High-Viscosity Oil Transfer Pump

What Counts as High-Viscosity Oil Transfer

Many everyday oil duties are high-viscosity duties. Heavy fuel oil, crude residue, lubricant base stocks and asphalt flux are pumped through storage, blending and tanker loading at viscosities from a few hundred to hundreds of thousands of centistokes (cSt). Because viscosity falls steeply with temperature, a transfer system is sized around its coldest credible condition.

Classifying the oil is the first step: viscosity decides which pump technology, pipe size, motor and heating arrangement can work. The wider map is drawn in our guide to the best pump for high-viscosity liquids, and the sizing logic in our high-viscosity pump selection article.

Why Positive Displacement Beats Centrifugal for Thick Oil

A centrifugal pump converts impeller velocity into pressure and flow. In a thick oil, friction inside the impeller makes head and flow collapse while efficiency drops. A positive displacement (PD) pump behaves the opposite way: each revolution traps and pushes a fixed volume, and a thicker oil seals the internal clearances better, so volumetric efficiency stays high. That is why Qingdao Green Power's published guidance for its IS/ISW centrifugal pump range is to move to a gear or screw pump above about 150 cSt.

Both screw-pump families are presented on the G and 3GB industrial screw pump product page.

The G-Type Single Screw Pump for Heavy Oil

The G-type is a progressive cavity machine: a helical metal rotor turns inside an elastomeric stator, forming sealed cavities that travel steadily from suction to discharge with smooth, low-shear flow. Qingdao Green Power publishes the G-type for high-viscosity oils and resins above about 1500 cSt, plus sludge and bitumen, at 0.1–150 m³/h and 0.6–2.4 MPa.

The stator is both the sealing element and the wearing element, so its elastomer must match the oil's chemistry and temperature — NBR, EPDM and FKM are the standard grades. One rule is absolute: a G-type pump must never run dry, because the rubber stator is destroyed within seconds. The same feeding discipline applies to bitumen and asphalt transfer and resin transfer.

Triple Screw and Gear Pumps for Cleaner Oils

Where the G-type excels with very thick media, the 3GB triple screw pump is engineered for oil kept hot to stay thin: three intermeshing screws convey the fluid axially, giving quiet, low-pulsation flow up to 350°C at 2.4–241.7 m³/h. It is a natural fit for heavy oil pump selection duties where the pumped oil lubricates the screws, so the medium must stay clean.

External gear pumps are compact and robust for clean fuels and lubricating oils at moderate viscosity. Gear pumps for heavy oil are a technical-reference topic on this site, so confirm current model availability and specifications with Qingdao Green Power before procurement.

System Practice: Heating, Suction and Protection

The methods in our guide to pumping extremely viscous fluids apply directly to oil transfer:

• Heat the oil, not just the pump. Tank coils, steam or electric tracing and jacketed suction piping keep the oil feeding the pump at a workable viscosity.
• Keep the suction short and flooded. Long suction lines starve a PD pump — place it near the source.
• Size the motor for the cold start. Starting torque rises with viscosity — confirm the coldest, thickest condition.
• Fit pressure protection. Confirm the maximum discharge pressure and fit a relief valve against a closed discharge line.
• Never run a G-type pump dry. Fit low-level or dry-run protection to guard the stator.

Frequently Asked Questions