Phosphoric acid corrosion behavior depends strongly on concentration, temperature, impurities (especially chlorides, fluorides, sulfates). This guide gives you direct, usable material recommendations.
1. Key Conditions That Decide Material Choice
Before selection, confirm:
* Concentration: dilute (10–50%) / semi-concentrated (50–75%) / concentrated (75–85% & ≥85%)
* Temperature: ambient/heated (≥40°C)
* Impurities: Cl⁻, F⁻, SO₄²⁻, solids (gypsum, sludge)
* Application: chemical dosing, filtration, circulation, transfer
2. Recommended Pump Materials by Service
A. Dilute & Semi-Concentrated H₃PO₄
(10–75%, ambient or moderate temperature, clean)
* First choice: PVDF (Kynar): Excellent corrosion resistance, good mechanical strength, long life.
* Economic choice: PP (Polypropylene): Only for low temperature (<50°C), no chlorides.
* Magnetic drive pump recommended: sealless, zero leakage.
B. Concentrated Phosphoric Acid (75–85% & ≥85%)
Best material: PVDF
Alternative: PTFE / PFA lined: For higher temperature or longer service life.
Avoid: 304, 316L stainless steel (rapid corrosion); Carbon steel, cast iron (not suitable at all)
C. Hot Phosphoric Acid (≥60°C)
* Only recommend:
PTFE / PFA lining
PVDF (short-term hot service)
* High temperature accelerates corrosion drastically.
D. Phosphoric Acid with Chlorides / Fluorides
(Common in wet-process phosphoric acid)
* PVDF is still preferred
* PTFE / PFA for severe service
* Stainless steels (316L, 904L) are not reliable
Pitting corrosion will occur.
E. Phosphoric Acid with Solids (Gypsum, Slurry)
Abrasion + corrosion: Use PVDForRubber-lined (natural rubber / EPDM)
Bearings: Silicon Carbide (SiC/SiC) for wear resistance.
3. Wetted Parts Material Summary
Casing / Impeller: PVDF > PTFE/PFA > PP
Shaft & Bearings: SiC/SiC > Ceramic > Carbon
Gaskets: EPDM, PTFE
4. Materials to Avoid in H₃PO₄
* Carbon steel, cast iron
* 304, 316L stainless steel
* Aluminum, zinc, brass
* Cheap recycled plastics
Final Recommendation
For 90% of industrial phosphoric acid applications:
👉 PVDF magnetic drive centrifugal pump is the most reliable, cost-effective, and maintenance-free solution.
https://www.xjy-pump.com/