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D3890-18 – Standard Test Method Technical Guide
🔍 Scope and Significance of ASTM D3890-18
This standard practice, designated D3890-18, establishes a uniform procedure for determining the number of actuations required to prime a mechanical pump dispenser. It covers both spray and flow types intended for consumer products. The primary goal is to provide a reliable method for visually comparing the priming characteristics of different pump dispensers and product formulations. This practice is suitable for establishing specifications for both the pump dispenser and the final package. It is noted that the standard does not address all safety concerns, placing the responsibility on the user to establish appropriate safety and environmental practices prior to use.
📦 Sampling, Conditioning, and Test Specimens
Proper preparation is critical to obtaining reproducible priming results. Specimens must be selected at random to ensure statistical validity. The standard outlines specific requirements for sample size, temperature conditioning, container selection, and pump age.
| 🟦 Parameter | 📏 Specification |
|---|---|
| Recommended Sample Size | 10 dry, unused pump dispensers |
| Minimum Acceptable Sample Size | 3 pump dispensers |
| Conditioning Temperature | 23 ± 3°C (73 ± 5.4°F) |
| Conditioning Duration | Not less than 4 hours |
| Pump Age at Test | No sooner than 24 hours after assembly |
| Recommended Container | Actual bottle of the final package |
Any deviations from the temperature or aging requirements must be documented in the final test report discussed in Section 8.1. The use of the actual final package bottle is specifically emphasized because the dip tube length directly influences the number of strokes required to achieve prime.
⚙️ Test Procedure and Actuation Parameters
The core of the practice lies in the precise execution of the priming procedure to minimize operator-induced variability. The standard provides clear parameters for the preparation and execution of the test.
| 📐 Parameter | 🎯 Specification |
|---|---|
| Container Fill Level | Actual level of final package target weight |
| Pump Attachment State | Pump must be in off, locked, or closed position |
| Pre-Actuation Setup | Remove overcap or release locking feature |
| Actuation Motion | Smooth, firm, even pressure to the full extent |
| Pump Return | Allow pump mechanism to fully return between strokes |
| Suggested Actuation Rate | 90 ± 15 strokes per minute |
| Variable Output Adjustment | If applicable, set desired dosage and report in Section 8.1 |
⚠️ Important Reporting Notes: If the actuator is placed onto the pump after the pump is secured to the container, this additional stroke must be reported in the final results (Section 8.1). Similarly, if an actuation is required to open or unlock the pump, this additional actuation must be included in the test report. These adjustments ensure an accurate accounting of the total priming sequence.
💡 Consideration for Viscous Products: The standard notes that depending on the venting system, mechanical pump dispensers can exhibit variation in strokes-to-prime based on the priming vent’s opening time. A rate of 90 ± 15 strokes per minute is suggested. For some viscous products, this rate may be too fast for the pump to function correctly. Any deviation from the recommended rate must be documented in the test report.
❓ Frequently Asked Questions
🔍 What is the primary purpose of ASTM D3890-18?
The standard provides a practice for determining the number of actuations (strokes) required to prime a mechanical pump dispenser. It is used to visually compare priming characteristics of different dispensers and products and helps establish performance specifications for both the dispenser and the final package.
💡 What is the recommended sample size for testing?
The standard recommends a sample size of ten (10) dry, unused pump dispensers selected at random. A minimum of three (3) specimens is acceptable if a larger sample is not available, though this will impact the precision of the results.
⚡ What are the key conditioning requirements for the test specimens?
Specimens must be conditioned at 23 ± 3°C (73 ± 5.4°F) for not less than 4 hours. Pumps should also be tested no sooner than 24 hours after assembly. Any deviations from these conditioning requirements must be noted in the final test report.
📌 How should the actuation rate be adjusted for different product viscosities?
The standard suggests a standard rate of 90 ± 15 strokes per minute. However, for highly viscous products, this rate might be too fast for the pump to fully return or properly vent. If the rate is adjusted, the specific rate used must be documented in the test report.