Photo By Raeanna Morgan | In the lower left hand corner is an example of grounding in a countermeasure facility....... read more read more
CRANE, Ind. – Ask explosives operators at Crane Army Ammunition Activity about handling energetics and it won’t be long until they are explaining how it is an inherently dangerous job. Safety procedures must be respected at all times to ensure every employee is protected should even the smallest spark cause a great catastrophe.
Although all buildings have safety measures in place and are tested and checked to make sure they are working properly, buildings that are designated for countermeasure flare operations have even more protection. This is due to the specific chemicals that are used during the production process and how they react to static electricity.
“We produce decoy flares in our building and the base material, or the energetic, is a magnesium Teflon with a Viton binder. The material itself is very electrostatic sensitive,” Crane Army Countermeasure Flare Commodity Manager Mark Benstin said. “It is most sensitive when we’re manufacturing, which is where we use solvents. In our mixing process one of the solvents is at a lower explosive limit vapor concentration.” Benston also pointed out that it takes about 300 times less static electricity to ignite the material in a countermeasure flare production building than it takes to shock your hand on a door knob.
“If the material were to ignite, those operators—and possibly anyone else in the building—would be in danger, so we have to mitigate how we control static,” Benstin said. “We do that through five layers of redundant systems, so if one system were to fail, there are backup systems that will continue to control the static.” The five levels of protection are considered a standard protocol for any company that makes these kinds of countermeasures. This layered system includes building protection, a technique called grounding and bonding, personal protective equipment, air ionizers, and temperature and humidity control.
In order to best protect employees, the preventative layering system begins with the building itself. Outside of the building, there is a lightning protection system in place to guard against static electricity created in the event of a storm. Inside the building, a high-speed deluge sprinkler system is in place over the areas where operators are working in case material should ignite and cause a fire. Deluges are a reactive measure that are present in the event that every other preventative measure fails and the material does ignite.
“These deluges can detect UV and IR light,” CAAA Supervisory Safety Engineer Bob Gillis said. “They are very responsive and will discharge in less than 50 milliseconds. To put it in perspective, you blink in 250 milliseconds. So before you even blink, there is water dumping and you don’t even realize what’s happening. This is primarily in place for worker protection; it’s to give people a chance to get out.”
Another protective measure built into the building is the conductive flooring found in the countermeasure facilities. The special type of flooring aids in dissipating any static on an operator’s body.
“Any static electricity that builds up on your body will dissipate down through your shoes, onto the floor, and into the ground,” Benstin said.
Grounding and bonding is the second layer of protection against static. This technique of grounding and bonding is essential to ensuring that static flows safely away from the operation and out of the facility. The building itself is bonded to the ground so that static from the building can pass through the floor and safely into the ground and all of the items inside the building are grounded or bonded as well. Every stationary item, such as a work table, is bonded to the floor with a chain. From that table, for example, there is a cable that connects the table to the item being worked on by the operator, effectively grounding it.
Personal protective equipment, commonly referred to as PPE, is an important third level of protection against static for operators in the countermeasure facilities.
“Our operators have another level of protection—clothing,” Benstin said. “We require workers to wear all cotton, so every article of clothing, including undergarments. On top of that, coveralls are required as well as gloves and special conductive shoes.”
While all cotton clothing prevents static buildup, operators also need to be protected in the event of a fire. An apron is worn over the coveralls that acts as a flame and heat repellant. An operator’s gloves are also fireproof, as most operators work directly on the material with their hands.
Each operator is also required to wear a certain type of conductive shoe. These shoes are another measure to help dissipate static build up, and they work best as a preventative measure when paired with the conductive flooring in the building. Every time an operator or visitor enters the building their shoes must be checked for static by standing on a “static electricity reader” to ensure the shoes are working at full capacity.
As a final measure of protection concerning PPE, operators use a spray called staticide. This spray works similarly to a dryer sheet, except it is in a liquid form. Staticide is sprayed on gloves and coveralls, as well as any tool being used during the operations.
According to Benstin, operators are required to spray their coveralls and gloves once a period, or four times in one shift. Any time an operator goes on break and returns to their work station they use the staticide to cut down on any static they may have generated during that time.
A small, but just as important layer of protection, is called an air ionizer. The device, a cylindrical air gun that emits millions of positive and negative items, hangs in every work station and is positioned over the material. The positive and negative charges take any static electricity in the immediate area and effectively neutralizes it so that it no longer poses a danger.
“The ionizers, what they do, is blow air through a cylinder that creates a cone with about a three foot distance,” Gillis said. “As long as the ionizer is positioned right in a workspace, it is nearly impossible to have a static discharge.”
