Industrial chemicals · Taylor, TXTechnical Data Sheet
Hydrofluorosilicic Acid 23% (HFS)
Technical · 23%
Identity & Composition
- Product Name
- Hydrofluorosilicic Acid 23% (HFS)
- Alliance Code
- hydrofluorosilicic-acid-23-hfs
- Grade
- Technical
- Concentration
- 23%
- CAS Number
- 16961-83-4PubChem
- Formula
- F6H2SiPubChem
- Molecular Weight
- 144.091PubChem
- Product Type
- solution
Specifications
| Test | Specification | Typical | Method | Source |
|---|---|---|---|---|
| Assay (H2SiF6) | 23.0 min. | 24.0 | — | Supplier specification |
| Free acid (HF) | 1.0 maximum % | 0.3 % | — | Supplier specification |
| Free hydrofluoric acid (HF) | maximum of 1 percent | Passes test | — | AWWA standard |
| Heavy Metals (as lead, Pb) | <0.02% | 0.0005 % | — | Supplier specification |
| Suspended matter | clean and free of visible suspended matter | Passes test | — | AWWA standard |
| Arsenic (As) | 10 mg/kg maximum | 1.0 mg/kg | ICP-MS | Interpreted |
| Sulfate (SO4) | 0.5 % maximum | 0.15 % | Ion chromatography / gravimetric (BaSO4) | Interpreted |
Specification values are guaranteed limits. Typical values are representative of production lots and are not guaranteed. Lot-specific certificates of analysis ship with every order.
Available GradesSame CAS, alternate grades and concentrations
| Grade | Concentration | Typical Assay | SKU | TDS |
|---|---|---|---|---|
| This grade Technical | 23% | — | current | current |
| ACS Grade | 23% | — | hydrofluorosilicic-acid-23-acs | View TDS → |
Typical assay shown is the rolling-window mean from the sibling product's most recent lots. Grade selection drives downstream end-use — verify the sibling grade matches your specification before substitution.
Physical & Chemical Properties
One or more physical-property values are temporarily suppressed pending verification against vendor COA data. For complete properties refer to the Safety Data Sheet (SDS) or contact sales@alliancechemical.com.
| Property | Value | Source |
|---|---|---|
| Form | Liquid | Published reference |
| Color | water white to straw yellow | AWWA standard |
| Odor | Sour, pungent | Published reference |
| Specific Gravity (20 °C) | 1.185 - 1.215 | Interpreted |
| Density | 1.19 (23% w/w aqueous solution, 20 °C) | Published reference |
| Boiling Point | Not characterized for the 23% solution | Published reference |
| Melting Point | Not characterized for the 23% solution | Published reference |
| Solubility (water) | DECOMP AT MP; DELIQUESCENT; WHITE CRYSTALS; SOL IN ALKALI; SOL IN COLD AND HOT WATER /DIHYDRATE/ | Published reference |
Strong acid — density and vapor-pressure values shown are at 20 °C; values shift markedly with concentration and temperature. Reference concentration-temperature curves before specifying equipment.
Materials of Construction
| Material | Rating | Conditions | Source |
|---|---|---|---|
| polyethylene | Compatible | — | s3.amazonaws.com |
| cross-linked high-density polyethylene (with UV stabilizer) | Compatible | polyethylene must be high-density, cross-linked, with a minimum of 0.25 percent ultraviolet stabilizer | s3.amazonaws.com |
| rubber-lined steel | Compatible | — | s3.amazonaws.com |
| glass | Not recommended | — | s3.amazonaws.com |
| ceramics | Not recommended | — | s3.amazonaws.com |
| steel (unlined) | Not recommended | — | s3.amazonaws.com |
| concrete | Not recommended | — | s3.amazonaws.com |
| wood | Not recommended | — | s3.amazonaws.com |
| rubber lining / saran | Compatible | source product is a 23-25 % H2SiF6 aqueous solution (TDS typical analysis 23.5 %) | cdn-contenu.quebec.ca |
| polyethylene shipping containers (vs. glass carboys) | Compatible | 23-25 % H2SiF6 aqueous solution per the TDS typical analysis | cdn-contenu.quebec.ca |
| high-density, cross-linked polyethylene | Compatible | — | s3.amazonaws.com |
| unlined steel | Not recommended | — | s3.amazonaws.com |
Compatibility is drawn from published manufacturer and supplier documentation for this product; each rating is sourced. Confirm against your specific duty cycle before equipment selection.
