Tank Sweeping & Oil Unloading Rotary Lobe Pumps

Separate Bulk Unloading from Residue Recovery

Bulk unloading and final tank stripping can impose different inlet conditions and flow requirements. This page covers transfer of pumpable oil and residues; removal or preparation of solid deposits and the wider tank-cleaning process need separate assessment.

Transfer stages

Bulk flow and final stripping. Provide the required flow, source and destination levels, transfer time, and expected changes as the tank empties.

Residual material

Oil, water, wax, and sediment. Describe viscosity at temperature, settled grit, hard debris, and any cleaning liquid mixed into the residue. Confirm that the material can reach the pump inlet.

Changing Suction Conditions & Seal Support

As the liquid level falls, gas or vapor may enter the suction and interrupt liquid supply. Review pump elevation, minimum source level, hose or pipe layout, and measured inlet pressure where available. Tank depth alone does not establish the operating suction lift.

Confirm priming conditions, seal arrangement and support, and shutdown criteria for the selected configuration. Any allowable empty-pipe or gas-liquid exposure depends on the actual fluid, speed, duration, and controls rather than a general self-priming height or unrestricted dry-running claim.

Loading, Unloading & Reverse-Flow Review

If the same pump is intended for loading and unloading, define the required flow, pressure, fluid, and inlet conditions in each direction. Confirm that the proposed pump and seal arrangement are suitable for both operating points.

Review valves, non-return devices, pressure relief, and control sequences for reversal. Reversing the motor alone does not establish a complete bidirectional system, and equal flow or pressure capability in both directions should not be assumed.

Skid or Trailer Layout & Site Requirements

Provide the installation envelope, mounting arrangement, connection locations, available drive, and space for lifting and maintenance. Compare proposed pump and reducer layouts using dimensioned drawings; confirm actual dimensions and service access if a built-in reduction arrangement is considered.

Review wetted materials against the oil, residue, and cleaning chemistry. Include H2S exposure where present and the site’s area-classification, electrical, and documentation requirements. Required certificates and equipment scope must be confirmed against the actual offer.