How to inspect the air pressure? 
Please follow the steps to adjust and replace it:
i check the original air pressure and the drain
1), Check to see if the air pressure is 0.5 Mpa.
2), If the pressure is outside the range from 0.45 Mpa to 0.55 Mpa, check to see if any air leaks at the factory. If you find no problem, follow the procedure below to readjust the air pressure.
3), Drain oil and water in the bottle connected to the drain.( discard oil or water collected in the bottle).

ii How to adjust the original air pressure. 
1) put the knob into the open state.
2) Pull the knob of the regulator downward, then rotate it so that the pressure of the used air can become 0.5 Mpa.

iii How to replace the filter element? See the procedure below for replacing the filter element.
1) when to replace a filter element: every two years or when the air pressures decreases to approximately 0.1 Mpa (1kgf/cm2).
2) How to replace a filter element:

• while moving down the slideing section, rotate the main unit to the left or right by 45 degrees to pull it downward.
• Remove the filter element B by rotately the resin part that fixes the filter element B to the left. Remove the filter element A by rotating it itself to the left.
• Attach each filter element by following this procedure in the reverse order.
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