Materials Selection Tool
Showing 17 of 17 materials compatible at the selected envelope.
| Material | Rating | Max T (°C) | Notes |
|---|---|---|---|
Buna-N (NBR) elastomer | Poor | — | Hardens and cracks; do not use. |
EPDM elastomer | Good | 80 | Standard for HCl and H2SO4 gaskets. |
Viton (FKM) elastomer | Good | 80 | Acceptable for HCl gaskets up to 37 %. |
PTFE fluoropolymer | Excellent | 200 | Universal acid compatibility. |
PVDF (Kynar) fluoropolymer | Excellent | 120 | Excellent for HCl piping at elevated temperature. |
Borosilicate Glass glass ceramic | Excellent | 100 | Inert to most strong acids (avoid HF). |
Glass (borosilicate) glass ceramic | Excellent | 100 | Inert under all conditions |
316 stainless steel metal | Poor | 25 | Severe pitting; use only for vapors |
Aluminium metal | Not recommended | — | Reacts to form H2 gas |
Carbon Steel metal | Not recommended | — | Catastrophic corrosion; never use. |
Hastelloy C-276 metal | Excellent | 80 | Preferred metal for concentrated HCl service. |
Inconel 625 metal | Good | 60 | Acceptable for dilute service |
Tantalum metal | Excellent | 100 | Best-in-class but expensive |
CPVC thermoplastic | Excellent | 90 | Higher-temp variant of PVC. |
FRP (vinyl ester) thermoplastic | Good | 60 | Common bulk-storage tank material |
HDPE thermoplastic | Excellent | 60 | Standard tank/drum material for HCl up to 37 %. |
PVC thermoplastic | Excellent | 60 | Common for piping; verify rating for service > 50 °C. |
Regulatory & Transport
DOT / 49 CFR
- UN Number
- UN177849 CFR 172.101
- Hazard Class
- 8Adjudicated
- Packing Group
- IIAdjudicated
- Proper Shipping Name
- Fluorosilicic acidAdjudicated
GHS / OSHA HazCom 2012
- Signal Word
- DangerAdjudicated
- H-Codes (Hazard Statements)
- H290, H302, H312, H314, H332Adjudicated
- P-Codes (Precautionary Statements)
- P260, P264, P270, P271, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P363, P405, P501Adjudicated
Occupational Exposure Limits
- OSHA PEL (29 CFR 1910.1000)
- —no canonical
- ACGIH TLV
- —no canonical
- NIOSH REL
- —no canonical
- NIOSH IDLH
- —no canonical
Transport descriptions reflect 49 CFR 172.101 lookup at time of publication. Sourced data: ECHA CLP Annex VI for harmonised classifications, NIOSH Pocket Guide for REL/IDLH, OSHA Z-Tables for PEL. Always verify against the latest regulatory text before shipment-critical decisions.
Supplier Qualification Packet
One zipped download containing the TDS, SDS, latest lot COA (when available), and a fresh Letter of Continuing Guaranty for Hydrofluorosilicic Acid 23% (HFS). Every file included is SHA-256 hashed and listed in a manifest your QA team can audit.
Applications
- Fluoridation of public drinking water supplies (NSF/ANSI 60-certified, AWWA B703 water-treatment grade material)cdn-contenu.quebec.ca
- Dosed to a water supply to reach about one part per million total fluoride for reduction of tooth decaycdn-contenu.quebec.ca
- Fed undiluted into water with liquid-feeding devices and metering pumps in water treatment plantss3.amazonaws.com
- Raw material for the production of silicofluoride saltss3.amazonaws.com
- Used in the ceramic, brewing, paint and metallurgical industriess3.amazonaws.com
- Used as the principal raw material in the production of silicofluoride salts.s3.amazonaws.com
Applications are drawn from published manufacturer and supplier documentation; each is sourced. Suitability for a specific use is the buyer's to confirm.
Storage & Handling
- Recommended Storage
- Bulk storage tanks and other containers can be made of polyethylene, rubber-lined steel, or other appropriate materials; in plant installations, rubber-lined vented storage tanks are usually mounted outside the building.s3.amazonaws.com
- Handling Precautions
- Use full PPE including face shield, acid-resistant gloves and apron. Add acid to water slowly with stirring; never reverse. Ventilation required.Class-level guidance — not product-specific; the SDS controls.
- Incompatibilities
- glass, ceramics, steel, concrete, woods3.amazonaws.com
- Shelf Life
- Consult Technical Services for product-specific shelf life
For full hazard, PPE, and emergency response guidance, refer to the Safety Data Sheet (SDS) for this product. The SDS controls in all cases where guidance differs.
Packaging & Logistics
Shipping Description (US DOT)
UN1778, Fluorosilicic acid, 8, PG II
Sourced from 49 CFR 172.101. Confirm against shipping documents and carrier requirements before tender.
Revision History
Last reviewed 2026-07-17 by Andre Taki, DOT Hazmat Specialist.
| Version | Date | Change | Trigger |
|---|---|---|---|
| 1.3 | 2026-08-05 | Canonical data updated: 4 fields changed via the provenance/adjudication pipeline.
| canonical_change |
| 1.2 | 2026-07-22 | Canonical data updated: 1 field changed via the provenance/adjudication pipeline.
| canonical_change |
| 1.1 | 2026-07-17 | Canonical data re-verified: 6 fields updated against independent vendor SDSs, CLP Annex VI, 49 CFR, and OSHA HazCom 2024 (GHS classification, hazard/precautionary codes, signal word, physical properties as applicable).
| canonical_change |
| 1.0 | 2026-05-20 | Initial URL-first TDS published from canonical chemistry registry. | initial |
This Technical Data Sheet is provided for technical reference. The Safety Data Sheet (SDS) controls in all cases where guidance differs. Values reflect Alliance Chemical canonical data at time of generation; subsequent revisions are recorded in the Revision History above.