Maintenance of valve boxes should be done twice a year like the valve maintenance schedule for operation.
Maintenance consists of cleaning out debris in the box, checking for corrosion, checking the elevation of the top, and checking alignment of the box, so the valve key can be inserted readily. When the valve box has corroded and is no longer serviceable, remove it and replace it with a new unit. When changes in street or ground level have left the valve box too high or too low, adjust the height so the cover is at street or ground level.
Different types of valves have different types of valve position indicators. Nonrising-stem gate valves may have indicators on the floor stand. Filter plant valves may have indicators on the filter operating table; and butterfly valves, or other valves, used for flow control or throttling, may have indicator units that are controlled electrically and look like an ammeter. The care required depends on the design of the indicator unit; for example, post indicators require lubrication quarterly and, position indicators, that are controlled electrically, should be checked for contact, wiring, and so on, yearly.
Q5. Floor stands with post indicators are used for operating what type of valve in what condition?
Q6. A cast-iron pipe, approximately 6 inches in diameter, has a yoke at the bottom to rest on the valve bonnet and a cover at street level. This is what type of valve accessory?
LEARNING OBJECTIVE: Identify types of water meters and methods of obtaining readings.
Water meters measure the flow of water within a line to a point of distribution, such as laundries, housing areas, and so on. There are various types of water meters. One type is the disk type of volume meter. This water meter is used chiefly for services supplied through pipes less than 1 l/2 inches in diameter, although water meters are made in sizes up to 6 inches.
Figure 4-16 shows the nutating disk volume meter. This type of meter is mainly used for individual service
Figure 4-16. - Nutating-disk meter.Continue Reading