Abstract: The present invention relates to a fluid agitator which may stir fluid in a closed space without leakage of the fluid. The fluid agitator has a motive means and a bearing means installed in the closed space.In the fluid agitator employing a electric motor as the motive means, only the stator coil of the motor which is weak in its resistance against high temperatures and humid atmosphere is sealed in a sealing chamber. The sealing chamber may be provided with a cooling device to cool the inside thereof. The driving shaft of the motor is supported by a bearing having resistance to high temperatures and high humidity and is provided with an agitating blade.In the fluid agitator employing a turbine system as the motive means, a turbine chamber and a turbine blade are set in the closed space. A fluid supply is furnished to introduce fluid into the turbine chamber from outside of the closed space for driving and rotating the turbine blade.

Abstract: A mechanical seal is, at a sliding surface and at its vicinity, formed of a pore-dispersed cemented carbide, so that the lubricating characteristics can be improved and the strength maintained by strictly stipulating the magnitude, shape, and volumetric ratio of the pores, such that pores are contained in an amount of 0.5 to 20 volume %, formed in at least one shape selected from the group of a substantially spherical shape and a substantially cylindrical shape, the pores in the substantially spherical shape having an average diameter of 3 to 20 .mu.m, the pores in the substantially cylindrical shape having an average diameter of 3 to 20 .mu.m and an average length in the range from the average diameter up to 300 .mu.m, and that the pores are prevented from linking to each other to give a length greater than 2 mm.

Abstract: A mechanical seal has a seal ring whose sealing face is divided into an inner part and an outer part by a circular groove through which sealing liquid is fed. The inner part of the sealing face is concave in the axial direction thereof.