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D3519-88 – Standard Test Method Technical Guide
📌 Scope, Significance, and Application
This standard describes the Standard Test Method for Foam in Aqueous Media (Blender Test), designated ASTM D3519 – 88 (Reapproved 2007). It is specifically intended for low-viscosity aqueous liquids where the kinematic viscosity is less than 3 cSt at 40°C. The values stated in SI units are to be regarded as the standard.
The results obtained by this test method are useful as guides in determining the tendency of a water-based metalworking coolant to produce foam under high shear conditions. No correlation with changes in heat transfer, pumpability, or other factors affected by foam is intended by this standard.
⚠️ Important Limitations: The foam produced by any given industrial process depends on the method by which the foam is generated and may not be directly proportional to that produced by this carefully controlled laboratory test. Furthermore, the foam generated at the specified test temperature of 25°C will not necessarily predict the foaming tendency of the liquid (for example, metalworking coolant) at some other use temperature.
⚙️ Apparatus, Materials, and Preparation
The core apparatus required is a commercial-type blender with a glass jar. The standard specifically designates the Waring Blendor Model 5012G or Model 91-264 (7012G), as tests with other blenders may be suspect due to differences in speed or jar shape. A constant-temperature water bath is essential to maintain the test fluid and blender jar at the precise test temperature.
💡 Blender Speed Calibration: The blender speed must be calibrated by a reliable means. A hand-contact tachometer can provide an initial speed order, followed by more precise determinations using a stroboscope (which does not touch the rotor). Settings must be selected to obtain the recommended speed range.
| 🟦 Component | 📏 Specification / Requirement |
|---|---|
| Blender | Waring Blendor Model 5012G or 91-264 (7012G) |
| Water Bath | Constant-temperature, 25 ± 1°C (77 ± 1.8°F) |
| Timer | Stop watch or timer capable of measuring 5 min ± 0.2 s |
| Measuring Rule | Millimetre rule, approximately 300 mm long, attached to jar |
| Hard Water Standard | 20,000 ppm (Dissolve 29.4 g CaCl₂·2H₂O in 1 L distilled water) |
📏 Test Procedure and Key Measurements
The increase in volume is determined by the increase in the total height of the test fluid, including the foam, after blending. The fluid is agitated for exactly 30 seconds at the specified temperature. The generated foam height is measured using the millimetre rule attached directly to the blender jar. This test covers high shear foam; for low shear foam, refer to Test Method D3601 (Bottle Test).
| 🎯 Parameter | ⚡ Specified Value / Range |
|---|---|
| Test Temperature | 25 ± 1°C (77 ± 1.8°F) |
| Full Agitation Speed Range | 4000 – 13,000 rpm |
| Preferred Speed Range | 8000 ± 1000 rpm |
| Blending Duration | 30 seconds |
| Measured Outcome | Increase in total height of fluid and foam (mm) |
❓ Frequently Asked Questions
🔍 What does the Blender Test actually measure?
This test method covers the measurement of the increase in volume of a low-viscosity aqueous liquid (less than 3 cSt at 40°C) due to its tendency to foam under high shear conditions generated by a blender.
💡 Why is a specific blender model required?
The standard specifically requires a 7-speed Waring Blendor Model 5012G or Model 91-264 (7012G). Tests with blenders of other shapes, sizes, or speed characteristics may produce suspect results that do not conform to the strict requirements of the standard.
⚡ How does D3519 differ from the Bottle Test (D3601)?
The primary difference is the shear condition. This Blender Test (D3519) measures foam generated under high shear conditions, while the Bottle Test (D3601) is intended to measure foam under low shear conditions.
📌 What is the role of the 20,000 ppm hard water standard?
Dissolving 29.4 g of reagent grade CaCl₂·2H₂O in freshly boiled distilled water creates a standard hard water stock. This allows the user to evaluate the foaming propensity of a metalworking coolant formulation under controlled conditions of high water hardness, which can significantly impact foam behavior.