blower-sized electric tugs. Once positioned, the screw jacks raised the SCM and the bladders were removed. Positioning of the first SCM was expected to take a week; it took two days. The system worked as slick as the stainless steel floor the bladders slid across.

Atop each SCM is a 4,000-pound filtration HEPA and HEGA system to filter out the chamber's air during testing. "This lets us test with liquids, vapors or solids," McCarty said.

Air filtered from the SCM goes directly into the MPC, where it is again filtered before release outdoors. Total weight of each SCM, with rooftop air filtration system and three gloveboxes is about 35,000 pounds. The MPC and both SCMs are monitored and controlled from the Materiel Test Facility's sealed control room, via instrumentation and cameras. "This way, we maximize operator safety and minimize the number of people required to operate the system. This reduces our test cost," said McCarty.

Entry to either SCM is via the sealed door of an attached 12-foot-long Support Module, containing a sealed room for changing into Personal Protective Equipment (PPE), six air lines for protective suits inside the chamber, and emergency decontamination shower. Attaching the Support Module to each SCM was challenging because the MPC's stainless steel floor is flexible. Bolt alignment was impossible, so designers connected them with a bellows gasket, typically seen on long transit buses.

Each SCM's 33-foot-long chamber displays great forethought and innovation. Basket-like cable trays span the ceiling, keeping cables, hoses and small pipes off the floor. Slotted, vertical struts line the walls, allowing the temporary installation of cabinets, fume hoods, lockers, shelves, instrumentation, etc. "We're not stuck with a feature in one place," said McCarty. "We can move it to accommodate the test."

One end of each SCM is removable, to place large equipment in the chamber. While an SCM is moving, an attached generator keeps everything powered. Once outside, the SCM is plugged into standard power. Each SCM will contain two or three gloveboxes, linked by sealed ports so items may be moved between. The floor is open-decked down both sides for air filtration, but solid down the middle for solid placement of equipment.

"We designed the glove boxes to provide as much enclosed test space as possible, while still allowing the operators to move around comfortably in their PPE," said McCarty.

Particularly innovative are Penetration Panels -- sealable, removable panels along the upper walls of each SCM. Most are for viewing, but these windows may be replaced anywhere along the chamber's length with solid panels, reconfigured to bring in cables, data, electricity, liquids, gases -- whatever the test requires.

Overall, using the two SCM chambers means lower test costs and greater testing efficiency, while making the cavernous MPC available for testing vehicles, large shelters or small aircraft fuselages. Ultimately, U.S. military and civilian agencies faced with a chemical attack or incident benefit from the innovation and efficiency realized at DPG by experienced workers who thought outside the chamber.