Pump Selection Guide: How to Choose the Right Chemical Pump

The Selection Logic at a Glance

Selecting a chemical pump is fundamentally a process of elimination. You begin with the complete product range and, at each step, narrow the field by one requirement until a single best-fit model remains. The six steps below — medium, duty, material, drive, priming, and NPSH/motor — are ordered so that the most decisive (and safety-critical) questions are answered first.

Always start with the medium. A pump that is hydraulically perfect but chemically incompatible will fail catastrophically; a pump that is chemically perfect but hydraulically marginal will simply run inefficiently. Chemistry is non-negotiable; hydraulics can usually be tuned.

Step 1 — Define the Medium

Record every property of the liquid that affects pump survivability or performance:

• Chemical name — e.g. sulfuric acid, sodium hydroxide, ferric chloride.
• Concentration — corrosion behaviour changes dramatically with concentration (e.g. concentrated vs. dilute sulfuric acid attack stainless steel very differently).
• Specific gravity (SG) — raises required motor power and reduces self-priming height.
• Temperature — sets the material ceiling and affects viscosity and vapour pressure.
• Solids content — presence, size, hardness, and concentration of abrasive particles.
• Vapour pressure / boiling point — low-boiling or volatile liquids demand magnetic drive (static seal).

Step 2 — Define the Duty

Quantify the hydraulic requirement the pump must meet:

• Flow rate (Q) in m³/h.
• Total head (H) in metres, accounting for static lift plus all pipe, valve, and fitting friction losses.
• Suction conditions — flooded suction (tank above pump) vs. suction lift (source below pump). Suction lift demands a self-priming pump.
• Duty cycle — continuous vs. intermittent; affects motor rating and bearing life expectations.

Step 3 — Choose the Material

Match the wetted material to the medium's corrosion and wear profile:

• Fluoroplastic (F46/FEP, PTFE, PFA, PVDF) — the universal answer for strong acids, strong alkalis, oxidisers, aqua regia, and mixed/corrosive organic solvents. Choose F46-lined pumps (IHF, CQB, FZB, ZMD) for the broadest acid coverage; add PTFE/PFA linings for high-temperature or high-purity duties.
• Stainless steel (304 / 316 / 316L, duplex) — for clean and moderately corrosive media: organic acids, alcohols, brines, oils, solvents. Note the chloride caveat — seawater and chloride brines can pit 316L; upgrade to duplex or move to fluoroplastic.
• UHMWPE — the only material that combines corrosion resistance with serious abrasion resistance. Choose the UHB-ZK for slurries, ore pulps, and any medium carrying hard solids.

When in doubt about a mixed or unknown chemistry, default to fluoroplastic. It has the broadest inertness and the lowest risk of an unpleasant surprise.

Step 4 — Choose the Drive / Seal Type

Now decide how the pump will be sealed against leakage:

• Mechanical seal (IHF, FSB, FZB, IH, UHB-ZK) — field-proven, tolerant of brief dry running and a wider temperature range. Acceptable whenever a small, controlled leak over the seal's lifetime is tolerable.
• Magnetic drive (CQB, CQL, ZMD, ZCQ) — static seal, zero leakage. Mandatory for toxic, volatile, precious, or flammable/explosive media where any release is unacceptable.

Step 5 — Choose Priming Method

• Standard (flooded suction) — use when the liquid source is above the pump or the suction line stays full.
• Self-priming (FZB, ZMD, ZCQ) — required when drawing from a sump or tank below the pump, when the line drains between cycles, or when a foot valve is undesirable. Remember that self-priming height falls as medium density rises.

Step 6 — Confirm NPSH and Motor

Finally verify the hydraulic and power details:

• Ensure the pump's required NPSH is below the system's available NPSH, with a safety margin of at least 0.5–1 m, to prevent cavitation.
• Size the motor for the actual SG and the maximum (not just duty) point on the performance curve, with a service factor. For the IHF, power spans 0.55–110 kW at 1450 / 2900 r/min.
• Confirm speed choice: 1450 r/min gives gentler, longer-life service for high flow; 2900 r/min delivers higher head in a smaller frame.

Decision Flowchart

From Medium to Model — a Text Flowchart

1. START: Identify medium, concentration, SG, temperature, solids.
   
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2. Solids present? — If YES → UHB-ZK (UHMWPE slurry pump). Stop.
   
