Tank Truck Unloading

Procedures for unloading tank trucks are similar to those for unloading tank cars except that pressures and fitting locations may vary from truck to truck.

The unloading operator should verify the location of all fittings before unloading. The driver of the truck should be familiar with these locations. It is recommended that you discuss with the driver the specifics of the vehicle before beginning unloading operations.

The driver of the caustic soda solution tank truck is usually responsible for their own unloading, requiring only a 2-inch male connector on the customer's permanent unloading system. Remember: It is the customers’ responsibility to sign off that the driver has attached the unloading hose to the proper tank and that the tank has adequate empty space to hold entire contents of the truck.

The tank truck unloading operator should wear the same protective equipment and obey the safety precautions as outlined in Personal Protective Equipment. Close-fitting chemical worker's safety goggles and chemical resistant gloves, as a minimum, must always be worn while handling caustic soda solution. In addition to the minimum personal protective equipment, a chemical protective suit (jacket and pants), hard hat with full face shield (in addition to chemical worker’s goggles), and chemical resistant boots are required while connecting and disconnecting hoses and during the start-up of the transfer process.

Safety showers and eyewash fountains should be conveniently located, clearly marked and readily accessible to personnel in areas where normal operations or maintenance could expose personnel to caustic soda solution. Safety showers should be located directly above the eyewash fountains. Self-draining and heated safety showers and eyewash stations may be required in freezing conditions. Safety showers and eyewash fountains should be tested frequently for proper operation and especially before work begins in the vicinity. It is recommended that a horn or other such alarm device be installed at the safety shower so that it can be activated to summon help if use of the safety shower and/or eyewash fountain becomes necessary.

It is common practice to unload by air, which is normally provided by the customer, but which also may be provided by the trucker. See Tank Truck Top Unloading Caustic Soda by Air Pressure illustration below.

For discharge elevations above 30-feet, it is recommended the caustic soda solution be unloaded using a pump provided by the customer, or if notified in advance, the trucker can provide a pump. See Tank Truck Bottom Unloading Caustic Soda by Pump illustration below.

Once the unloading is completed, the customer must provide water so that the trucker can wash out and dilute any caustic soda solution remaining in the unloading hose and wash off any minor spillage on the truck or ground. Collection facilities should be provided to handle spills and wash out streams.

Remember: During cold weather operations, most tank trucks do not have heating coils. The viscosity of 50% caustic soda solution increases rapidly as the caustic soda solution falls below 65°F (18°C). At higher viscosities, the unloading pump discharge pressure may not be high enough to overcome the elevation head required to pump into the storage tank.

For additional information on tank truck offloading, review Pamphlet 088 "Sodium Hydroxide Solution and Potassium Hydroxide Solution (caustic): Tank Motor Vehicle Load/Unload." This pamphlet and additional resource materials can be purchased through the Chlorine Institute web site or send your request via fax to (703) 741-6068.




The information contained above is supplemental to the Internet Disclaimer and is not intended to be all-inclusive as it relates to use, handling, storage, disposal and all other described activities. Recipients must make their own determination of suitability and are responsible for compliance with all applicable federal, state, provincial, municipal laws and/or other regulations. This information is offered solely for your consideration and verification and in no event will The Dow Chemical Company be responsible for damages of any nature whatsoever resulting from the use or reliance upon this information or the product to which this information pertains.