H-VALVE for PD Truck and Railcar Unloading

Among the more popular ways to bring large amounts of dry bulk materials to a plant are PD trucks and PD railcars. These units are designed to act as large low pressure vessels on wheels (or rails as it were). A PD blower typically pressurizes this vessel and conveys material out through a discharge piping manifold. On trucks this discharge is usually a 4” discharge and railcars vary more widely between 4” – 6”, with 5” the most common.

What rate you can unload from these units is a function of the product, pipe size and distance. Most 4” trucks, backed up to a silo base, can unload 50,000 lbs. in about an hour (+/- 15 minutes). But what if that is not possible or not fast enough? An example might be a high consumption terminal that needed unloading every 30 minutes or a silo that wasn’t accessible from a road and was 200-300 feet away?

To confront these problems, Magnum Systems developed what is known as an “H-Valve” assembly. This valve assembly allows the product to be unloaded more quickly and/or farther by stepping the line size just after discharge from the container and proportioning blower air both to and around the vessel for most efficient use (picture a traffic cop at rush hour redirecting lanes and giving you 5 lanes instead of 3, speeding everything up).

In addition to this main feature, it allows controlled blow down of the empty container and automated switching of compartments of railcars as well, increasing unloading automation. Please keep in mind that this is not without limits, however. Your maximum rate is still going to be what you can push through the opening of the discharge manifold pipe, prior to the valve but this rate is usually much higher than trying to stay in the same line size all the way to a silo.

Thanks to Magnum Systems H-Valve, the limits of your truck or railcar do not have to limit your unloading rates.