What material should a diaphragm valve for Phosphoric Acid (H₃PO₄) be?

Hastelloy C-276 (Excellent): Best choice for wet process phosphoric acid with fluoride impurities. SS 316L (Good): Food-grade or pure H₃PO₄ up to 85% at ambient. Not for wet process acid with fluoride. Rubber-lined (natural rubber) (Good): Excellent for wet process acid - industry standard for large bore piping. FRP / PVDF-lined (Good): PVDF good for clean phosphoric acid service. PTFE-lined (Good): Excellent for clean phosphoric acid. Caution with fluoride-bearing wet process acid at elevated temperature.

Phosphoric Acid (H₃PO₄) service

Service Selection

Diaphragm Valves for Phosphoric Acid (H₃PO₄) Service

Which diaphragm valves configuration suits Phosphoric Acid (H₃PO₄) (H₃PO₄), in which material, to which standard — from real service data, with the pitfalls flagged.

Which diaphragm valves for Phosphoric Acid (H₃PO₄)?

PTFE-lined diaphragm valve - Clean phosphoric acid in pharmaceutical and food processing Typical service window: 1–16 bar, Ambient to 100°C.

Recommended Configurations

PTFE-lined diaphragm valve

Clean phosphoric acid in pharmaceutical and food processing

Body Material for Phosphoric Acid (H₃PO₄)

Rated from real compatibility data - click any material for the full decision page.

Hastelloy C-276Best choice for wet process phosphoric acid with fluoride impurities.Excellent SS 316LFood-grade or pure H₃PO₄ up to 85% at ambient. Not for wet process acid with fluoride.Good Rubber-lined (natural rubber)Excellent for wet process acid - industry standard for large bore piping.Good FRP / PVDF-linedPVDF good for clean phosphoric acid service.Good PTFE-linedExcellent for clean phosphoric acid. Caution with fluoride-bearing wet process acid at elevated temperature.Good Carbon SteelHigh corrosion rate in most phosphoric acid concentrations.Poor

Governing Standards for Phosphoric Acid (H₃PO₄) Service

ASME B16.34FDA 21 CFR 178 (food grade)API 607

What to Avoid in Phosphoric Acid (H₃PO₄) Service

Carbon steel valves (high corrosion rate)
Copper alloys
Standard SS 304 in concentrated acid

Service Considerations

Wet process acid: always specify full material compatibility review including fluoride content
Food/semiconductor grade: full-bore, electropolished SS 316L, zero dead-legs
Scale and gypsum deposition in wet process systems - ball valves preferred over globe

Other valve types for Phosphoric Acid (H₃PO₄)

Ball Valves for Phosphoric Acid (H₃PO₄)Butterfly Valves for Phosphoric Acid (H₃PO₄)

Diaphragm Valves for other services

Diaphragm Valves for Sulphuric Acid (H₂SO₄)Diaphragm Valves for Hydrochloric Acid (HCl)Diaphragm Valves for Nitric Acid (HNO₃)Diaphragm Valves for Slurry - Abrasive Pulp / Mineral Slurry Diaphragm Valves for Demineralised Water (DM Water / Deionised Water)Diaphragm Valves for Ethanol / Industrial Alcohol (C₂H₅OH)Diaphragm Valves for Urea Solution (Carbamide / DEF / AdBlue)Diaphragm Valves for Acetic Acid (CH₃COOH)

Reviewed by Process Engineering, Vajra Industrial SolutionsDiscipline: Process & Fluid Service EngineeringLast reviewed: 20 June 2026

Connected Engineering

Standards

ASME B16.34 API 607 Fire-Safe

Products

Diaphragm Valves

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Relevant Products

Vajra Diaphragm Valves

Engineering references

Phosphoric Acid (H₃PO₄) service guideFull compatibility, standards & considerations Vajra Diaphragm ValvesFull range, specs & standards Spec Check engineValidate this spec before the RFQ