Getting to Know Dry Bulk Tanks and Other Equipment

Posted on July 02, 2018 by Jim Cordock

Right now, you’re probably surrounded by items made of plastic—phones, pens, eyeglasses, yogurt cups, you name it. Practically every ounce of that plastic started as a load of resin pellets or powder transported in dry bulk tanks. 

Dry bulk shipping is an important component of today’s supply chains, but transporting it is no simple matter. Even if you’ve shipped these kinds of products in boxes, drums or totes in a dry van, that doesn’t prepare you for the challenges of managing tank loads of dry bulk. For newcomers to dry bulk transport (and for more experienced people who just want to refresh their knowledge), Bulk Connection has created a new eBook, Dry Bulk Freight 101. 

In this article, we’ll review the first section of this eBook and examine the equipment used in dry bulk transport.

Dry Bulk Equipment

Dry Bulk Tanks

dry bulk tankThe dry bulk tank (aka “pneumatic trailer”) is basically a metal cylinder with a series of cone-shaped hoppers at the bottom and a series of openings (or “manholes”) at the top and back of the tank.  At the bottom of each hopper is a valve, opening into a pipe that runs below the trailer. Those valves are closed when a shipper loads the truck. When it comes time to unload, the driver opens them, letting product run out of the hopper and into the pipe.

Download the new Dry Bulk Freight 101 eBook from Bulk Connection

Dry bulk carriers pay a lot for their equipment—about $110,000 for a tank that carries sand and clay, and up to $140,000 for a trailer with a special vacuum unit for plastics. Other equipment for on- and off-loading costs extra. By way of contrast, a dry van trailer costs $35,000-$40,000.

The biggest concern for these carriers?  Contamination.  A responsible carrier diligently visits the truck wash after each load, but there’s always a chance that a little stray material—a few beads of plastic or a bit of clay residue—will survive the wash, stuck deep in the piping (note: there are more extensive methods of tank washing that can further prevent this). What happens then? Picture a load of white plastic pellets shipped in a trailer that still has a few black pellets lodged in a crevice. If those black pellets get dislodged, they’ll mix in with the white product. Then, when that plastic goes through a manufacturing process—say, to produce shampoo bottles—you’ll get an ugly black slash across hundreds of units. The customer will have to toss those bottles, and someone—possibly you, the shipper—will pay for that loss.  

The problem can be even worse if, instead of production, the load goes into a silo already filled with white beads.  Those few black beads could ruin hundreds of thousands of pounds of white plastic.  Because of this, many carriers that move bulk plastic pellets reserve some trailers for white pellets, some for black, some for blue, and so on.  They then dedicate other trailers to loads such as sand or clay.

Hoses, vacuums and blowers

For plastic-hauling tanks, a vacuum unit on the back suctions the pellets or powder through the bottom pipe and along a hose to the silo or other vessel where the receiver stores product.  Tanks for other commodities such as sand or clay come equipped with blowers, which are about half the size of vacuum units and less powerful.

Dry bulk carriers generally use hoses, four inches in diameter, to blow material into and out of a trailer. When loading product from a rail car or offloading to a silo, those hoses may need adapters to connect them to other equipment.

Weight and Volume

Dry bulk commodities vary a lot in density. A cubic foot of dry sand weighs roughly 100 lbs., while the same volume of a material called perlite (used in industry and horticulture) might weigh only 5-8 lbs. Those differences have big consequences for transportation, especially when it comes to staying within the Department of Transportation’s 80,000-lb. limit on gross vehicle weight.

The newer trailers come with onboard scales which can tell drivers – approximately – how much weight they have onboard, accurate to within a couple of hundred pounds. To get a precise measure of the product weight, the driver first takes the empty truck to a certified scale to obtain a “light weight.” Once the product is loaded, the driver returns to the scale to get the loaded weight, which is printed on a scale ticket. Of course, that number, minus the light weight, gives you the weight of the product.

Key questions to determine your equipment needs

Before you start looking to put all this equipment into action for your products, make sure you can answer the questions that your carrier or broker will ask, including:

  • What is the product?
  • What is the value of the cargo?
  • What are its special properties? (It’s best to give the carrier a Safety Data Sheet (SDS) for the commodity, so there will be no mistake about any special handling required)
  • If the product is plastic pellets, what color?
  • How much weight are you moving?
  • Is there a scale available at the loading site?
  • From what will you load the product? Silo? Rail car? etc. And into what kind of receptacle will you unload it?
  • How close can you get the truck to the product for loading and unloading?
  • How many 20-foot lengths of hose will you need to load and unload?
  • What fittings and adapters, if any, do you need for loading and unloading?
  • Does your facility – or the receiver’s – require any specific safety equipment?

If you don’t know – or are unsure – how to answer these questions, there are carriers and freight brokers that can guide you through the process. Bulk Connection is one such freight broker, and is committed to providing personalized, 1-on-1 service to ensure that no stone is left unturned in finding the right carrier for your loads.  Contact Bulk Connection today to learn how they can put over 30 years of dry bulk experience – and the largest network of bulk carriers in North America – to work for you. 

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This entry was posted in Dry Bulk Transport by Jim Cordock