CH-STW-07 Professional AC Torque Wrench Set 17-29 mm (10-75 Nm)

The CH-STW-07 AC torque wrench set is a professional service kit used in split air conditioners and refrigeration systems to tighten flare nuts to the torque value specified by the manufacturer. The adjustable torque body works in the 10-75 Nm range, and the set comes in a black carrying case with six interchangeable open-end (crowfoot) heads: 17, 22, 24, 26, 27 and 29 mm.

Tightening torque is critical in flare connections: an under-tightened flare nut leaks refrigerant, while an over-tightened flare nut crushes and cracks the copper flare, and the leak often appears months later. With high-pressure refrigerants such as R410A and R32, this margin of error becomes even narrower. When the target value is reached, the torque wrench gives an audible "click" that tells you when to stop tightening; a measurable value replaces tightening by feel and experience.

Set Contents and Torque Values by Wrench Size

• Product Code: 01 41 495  |  Model: CH-STW-07
• Torque Range: 10-75 Nm (100-750 kgf·cm), adjustable scale
• Head Sizes: 17, 22, 24, 26, 27, 29 mm (6 open-end heads)
• Connection: Square-drive head socket, heads change in a single movement
• Body: Chrome-plated steel, knurled adjustment collar and locking knob
• Compatibility: Split air conditioners, VRF and refrigeration systems operating with R410A, R32, R22, R134a and equivalent refrigerants
• Certificate: CE
• Delivery: Torque body + 6 heads + user manual, in a plastic carrying case

Setting values specified in the manufacturer's manual (from the table in the box):

• 17 mm → 18 Nm (180 kgf·cm) — 1/4" flare nut
• 22 mm → 42 Nm (420 kgf·cm) — 3/8" flare nut
• 24 mm → 55 Nm (550 kgf·cm) — 1/2" flare nut
• 26 mm → 55 Nm (550 kgf·cm) — 1/2" flare nut
• 27 mm → 65 Nm (650 kgf·cm) — 5/8" flare nut
• 29 mm → 65 Nm (650 kgf·cm) — 5/8" flare nut

These values are the manual's reference table; if the equipment manufacturer specifies a different torque, its value takes precedence. The set covers 1/4"-5/8" flare nuts; for 3/4" and larger flare nuts, a larger head is required.

Usage Steps, Calibration Protection and Compatibility

• 1) Fit the head. Seat the head matching the flare nut size in the square socket, with the face showing the size on the correct side.
• 2) Unlock. Turn the knob at the end of the handle counterclockwise to release the scale.
• 3) Set the value. Bring the vertical scale to the target Nm value and turn the horizontal scale into line with the reference line.
• 4) Lock. Turn the knob clockwise to fix the setting; otherwise the value will shift during tightening.
• 5) Tighten. Tighten the flare nut on a straight axis; when the target torque is reached, a single click is heard, and you should stop at that point. Continuing to force after hearing the click crushes the flare.
• 🔧 Always reset to 10 Nm after use. This is a specific warning in the manufacturer's manual: if the wrench is left at a high setting, the internal spring remains under constant load, fatigues over time and torque accuracy deteriorates. After each job, turn the scale down to the lowest value (10 Nm or slightly below) before storing it.
• Correct usage notes: Do not use the torque wrench for loosening or for impact tightening; do not drop it — the calibration of a dropped torque wrench becomes questionable. Keep the flare surface clean and burr-free, and if necessary apply a small amount of refrigeration oil according to the manufacturer's instructions.
• Do not skip the leak check. Correct torque does not replace a leak test. After connecting, pressurize with nitrogen and check for leaks, then pull a deep vacuum.