Drum Pump

Overview

A drum pump (barrel pump) empties 200-litre drums, IBCs, and carboys from the top bung opening, replacing the dangerous practice of tipping a quarter-tonne drum to pour from it. The machine is two separable pieces: a hand-held Motor Head and a long Immersion Tube that reaches the drum bottom. One motor can drive a rack of different tubes, polypropylene for acids and alkalis, PVDF for concentrated oxidisers, stainless steel for solvents and flammables, so a single drive serves an entire chemical store. Typical performance is up to 200 L/min and 20 m head, enough to empty a drum in about ninety seconds.

How it works

The Motor Head contains a series-wound universal motor: a wound Rotor Assembly running inside the Stator Assembly field at up to 10,000 rpm, fed through a pair of Carbon Brush contacts and cooled by a shaft-mounted Cooling Fan. The armature rides on two Ball Bearing sets inside the splash-protected Motor Housing Shell. High speed is the point: it lets a very small impeller make useful head, which keeps the whole wetted end slim enough to pass a 2-inch bung.

Torque passes through the Quick-Release Coupling, where a knurled Coupling Hand Nut clamps the tube and a Drive Dog engages the Shaft Socket on the tube's inner shaft, no tools, a few seconds to swap tubes. Inside the Outer Tube, the Inner Shaft runs the full tube length, steadied every few hundred millimetres by a PTFE Shaft Bushing. At the foot, the Impeller, an open axial rotor about 38 mm across, sits in the Suction Foot behind a slotted Foot Strainer. It throws liquid up the annulus between shaft and tube to the Discharge Spout, through the Discharge Hose, and out the trigger-operated Hand Nozzle.

Sealless tubes are standard for most chemicals: the liquid simply drains back when the pump stops. Where vapours are aggressive or the liquid must not contact the upper shaft, a Tube Shaft Seal makes the tube gas-tight.

Mounting and control

The pump hangs in the drum on the Drum Adapter. Its polypropylene Bung Adapter threads into the standard 2-inch buttress bung, the Adapter Seal limits vapour escape, and the sliding Depth Collar sets how close the Suction Foot rides to the drum bottom, close enough to strip the drum nearly dry, leaving residues of under 100 mL with an angled foot.

Electrically, the head carries a 5 m oil-resistant Power Cord, a splash-protected Rocker Switch with low-voltage release (the pump cannot restart by itself after a power cut, a requirement for unattended safety), and a triac Speed Control Board that phase-angle-modulates the universal motor for stepless flow control. A Thermal Fuse in the windings protects against stall and blocked-rotor overheating.

Variants

The centrifugal-impeller tube described here handles thin liquids to roughly 1,000 mPa·s. For honey, resins, and greases up to 100,000 mPa·s, the same motor heads drive progressive-cavity tube ends with a helical rotor in an elastomer stator. Air-motor versions replace the electric head where compressed air is the preferred utility, and ATEX-certified sets with conductive tubes, earthing cables, and gas-tight seals are mandatory for flammables: a stainless tube, an explosion-proof motor, and bonding clamps between pump, drum, and receiving vessel prevent static ignition during solvent transfer.

Selection

Tube material is chosen against a chemical resistance table for the exact concentration and temperature: polypropylene covers most acids and alkalis to 50 °C, PVDF extends to concentrated nitric and chromic acid at 100 °C, stainless 316 covers solvents, and Hastelloy C handles the worst oxidising chlorides. Tube length matches the container, 1,000 mm for a standard 200 L drum, 1,200 mm for IBCs. Sizing errors show up fast at 10,000 rpm, so manufacturers publish viscosity and density derating curves; running a thin-liquid impeller in 5,000 mPa·s product simply stalls the flow while the motor overheats.