Abstract: A communication hole inspection device for inspecting a communication hole in a structure, a casting surface being formed on an inner surface of the hole, said communication hole inspection device having: a light-emitting body that is arranged in a portion of the communication hole and emits a beam of light; a light-receiving body that is arranged in a different portion of the communication hole and receives the light beam from the light-emitting body; a rotation mechanism for changing the rotation angle of the light-emitting body and thereby changing the light beam received by the light-receiving body; and a determination unit for determining the open state of the communication hole at least on the basis of based on the light beam received by the light-receiving body when the rotation angle of the light-emitting body is set at a first angle, and at a second angle different from the first anile.

Abstract: When a first electromagnetic valve of a first stirring tank is turned ON and a second electromagnetic valve of a second stirring tank is turned OFF, the air pressure inside the first stirring tank increases and the liquid in the first stirring tank is sent into the second stirring tank via piping. When the volume of the liquid inside the second stirring tank reaches an upper limit, the first electromagnetic valve of the first stirring tank is turned OFF and the second electromagnetic valve of the second stirring tank is turned ON. As a result, the liquid inside the second stirring tank is now sent into the first stirring tank via the piping. Ultimately, because the liquid is circulated between the first and second stirring tanks and the liquid is flowing at all times due to the repetition of said actions, separation does not occur.

Abstract: When a first electromagnetic valve of a first stirring tank is turned ON and a second electromagnetic valve of a second stirring tank is turned OFF, the air pressure inside the first stirring tank increases and the liquid in the first stirring tank is sent into the second stirring tank via piping. When the volume of the liquid inside the second stirring tank reaches an upper limit, the first electromagnetic valve of the first stirring tank is turned OFF and the second electromagnetic valve of the second stirring tank is turned ON. As a result, the liquid inside the second stirring tank is now sent into the first stirring tank via the piping. Ultimately, because the liquid is circulated between the first and second stirring tanks and the liquid is flowing at all times due to the repetition of said actions, separation does not occur.