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D595-85 – Standard Test Method Technical Guide
The ASTM D595-85 standard provides specifications for tetrasodium pyrophosphate (anhydrous), a material used in various washing, cleaning, and scouring processes with soaps or detergents. It is valued for its mild alkalinity and water softening properties. This article outlines the key requirements from the standard.
📐 Specifications and Chemical Composition
Tetrasodium pyrophosphate (anhydrous) shall be a white, uniform product in either granular, powdered, or flake form, as specified by the purchaser. The chemical composition must conform to the requirements prescribed in Table 1 of the standard, which includes specific limits for impurities and the pyrophosphate content. For ordering purposes, a minimum content of 97.5% is used as the baseline for net weight calculations. Additionally, if the material absorbs sufficient water to reduce the pyrophosphate content to 95% or lower, it may be rejected at the purchaser’s option. Sampling and analysis should be performed in accordance with ASTM D501 test methods.
| 🟦 Parameter | 📏 Requirement |
|---|---|
| Minimum tetrasodium pyrophosphate content (for net weight) | 97.5% as received |
| Rejection limit | Content ≤95% due to moisture absorption |
| Physical form | Granular, powdered, or flake |
| Appearance | White and uniform |
For complete chemical composition requirements, refer to Table 1 in the ASTM D595-85 standard.
⚙️ Ordering and Weight Calculation
Tetrasodium pyrophosphate shall be purchased by net weight. Due to its hygroscopicity, the net weight is adjusted if the pyrophosphate content is less than 97.5%. The net weight to be paid for is calculated using the formula:
W = (R × T) / 97.5