ARCO adapter Combi 3/8"F x 3/4"M COMBI89 — plumbing threaded connector

ARCO adapter Combi 3/8"F x 3/4"M COMBI89 is a threaded plumbing connector that provides a secure mechanical transition between a 3/8-inch female thread and a 3/4-inch male thread. Manufactured by ARCO, this adapter is intended for use in household and light commercial plumbing systems where components with different thread sizes need to be joined without modifying existing piping or fittings. The compact design allows integration in confined spaces and supports common plumbing materials such as metal and reinforced hose connections.

Advantages

The adapter offers a simple and reliable method to connect mismatched threaded components, avoiding the need for cutting or rethreading pipes. Its threaded interface ensures repeatable mechanical engagement and easy disassembly for maintenance. The compact form factor minimizes additional bulk in piping runs and helps maintain a neat installation. Because it converts between two widely used thread sizes, it reduces the need to source specialty fittings during repair or installation work.

Suitable for

• Connecting a 3/8" threaded outlet or fitting to a 3/4" threaded hose or pipe
• Temporary or permanent plumbing repairs in kitchens, bathrooms, and utility rooms
• Light commercial installations where mixed thread sizes are present
• Workshop or maintenance settings for testing or assembling plumbing assemblies

Key specifications

• Thread connection: 3/8" female to 3/4" male
• Type: Threaded adapter / connector
• Application: Plumbing connections for pipes, hoses and fittings
• Typical use environment: Household and light commercial
• Form factor: Compact inline adapter

How to use

Ensure both mating threads are clean and free of debris or old sealant before installation. Apply an appropriate thread sealant or PTFE tape to the male thread if a watertight joint is required. Hand-start the adapter onto the female thread to avoid cross-threading, then tighten with an appropriate wrench until the connection is secure; avoid excessive torque that could damage threads. When connecting to a hose, make sure any hose ferrules or fittings are correctly aligned and tightened to manufacturer recommendations. After installation, inspect for leaks under normal operating pressure and retighten if necessary.

Usage recommendations

Use compatible sealants for the materials being joined and verify thread type and pitch before installation. For pressurized systems, test the connection at working pressure and check periodically for leaks. Replace the adapter if threads show wear or damage.