1 Hydroxy Ethylidene 1 1 Diphosphonic Acid HEDP and HEDP·Na4 FAQ: Grade Selection, Packaging and Safety Notes

This FAQ is for procurement teams and distributors comparing 1 hydroxy ethylidene 1 1 diphosphonic acid HEDP with its tetra sodium salt, HEDP·Na4, from Hebei Longke Water Treatment Co., Ltd. It covers grade selection, packaging, storage and the safety notes published on each product page. The figures below are the published specification indexes. Confirm the exact values, packaging and documents with the supplier for each order and target market.

1. What is HEDP, and how is HEDP·Na4 related to it?

HEDP (1-Hydroxy Ethylidene-1,1-Diphosphonic Acid, CAS No. 2809-21-4, C2H8O7P2, molecular weight 206.02) is an organophosphoric acid corrosion inhibitor. It chelates Fe, Cu and Zn ions and forms stable complexes with metal ions, particularly calcium. HEDP·Na4 is the sodium salt of HEDP (CAS No. 29329-71-3 for x-Na and 3794-83-0 for 4-Na, C2H4O7P2Na4, molecular weight 294). Its product page describes it as a calcium carbonate scale inhibitor that also has scale and corrosion inhibition properties.

2. Which grades are published?

• HEDP acid: liquid (clear, colorless to pale yellow aqueous solution, 58–62% active HEDP) and white crystal powder (90.0% min HEDP; 98.0% min as HEDP·H2O).
• HEDP·Na4 liquid: colorless to yellowish transparent liquid, 29.0–31.0% HEDP·Na4 (20.3–21.7% as HEDP).
• HEDP·Na4 powder: white powder, 85.0% min HEDP·Na4 (60.0% min as HEDP), moisture 10.0% max.
• HEDP·Na4 granule: white granule, 81.0–90.0% HEDP·Na4 (57.0–63.0% as HEDP).
• HEDP·Na2 (disodium salt): liquid and white powder. This is a related salt with a different pH range.

3. How does pH affect the choice between HEDP acid and HEDP·Na4?

The published pH values (1% water solution) are 2.0 max for HEDP acid (liquid and solid), 10.0–12.0 for HEDP·Na4 liquid, 11.0–12.0 for HEDP·Na4 powder and granule, and 4.0–6.0 for HEDP·Na2. The product pages describe HEDP as acidic, HEDP·Na4 as alkaline and HEDP·Na2 as weakly acidic. Check which pH suits your formulation or system before you choose a grade.

4. When should I choose liquid, powder or granule HEDP·Na4?

The liquid grade has a published density of 1.26–1.36 g/cm3 (20℃). The solid HEDP·Na4 is a water-soluble white powder that absorbs moisture easily (deliquescent), and the product page says it is suitable for use in winter and freezing areas. The granule is described as even, free-flowing, low in dust and low in hygroscopicity, so it is easy to handle. It has a bulk density of 0.70–1.10 g/cm3 and published particle-size limits of 4.0% max below 250 μm and 5.0% max above 800 μm.

5. What applications are published for each grade?

The published uses for HEDP and HEDP·Na4 include scale and corrosion inhibition in circulating cooling water, low-pressure boilers (medium and low pressure for HEDP·Na4) and oil field water systems. They are also used as metal and nonmetal detergents in light textiles, as peroxide stabilizers and dye-fixing agents in dyeing, and as chelating agents in non-cyanide electroplating. The HEDP·Na4 liquid/powder page also lists industrial and municipal cleaning water systems and swimming pools. The granule page focuses on household and industrial cleaners, cosmetics and personal care (to restrain rancidity and discoloration), slow-release tablets made with other auxiliaries, and oxygen bleaching stabilization in dyeing and papermaking.

6. What dosage is published?

For HEDP acid, the published preferred dosage is 1–10 mg/L as a scale inhibitor, 10–50 mg/L as a corrosion inhibitor and 1000–2000 mg/L as a detergent. HEDP is usually used together with polycarboxylic acid. For HEDP·Na4 granule used as a chelating agent in cleaning, the published dosage is about 1.0–5.0%. It works better when combined with polyacrylate sodium or a maleic-acrylic copolymer. No water-treatment dosage is published for HEDP·Na4 liquid or powder, so ask the supplier to confirm it for your system.

7. How is HEDP·Na4 packaged?

HEDP·Na4 liquid comes in 200L plastic drums, 1000L IBCs or to customer requirements. HEDP·Na4 powder comes in 25kg bags or to customer requirements. HEDP·Na4 granule is packed in film-lined kraft valve bags (25kg net), 1000kg tonnage bags or to customer request. HEDP acid liquid uses 200L plastic drums or 1000L IBCs, and HEDP acid solid uses 25kg bags, with customer requirements also accepted.

8. What storage period and conditions are stated?

All grades should be stored in a shady, dry room. The published storage periods are ten months for HEDP·Na4 liquid and powder, one year for HEDP·Na4 granule and twelve months for HEDP acid. For HEDP·Na2, the period is twelve months for the liquid and ten months for the solid.

9. What safety information is published, and is an SDS included?

The product pages carry short safety notes. HEDP is acidic and HEDP·Na4 is alkaline. Use labor protection during handling and avoid contact with eyes and skin. If the product splashes on the body, rinse immediately with plenty of water. For the granule, flush with water after contact and then seek medical advice. These notes are not a full safety data sheet. An SDS, transport classification and market-specific regulatory documents are not part of the published product information. Request them from Hebei Longke Water Treatment Co., Ltd. and check them against the rules in your country or region before ordering.