or more pieces and telescope to provide adjustable lengths.
Valve controls may be mounted on floor stands for operating valves below a floor. They are operated manually by turning the handwheel or by automatic controls. Some floor stands are equipped with indicators to show when the valves are open or closed. Floor stands (fig. 4-14) are essentially an extension of the valve stem.
Post indicators (fig. 4-15) provide for operating nonrising-stem gate valves that are below the ground or floor level. They are used principally in fire-flow systems, and in this function must be fully approved by the Underwriters Laboratories and the Associated Factory Manual Fire Insurance Companies (indicated on the post by the letters UA and FM). The indicator post is operated by an attached vise when not in use. The valve is opened by turning the wrench to the left, unless otherwise indicated. The OPEN or CLOSED position of the valve is clearly indicated by the target places which show the words Open and Shut in glass protected openings on both sides of the post. Most post indicators are sealed open for safety. If the seal has been broken, the operator should report this condition to higher authority immediately.
Most large manually operated valves are operated through gears as are motor-operated valves. These gears are housed in gearboxes.
Monthly or quarterly, lubricate the gearing under the manufacturer's instructions.
Semiannually, check gear operation through a complete cycle of opening and closing. Listen for undue noise and observe smoothness of operation of the valve opening, and check for lubricant leakage from the flanges. Upon finding any evidence of improper operation, the operator should open the gearbox, inspect the gears, and make necessary repairs.
Annually, inspect the housing for corrosion; clean and paint it as necessary.
Figure 4-14. - Floor stand.
All buried valves must have means for the valve key to reach the operating nut. This unit consists of a cast-iron pipe about 6 inches in diameter with a special yoke at the bottom to rest on the valve bonnet and a cover at the street level (or ground level, if not in the street). These valve boxes are adjustable in height; some have covers with locknuts to prevent unauthorized access.
Figure 4-15. - Floor stand with post indicator.Continue Reading