Method for mixing gas into high-viscosity material and apparatus for the same

A gas mixing apparatus for mixing gas into a high viscosity material, the gas mixing apparatus comprising:

• a piston pump including a cylinder, a discharge port for gas formed at an end of the cylinder so as to make the cylinder communicate with a conduit through which a high-viscosity material can flow, a suction port formed in the cylinder so as to fill the cylinder with gas, and a piston slidable between a first position and a second position inside the cylinder;
• a discharge valve that opens and closes the discharge port,
• wherein the cylinder forms a cylinder space having a predetermined volume for filled gas when the piston is located at the first position;
• and
• a controller,
• the controller being configured to control the apparatus to execute each of the steps of:
• closing the discharge valve;
• moving the piston to the first position to form the cylinder space having the predetermined volume;
• filling the cylinder space with the gas having the predetermined pressure from the suction port;
• moving the piston toward the second position to compress the gas;
• and
• opening the discharge valve to mix the compressed gas into the high-viscosity material that flows through the conduit.