Match the fitting size to your tube's outer diameter (OD). For example, a 6mm fitting is for 6mm OD copper tube, and 9.52mm (3/8") fits standard 3/8-inch OD tubing commonly used in refrigeration and HVAC lines. Measure your tube OD with calipers before ordering — do not rely on nominal pipe size labels alone.

Brass compression fittings are generally rated for working pressures up to 200 PSI for water applications, though the exact rating depends on tube wall thickness and the specific system. They are typically suitable for residential plumbing, HVAC, and refrigeration lines operating at normal system pressures. Always verify the pressure rating against your system requirements.

Yes. Brass offers good corrosion resistance and is generally suitable for outdoor and humid environments. For highly corrosive or marine environments, additional protection or stainless steel alternatives may be worth considering. In most standard outdoor plumbing and HVAC installations, brass compression fittings perform reliably.

The 6mm, 8mm, and 10mm sizes follow metric OD standards common in European and Asian plumbing systems. The 9.52mm size corresponds to the 3/8-inch imperial OD standard widely used in North American HVAC and refrigeration. Always verify your tube's OD before purchasing to ensure a proper compression seal.

No soldering or special tools are required. A standard adjustable wrench or open-end wrench is typically all you need. Insert the tube, slide on the nut and ferrule, and tighten — the ferrule compresses onto the tube to create a leak-free seal. In most cases, hand-tightening plus 1–1.5 turns with a wrench is sufficient.

A 4-way cross fitting connects four copper tubes meeting at a single junction point, allowing flow to split or merge in four directions simultaneously. It is commonly used in manifold systems, irrigation distribution lines, HVAC branch circuits, radiant floor heating loops, and custom copper tube fabrication projects where a single junction must serve multiple runs.

We offer 1-piece, 3-piece, and 5-piece options. For a single repair or prototype, 1 Pcs is sufficient. For multi-zone systems or to keep spares on hand, the 3 Pcs or 5 Pcs bundles offer better value per fitting. Select your preferred quantity in the variant selector above.

In many cases, compression fittings can be disassembled and reassembled during the same installation session. However, once a ferrule has been fully compressed onto a tube, it is generally recommended to replace the ferrule before reusing the fitting on a different tube section to ensure a reliable seal. Reusing on the exact same tube cut is typically acceptable.