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Total Terminal Transfer with Sliding Vane Pumps

Contributed by: Ted Ratcliff at Blackmer

Sliding vane pumps make transferring liquids more efficient, safer.

The liquid-terminal industry transfers millions of gallons of raw materials every day. While speed and the complete transfer of product is paramount to profitable and responsible shipments, the shipping and transfer of liquid commodities inevitably leads to some loss of the product along the way. However, positive displacement sliding vane pumps can significantly decrease that loss, while improving efficiency and safety.

When it comes to liquid transfer, there will always be a “heel” left behind. For example, in the delivery of petroleum products, the heel would be the amount of crude or refined oil left in the barge, railcar, or tanker that cannot be extracted by the pumping system being used at the business end of each link in the supply chain. While this heel will always exist to some extent, certain pumping technologies are available to ensure that the greatest possible amount of product is transferred while maintaining efficiency.

Total terminal transfer of liquid materials is important for several reasons. The buyer wants to receive the full value of their payment; if they pay for 6,000 gallons, they want to get as close to 6,000 gallons as possible. Likewise, the supplier wants to provide the agreed upon amount to ensure a lasting relationship with the buyer and to maintain their reputation. If a significant amount of product remains after transfer, contamination of the next shipment is also a concern.

Discharge hoses and piping used to transfer liquid between the storage unit and delivery vehicle require a pumping system that is capable of clearing any remaining product from the lines. This not only ensures a full delivery but can prevent spills, reduce risk of cross-contamination, and increase safety. Positive displacement sliding vane pumps offer all of the above.

Robert Blackmer invented sliding vane technology 1899 as an alternative to the less-efficient gear-type pumps that dominated the market at the time. While gear-type teeth erode with age, affecting the pump’s efficiency and flow rate, sliding vane pumps feature vanes that slide out of the pump rotor as they wear, eliminating the decrease in volumetric efficiency and flow rate.

Sliding vane pumps feature a series of vanes that slide in or out of slots in the pump rotor. As the pump rotates, it draws liquid in behind each vane, through the inlet port and into the pumping chamber. While the rotor turns, the liquid is transferred between the vanes to the outlet where it is discharged. The pump offers high volumetric efficiency without sacrificing energy through turbulence or slippage by displacing a constant volume of fluid, regardless of variances in pressure. Similarly, the pump is able to maintain consistent performance over time since the vanes constantly adjust to accommodate for wear.

Sliding vane pumps are especially well-suited to liquid terminal transfer because of their incredible dry suction capabilities, which allows them to remove the majority of heel from delivery vehicles and storage units. They are also able to “blow down” the discharge lines, clearing then of any remaining liquid.

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