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D5773-21 – Standard Test Method Technical Guide
📐 Scope and Applicability
This standard, designated D5773-21 / IP 446/09, specifies a test method for the determination of the cloud point of petroleum products and biodiesel fuels using an automatic instrument operating at a constant cooling rate. The method is strictly applicable to samples that are transparent in layers 40 mm in thickness.
The standard covers a full scope temperature range of −60 °C to +49 °C with a required temperature resolution of 0.1 °C. It is critical to note that the official interlaboratory cooperative test program only validated the method over the narrower range of −56 °C to +34 °C. All stated values are measured in SI units.
⚙️ Test Procedure and Relationship to Manual Methods
D5773 serves as an automatic alternative to the manual Test Method D2500 / IP 219. The standard’s introduction explicitly confirms that the temperature results from this automatic constant cooling rate apparatus have been found to be strictly equivalent to the manual reference method.
⚠️ Critical Substitution Rule: When a contractual specification explicitly requires Test Method D2500/IP 219, this test method must not be substituted without first obtaining comparative data and explicit agreement from the specifier. The standard expressly forbids substituting any alternative method without this formal approval to maintain industry consistency.
The method references several essential ASTM and Energy Institute standards for proper sampling and product quality assurance during cloud point determination:
- ASTM D2500 / IP 219 – The equivalent manual cloud point test method.
- ASTM D4057 – Practice for manual sampling of petroleum and petroleum products.
- ASTM D4177 – Practice for automatic sampling of petroleum and petroleum products.
- ASTM D6751 – Specification for Biodiesel Fuel Blend Stock (B100).
📊 Key Technical Specifications and Related Standards
The following tables summarize the critical parameters and associated standards defined within D5773-21.
| 🟦 Parameter | 📏 Specification / Value |
|---|---|
| Method Designations | D5773-21 / IP 446/09 |
| Full Scope Temperature Range | −60 °C to +49
📥 Standard Documents Download |