Abstract: The present invention relates to a pump apparatus for delivering a liquid. The pump apparatus includes a pump (1) having an impeller (5), an electric motor (7) for rotating the impeller (5), and an inverter (10) for driving the electric motor (7) at variable speed. The impeller (5) has a non-limit load characteristic in a predetermined discharge flow-rate range (R). The inverter (10) is configured to drive the electric motor (7) at a preset target operating point (TO) with a rotation speed higher than a rotation speed corresponding to a power frequency of a commercial power source.

Abstract: The impeller (1) includes a main plate (3) formed from a metal plate; and vanes (5) each formed from a metal plate. Each of the vanes (5) has a three-dimensional portion (5A) having a surface inclined with respect to a rotation axis (CA) of the impeller (1) and a two-dimensional portion (5B) having a surface parallel to the rotation axis (CA) of the impeller (1), and the two-dimensional portion (5B) is fixed to the main plate (3) by a first weld (10) formed by projection welding.

Abstract: The present invention relates to a pump apparatus for delivering a liquid. The pump apparatus includes a pump (1) having an impeller (5), an electric motor (7) for rotating the impeller (5), and an inverter (10) for driving the electric motor (7) at variable speed. The impeller (5) has a non-limit load characteristic in a predetermined discharge flow-rate range (R). The inverter (10) is configured to drive the electric motor (7) at a preset target operating point (TO) with a rotation speed higher than a rotation speed corresponding to a power frequency of a commercial power source.

Abstract: The impeller (1) includes a main plate (3) formed from a metal plate; and vanes (5) each formed from a metal plate. Each of the vanes (5) has a three-dimensional portion (5A) having a surface inclined with respect to a rotation axis (CA) of the impeller (1) and a two-dimensional portion (5B) having a surface parallel to the rotation axis (CA) of the impeller (1), and the two-dimensional portion (5B) is fixed to the main plate (3) by a first weld (10) formed by projection welding.

Abstract: A coupling guard for covering a coupling which couples a drive shaft of a prime mover and a rotational shaft of a rotary machine to each other. The coupling guard includes a cylindrical guard body having an upper semicylindrical member and a lower semicylindrical member coupled to the upper semicylindrical member, and a guard leg supporting the guard body. The guard body has a flange portion to which the guard leg is attached. The guard leg includes a vertical wall parallel to a central axis of the guard body, an upper wall, a bottom wall, a left-side wall, and a right-side wall which project perpendicularly outwardly from the vertical wall. The vertical wall, the upper wall, the bottom wall, the left-side wall, and the right-side wall are made of a single plate material.

Abstract: There is disclosed a coupling guard that can easily be installed and removed while a drive shaft of a prime mover and a rotational shaft of a rotary machine are coupled to each other. The coupling guard includes a cylindrical guard body having an upper semicylindrical member and a lower semicylindrical member coupled to the upper semicylindrical member, and a guard leg supporting the guard body. The guard body has a flange portion to which the guard leg is attached. The guard leg includes a vertical wall parallel to a central axis of the guard body, an upper wall, a bottom wall, a left-side wall, and a right-side wall which project perpendicularly outwardly from the vertical wall. The vertical wall, the upper wall, the bottom wall, the left-side wall, and the right-side wall are made of a single plate material.