1/4 in. x 1/8 in. Push-In x Male NPT DOT Adapter
1/4 in. x 1/8 in. Push-In x Male NPT DOT Adapter
Sizes in This Series
Brass DOT push-in to male NPT straight adapters. Jump to another size or add it straight to your cart:
| Size | Part # | Price | Cart |
| 5/32 in. x 1/8 in. | 685322 | $7.99 | Add to cart |
| 1/4 in. x 1/8 in. (this page) | 680402 | $4.51 | — |
Overview
The Midland 680402 is a forged brass D.O.T. adapter that joins 1/4 in. push-in air brake tubing to a 1/8 in. male NPT port. It seats the tube in one push and locks it against vibration and pressure cycling, making it a fast field connection for commercial-vehicle air systems. Built to FMVSS 571.106 and SAE J1131.
Technical Specifications
| Manufacturer Part # | 680402 |
| Tube Size (Push-In) | 1/4 in. |
| Thread Size | 1/8 in. Male NPT (1/8 - 27) |
| Connection Type | Push-to-Connect x Male NPT |
| Pressure Rating | 150 psi |
| Temperature Rating | -40°F to 200°F |
| DOT / SAE | FMVSS 571.106, SAE J1131 |
Materials of Construction
| Body | Brass |
| Collet / Grip Ring | Stainless steel gripper with O-ring seal |
Typical Applications
Connects 1/4 in. DOT air brake tubing to threaded ports on valves, gladhands, and reservoirs across truck, trailer, and bus air brake systems. Also serves pneumatic control and instrumentation air lines where a tool-free, DOT-rated connection is needed.
Cross-Reference and Interchange
This DOT push-in adapter cross-references to these competitor and industry part numbers: 1568-4-2, 268PC-4x2, 268PPDOT-4A, 68PMT-4-2, APTC68-4A, AQ68-DOT-4X2, D7068DT-4A, DOT68-4-2, PC1468-4A, PL-1368-4A, PP68C-DOT, S68PMT-4-2. Replacing one of these? Match nominal size, connections, and rating, or send us your part number and we will confirm the interchange.
Sizing and Installation Resources
- Push-to-Connect Fittings Selection Guide
- NPT Thread Tightening: Turns Past Hand-Tight
- Pipe Size Reference Chart
- Teflon Tape vs. Pipe Dope
Frequently Asked Questions
Is this fitting DOT approved for air brakes?
Yes. It meets FMVSS 571.106 and SAE J1131 for commercial-vehicle air brake systems.
What tubing does it accept?
1/4 in. OD DOT-rated nylon air brake tubing. Cut the tube square and push it fully in until it bottoms.
Does it need thread sealant?
A thin band of PTFE tape or pipe dope on the male NPT threads is recommended for a leak-free joint.
Can the connection be reused?
Yes. Push the collet in and pull the tube out to release, then reconnect.
WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.