How to Match Water Fittings on a 20 Series Water-Cooled Torch

By MIG/TIG/Stick Welders & Plasma Cutters | USA Weld – HTP ... | Published: 2026-11-03

Category: How-to Guides

Match your 20 Series torch to your cooler by checking water fittings, gas connection, and power adapter—here's a step-by-step process to avoid leaks and downtime.

Quick answer

Match your 20 Series torch to your cooler by confirming three connections: water fittings (5/8"-18 LH or 9mm quick connect), gas delivery (quick connect or flow-thru), and power adapter (35 Dinse). Choose the torch variant that mirrors your cooler's existing ports.

Why water fitting mismatch causes leaks and downtime

A water-cooled torch relies on a sealed loop between the cooler and the torch head. If the threads or quick-connect style don't match, you'll either force a connection that leaks under pressure or need adapters that add failure points. The 20 Series torches use 5/8"-18 LH threaded water fittings, and some coolers use 9mm quick connects—these are not interchangeable without the correct torch variant.

Thread direction matters too: 5/8"-18 LH is left-hand thread, so turning it the wrong way can loosen the connection. Always hand-tighten first and check for drips before full flow.

Gas connection: quick connect vs flow-thru

The gas path is separate from water. Some 20 Series torches use a 9mm quick connect gas fitting, while others route gas through the power adapter (flow-thru). If your cooler or gas line already has a 9mm quick connect, a torch with a matching gas fitting simplifies setup. If your setup supplies gas through the Dinse connector, a flow-thru torch avoids an extra hose.

Mixing these up won't necessarily damage the torch, but it can leave you with an unused port or a gas leak at the back cap. Check your existing torch or cooler manual for which style you have.

Step-by-step fitting match

Identify your cooler's water ports: Look at the water-in and water-out ports on your cooler. If they are threaded, measure the thread or check the manual for 5/8"-18 LH. If they are push-to-connect, note the size (often 9mm). Common mistake: assuming all quick connects are the same size—9mm is not the same as 1/4" or 3/8".
Check your gas delivery method: Trace the gas line from your regulator. If it ends in a quick connect that plugs into the torch, you need a torch with a matching gas fitting. If gas goes into the power adapter, you need a flow-thru torch. Checkpoint: the gas fitting on the torch must match the gender and size of your gas line—don't force it.
Confirm the power adapter: The 20 Series torches here use a 35 Dinse (1/2" OD) adapter. Verify your welder's torch connection accepts 35 Dinse; if it uses a different size, you'll need an adapter or a different torch. Mistake: ordering a torch with the right water fittings but the wrong power adapter—check all three connections before buying.
Select the torch variant: If your cooler has threaded water ports and your gas line uses a 9mm quick connect, choose the torch with 9mm gas quick connect (product 1278898). If your cooler has threaded water ports and gas is flow-thru, choose product 1278901. If your cooler uses 9mm quick connects for water, you'll need a different variant—contact support for options.
Test for leaks before welding: Connect the torch, turn on the cooler, and run water for a minute. Check all fittings with a dry paper towel. Then check gas flow with the machine off—listen for hiss at the torch head. Always hand-tighten water fittings first; over-tightening can damage the threads.

Product facts to guide your match

20 Series (250A) Water-Cooled Torch w/35 Dinse Power Connection, 5/8"-18 LH Water Connections, & 9mm Quick Connect Gas Fitting: 20 Series (250A) water-cooled torch with 35 Dinse power connection, 5/8"-18 LH water fittings, and 9mm quick connect gas fitting. This variant suits coolers with threaded water ports and a gas line that ends in a 9mm quick connect.
20 Series (250A) Water-Cooled Torch w/35 Dinse Power Connection, 5/8"-18 LH Water Connections, & 9mm Quick Connect Gas Fitting
20 Series (250A) Water-Cooled Torch w/35 Dinse Power Connection with Flow Thru Gas & 5/8"-18 LH Water Fittings: 20 Series (250A) water-cooled torch with 35 Dinse power connection, flow-thru gas, and 5/8"-18 LH water fittings. Choose this if your gas is supplied through the power adapter and your cooler uses threaded water connections.
20 Series (250A) Water-Cooled Torch w/35 Dinse Power Connection with Flow Thru Gas & 5/8"-18 LH Water Fittings