Chemical Processing Pumping Solutions

Rotho peristaltic pumps deliver chemical dosing accuracy of ±1% at steady state and ±2% during flow ramp-up or ramp-down. This precision comes from the inherent positive displacement design: flow is directly and linearly proportional to pump RPM. Double the speed, double the flow - with no slip, no recirculation, and no performance curves to consult.

Unlike diaphragm chemical metering pumps, Rotho pumps require no check valves. This eliminates the most common failure point in chemical dosing systems - stuck or fouled check valves that cause inaccurate dosing or complete pump failure. The valve-free design also means the pump handles off-gassing chemicals without vapor lock, a critical advantage when dosing sodium hypochlorite and similar products.

Flow direction is fully reversible, allowing operators to clear lines between chemical batches or recover product from piping. When paired with the Keco Drive VFD (Variable Frequency Drive), operators gain precise speed control from 0-100% with 4-20mA signal input, enabling automated dosing that responds to process demand in real time. The linear flow-speed relationship means simple PLC programming without complex calibration curves.

For applications requiring multiple chemical feeds, each Rotho pump operates independently with its own flow rate, eliminating the cross-contamination risks inherent in multi-head diaphragm pump systems.

Acids

Rotho pumps handle a broad spectrum of acids including sulfuric acid, hydrochloric acid, phosphoric acid, and citric acid. TEKMETAL in Italy uses Rotho pumps for concentrated sulfuric and hydrochloric acid transfer, achieving leak-free operation where mechanical seal pumps repeatedly failed. EPDM and Hypalon hoses provide excellent chemical resistance to most mineral and organic acids.

Bases & Caustics

Caustic soda (sodium hydroxide), lime slurry, potassium hydroxide, and other alkaline solutions are safely contained within the hose element. At Vale do Rio Doce in Brazil, Rotho pumps handle caustic soda in combination with abrasive mineral slurries - a dual challenge that destroys conventional pump seals within weeks.

Oxidizers & Sodium Hypochlorite

Sodium hypochlorite (NaOCl) is one of the most problematic chemicals for conventional pumps. It continuously off-gasses chlorine, creating air pockets that cause diaphragm pumps to lose prime and vapor lock. Peristaltic pumps handle this effortlessly because there are no check valves or air-sensitive chambers. The gas simply passes through with the liquid. Hypalon hoses provide excellent resistance to oxidizing chemicals.

Polymers & Flocculants

Chemical dosing pumps for polymer and flocculant feed must preserve the long-chain molecular structure that gives these chemicals their effectiveness. High-shear pumps break polymer chains, reducing flocculation performance by up to 50%. The gentle peristaltic action maintains full polymer chain length, delivering maximum treatment efficiency at lower chemical consumption rates.

Solvents

With appropriate hose material selection, Rotho pumps transfer various solvents and solvent-based products. NBR (Nitrile) hoses offer good resistance to hydrocarbon solvents, while specialty compounds are available for more aggressive solvent chemistries. Contact our engineering team for specific solvent compatibility recommendations.

vs. Diaphragm Pumps

Diaphragm chemical metering pumps rely on check valves to control flow direction. These valves are the Achilles heel of the system - they clog with particulates, stick from crystallizing chemicals, and fail to seal when off-gassing creates air pockets. Sodium hypochlorite is the most notorious example: continuous chlorine off-gassing creates vapor pockets that prevent check valves from seating, causing the pump to lose prime and stop dosing entirely. Rotho peristaltic pumps have no valves at all, making them immune to these failure modes.

vs. Progressive Cavity Pumps

Progressive cavity (PC) pumps use a metal rotor turning inside an elastomer stator. Aggressive chemicals attack the stator material from the outside in, causing swelling, softening, and eventual failure. When the stator fails, chemical leaks around the rotor and into the gearbox. In a peristaltic pump, the chemical never contacts anything except the hose interior. If the hose fails, a leak detector triggers an alarm before any chemical escapes the pump housing.

vs. Centrifugal Pumps

Centrifugal pumps are not positive displacement devices - their flow rate changes with back pressure, viscosity, and specific gravity. This makes them unsuitable for accurate chemical dosing. A peristaltic pump delivers the same volume per revolution regardless of discharge pressure or fluid properties, ensuring consistent dosing even when system conditions change.