Push-in lubrication fitting overview
A push-in lubrication fitting is a quick-connect fitting for oil and grease lines: push the tube in to lock, press the release ring to pull it out. No wrench, no olive, no sealant on the tube side. It suits builders and maintenance teams who re-route lines often.
The body is nickel-plated brass with an NBR seal, rated to 80 bar maximum; an optional variant goes to 150 bar on request. Seven threads and tube sizes from 3 mm to 12 mm cover common ports and lines.
How the connection works
Two internal elements divide the work. The NBR O-ring seals radially around the tube; a grab ring grips it axially so line pressure cannot walk it back out. If a joint weeps, inspect the O-ring; if the tube slips, inspect the grab ring and tube end.
Types, tube sizes, and tube materials
Four body shapes cover most routing: straight, 90° elbow, tee, and male stud. The 90° elbow comes in fixed and swivel forms: fixed points the tube one way, swivel lets it swing to clear adjacent parts.
Tube sizes are 3 mm, 4 mm, 6 mm, 8 mm, and 12 mm, in PA66, PA12, nylon, or polyurethane. In the 4 – 6 mm range the outside diameter must hold within 0.05 mm or the O-ring and grab ring cannot seat. The 4 mm size pairs with the 4 mm nylon pipe on small lubrication lines.
Specification
| Body material | nickel-plated brass |
| Seal | NBR |
| Maximum pressure | 80 bar (optional variant up to 150 bar on request) |
| Temperature | -20°C to +70°C |
| Threads | M3x0.5, M6x1, M8x1, M10x1, 1/8 BSP, 1/4 BSP, 1/4 UNF |
| Tube sizes | 3 mm, 4 mm, 6 mm, 8 mm, 12 mm |
| Tube materials | PA66, PA12, nylon, polyurethane |
| Tube OD tolerance | within 0.05 mm (4 – 6 mm tube range) |
| Types | straight, 90° elbow (fixed / swivel), tee, male stud |
Where it is used
Common placements include machine tools, conveyors, bearing housings, agricultural machinery, construction machinery chassis, and factory automation. It feeds oil or grease from a divider or pump outlet to the point; the joint reopens for inspection without cutting.
Honest limitations
- Pressure ceiling: 80 bar. A manual lever grease gun can deliver far more at the outlet, so do not use push-in fittings on high-pressure gun points; where line pressure may spike, compare working and surge pressure first.
- Tube fit: outside diameter must hold within 0.05 mm in the 4 – 6 mm range, and tube material is limited to PA66, PA12, nylon, and polyurethane; other plastic tube is not a free substitute.
- Temperature: -20°C to +70°C. Outside this window, confirm suitability when ordering.
How to choose
Match the thread to the port, the tube size to the line, then check pressure and temperature headroom. If unclear, ask for a quote with your tube and thread details.
Frequently Asked Questions
Push-in fitting or compression fitting, which should I choose?
Pick push-in for frequent re-routing or fast assembly: no tools, and the tube can be removed and refitted after inspection. Pick compression for lines with pressure shock, strong vibration, or sustained high pressure; the olive grips harder but is single-use. For block, tube, and fittings as one kit, see the remote grease line with reusable fittings.
How does a push-in fitting seal and hold the tube?
An NBR O-ring seals radially around the tube and a grab ring grips it axially against line pressure. The seal keeps oil or grease in; the grip keeps the tube from backing out.
How do I disconnect the tube?
Press the release ring evenly and pull the tube straight out; hold the body so the line does not twist.
What should I check before refitting a tube?
The fitting is reusable after inspection. Check the tube end for bite marks, scores, or ovality; a cut or swollen O-ring must be replaced before refitting. A damaged tube end should be cut square again.
How should the tube be cut before insertion?
Cut the tube at 90° square, deburr inside and outside, then push it in to full depth. A ragged or angled cut stops the O-ring from seating.
Can I swap in a different tube material?
Only if hardness, outside diameter, and wall match the gripping geometry. PA66, PA12, nylon, and polyurethane are the four supported options; other plastic tube can slip or weep at the seal, so it is not a free substitute.
Is 80 bar enough for my system?
Compare it against working pressure and any surge pressure, not just the pump rating. The standard ceiling is 80 bar; an optional variant goes up to 150 bar on request. If a manual lever gun feeds the point, this fitting is the wrong place for it.
How do I pick among the seven threads?
Match the port on your equipment: metric M3x0.5, M6x1, M8x1, M10x1; pipe 1/8 BSP and 1/4 BSP; UNF 1/4 UNF. If the port type is uncertain, gauge the thread before ordering.
Fixed or swivel 90° elbow?
Pick the fixed elbow when the routing direction is known and space beside the port is free; pick the swivel elbow when the tube needs lateral swing to clear adjacent parts or settle without twisting.
Who manufactures this push-in fitting?
IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, supplies these push-in fittings for oil and grease lines. Send your tube size, thread, and pressure details through our quote form or write to inquiry@isohitech.com.
