Adapter G1/4 male to 7/16 UNF female with PTFE seal

UNDERSEA Centre Ltd has manufactured precision high-pressure diving gas fittings and adaptors in Southampton, UK, since 1970. Reference 1268, from the Gauge Adaptors product line, connects a G1/4 BSP male flat-face port — parallel thread per ISO 228-1 / BS 2779, 19 TPI, 13.16 mm bore — to a 7/16"-20 UNF female connection. Each unit ships with a PTFE washer for immediate flat-face sealing without thread tape or sealant compound. The body is machined from brass and chrome-plated throughout for corrosion resistance in marine and humid compressor room environments.

Technical specifications

• Manufacturer reference: 1268
• Male inlet thread: G1/4 BSP (ISO 228-1 / BS 2779, parallel, 19 TPI, Ø 13.16 mm)
• Female outlet thread: 7/16"-20 UNF (Unified National Fine, 20 threads per inch)
• Seal: PTFE washer supplied for flat-face connection — no thread tape required
• Material: machined brass, chrome-plated finish
• Weight: 200 g · Dimensions: 5 × 5 × 5 cm
• Lead time: assembled to order, typically 2-3 working days (UK)
• Country of manufacture: United Kingdom (Southampton)
• Standards: British Standards / DIN Standards
• Working pressure: 232-300 bar (HP diving components — UNDERSEA high-pressure range)

Choosing the right reference: the 1268 is a male flat-face to 7/16 UNF female adaptor — distinct from the 1265 (male flat to male 60° cone) and the 1267 (female to 7/16 UNF male) — verify the flow direction of your gas circuit before ordering.

Fluid compatibility

Suitable for compressed air, Nitrox, and inert gas mixtures (Trimix, Heliox). For oxygen or oxygen-enriched applications, verify that the fitting has been cleaned to O2-clean standard prior to installation in accordance with UNDERSEA guidelines; dedicated oxygen-service variants are available for other references in their range.

Applications

The 1268 is used in high-pressure gas distribution and transfer systems at dive centres and private fill stations: connecting G1/4 BSP male gauge ports or panel fittings to 7/16 UNF female hose ends, manifold valves, or first-stage regulator HP ports of North American origin; building Nitrox and Trimix blending panels; cylinder-to-cylinder decanting rigs where the outlet terminates in 7/16 UNF. The 7/16 UNF thread is also common on Bauer compressor accessories and various North American diving equipment items.

Key features

• Chrome-plated brass construction: proven corrosion resistance in salt-air and humid compressor environments — outperforms zinc-plated steel over extended service life
• PTFE washer included: ready for immediate installation, no additional consumables required for a gas-tight flat-face connection
• Assembled to order by UNDERSEA: precision-machined to British and DIN standards, ensuring consistent dimensional quality on every delivery since 1970
• Broad gas media compatibility: suitable for compressed air, Nitrox, and inert gas mixtures in technical diving gas systems
• Precise G1/4 to 7/16 UNF interface: engineered thread profiles eliminate improvised connections and maintain HP system integrity in your gas installation

Standards and warranty

All UNDERSEA fittings are designed to British Standards and DIN Standards for high-pressure diving gas equipment. UNDERSEA Centre Ltd has produced chrome-plated brass adaptors at their Southampton, UK facility for over 50 years.