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D6371-24 – Standard Test Method Technical Guide
The Cold Filter Plugging Point (CFPP) test, performed in accordance with ASTM D6371‑24, is a fundamental procedure for assessing the low‑temperature operability of diesel and domestic heating fuels. This standard determines the temperature at which a fuel sample, cooled under rigorously controlled conditions, fails to pass through a standardized wire mesh filter, indicating a potential for wax precipitation to block fuel filters in service.
📐 Scope and Application
D6371‑24 applies specifically to distillate fuels intended for use in diesel engines and domestic heating installations, including those containing flow‑improving or other additives. Both the manual and automated apparatus configurations detailed in the standard are recognized as suitable for referee purposes, providing laboratories with flexible yet equivalent testing options. The standard is technically equivalent to international methods IP 309 and EN 116, ensuring global harmonization of low‑temperature fuel testing. All values in the standard are stated in SI units, and users must observe strict safety precautions regarding the handling of mercury and mercury‑containing products as noted in Section 1.5.
⚙️ Test Procedure and Apparatus Requirements
The core apparatus consists of a jacketed test tube, a pipette assembly, a calibrated cooling bath, and a standardized 45 µm wire mesh filter. A 45 mL sample is cooled at a linear rate of 1.0 °C per minute. At each 1 °C interval, a controlled vacuum is applied to draw the fuel through the filter. The test concludes at the highest temperature at which the filter blocks, defined by the sample failing to fill the pipette to a set mark within a specified time. The final CFPP is reported as this temperature.
| ⚙️ Parameter | 📏 Specification | 🎯 Standard Reference |
|---|---|---|
| Filter Screen Aperture | 45 µm (Woven Wire Cloth) | ISO 3310‑1 |
| Cooling Rate | 1.0 °C per minute | D6371 § 8.2 |
| Sample Volume | 45 mL | D6371 § 8.1 |
| Temperature Intervals | 1.0 °C | D6371 § 9.2 |
📊 Referenced Documents and Standards
Compliant execution of D6371‑24 depends on a framework of supporting standards for sampling, temperature measurement, and terminology. The table below lists key references cited within the standard.
| 🟦 Standard | 📐 Title / Description | 🔗 Relevance to CFPP |
|---|---|---|
| D2500 | Cloud Point of Petroleum Products and Liquid Fuels | Low‑temp flow property context |
| D4057 / D4177 | Manual / Automatic Sampling of Petroleum Products | Representative sample acquisition |
| E1 / E2251 / E2877 | Liquid‑in‑Glass and Digital Contact Thermometer Specs | Accurate temperature sensing |
| IP 309 / EN 116 | Determination of Cold Filter Plugging Point | Technically equivalent methods |
⚠️ Safety Precaution — Mercury Handling: As per Section 1.5, mercury has been designated by many regulatory agencies as a hazardous substance. Users must exercise caution when handling mercury or mercury‑containing products, consult the applicable Safety Data Sheet (SDS), and determine the legality of sales in their location.
💡 Referee Purpose Designation: D6371‑24 explicitly states in Section 1.2 that both the manual apparatus and the automated apparatus are suitable for referee purposes, allowing flexibility in testing without compromising the authority of the results.
❓ Frequently Asked Questions
🔍 What is the Cold Filter Plugging Point (CFPP)?
The CFPP is the highest temperature at which a fuel sample, cooled at a standardized rate, will fail to pass through a 45 µm filter under a specified vacuum. It is a critical measure of low‑temperature fuel operability for diesel and heating fuels.
💡 Does the standard apply to fuels with additives?
Yes. Section 1.3 explicitly states the test method is applicable to distillate fuels including those containing a flow‑improving or other additive intended for use in diesel engines and domestic heating installations.
⚡ How does D6371 relate to other international CFPP standards?
Per Note 1 of the standard, D6371 is technically equivalent to IP 309 and EN 116. Laboratories using any of these methods can expect comparable results under similar test conditions.
📌 What is the required precision for temperature measurement?
The standard mandates the use of thermometers or temperature sensors conforming to specifications like ASTM E1, E2251, or E2877, ensuring a high degree of accuracy and reproducibility for the critical temperature readings.