How to Install Anti-Spark Tubing with One-Touch Fittings: Insertion Depth and Stripping Length
Installation Principle for Anti-Spark Tubing and One-Touch Fittings
Anti-Spark Tubing consists of a PU inner tube and an outer flame-retardant layer. The outer material meets the UL 94 V-0 flammability classification and provides additional surface protection when the tubing is occasionally exposed to sparks or weld spatter.
The one-touch fitting grips and seals against the PU inner tube, while the outer flame-retardant layer is intended primarily for surface protection. Therefore, the outer layer at the tube end must be stripped before the PU inner tube is inserted into the fitting.
Confirming the Fitting Series Before Installing Anti-Spark Tubing
After confirming the tubing size, also confirm whether a standard or compact one-touch fitting will be used.
For more information on the classification and selection of one-touch fittings, refer to “One-Touch Fittings Overview | Classification and Selection Criteria.”
Insertion Depth and Stripping Length for Anti-Spark Tubing with One-Touch Fittings
Insertion depth D varies depending on the Anti-Spark Tubing size and fitting series. Before stripping the outer layer, confirm the corresponding D value in the table below.
D: Insertion depth of the PU inner tube into the one-touch fitting.
L: Stripping length, meaning the exposed length of the PU inner tube after the outer layer is removed.
Recommended stripping length: L = D + 1.5 mm
Allowable range: D + 1.5 mm ≤ L ≤ D + 3.0 mm
| Anti-Spark Tubing PU Inner Tube O.D. | One-Touch Fitting Series | Insertion Depth D | Recommended Stripping Length L | Allowable Stripping Length Range |
|---|---|---|---|---|
| 6 mm | Compact | 12.5 mm (0.49 in) | 14.0 mm | 14.0–15.5 mm |
| 6 mm | Standard | 16.0 mm (0.63 in) | 17.5 mm | 17.5–19.0 mm |
| 8 mm | Standard | 18.0 mm (0.71 in) | 19.5 mm | 19.5–21.0 mm |
| 10 mm | Standard | 20.0 mm (0.79 in) | 21.5 mm | 21.5–23.0 mm |
| 12 mm | Standard | 23.0 mm (0.91 in) | 24.5 mm | 24.5–26.0 mm |
| 1/4 Inch | Standard | 16.0 mm (0.63 in) | 17.5 mm | 17.5–19.0 mm |
| 5/16 Inch | Standard | 18.0 mm (0.71 in) | 19.5 mm | 19.5–21.0 mm |
| 3/8 Inch | Standard | 20.0 mm (0.79 in) | 21.5 mm | 21.5–23.0 mm |
| 1/2 Inch | Standard | 23.0 mm (0.91 in) | 24.5 mm | 24.5–26.0 mm |
Insufficient Stripping Length
If the stripping length is below the allowable range, the outer flame-retardant layer may interfere with tube-end installation and prevent the PU inner tube from reaching the corresponding insertion depth D. This may affect proper gripping and sealing of the fitting.
Excessive Stripping Length
If the stripping length exceeds the allowable range, more of the PU inner tube remains exposed. This reduces the surface protection provided by the outer flame-retardant layer and increases the risk of sparks or weld spatter coming into direct contact with the PU inner tube.
Installation Steps for Anti-Spark Tubing and One-Touch Fittings
1. Select the appropriate one-touch fitting based on the PU inner tube O.D., and confirm whether a standard or compact series will be used.
2. Cut the tubing squarely to obtain a flat, even tube end.
3. Confirm D from the insertion depth table, then calculate stripping length L and remove the outer layer.
4. Insert the PU inner tube into the one-touch fitting to insertion depth D.
5. After installation, confirm that the tubing is securely retained and perform the necessary leak test.
FAQ
Can Anti-Spark Tubing be inserted directly into a one-touch fitting without stripping the outer layer?
No. The outer layer must first be stripped to the corresponding length before the PU inner tube is inserted into the fitting.
Does stripping the outer layer leave adhesive residue?
No adhesive is used between the inner and outer layers of SHPI Anti-Spark Tubing, so stripping the outer layer does not leave adhesive residue. Care should still be taken not to scratch the PU inner tube during stripping, and the tube surface should be clean and undamaged before insertion.