Abstract: A valve chamber is provided inside a valve element including a liquid inlet and a liquid outlet at positions facing each other. Inside the valve chamber, a ball is disposed to be movable in a direction of a straight line connecting the liquid inlet and the liquid outlet. A ball seat is fitted in the liquid inlet portion of the valve element. The ball seat includes a flow path forming the liquid inlet inside itself and allows the ball to be seated at an edge portion of the flow path. The ball seat is made of material having a hexagonal crystal structure and formed while controlling an orientation of a crystal axis so that a C axis which is the crystal axis of the material is oriented in the same direction as a central axis of the flow path forming the liquid inlet.

Abstract: A liquid pump has a pump head, a head holder which can be assembled with the pump head and a housing connected to the head holder, providing an internal space which connects to a liquid flow route through the pump head. A plunger assembly is disposed inside this internal space, having a plunger rod which penetrates the head holder and reaches the flow route, and a male screw part. A cross head for driving the plunger assembly is also inside this internal space, and a return spring is supported between the head holder and this cross head so as to provide a biasing force thereto. The cross head has a female screw part which is engageable with the male screw part of the plunger assembly. The plunger assembly has a hexagonal flange to which a dedicated simple jig can be engaged to rotate the plunger assembly and to thereby engage or disengage them.