1/4 in OD Push-In Tube Union for Lubrication Tubing

What a Push-In Tube Union Does

This fitting is a straight splicer that joins two sections of 1/4 in OD nylon lubrication tubing. It works without threads, ferrules, or compression nuts, so installation is tool-free and fast. Use it to repair a damaged line, extend an existing run, or create a clean connection point in a centralized lubrication system. It can be placed anywhere along a tube run where two tube ends need to meet.

Because it relies on an internal collet and seal, the union holds tubing securely while allowing repeated disconnects. It is a serviceable part for maintenance crews who need to rework or adjust lines in the field. This fitting is not manufactured, sponsored, or endorsed by any original equipment maker. Quicklinc is a trademark of its respective owner.

Positioning matters with this union. Install it where you can reach the release collar and where the tubing path remains straight on both ends. The body is compact enough for tight enclosures, but the insertion depth on each side is about 5/8 in (16 mm), so allow room for full tube entry.

Specifications

How the Collet and Seal Work

Insertion is simple: push the tube end squarely into the port until it reaches full depth. Inside the fitting, a collet gripping ring slides over the tube OD. When you pull back lightly on the tube, the collet teeth bite into the tube surface and hold it in place.

The NBR seal sits around the tube OD. As the tube enters, the seal compresses against the tube and the fitting body, creating a tight joint. This compression keeps lubricant inside the line under normal operating pressure. The collet and seal work together: the collet holds position, the seal handles the fluid boundary.

To disconnect, press the release collar toward the fitting body. This pushes the collet teeth away from the tube, letting the tube slide out. You can reuse the fitting after disconnecting, as long as the tube end is clean and not heavily scored. Do not pull the tube out without pressing the release collar; forced removal can damage the collet or seal.

Repair or Replace a Tubing Run

Start with a clean, square, burr-free cut. Use a tube cutter made for nylon or polyurethane lubrication tubing. A diagonal cut or a ragged edge can prevent full insertion or nick the NBR seal. After cutting, wipe the tube end clean and inspect for scratches or flattening.

Push the tube into the union until it stops, then push a little more to confirm it is bottomed out. Pull back with a firm tug to test seating. The collet should grip and the tube should not slide out. If it moves, push it in again and re-test.

To splice a damaged section, cut out the bad area and use two unions to install a fresh piece of matching 1/4 in OD tubing. Measure carefully so the replacement section does not stretch or bow. In cases where the entire run is aged, brittle, abraded, or has multiple kinks, replacing the whole line is the better choice. One new continuous run avoids multiple joints and keeps the system simple.

Tubing and System Limits

This union works with nylon PA12, polyurethane, and other semi-rigid lubrication tubing. Typical wall thickness should be 0.040-0.065 in. Tubing outside that wall range may not seat or grip properly, even if the OD is correct. Always check the tube condition before reuse.

Do not confuse 6 mm OD tubing with 1/4 in OD tubing. 6 mm is about 0.236 in, while 1/4 in is 0.250 in. These sizes do not interchange. A 6 mm tube in a 1/4 in push-in union can slip or leak. A 1/4 in tube forced into a 6 mm port can damage the fitting.

This union is suitable for oil and grease systems where the lubricant works with NBR seals. For high-pressure circuits above 250 psi, do not use this push-in fitting. Use a threaded compression fitting instead. See threaded compression sleeves for high-pressure hose for a better option in those circuits. For general guidance on push-in versus compression styles, read this comparison of compression and push-in fittings. For help matching line material to your lubricant and pressure, review this tubing selection guide.

Where It Is Used

This push-in union appears in single-line, dual-line, and progressive centralized lubrication systems. Maintenance technicians use it on industrial machines such as presses, conveyors, packaging lines, and CNC equipment. It also fits mobile equipment lubrication systems where 1/4 in OD nylon or polyurethane lines run from pumps to bearings or metering devices.

The union works well in moderate-pressure oil and grease distribution blocks where tube routing must change over time. Because it disconnects without tools, it helps simplify seasonal maintenance or reassembly. Keep it away from high heat sources above 80°C and from circuits that exceed 250 psi.

Quicklinc-style push-in connectors are common in many centralized lubrication installations. This fitting uses the same push-in connection style and can serve as a compatible splice point in those line layouts. For other push-in connection options, see quick-connect lubrication fittings. For broader fitting selection help, check this guide to fitting types.

Frequently Asked Questions

What is this fitting?

This is a straight push-in union that joins two pieces of 1/4 in OD lubrication tubing. It has no threads, ferrules, or compression nuts.

What tubing fits this union?

Use 1/4 in OD nylon PA12, polyurethane, or similar semi-rigid lubrication tubing. 6 mm OD tubing does not fit because it is smaller.

What is the maximum pressure?

The maximum operating pressure is 250 psi (17 bar). For higher-pressure circuits, use a threaded compression fitting with a sleeve instead.

Do I need any tools for installation?

You only need a tube cutter that makes a square, burr-free cut. No wrenches or assembly tools are required.

Can I disconnect and reuse this fitting?

Yes, press the release collar and pull the tube out. The fitting is reusable for multiple connect and disconnect cycles.

What temperature range is allowed?

Operating temperature range is -20°C to +80°C. Keep the fitting away from heat sources outside that range.

Is this compatible with oil and grease systems?

Yes, it works with oil and grease systems when the lubricant is compatible with NBR seals. NBR is the seal material in this union.

How do I know the tube is fully seated?

Push the tube in until it stops, then pull back firmly. If the collet holds the tube, it is seated.

What are common causes of leaks?

Leaks usually come from a slanted cut, a burr, or incomplete insertion. Never pull the tube out without pressing the release collar.

How do I order or get a quotation?

IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, builds and supports every unit. Email inquiry@isohitech.com for specifications and a quotation.

For pricing or application questions, visit our contact page or request a quotation here.