Since the registers are never reset while the meters are in service, the amounts recorded for any period of time must be determined by subtraction. To obtain a current reading, subtract the last recorded reading from the current. dial reading. Remember, the maximum amount that can be indicated on the usual line meter before it turns to zeros and begins all over again is 99,999 cubic feet, or 999,999 gallons. Thus, to obtain a current measurement when the reading is lower than the last previous one, add 100,000 to the present reading on a cubic foot meter, or 1,000,000 to the present reading on a gallon meter. The small denomination scale, giving fractions of one cubic foot or ten gallons, is disregarded in the regular reading. It is used for testing only.
Q7. What is the purpose of a water meter?
Q8. What should you determine about flow in a water meter before reading it?
Q9. For a circular meter, you should read the meter in what direction?
LEARNING OBJECTIVE: Recognize types of fire hydrants and methods for inspection, flushing, and testing.
The fire department (or safety office) is responsible for the selection and use of fire-fighting equipment, including fire hydrants. It is the responsibility of a Utilitiesman to ensure that water is available to the hydrant and that control valves operate properly.
Most fire hydrants consist of a cast-iron barrel with a bell or flange fitting at the bottom to connect it to a branch from the main; a valve, of the gate or compression type, has a long stem terminating in a nut above the barrel and one or more outlets. There are many designs of fire hydrants, two of which are the DRY-BARREL HYDRANT and the WET-BARREL HYDRANT.
In cold climates, where freezing occurs, dry-barrel hydrants are used (fig. 4-19). With this type of hydrant, the drain valve or weep hole must be kept open in systems where the groundwater level is below the hydrant foot, so the barrel can drain and not freeze in 4-13 cold weather. A box placed over a hydrant affords some protection against freezing and leaves the top of the hydrant free of snow and ice. The hydrant is equipped with two 2 1/2-inch hose outlets and a 4 l/2-inch pumper outlet whose threads conform exactly to the standards specified in Screw Threads and Gaskets for Fire Hose Connections, NFPA, 1963.
Where freezing temperatures do not occur, use wet-barrel (or California) hydrants (fig. 4-20). With this type of hydrant, all the packing glands must be kept in good condition to prevent leakage as well as to allow free operation of the stem controlling each outlet. Valve seats for wet-barrel hydrants afford easy access for inspection.
Hydrants exposed to traffic hazards must be protected by appropriate guards. Most damage is caused by an accident or by improper or careless operation.
Much of this can be prevented when operating personnel are made to realize that a properly functioning fire hydrant is critical to the protection of life and property at the activity. Without much extra labor or effort, operating personnel can take several precautions to keep the hydrant structure in good condition. General precautions are listed below.
1. The operation of fire hydrants should be restricted to personnel trained in this and allied work, such as fire fighters, utility maintenance, and operating personnel ONLY.
2. For opening and closing the hydrant, use ONLY an approved hydrant wrench. The reason is that ordinary wrenches can ruin the operating nut.
3. Keep the hydrant drained when it is not in use. This is particularly important in cold climates where ice in the hydrant may make it inoperative.
4. Pipes should be connected only to draw off water for fire-fighting purposes except in an emergency. Any such connection must be removed immediately after an emergency. Connections made to provide a temporary supply for vehicle washing, irrigation, and so on, is not permitted.
5. The hydrant valve should be kept in either the wide
CLOSED position and never used to throttle the flow of water. When it is necessary to restrict the flow, separate globe valves should be attached to the hydrant discharge outlet.Continue Reading