Attaching Schrader Valves: The Permanent Access Solution

SAFETY MESSAGE: Brazing Schrader valves involves using high-heat torches near flammable refrigerants (like R600a) and oil. Ensure the system is completely empty and "purged" with nitrogen or air before applying heat. Always remove the internal valve core before brazing to prevent the rubber seals from melting.

If you want to move beyond temporary "piercing" valves, brazing a permanent Schrader valve (access fitting) to the suction line is the professional way to go. This allows for clean, leak-free pressure testing and charging for years to come.

Two Ways to Connect:

1. The "Bullet" Piercing Valve (Temporary): Clamps onto the pipe and pierces it with a needle. Good for a quick diagnosis, but prone to leaking over time.

2. The Brazed Schrader Fitting (Permanent): A 1/4" copper tube with a threaded valve head that is soldered directly into the compressor’s "process" or suction line.

Key Diagnostic Tips:

• Remove the Core: The most common mistake is leaving the Schrader core (the little pin inside) in while brazing. The heat will melt the tiny rubber gasket, causing an instant, invisible leak the moment you try to charge the system.

• The "Process Tube" Advantage: Most compressors have a short, pinched-off copper tail called the "process tube." This is the best place to attach your valve—it’s designed specifically for factory charging.

• Surface Prep: Refrigeration pipes are often greasy or painted. Use an emery cloth or sandpaper to clean the copper until it shines like a new penny. Solder will not stick to dirty pipe.

Step-by-Step Installation:

1. Preparation: Use a tubing cutter to remove the pinched end of the process tube. Ensure no copper shavings fall into the compressor.

2. Cleaning: Sand the last inch of the compressor tube and the base of your Schrader fitting.

3. The Internal Core: Use a valve core tool to unscrew and remove the rubber-sealed core.

4. Brazing: Use an oxy-acetylene or MAPP gas torch. Apply heat to the thickest part of the joint first. Once the copper turns cherry red, touch the silver solder (brazing rod) to the joint. It should flow instantly into the gap via capillary action.

5. Cooling & Reassembly: Let the joint cool naturally (don't quench with water). Once cool, thread the core back in and tighten with your tool.

Removable line tap type Schrader valve , look for the best place to fit one on the pipe work most of these valve fit to 6mm to 8mm copper pipe. I would recommend you measure this first as if it does not fit your in a bit of a mess.

Ensure the collar is an exact tight fit to the pipe work , bent or misshaped piping can cause leakage.

Assemble the valve around the collars on the pipework and tighten the two clamping screws / bolts 

Wind down with equal turns on each side to prevent damage to pipe and an equal seal all round do not over tighten as to damage or misshape the pipework.  

Once in place tight enough for its purpose and your happy everything looks good you can now pierce the pipe , to do this you screw the cap on with the plunger fitted this then pushes the pipe piercing tool into pipe

Sometimes it may not be possible to fit the line tap version and you need to fit a fixed Schrader valve to the charging port on the compressor.

lokring Schrader 

Before cutting the pipe prepare the surfaces as it is easier emery cloth the out side and make it clean, paint free and smooth.

Measure the pipe before cutting and ensure you have the correct sized lokring. 

When you have cut the pipe work prepare the surfaces more for the joint. Apply some prep fluid to clean the surfaces. Fully insert both pipes ends into the lokring and use the lokring tool to tighten the fitting onto the pipework. 

Remember R600a in flammable so this type of cold pipe working is preferred as to the older braising at high heat. But they can be very expensive especially when fitting a new compressor with all the connections and then to regas system it can work out too costly for some.