Chemical Process Precision Dosing
Reactor feeding, pH neutralization and catalyst injection with hydraulic diaphragm and plunger pumps.
Challenges
Chemical processes dose catalysts, initiators, inhibitors, neutralisers and corrosion inhibitors continuously, and blend reactants in fixed ratios. Media may be highly corrosive, flammable, viscous or contain particles; injection pressure ranges from atmospheric to high; and many processes require tight accuracy and repeatability, because dosing errors affect product quality, reaction rate and even plant safety.
Most units are in hazardous areas, so explosion protection, corrosion resistance and leak control are mandatory, and continuous production makes unplanned downtime expensive. Ordinary solenoid or small mechanical pumps often fall short on pressure, accuracy or hazardous-area certification.
Our Approach
Selection for precision chemical dosing follows three rules: pump type by pressure and medium, control method by accuracy, and explosion protection by area classification.
1. Hydraulic diaphragm metering pumps: the diaphragm is driven evenly by hydraulic oil, suiting medium to high pressure and toxic or valuable media with no leakage. Double diaphragms with rupture detection give early warning before media can escape.
2. Plunger metering pumps: for higher discharge pressures and tight accuracy. The plunger packing contacts the medium, so seal materials must suit it and packing needs routine maintenance; for hazardous media a hydraulic diaphragm pump is preferred.
3. Accuracy and control: electric stroke actuators or VFD motors accept a 4–20 mA signal from the DCS; for higher accuracy a mass flowmeter on the discharge can close the loop.
4. Online pH: neutralisation steps use process pH sensors selected for temperature, pressure and media containing solvents, fluoride or sulfide, with retractable holders or automatic cleaning when needed.
5. Explosion protection and materials: motors, actuators and instruments are rated for the area; heads in 316L, Hastelloy, PVDF or PTFE are chosen by chemical compatibility.
6. Skid integration: pumps, relief and back-pressure valves, dampers, strainers, calibration column and instruments on one base, pressure-tested before shipment.
Please send medium and concentration, temperature, viscosity, flow range, discharge pressure, area classification and control requirements for a pump comparison and material recommendation.
Practical notes: a small pressure difference between pump and injection point causes siphoning and overdosing, so fit a back-pressure valve. Viscous media need lower stroke rates and larger suction lines. Verify flow with a calibration column before commissioning.