Model DU
Straight tube-to-tube compression union in 316 stainless steel with a double-ferrule seal, for joining instrument and process tubing. Equal sizes from 1/8" to 3/4" tube OD, plus DUR reducing sizes joining two different tube diameters.
Prices on request. Contact us for availability and quotations.
The DK-Lok DU series is a straight tube-to-tube union used to join two lengths of instrument or process tubing without welding the tube or cutting a thread on it. Body, nut and ferrules are 316 stainless steel throughout, which suits it to corrosive service and to outdoor plant.
Sealing is by the double-ferrule principle. As the nut is drawn up, the front ferrule forms the seal against the fitting body while the back ferrule bites onto the tube and holds it, so the joint resists vibration and pressure cycling and can be broken and re-made with ordinary spanners.
Typical duties are instrumentation and control lines, hydraulic and pneumatic tubing, and process and utility service lines. Equal-ended unions are offered in 1/8", 3/16", 1/4", 5/16", 3/8", 1/2" and 3/4" tube OD; where a line changes size, the DUR reducing union joins two different tube diameters in one fitting.
When ordering, state the tube outside diameter required at each end and quote the order code from the specification table — DU-8-S for a 1/2" x 1/2" union, DUR-8-4-S for a 1/2" x 1/4" reducing union. Every code listed is the -S build in 316 stainless steel.
| Configuration | Straight tube-to-tube union, two tube ends |
|---|---|
| End Connections | Compression tube fitting, tube OD at both ends |
| Ferrule Design | Double ferrule (front and back ferrules) |
| Body Material | 316 stainless steel |
| Nut and Ferrule Material | 316 stainless steel |
| Equal Tube Sizes Available (Order Code / SKU) | 1/8" x 1/8" — DU-2-S (DK-VA86860202); 3/16" x 3/16" — DU-3-S (DK-VA86860303); 1/4" x 1/4" — DU-4-S (DK-VA86860404); 5/16" x 5/16" — DU-5-S (DK-VA86860505); 3/8" x 3/8" — DU-6-S (DK-VA86860606); 1/2" x 1/2" — DU-8-S (DK-VA86860808); 3/4" x 3/4" — DU-12-S (DK-VA86861212) |
| Reducing Tube Sizes Available (Order Code / SKU) | 1/4" x 1/8" — DUR-4-2-S (DK-VA86860204); 3/8" x 1/4" — DUR-6-4-S (DK-VA86860406); 1/2" x 3/8" — DUR-8-6-S (DK-VA86860608); 1/2" x 1/4" — DUR-8-4-S (DK-VA86860408) |
| Series Designation | DU (union) and DUR (reducing union); every order code listed carries the -S suffix for 316 stainless steel |
