Abstract: A method for deliberately plugging the inlet and outlet ends of a reactor tube in a recoverable manner, which method employs at least one vented plug whereby fluid communication within the tube can be established or terminated at will, and the tube is unplugged only after the fluid content of the tube has been drained through the vented plug.

Abstract: Disclosed is a laser level device that includes a reference surface, and a laser beam generator that is coupled to the reference surface. The laser level device also includes a compensator that is supported proximate to the reference surface. The compensator has a pendulum that includes a polygonal body with at least a four point suspension. The compensator also has optics that are coupled to the polygonal body in the path of a laser beam that is produced by the laser beam generator to redirect the laser beam, and a keeper that is coupled to the reference surface and is at least partially surrounding the polygonal body such that an air gap may be provided between the polygonal body and the keeper. The laser level device further includes a beam sweeper that is supported above the reference surface in the path of the redirected laser beam to sweep the redirected laser beam in a plane.

Abstract: A simple structure for providing a level laser beam. A pendulum is suspended by at least two suspension supports along the line parallel to a path of a laser beam emitted from a laser. An optical element is mounted on the pendulum to intercept the laser beam and reflect it along a path orthogonal to the first path. The pendulum will maintain the optical element in a vertical alignment, and accordingly the beam reflected off the optical element will be horizontal.