When your products are shipped via dry van, there isn’t much to think about in regard to the dry van trailer. Temperature concerns aside, just about any dry van trailer is capable of transporting product. The same is not the case with bulk liquid transportation, where the tank can make all the difference between a successful load and an expensive mess. In this article, we’ll examine bulk liquid tanks in greater detail and tell you what you need to know about them before scheduling your next load.
Bulk liquid tank characteristics
Bulk liquid tanks are made of stainless steel or aluminum, with stainless steel being most common. 307-alloy stainless steel – known for its versatility – was once an industry standard and is still used to ship certain classes of chemicals. In recent years, however, alloys such as 316 and 317 have become more popular due to their higher levels of nickel and their enhanced ability to handle certain corrosive materials.
Bulk liquid tanks are either insulated or non-insulated. Non-insulated tanks are also referred to as “skin tanks.” Insulated tanks have a layer of fiberglass that surrounds the tank and a sheath of stainless steel over that. Insulated tanks are most common due to their Thermos®-like ability to keep warm products warm and cold products cool during transit. Insulated tanks can also carry products that non-insulated tanks can carry, but the reverse is not true. And, as they are the most common type of tank, insulated tanks also increase the odds of securing a backhaul after product delivery, which can reduce the cost of the load.
Bulk liquid tankers with in-transit heating capabilities have a series of steam coil lines at the bottom of the tank. This in-transit system does not actually heat the liquid in the tank. Rather, it assists in maintaining the product’s existing heat. Power from the truck heats and circulates coolant from the radiator through the steam coil lines in a continuous cycle. When running at full strength – typically after 4 hours of continuous driving – this system reaches a maximum temperature of 160˚F.
The typical liquid bulk trailer holds 6,000-7,000 gallons. Some carriers offer “tight fill” tanks that hold only up to 5,000 gallons. By filling these smaller tanks completely, you ensure that the liquid won’t get agitated in transit, reducing the chance of forming foam. Foam is nearly impossible to unload from a trailer, leaving you with a “heel” of unusable product, which you’ll be forced to discard.
Most bulk liquid tanks are single compartment tanks – the entire tank is one big compartment. Other tanks are segregated into two, three, four, or even five compartments. With multi-compartment tanks, each compartment can house a different chemical and has its own unloading valve.
Loading and unloading
At the top of the tank is a dome, which is opened for loading the trailer. Air compressors or pumps are used to load and unload bulk liquids. An air compressor – which blows compressed air through a hose – is typically the preferred method as it’s more convenient and makes less of a mess.
For unloading, the tank will have either a rear or center unload mechanism. With rear unload, there is a discharge valve in the back of the trailer. This is preferable when the driver is backing down a ramp to unload. With center unload, the trailer floor will slope down to the middle from the front and rear, and there is a valve in the center. Some center-unload tanks will have a pipe running along the middle of the tank so that it can also be unloaded in the rear.
In addition to the characteristics described above, there are specialized tanks designed to haul specific types of products. Food-grade trailers, for instance, are insulated stainless steel tanks that have a sanity valve (a special covering that protects the valve from dirt and elements). Kosher tanks have been blessed in accordance with religious customs. And tanks for acids or other types of chemicals may use rubber-lined tanks, polyethylene tanks or plastic tanks to transport product.
Lean on Bulk Connection to get liquid products in motion
With all of these bulk liquid tank variables at play, it can be difficult to match your product with the precise equipment needed to haul it. Fortunately, there are experts that can take care of this for you. Bulk Connection is an ISO-9001-certified freight specialist that has been handling bulk liquid loads since 1987. We have a team of bulk freight specialists – many with over 20 years of industry experience – at the ready to help you protect the safety and integrity of your products in transit. To learn more about working with a true bulk liquid freight expert, contact Bulk Connection today.