Water distribution level 3(questions with complete solutions)

A factor or value used to indicate the smoothness of the interior of a pipe Cfactor Major parts of water distribution Pipes, storage facilities, pumping stations, valves ,fire hydrants, meters, and other appurtenances 00:02 01:14 Main purpose of water storage facilities To provide sufficient amount of water to average or equalize the daily demands on the water supply system Types of storage facilities Clear wells, elevated tanks,standpipes,ground level storage tanks , hydro pneumatic or pressure tanks, and surge tanks 20 psi Absolute minimum pressure 35 psi Minimum working pressure Basic requirements of pipes Adequate strength, durability,maximum corrosion, resistance and no adverse effect on water quality Four classes of working pressure are commonly encountered 100,150,200,250 psi Push on and mechanical joints are most often used for Ductile iron pipe. Flanges, restrained, flexible, and sleeve joints are also used Flange joints Not flexible Restrained joints Prevent movement Flexible joints Permits one joint to move PE pipe Has the highest cfactors 150 Pipe protection Paint Rock must be excavated 6inches Ladder must b located 25 ft and 3ft above hole Laying pipe is also called Stringing The horizontal shoring members are generally referred to as Stringers or walers Shield shoring Consists of a rectangular box that must b open on the top and bottom and usually the ends are open too Solid sheeting Used when materials will not stand in a vertical position or not practical to slope the trench Types of valves Plug, rotary,butterfly, diaphragm, gate Entrained Air to escape a line is operating under pressure 4 parts to a hydrant Inlet pipe connection from the water supply main,the main valve,the barrel,the head Post hydrants Extend above ground most commonly used Rule of thumb Meter should b one size smaller that service line 3basic backflow devices Double check valve, reduced pressure(rp),air gap-provides greatest protection The source of supply might b a Well Preventive Scheduled Corrective Equipment failure Predictive Maintenance program Bacteriological samples are analyzed for the presence of Total coliform. Presence of these bacteria indicates other forms may b present Minimum chlorine residual Free 0.2mg/l Combined 0.6mg/l Cross connection A connection between potable water system and an unknown water supply The particular type of device most suitable for a given situation depends on The degree of hazard Pressure vacuum breaker and atmospheric vacuum breaker Irrigation backflows Leak detection Done at night Backsiphonage Caused by a negative or below atmospheric pressure within a water System Packing glands Should never b tightened to the point of no leakage, as this could cause excessive wear Wet tap connection 45 degrees from top of pipe Pipe flushing should b done at Low periods of demand Min flushing velocity 2.5ft/sec Preferred flushing velocity 5ft/sec Ensure pressure does not drop below 20psi De-chlorinate tablets Sodium thiosulfate Clear wells Usually located at treatment plants. More susceptible to contamination from ground Storage levels Sight glass Psi 2.31 feet of water or each foot is .433psi Dose Demand+residual Chlorine residual must b below 4.0mg/l (free or total) Catholic protection Paint,coupons, prevention of rust, corrosion and pitting of metal surfaces that are in contact w/ water Entrain To trap bubbles in water either mechanically through turbulence or chemically through reaction Galvanize To coat a metal (iron or steel) with zinc Invert The lowest point of the channel inside a pipe, conduit, canal or manhole Pressure head The vertical distance equal to the pressure at a specific point 3 types of plastic Pvc-polyvinyl chloride PE-polyethylene PB-polybutylene Cathodic protection may b needed if Pipe is electrically conductive Vacuum, pressure relief, and pressure reducing valves will Prevent pipe damage from negative or excessively high pressures If the pipe does not ring or hum clearly Then the pipe is damage and should b rejected Gate valves Most commonly used Osy Fire line only. Outside screw and yoke Meter accuracy Small- 98.5-101.5 15psi Large-97-103 20psi All backflow devices should b located On the customers side of the service Contaminants a May degrade in the distribution because Temp,flows,water age,and dead ends Contaminants may degrade inside the customers home because of Hot water tanks,water softeners,old galvanized pips Disease causing organisms r called Pathogenic Aerobic A condition in which atmospheric or dissolved oxygen is present in the aquatic (water) environment Carcinogen Any substance that tends to produce cancer in an organism Tubercle A crust of corrosion products(rust) that builds up over a pit caused by the loss of due to corrosion Common example of biofilm Black staining around the bottom of a shower curtain Free chlorine is The most powerful disinfectant Physical means of disinfection Uv,heat,ultrasonic waves Chemical means of disinfection Chlorine,chloramine 1 liter of chlorine yeilds 450 liters of chlorine gas Chlorine is 2 1/2 times heavier than air Free chlorine Provides residual The best Creates THMs Kills fish Chloramine Provides residual More stable than free Must b removed for dialysis Alternative to free chlorine Dose-demand Residual Demand + residual Dose Dose-residual Demand