The final layer of protection is temperature and humidity control of the building. This is the most efficient way to control the amount of static electricity in the facility and the levels are constantly and consistently monitored by building supervisors to make sure they stay within the appropriate range.
Regulating the temperature so that it is not too cold protects against the building becoming dry and creating a static conducive environment. This measure protects the operator from the material potentially igniting. Regulating the humidity so that the air does not become heavy with moisture protects the material more than the operator.
“In the fall and winter it’s really dry, and that creates a lot of static,” Benstin said. “So we keep our humidity level up to at least 40 percent. On the other hand, too much humidity is very bad for the material and causes it to deteriorate, so we put an upper limit of 60 percent humidity so we don’t damage our material.”
Gillis explained that should the humidity level be above 60 percent there will be no static discharge, however moisture will be introduced into the material, which could create a dud flare that would not work as intended for the Warfighter.
The ability to create a safe environment for employees on the production line was one of the reasons Naval Surface Warfare Center, Crane, approached Crane Army to produce countermeasure flares back in 2003. Brad Stevenson, the Integrated Product Team Lead for Air Expendable Infrared Countermeasures, cited proximity and communication as some of the most important factors in asking CAAA to partner in the production of the decoy flares.
“NSWC and CAAA are co-located, so the engineering design team from the Navy side can more easily interact with the Army to work out any safety issues and issues in the production line,” Stevenson said. “Our partnership also allows for crosstalk between the Navy and the Army for the purpose of working out issues of safety concerns, and we can more quickly and easily go from design to production. It also ensures that we are always using the best safety equipment available to us.”
In the United States, there are only three suppliers of these types of countermeasure flare products, Crane Army being one of them. What sets CAAA apart from the other suppliers is the attention to detail in this line of work.
“We pay a lot more attention to static, a lot more attention to detail than what the other suppliers do,” Benstin said. “We have not had an incident related to static since 2003, but we do hear at least a couple times a year about an injury at one of the other two suppliers.”
Benstin explained that CAAA does two things differently that contribute to the low accident rate. One of them is being diligent and paying attention to details in every layer of protection. The other is the low employee turnover and average crew size at CAAA.
“We try to keep our same experienced operators on the line and I think the other suppliers have a lot of employee turnover, so they’ll get a new employee on the line and they may forget a step or there could be a miscommunication,” Benstin said. “At CAAA we keep our crews small to avoid chaos, and I like to think they look out for each other as well.”
The current process in place has kept employees safe and the product working well for over a decade. However, safer and more productive ways of creating the product have become available to Crane Army with advancing technology
“Our current process uses a bladed mixer, and it mixes all the solvents,” Benstin said. “NSWC found a new mixing technology using acoustics that does a lot better job than the standard mixing techniques and is much better for static safety.”
The new mixer is much smaller and sits on a table top. Compared to the current mixing technique in place it is more effective and much faster. It also eliminates the primary risk of fire caused by the hexane solvent used in the current process. According to Benstin, this aspect made the mixing process ten times safer for operators. The new technology also increases productivity.
“Right now the process to make a 60-pound batch takes a little over three hours to mix,” Benstin said. “The new mixer produces smaller batches but it will mix it in six minutes. So it eliminates the hazardous solvent, improves productivity, and it does a lot better job mixing, meaning our product will be identical from batch to batch.”
Currently, Benstin is in the process of incorporating a few small mixers into the process that is in place. “This is a pretty big change. We’re kind of getting our foot in the door for larger scale production.”
“As the countermeasure program manager, Mark Benstin has been very innovative when it comes to static safety,” Gillis said. “He’s got a real interest in making sure everything is safe. He’s done a great job ensuring all of our countermeasure operations are run smoothly, safely, and effectively.”
Established Oct. 1977, Crane Army Ammunition Activity produces and provides conventional munitions requirements in support of U.S. Army and Joint Force readiness. It is one of 14 installations of the Joint Munitions Command and one of 23 organic industrial bases under the U.S. Army Materiel Command, which include arsenals, depots, activities and ammunition plants.
| Date Taken: | 04.03.2017 |
| Date Posted: | 04.03.2017 14:35 |
| Story ID: | 228998 |
| Location: | CRANE, INDIANA, US |
| Web Views: | 362 |
| Downloads: | 1 |
This work, Combating Dangers of Static Electricity, by Raeanna Morgan, identified by DVIDS, must comply with the restrictions shown on https://www.dvidshub.net/about/copyright.
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