Sulfuric Acid (H₂SO₄) Pump Selection Guide: PTFE Lined vs Metallic Alloys
Engineering guidelines for dilute and concentrated sulfuric acid transfer across 0% to 98% concentration. Avoiding motor overload from high specific gravity (1.84) and choosing robust mechanical seal configurations.
Handling sulfuric acid requires strict metallurgical matching based on acid concentration, operating temperature, and flow velocity. While concentrated acid (93–98%) at ambient temperatures is sometimes transferred with metallic cast iron or 316L, IHF Series Fluoroplastic (PTFE/FEP) Lined Centrifugal Pumps represent the universal, leak-free industry benchmark across 0% to 98% concentrations up to 120°C, eliminating catastrophic erosion-corrosion.
Sulfuric Acid Concentration & Metallurgy Matrix
| Acid Concentration | Operating Temp | Recommended Pump Body | Seal Configuration |
|---|---|---|---|
| 0% – 70% (Dilute) | < 80°C | Virgin PTFE Lined (IHF) | External Bellows Seal (WB2 SiC/SiC) |
| 70% – 93% | < 100°C | IHF / CQB-F Magnetic Drive | Silicon Carbide Faces |
| 93% – 98% (Concentrated) | < 120°C | IHF PTFE Lined (Iron Armored) | External PTFE Bellows or Sealless Mag |
1. Why Metallic 316L Pumps Suffer Rapid Failure in Acid Service
A frequent misconception in chemical plant procurement is assuming 316L stainless steel provides universal acid immunity. In dynamic pump service, 316L relies on a delicate iron sulfate passive film. When fluid velocity exceeds 1.5 m/s inside a pump casing, turbulence strips this film away, resulting in catastrophic wall penetration within months. For comprehensive technical specifications, explore our IHF Fluoroplastic Pump series and FSB Centrifugal Chemical Pump series.
GreenPower IHF series solves this problem by encasing thick virgin fluoropolymer liners (PTFE/FEP/PFA) inside heavy ductile iron casings. The ductile iron takes all mechanical piping stresses, while the wetted fluoroplastic guarantees complete chemical inertness.
2. Motor Sizing: The 1.84 Density Multiplier Rule
Standard centrifugal pump curves are calibrated for water (SG = 1.0). Concentrated sulfuric acid has a specific gravity of 1.84 kg/dm³. Sizing an electric motor without applying an 84% power correction factor and a 20% safety margin will cause immediate thermal overload upon startup:
You can instantly compute your required motor rating and match it to standard IEC electric motors using our interactive Chemical Pump Power & Sizing Calculator.
3. Frequently Asked Questions
Can 316L stainless steel be used for 98% concentrated sulfuric acid?
Only under strictly low temperatures (<25°C) and static tank storage. In dynamic centrifugal pumps, fluoroplastic lining (IHF series) is mandatory to eliminate erosion-corrosion from high fluid velocities.
Why do sulfuric acid pump motors trip frequently?
98% sulfuric acid is 84% heavier than water (SG 1.84). Standard motors sized for water will immediately overload unless the motor rating is scaled by at least 1.85 to 2.0 times.
What shaft seal configuration prevents sulfuric acid leaks?
GreenPower recommends external PTFE bellows mechanical seals (WB2 series with SiC/SiC friction pairs) where metallic springs sit completely outside the acid stream, or sealless magnetic drive pumps (CQB-F series) for zero-leakage requirements.
Handling concentrated or dilute sulfuric acid? Tell us your acid concentration, temperature, flow and head — our chemical pump engineers will calculate motor rating and recommend the optimal lining and seal plan for your duty.
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