A One-Stop Shop for Process Safety

Bullet List Housekeeping: Avoiding surface dust accumulations on floors, equipment, rafters, in storage areas, etc. It is also important to use equipment and cleaning methods that do not generate dust clouds. Plants should conduct regular inspections for dust accumulations in open and hidden areas.

When it comes to protecting your food plant from dust explosions, sometimes asking for help from an expert is your best bet.

When most think of industrial explosions and fires, highly flammable chemicals immediately come to mind as potential sources of accidents. Plants that process or use hydrogen gas, for example, are well-versed in hydrogen's flammability and the necessary precautions that must be taken during handling, storage, transfer, etc. There are established safety protocols that must be followed, as well as old-fashioned common sense.

However, recent incidents provide tragic proof that industrial explosions are not limited to the chemical industry. The food industry is quickly realizing that given the right circumstances, something as commonplace as coffee could potentially be the cause of catastrophic destruction and loss of life.

"The level of awareness is very high in the chemical and pharmaceutical industries," points out Dr. Vahid Ebadat, CEO at Chilworth Technology, a firm that specializes in process safety, however when it comes to the food industry, "to some degree there is a lack of appreciation for the dangers of dust explosions."

But as more food manufactures acknowledge that combustible dust falls into the same dangerously explosive category as flammable liquids and gases, they are doing more to protect their plants.

What plants can do

There are basic, inexpensive precautions that can help keep food plants relatively safe from dust explosion hazards. These include:

Many plants are becoming increasingly proactive — going beyond basic precautions and taking the next step in safety by seeking the help of dust explosion experts.

Paying attention to detail

The basic philosophy behind dust explosion prevention is pretty simple — eliminate one of the three causal factors — the dust, the ignition source or the oxygen.

But when it comes to developing specific dust explosion prevention strategies, the devil is most certainly in the details. Food plants must test their products to determine not just whether or not the dust can explode but how easily it can ignite by the likely ignition sources that might be found in the plant and also the severity of the resulting explosion.

In most cases, an in-house process safety lab would not be economical for food manufacturers, so most turn to outside consultants and laboratories for help.

Chilworth Technology currently serves the process safety needs of hundreds of food manufacturers in the U.S. alone, boasting arguably one of the most comprehensive process safety labs in the country, as well as having international facilities in Italy, the UK, France, and India.

The key for Chilworth is quantifying the problem in order to find the best possible practical solution. "This is not a situation where you want to guess," says Dr. Ebadat. A scientific, systematic approach is necessary.

The process

Chilworth experts visit clients' plants in order to indentify the locations of potential dust clouds as well as potential ignition sources. When hired by a food manufacturer, Chilworth aims to audit all of a company's plants and bring them all to the same standard of safety. As can be expected, one reported dust explosion incident will prompt agencies to investigate all of a manufacturer's facilities.

In order to continually monitor food plants for hazards and implement safety measures, plant safety managers need a technical understanding of dust explosions, as well as practical experience. In house-training courses conducted by Chilworth consultants or other qualified experts can help assure that a food plant's safety team is up-to-date with dust explosion prevention.

Back at one of its three U.S. labs, Chilworth can test and quantify numerous dust explosion variables. Testing focuses on assessing the combustibility, thermal instability, reactivity, electrostatic, and fire properties of materials, and specifically determining the temperature, pressure, and other conditions under which a fire or explosion will occur. One common test offered by Chilworth is an Explosibility Screening Test. This test determines whether a powder or dust, when in the form of a dust cloud, will explode when exposed to an ignition source.

The test is performed using a Modified Hartmann Tube apparatus, which consists of a 1.2-liter vertical tube mounted onto a dust dispersion system. Powder samples are dispersed in the tube and attempts are made to ignite the resultant dust cloud by a constant electrical arc ignition source.

Other tests include:

Scenarios specific to food plants are reenacted in the lab, such as heating powders in a dryer or transferring powders out of a bulk bag, yielding results specific to each food plant's ingredients and equipment.

Testing in the lab is done on a progressive scale — starting with samples as small as 1 gram and gradually working up to a magnitude of testing that requires a reinforced, concrete room with blowout panels. For explosion testing of an even higher scale, Chilworth offers a 100-acre large-scale testing facility located in a former quarry 90 miles from Chicago, IL.

Industry awareness

Chilworth has seen a rise in dust explosion inquiries from food manufacturers, which Dr. Ebadat attributes both to very public explosions, as well as OSHA's Combustible Dust National Emphasis Program (NEP) directive issued in October 2007, and the reissued instruction on the same topic last March. The NEP mandates OSHA inspections of any facilities that generate or handle combustible dusts. The agency aims to conduct at least 300 inspections by the end of 2008. In addition, OSHA also sent letters and copies of OSHA's Combustible Dust SHIB in February 2008, to an estimated 30,000 employers across the country in industries where combustible dusts are commonly found.

This recent industry awareness and educational push pertaining to the dangers of dust explosions is encouraging food manufacturers to become more proactive. Recognizing that the threat is real and the risk is one that no plant can afford to take is the first step to launching a proper explosion prevention strategy. And while these manufacturers may spend thousands of preventative dollars avoiding a situation that they could potentially never face, anyone who has dealt with the alternative would agree that it is money well spent.
For brief video of a dust explosion test performed in the Chilworth lab, visit www.foodmanufacturing.com/videos and use keyword: explosion u