Railcar Unloading Doesn’t Have to Be in the Pits

Railcar Unloading Doesn’t Have to Be in the Pits

Railcars offer a cost-effective dry bulk material handling alternative for companies with available rail side unloading points and high raw materials or materials consumption. Railcars typically can hold 3,500 to 5,500 cubic feet and transport up to 120 tons of raw material at a time.

Evaluating cost-effective alternatives for material unloading systems is critical when considering the best way to receive shipments. The demurrage costs of holding a railcar can become relatively high in some cases, so rapid unloading may be desired. This must be balanced against the high operating costs of huge blower packages when pneumatically unloading and the high cost of ongoing maintenance and material exposure from open pit mechanical systems.

There are various railcars on the market today, each with differing ways to unload them. The covered hopper bottom car is the most common of these cars in the dry bulk material handling industry. These cars have internal compartments that slope to discharge gates that allow material to be expelled from the bottom of the vehicle. Various car designs exist from different railcar manufacturers and have anywhere from 2 to 5 hoppers with discharge gates ranging from 18” x 42” to 24” x 30” and beyond, including round “Cabot” cars. These cars can be typically unloaded in one of two ways: dumping them into a pit or attaching a pan and vacuuming the material via a pneumatic conveying system.

Unloading these cars using an open pit is the fastest way to empty the car. The operator positions the vehicle over a dumping point and opens the railcar hopper(s) to an underground hopper below. For dusty powders, a boot lift connection may be engaged to help contain fugitive dust during this time. Using a boot lift may also require a railcar “puller” to move the car along the rails to position the next compartment over the discharge point.

While fast, this method has its drawbacks. Railcar pits are often exposed to the outdoor elements and can collect rain and snow. Also, because they exist under the tracks, digging them out and then reinforcing and supporting the tracks above the pit can be pretty expensive in terms of capital cost and installation. Once they are built, connections for screws, belts, rotary valves, etc., can be cumbersome and difficult to keep maintained since they are underground.

An alternative to these pits, a Railcar Discharge Adapter (RCDA), can transition from the car’s hopper discharge gate to a vacuum pneumatic conveying line. This device can be inserted between the gate and the grade. It serves as a transition to a pipe stub (4” to 8” line) with a hose fitting, allowing flexibility in positioning of the car by using a flexible hose connection to attach to a trackside pipe manifold where the material can be vacuumed out of the vehicle to its destination or transitioned to a pressure conveying system where it can be sent on to farther distances and multiple destinations more efficiently. Each adapter also includes a bleed-air gate to allow for manual balancing of the material-to-air ratio of the conveying system at the pick-up point.

These adapters come in two basic types: a manual clamp style and a single-operator sled style. In the clamp style, usually, two operators manually clamp an ~175-pound RCDA to the discharge gate frame and then attach a hose to it. It is lower in cost to purchase but more cumbersome to operate. In the sled-style unit, a single operator can take a team on wheels that is retracted to a low profile (7” to 9”) and then raised to form a dust-tight connection when under the car. (Note: pneumatic cylinders are provided to allow the RCDA to rise with the vehicle as it loses weight from unloading and raises on its shocks). This unit type is more accessible but requires a reasonably even surface near the tracks to be pushed around.

Whether you have an existing unloading system and want a better way to connect to the railcar or are looking for a complete railcar unloading system, Magnum Systems can help you build an integrated solution to keep your line moving.

Additionally, If you have a PD Railcar, check out our H-Valve Unloading System.

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