Understanding the Danger

Dust is a normal result of the grain manufacturing process. But grain dust is highly combustible and can burn or explode if enough becomes airborne or accumulates on a surface and finds an ignition source, such as hot bearing, an overheated motor, a misaligned conveyor belt, welding, cutting, and brazing.

According to OSHA, grain dust explosions are often severe, involving loss of life and substantial property damage. There have been more than 500 explosions in U.S. grain handling facilities in the past 35 years which have killed more than 180 people and injured more than 675.

OSHA standards require that grain dust and ignition sources be controlled in grain elevators. Fans, blowers, and other methods are used to mitigate dust and keep levels down. OSHA also requires grain dust hazard monitoring. But many grain facilities have ineffective hazard monitoring systems.

How an Inadequate Grain Hazard Monitoring System Can Create Problems

Grain hazard monitoring follows the predeflagration detection and control of ignition sources as outlined by NFPA 69 Standard on Explosion Prevention Systems. By monitoring grain elevators for rub, bearing temperature, and motor speed, hazard monitoring systems shut off electrical equipment to keep it from causing enough heat to become an ignition source that ignites the dust.

Problems with grain hazard monitoring systems typically occur for common reasons:

• Outdated systems provide limited information: Older systems can make it difficult to identify the source of an alarm or what equipment got shut down. It can take facility operators hours or even days to properly troubleshoot and determine the exact source of the problem;
• The system has been bypassed: If production is down and operators feel they must run the equipment to meet the production needs of their customers, they may choose to run it manually and bypass the safety system;
• The system is faulty, due to broken equipment, failed sensors, or other problems: Operators may think sensors are working functionally, but that may not be the case. Some facilities don’t regularly test equipment to ensure that instruments are functioning properly.

Advantages of Control System Upgrades for Grain Hazard Monitoring

While the basic role of a monitoring system hasn’t changed since the OSHA standard became law in 1987, new technology and automated controls that didn’t exist 30 years ago have transformed hazard monitoring and management.

• Modern systems have better instruments with individual alarms to pinpoint a problem faster and in more specific places. Systems monitor individual equipment, enabling operators to identify a specific sensor on a piece of equipment that is detected to be potentially out of range. Operators then can shut down that exact equipment and get more feedback on the actual problem. Updated sensors also reduce the likelihood of a false occurrence, which helps avoid downtime and increases production.
• An automated control system makes it easier for operators to run the system by removing manual devices, such as on/off switches to start equipment. New systems use controllers and PLCs and have sophisticated displays that are easier to use than the old “Star Trek” types of control panels.

The Challenges of Planning an Upgrade

Retrofitting or upgrading a grain hazard monitoring system enables grain facilities to operate more efficiently, pinpoint problems faster, and prevent problems from occurring. Upgrades can unfortunately be challenging:

• Grain facility operators may do just one or two retrofits in their entire career. With little to no experience with an upgrade, they may not know what systems are available or what they need. And though OSHA requires monitoring, OSHA does not tell operators specifically how to do it, offering little guidance;
• Operators sometimes look to replace equipment kind-for-kind, but in many cases, the original manufacturer no longer exists or has consolidated with other companies. It can be hard to know where to start to find the right equipment;
• Documentation on the current system may not exist, which can make retrofitting and upgrading difficult to assess and plan;
• Cost can be an issue. Safety modifications can get pushed back due to budget constraints or more immediate concerns.

Delaying the investment now can lead to far higher costs later if a facility has an event, especially if workers are injured. It also is much more expensive to repair the damage from an explosion than to prevent it, or to replace equipment than to fix it.

For these reasons, many grain companies find they need professional expertise from an integrator skilled in grain hazard monitoring to plan a control system upgrade.

How Matrix Helps Grain Manufacturers modernize

Matrix Technologies has in-depth experience in helping grain processing and food manufacturing companies modify and upgrade grain hazard monitoring systems. We are an integration partner of CMC Industrial Electronics and possess extensive knowledge of the unique issues of grain facilities and OSHA’s requirements.

Here are the steps we recommend when planning a grain hazard monitoring system upgrade:

• Assess the existing system and determine the kind of equipment to be monitored. In larger facilities, it may make sense to approach the project in phases, tackling a portion of the operation or a specific number of conveyors at a time;
• Determine the facility’s needs and evaluate the options for retrofitting or upgrading. In some cases, it’s possible to retrofit existing systems with new equipment. In other cases, a new system is required to achieve the desired end result;
• Define the project scope and develop a project plan, paying particular attention to seasonal production and harvest schedules. During harvest, grain facilities must operate at 100% capacity and cannot be down for a system upgrade.

Next in this series: A grain hazard monitoring system upgrade case study

Matrix Technologies is one of the largest independent process design, industrial automation engineering, and manufacturing operations management companies in North America.

In addition to the integration of grain hazard monitoring systems to electrical infrastructure, Matrix audits existing wiring systems to identify deficiencies in electrical bonding, grounding; and electrical code/classification compliance; designs new control systems for previously hard-wired systems; conducts arc flash studies; designs electrical and mechanical systems; and conducts dust mitigation analysis and design. Matrix also offers complete control system automation services.

To learn more about our control system automation services and grain hazard monitoring expertise, contact Tony Ferguson, Senior Client Solutions Manager.

© Matrix Technologies, Inc.