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D1155-10 – Standard Test Method Technical Guide
📋 Overview and Scope
ASTM D1155-10 (Reapproved 2020) is a standard test method issued under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings. It specifically covers the determination of the percent of true spheres in glass spheres used for retroreflective marking purposes and industrial uses. The standard provides two procedures for splitting the selected specimen into size ranges prior to mechanical separation into true spheres and irregular particles.
Procedure A splits the specimen into two size ranges or groups, while Procedure B splits it into five size ranges. Procedure B is designated as the referee test method when disputes arise regarding compliance. The values stated in SI units are regarded as the standard, with values in parentheses provided for informational purposes only.
⚙️ Apparatus and Test Setup
The core apparatus consists of an electrical feeder-vibrator supporting a smooth glass panel. The panel must measure exactly 152.4 mm (6 in.) in width and 381 mm (15 in.) in length. A hinged base supports the vibrator, allowing the angle of slope of the glass panel relative to the horizontal to be varied and fixed in any predetermined position. This adjustability is critical for the mechanical separation process.
The vibrator operates at a fixed frequency of 60 impulses per second. It must also include a means of varying the amplitude or strength of the vibrations transmitted to the glass panel. The controlled vibration on the sloped glass plate is the fundamental mechanism by which true spheres are separated from irregular particles.
💡 Key Setup Consideration: The glass plate must be perfectly clean and free of any residue that might impede the rolling of spheres. The slope angle and vibration amplitude should be optimized so that true spheres roll freely toward the collection container while irregular particles and debris do not traverse the plate. Verification against a known standard is recommended prior to testing.
| 🛠️ Apparatus Component | 🔬 Specification / Requirement |
|---|---|
| Glass Panel | 152.4 mm (6 in.) wide × 381 mm (15 in.) long |
| Support Base | Hinged base for variable and fixable slope angle |
| Vibration Frequency | 60 impulses per second (fixed) |
| Vibration Amplitude | Adjustable to control impulse strength |
📊 Test Procedures and Key Metrics
The test method mechanically separates glass particles into true spheres and irregular particles through controlled vibration on the predetermined sloped plate. The primary metric reported is the weight percentage of true spheres relative to the total specimen. The roundness of glass spheres is a measurable aspect directly relating to their performance as a retroreflective media.
| 📏 Procedure | 📐 Number of Size Groups | 🎯 Intended Application |
|---|---|---|
| Procedure A | 2 size ranges or groups | General compliance determination |
| Procedure B | 5 size ranges or groups | Referee test for disputed results |
Either procedure may be used to determine compliance with specification requirements. However, if tests indicate a failure to meet the specified percent of true spheres and irregular particles, the referee test shall be made strictly in accordance with Procedure B. Referenced documents include ASTM E11 for the woven wire test sieve cloth and E177/E691 for precision and bias practices.
⚠️ Regulatory Consideration: This standard does not purport to address all safety concerns associated with its use. The user of this standard is responsible for establishing appropriate safety, health, and environmental practices and determining the applicability of regulatory limitations prior to use. The international standard was developed in accordance with WTO TBT principles.
❓ Frequently Asked Questions
🔍 What is the primary purpose of ASTM D1155-10?
The standard is designed to determine the percent of true spheres in glass spheres used for retroreflective marking purposes and industrial uses. This directly impacts the performance of the spheres as a reflective medium.
💡 When is Procedure B required over Procedure A?
Procedure B, which splits the specimen into five size ranges, is designated as the referee test method. It must be used when initial tests indicate a failure to meet the specified percent of true spheres or when a formal dispute regarding compliance arises.
⚡ What are the specific dimensional and operational requirements for the apparatus?
The glass panel must be 152.4 mm (6 in.) wide and 381 mm (15 in.) long. The vibrator must operate at a fixed frequency of 60 impulses per second and allow for adjustment of the vibration amplitude.
📌 How does the test method physically separate true spheres from irregular particles?
The separation is achieved by mechanically vibrating the particles on a clean, smooth glass plate fixed at a predetermined slope. True spheres roll freely down the incline, while irregular particles and broken spheres do not roll efficiently and are physically separated from the spherical fraction.