Chemical Metering Pumps — Precision Dosing by Beibangpu

A chemical metering pump (sometimes called a chemical dosing pump in water treatment, or a chemical injection pump in oil and gas service) is a positive displacement pump that delivers a known, repeatable flow of liquid – regardless of back pressure fluctuations in the system. The metering pump differs from a centrifugal pump, which varies flow rate based on system pressure, by controlling flow rate through manipulation of stroke length and stroke rate (prevents variable flow with change of system pressure). If accurate and repeatable feeding of chemicals is important for any reason- science behind the process or end product, quantity of product, or regulatory standards; metering pumps could be used. Pump is identified by the accurate dosing that occurs across its entire operating range, not only at the design point.

A diaphragm metering pump moves an elastomeric diaphragm—a mechanically driven by a solenoid or a motor driven eccentric—back and forth to maximum and minimum deformation of the contained liquid chamber. During the pumping cycle, a check valve at the suction inlet is opened on the part of the cycle drawing fluid into the pump, and closed when the pump expands, while the discharge check opened with the pump compresses. Thanks to the diaphragm, the wetted end is physically separated from the drive and motor end, diaphragm pumps can be used with dangerous chemicals, acids, and caustics without concern. Discrete at a pump system, pump motions can be precisely controlled to attain specific volumetric flow rates. The critical parameters are stroke length (how far the pump moves back and forth) and stroke rate (how fast the pump moves back and forth).

Flow rate selection will vary depending on dose concentration and carrier flow volume being treated. For chlorination in a water treatment process, 0.5-5 mg/L residual into flow streams from 100 GPM to 10+ MGD is typical – equating to metering pump flow rate from 0.5 to 30 GPH for typical chemical concenration application rates. Pressure rating must exceed the maximum back-pressure at the injection point (system pipeline pressure + injection valve pressure drop + surge conditions). Beibangpu application engineers offer a free sizing review — send us chemical type, carrier flow, target dose, injection point pressure, and suction lift conditions for a 24-hour specification recommendation.

Yes. Oil End material selection (contaminants) influence the chemical compatibility. Standard PVDF and PTFE wetted parts can contact 98% saturated sulfuric acid, sodium hypochlorite, hydrochloric acid, sodium hydroxide, ferric chloride and most inorganic process chemicals over full pH range. Contact Beibangpu engineering for concentrated oxidisers, hydrofluoric acid or extreme specialist organic solvents having your chemical and concentration for a compatibility check. BBP-H series hydraulic diaphragm models using 316SS trim with PTFE faced diaphragms can be used for upstream oil and gas corrosion inhibitor injection service where hazard duty designation applies.

A solenoid-driven pump (BBP-S) applies the electromagnetic solenoid to actuate the diaphragm stroke for each pulse of electricity, making it simple, small, and suitable for low-flw applications (up to about 20 GPH). Strokes per minute are under the pulse train. Stroke width (length) is a Variable, controlled with a micrometer. Solenoid pumps are reliable at moderate back-pressures, and tend not to lose prime when operating on outgassing media, but tend to lose prime with even low back-pressure, or at high stroke rates greater than rated capacity. A motor-driven pump (BBP-M) direct drives a variable-speed gearmotor and eccentric to produce a translation of the diaphragm at a smooth, continuous rate (no pulses). The 1,000:1 turndown of the motor-driven platforms makes this the best choice for process control systems where high and low flow conditions need to be handled at a single pump without reconfiguration.

While a few solenoid pump platforms have achieved 400:1 turndown ratios, the industry standard for solenoid-driven platforms is 100:1 turndown; no more. The industry standard for hydraulic (diaphragm) pump platforms (BBP-H series) is 500:1 turndown; the industry standard for motor-driven platform (BBP-M) is 1,000:1. This means that with 100 GPH maximum capacity, a pump will reliably dose down to 1.0 GPH, with 250 GPH, dependable down to 2.5 GPH, at full capacity. In water treatment plants that ramp from low seasonal flow to high seasonal flow, or batch processes that ramp over the life of the batch, high turndown is the number one choice; the ability to handle a wide dynamic range with minimal components working in harmony is more important than maximum throughput. Solenoid-driven platforms normally have 100:1 turndown (up to 400:1 in a few cases); motor-driven platforms (BBP-M) is 1,000:1 as a standard. Hydraulic diaphragm platforms (BBP-H) is up to 500:1 for high-pressure service.

Beibangpu accepts trial orders of 1 unit – no minimum order constraint for initial qualification. Standard configurations (BBP-S and BBP-M, PVDF liquid end, standard flow ranges) ship in 2-3 weeks ex-works Beijing. Custom configurations – modified stroke length, alternative wetted materials, OEM labeling – require 4-6 weeks. Spare parts (diaphragms, check valve assemblies, liquid end rebuild kits) ship within one week of order regardless of order size. We understand that a 6-week wait for a replacement diaphragm during an unplanned outage is unacceptable – Beibangpu’s factory-direct spare parts model is designed specifically to eliminate that scenario.

Yes. Beibangpu works with equipment integrators, system builders, regional distributors, OEMs, and private-label account sponsors directly. OEM scope of production include: custom body color, private label nameplate and documentation, modified stroke and flow configurations beyond the standard catalog, alternative wetted material combinations, and co-engineering support for application-specific requirements. The specifications are NDA with documented OEM account. No minimum volume is required for initial R & D efforts. The minimum order commitment is arrived at by the OEM account at the end of a selection process where volume projections are made. Provide the target series, application, and your company name, and we will get back in touch.