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3. Strong acid / alkali / oxidiser / aqua regia? — If YES → use fluoroplastic material. If NO (clean/mild media) → branch to stainless steel family.
   
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4. Toxic / volatile / precious / flammable media? — If YES → require magnetic drive (zero leakage). If NO → mechanical seal acceptable.
   
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5. Suction lift or intermittent dry line? — If YES → require self-priming. If NO → standard centrifugal.
   
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6. Inline / booster / closed-loop circulation? — If YES → GF (GDF) pipeline pump.
   
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7. Confirm NPSH + motor → finalise size, impeller trim, speed (1450/2900), and motor kW. Done.

Product Comparison: 11 Models and Best-Use Media

Worked Selection Examples

Example A — Concentrated Sulfuric Acid Transfer

• Medium: 98% sulfuric acid, SG ≈ 1.84, 40°C, no solids.
• Duty: 60 m³/h at 35 m head, flooded suction from storage tank, continuous.
• Reasoning: Step 3 — concentrated sulfuric acid demands fluoroplastic (stainless is unsuitable). Step 4 — not volatile or precious, so a mechanical seal is acceptable. Step 5 — flooded suction, no self-priming needed. Step 6 — check NPSH; size motor for SG 1.84 (power scales with SG).
• Selected model: IHF fluoroplastic-lined centrifugal pump, 1450 r/min for smooth continuous service, with external alumina-ceramic/PTFE mechanical seal and motor derated for SG.

Example B — Toxic, Volatile Solvent with Suction Lift

• Medium: Corrosive volatile solvent, toxic, SG ≈ 1.1, 35°C.
• Duty: 8 m³/h at 25 m head, drawing from a sump 2.5 m below the pump.
• Reasoning: Step 3 — corrosive + organic → fluoroplastic. Step 4 — toxic and volatile → magnetic drive is mandatory (zero leakage). Step 5 — suction lift of 2.5 m → self-priming required. The ZMD uniquely combines magnetic drive + self-priming + fluoroplastic.
• Selected model: ZMD fluoroplastic magnetic self-priming pump with silicon-carbide shaft and all-plastic isolation sleeve.

Example C — Abrasive Acid Slurry

• Medium: Acidic ore pulp, 30% solids by mass, abrasive, pH 1, 50°C.
• Duty: 40 m³/h at 28 m head, flooded suction.
• Reasoning: Step 1 — solids present → flowchart exits immediately to the slurry family. Fluoroplastic alone would erode; stainless would corrode. Only UHMWPE gives both corrosion and abrasion resistance. The 8–20 mm lining absorbs wear; choose an open or closed impeller per solids size.
• Selected model: UHB-ZK corrosion & wear resistant slurry pump.

Example D — Clean Pharmaceutical Solvent Circulation

• Medium: Ethanol/glycol mix, clean, no solids, SG 0.9, 30°C.
• Duty: 25 m³/h at 30 m head, inline on a closed-loop reactor cooling circuit.
• Reasoning: Step 3 — clean, mild media → stainless steel is sufficient (no chlorides). Step 5/flowchart step 6 — inline closed-loop duty → pipeline configuration. A stainless in-line pump with magnetic drive would give both zero leakage and pipeline mounting.
• Selected model: GF (GDF) pipeline pump in stainless steel for inline circulation (or a CQL stainless magnetic pump if zero-leak containment is also required).

For the chemical-resistance data behind every material decision above, consult the Pump Material Guide. Once a pump is selected, the Maintenance Guide and Troubleshooting Guide will help you keep it running.

© Youfu Lanke (优氟蓝科) · Corrosion-resistant chemical pumps · cnchemicalpump.com

Part of the Resources knowledge series: Knowledge Base · Selection Guide · Material Guide · Maintenance Guide · Troubleshooting

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  YFTEL Pumps

  Fluid Engineers & Technical Support, YFTEL Pump

  YFTEL is a chemical pump manufacturer based in Hangzhou, China, with a 26,000 m² production base in Hangzhou, China, with a 26,000 m² production base in Anhui. Using the CAS-patented Fluoroplastic Alloy material, we produce 300+ models of corrosion-resistant pumps, valves and piping, exported to 30+ countries.