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D3899-93 – Standard Test Method Technical Guide
📖 Scope, Classification, and Referenced Documents
ASTM D3899 – 93e2 establishes the standard specification for contraceptive vaginal diaphragms. As delineated in Section 1.2, this specification explicitly excludes cervical caps, vaginal sponges, and female condoms. The standard classifies diaphragms into three distinct types based on their rim reinforcement architecture, as defined in Section 3. Referenced documents include ASTM D412, D573, D3040, D3767, and the U.S. Code of Federal Regulations Title 21 Section 177.2600.
| 🟦 Type | 🔍 Designation | ⚙️ Construction Details |
|---|---|---|
| Type 1 | Coil Spring Diaphragm | Helically wound spring reinforcement |
| Type 2 | Flat Spring Diaphragm | Flat leaf (watch spring / Mensinga) construction |
| Type 3 | Arching / Bow-Bend Diaphragm | Spring designed to form an arc when compressed |
🏗️ Materials, Construction, and Manufacture
Section 4 mandates that diaphragms be fabricated from an elastic polymer. The integral peripheral rim must be reinforced with metal or a suitable material. A critical safety requirement (Section 4.2.3) dictates that this reinforcing spring must be completely encapsulated and centrally located within the rim, with its ends joined so they cannot project through the surface (Section 4.2.4). The dome and the rubber portion of the rim must constitute one continuous film (Section 4.2.1). All materials—including dressing, compounding, and reinforcing components—must adhere to the safety standards defined in 21 CFR 177.2600 and must not harm the user under normal conditions of use.
⚠️ Critical Construction Note: The requirement in Section 4.2.2 states that the spring must be “sufficiently rigid to hold the rim in a flat, circular position.” This flat-state characteristic is distinct from the functional arching of Type 3 diaphragms and is a key factor in the rim deviation test (Section 5.1.1).
⚙️ Physical and Mechanical Property Requirements
The mechanical integrity of the diaphragm is verified through specific compression and tensile tests. Section 5 defines the physical requirements for compliance. The table below outlines the key performance metrics extracted from the specification.
| 📏 Parameter | 🎯 Specification Criteria | 📐 Test Method Reference |
|---|---|---|
| Rim Deviation from Plane | ≤ 20° deviation (Type 2 only, per Note 1) | Annex A1—Diametric Compression |
| Diametric Spring Compression | 55% to 78% of original diameter under 280 g suspended mass | Annex A2 (Not applicable to Type 3) |
| Tensile Strength & Elongation | Conformance to D412 requirements for dome rubber | ASTM D412, D573 (Air Oven Aging) |
| Material Safety Compliance | No deleterious effects on rubber or harm to user | 21 CFR 177.2600 |
🔬 Test Applicability Alert: When evaluating rim performance, it is crucial to distinguish between the two compression tests. The 20° deviation test (Annex A1) applies specifically to flat spring diaphragms (Type 2). Conversely, the 280 g compression test (Annex A2) is not applicable to Type 3 arching diaphragms. Using the incorrect protocol may invalidate results.
❓ Frequently Asked Questions
🔍 Are cervical caps and female condoms regulated under this standard?
No. Section 1.2 explicitly excludes cervical caps, vaginal sponges, and female condoms from this specification. D3899–93e2 is strictly intended for vaginal diaphragms.
💡 Why is the diaphragm spring required to be completely encapsulated?
According to Section 4.2.3, the spring must be centrally located and encapsulated entirely within the rim to prevent it from being exposed under normal conditions of use. This design requirement, detailed in Section 4.2.4, prevents the spring ends from projecting through the surface of the rim, ensuring user safety and device integrity.
⚡ What are the specific limits for the rim compression test?
When a diaphragm is compressed across its diameter by a suspended mass of 280 g, as described in Annex A2, the resulting diameter must be between 55% and 78% of the original uncompressed diameter. Note that this test is not applicable to Type 3 arching diaphragms.
📌 Which ASTM and CFR standards are explicitly referenced in D3899?
The standard references ASTM D412 (Tension), D573 (Oven Deterioration), D3040 (Precision Statements), D3767 (Measurement of Dimensions), and the Code of Federal Regulations Title 21, Section 177.2600 (Rubber Articles Intended for Repeated Use) for material compliance.