What is the rule of thumb for TIG post-flow time?

The universal rule of thumb is 1 second of post-flow for every 10 Amps of welding current. For example, at 150 Amps, set post-flow to 15 seconds. This keeps the glowing red tungsten electrode shielded until it cools below oxidizing temperature.

Why does my tungsten electrode turn black immediately after stopping?

A black or discolored tungsten electrode indicates premature oxidation. Either your post-flow time was set too short, you pulled the torch away from the weld before post-flow finished, or there is a loose fitting sucking air into the torch hose.

How do I convert CFH to Liters Per Minute (L/min)?

Multiply CFH by 0.4719 to get L/min. Conversely, multiply L/min by 2.119 to get CFH. For example, 15 CFH equals approximately 7.1 L/min.

Free Welding Shielding Gas Flow & Cup Size Calculator

🔥 Process & Torch Setup

Welding Process & Hardware

Cup Size / Nozzle Diameter

Shielding Gas Mixture

Welding Current (Amps) Determines post-flow tungsten protection

Argon Cylinder Size

📊 Recommended Gas Flow & Purge Settings

Shielding Gas Flow 16 CFH 7.5 Liters/min (L/min)

Post-Flow Purge Time 12.0 sec 1 sec per 10 Amps rule

Continuous Arc Run Time: 5.0 Hours trigger time

Pre-Flow Time: 0.5 - 0.8 seconds

Maximum Recommended Tungsten Stickout: 1/2" (12.7 mm) with gas lens

✅ Optimal Gas Flow: Gas lens laminar stream delivers crisp shielding without atmospheric swirl.

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The Physics of Welding Shielding Gas Flow

Shielding gas displaces ambient air (specifically oxygen, nitrogen, and hydrogen) from molten weld pools. If molten metal contacts air, oxygen creates brittle porosity and iron oxides, while hydrogen causes delayed cracking.

Why More Gas Flow Is NOT Better (Turbulence Threshold)

A common beginner mistake is cranking flowmeters up to 30-40 CFH thinking "more gas equals better protection". In reality, excessive gas velocity exceeds the Reynolds number for laminar flow, creating a Venturi suction effect that violently aspirates atmospheric air directly into the molten pool, ruining the weld!

Gas Lens Mesh Screen vs Standard Collet Body

A standard collet body fires gas out in an uneven swirling cone, limiting electrode stickout to 1 or 2 cup diameters. A gas lens features multiple micro-stainless wire mesh screens that laminarize the gas stream into a smooth, parallel column, allowing up to 3 to 4 times longer tungsten stickout for tight-access joints.