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SAE J562 Nonmetallic Loom: Standards, Testing, and Design Insights
SAE J562, originally issued in 1922 and cancelled in June 2005, specifies requirements for nonmetallic flexible loom used as an insulated covering for mechanical protection of wires, tubing, and other parts requiring water-, oil-, and acid-proof coverings resistant to fire or abrasion. Although superseded by SAE J2192, this standard remains a reference for legacy designs and offers foundational knowledge for engineers working with protective sleeving in automotive applications. 🛠️
Construction and Saturation Requirements
The loom must be of single-wall construction using strictly nonmetallic material with sufficient mechanical strength to pass all specified tests. The finished loom must be free from obstructions and allow easy introduction of the maximum size wire for which it is suited. A 12-inch polished mandrel of minimum inside diameter must slip freely through any length of loom.
For fire resistant loom, the asphaltic compound or equivalent must thoroughly impregnate the outside and lightly impregnate the inside. For oil proof loom, a gum saturator or equivalent is used, which when dry must be non-tacky. This impregnation prevents moisture, oil, or gasoline absorption and provides wall strength while preventing fraying.
Dimensional and Tensile Specifications
| Nominal Size (in) | Min Tensile Requirement (lb) |
|---|---|
| 3/16 | 75 |
| 1/4 | 85 |
| 5/16 and 3/8 | 100 |
| 7/16 or larger | 150 |
Full dimensional tables for inside and outside diameters are provided in the standard for nominal sizes from 5/32 to 1 inch.
Testing and Performance Criteria
The standard specifies several mandatory tests to ensure durability and environmental resistance:
- Water Immersion Test: A 6-inch piece of loom immersed in water at 70°F for 24 hours must not show a weight increase greater than 35% after gentle air drying.
- Bend Test: The wall must not collapse when bent to a radius of five times the inside diameter at 70°F, and the finish must not crack.
- Flattening Test: A 3-inch length flattened between steel plates to specified gaps must not crack or break.
- Oil and Flame Resistance: Additional tests ensure resistance to oils and flame. The flame test uses five 15-second applications of a standard blue flame with 15-second intervals; the loom must not convey fire or support combustion for more than one minute after the fifth application.
⚠️ Common Mistake: Inadequate saturation is a frequent error, leading to moisture absorption, fraying, and loss of wall strength. Another pitfall is applying heavy finishes or saturators to artificially enhance appearance, which is explicitly prohibited by the standard.
Engineering Design Insights
When designing or specifying nonmetallic loom, note these key insights from SAE J562:
- For fire resistant loom, the finish should consist of an asphaltic compound, optionally topped with a thin paraffin wax coating. For oil proof loom, at least two coats of black pyroxylin lacquer are required, with good luster and bond.
- Loom must allow easy insertion of maximum size wire and slip freely over a polished mandrel of minimum inside diameter.
- The pyroxylin must be plasticized to avoid cracking after aging; a bend test after three months at room temperature should not produce cracks.
- Heavy finishes or saturators that artificially enhance appearance are not permitted.
- Dimensions and tensile requirements vary by nominal size and must be verified against the standard’s tables.
Design Insight: Although SAE J562 is cancelled, its test methods and material guidance remain valuable for legacy products. For new designs, refer to SAE J2192 for current requirements.
Frequently Asked Questions
- What are the tensile strength requirements for nonmetallic loom per SAE J562?
For nominal size 3/16 in, minimum 75 lb; 1/4 in, 85 lb; 5/16 and 3/8 in, 100 lb; 7/16 in or larger, 150 lb. - How is the flame test performed and what determines pass/fail?
A 6-inch piece of loom has both ends sealed to prevent air passage. It is held vertically and a standard blue flame (from a 1/2 in Bunsen burner) is applied horizontally for 15 seconds, five times with 15-second intervals. The loom fails if it conveys fire or supports combustion for more than one minute after the last application. - Why was SAE J562 cancelled and what replaced it?
The standard was cancelled in June 2005 because it was rendered obsolete by SAE J2192, which provides updated requirements for automotive wiring protection. Engineers should use J2192 for new designs.
