In the early 1980’s sodium chlorate began to replace chlorine as a bleaching agent in the paper making process. Historically, sodium chlorate had been transported in solution form in tank cars. With significant increase in demand, a more efficient delivery method was needed. Transportation in crystal form by covered hopper car was a natural solution. However, a means to address the corrosive properties of sodium chlorate was required.

Initially, conventional steel bodied covered hopper cars equipped with protective internal coatings were deployed. However, corrosion damage related to coating failures resulted in significant maintenance costs. Procor took on the challenge to come up with an alternative and went on to develop an all-aluminum construction covered hopper car. Parallel in concept to the aluminum bodied wheat board covered hopper previously built by National Steel Car (NSC), the Procor-engineered car incorporated two fundamental design changes; a lower cubic volume due to higher commodity density (3,000 cu. ft. compared to 4,100 cu. ft.) and an upgrade from 70 ton (220,000 lb gross rail load) to 100 ton (263,000 lb gross rail load) capacity. Compared to a conventional gravity discharge covered hopper car, operation of the aluminum equivalent is unorthodox. Loaded as a dry crystal through the round roof hatches, sodium chlorate is emptied as a slurry. A cross wise mounted pipe fitted with spray nozzles, known as a sparger, is fitted to each outlet gate assembly. Located above the discharge openings and just below the side sills, the sparger is used to introduce hot water - liquefying the sodium chlorate crystal. Outlet fittings at the very bottom of the gate assemblies facilitate complete evacuation of the payload.

The first group of twenty sodium chlorate cover hopper cars was constructed at Procor's Oakville, Ontario facility in 1982. During production, a number of refinements were incorporated, including steel end structures and retractable handrail assemblies. Production at the Oakville facility ceased in 2001. Over the years Procor would assemble a fleet of more than 1,300 aluminum sodium chlorate service covered hopper cars, a portion of which was constructed by NSC and Thrall. The Rapido version is representative of later production cars fitted with steel gull wing end structures.

      The Rapido Trains HO scale Procor 3000 cu ft sodium chlorate covered hopper features:

• Correct outlet gates with sparger fittings
• Etched roof walks and end walkways
• Separate roofwalk handrails as appropriate
• Separate grab irons installed at the factory
• Full end cage details
• All-new 100-ton Ride Control trucks with HydraShox integrated hydraulic snubbers
• Etched placards included in polybag
• Accurate paint and lettering
• Multiple road numbers available for each variation
• Available in singles or multi-packs