General Specifications for NRG COMPANY, INCORPORATED Scum Skimming Trough Part 1 - General 1.1 Scope of Work   Under this item, the Contractor shall furnish and install ______ rotatable type Scum Skimming device(s) as manufactured by NRG Company, Incorporated in ______ Tank(s). The installation shall be as shown on the drawings and in substantial compliance with these specifications. Part 2 - Products 2.1 Scum Troughs A. Scum tipping troughs shall be NRG "Scummer". Each trough shall consist of a ________ (6,8, 10, 12, 14, 16, 18, 20) inch steel pipe having a minimum wall thickness of 1/4" and a minimum 60 degree wide slot cut symmetrically about the vertical axis of the pipe, with the edges of the slot serving as a weir. At regular intervals of not more than 2.5 ft., 2" wide bands of pipe shall be left as a stiffener.   B. Each rotating trough shall be supported at each end by a grease packed wall bearing to insure water tightness and full lubrication at all times. Each trough shall operate independently of its adjoining basin. 2.2 Scum Trough Drives A. The troughs shall be manually operated through the use of a steel lever actuator. Alternates B. The trough shall be manually operated through the use of a worm gear and handwheel. Rack and pinion actuators will not be acceptable.    C. The trough shall be automatically operated through the use of a worm gear connected to an electric valve actuator. Electric actuator to have six contacts with two contacts per position for geared limit switches, fully enclosed and lubricated gearing. All contacts shall be suitably rated for 600 volts. All motor starter equipment and actuator controls to be provided by others.