Leaky faucets in the kitchen sink are one thing. A leak on a HazMat rail car filled with chlorine, sulfur dioxide, anhydrous hydrogen chloride, anhydrous ammonia, or methyl chloride is quite another.
A recent headline, “Rail Car Gas Leak Forces Evacuation,” underscores the danger of toxic chemicals such as hydrochloric acid that can burn people’s skin, eyes, and lungs when an uncontrolled leak occurs. The accident in Salt Lake City in early March sent plumes of the toxic gas into the air, forcing the evacuation of more than 6,000 people in the surrounding area. Such events, while rare, can happen. They are, however, highly dangerous to the community, people in the workplace, customers, and can be challenging to operators charged with their management and prevention. In the case of rail tank cars carrying liquid chlorine, for example, it can be difficult and unsafe for operators to isolate and reach equipment leaks that can in turn cause serious harm. Traditional emergency shutdown systems require an operator to climb a ladder and/or cross an elevated gangway to reach the leak source on top of the car. With field-engineered or automated ball valve shutdown systems typically located upstream of the chemical tank car, reliability of valves and attendant safety of operators are often major issues. Proper selection of an emergency shutdown system is vital, not only for its optimal performance, but also for that of the equipment and tasks with which it interfaces. Considerations for selecting such HazMat systems focus on several key considerations: Function, durability, safety, and service among them. Newer technology today includes a remote valve actuator (RVA) system used on railroad tank cars carrying toxic chemicals such as liquid chlorine used for water treatment. The RVA automatically shuts down chemical flow right at the isolation valve on the railcar, versus farther downstream along the piping system without compromising human safety. Consisting of an air-driven actuator, and a manifold, the RVA system functions at the transfer valve on the tank car, as opposed to working downstream on vulnerable piping and hoses (as does the field-engineered automated ball valve) to eliminate potential leaks.
Typical chlorine unloading rack for railcars incorporating Midland valve actuator system. |