Water Distribution 1 Questions and Answers 100% Pass

Water Distribution 1 Questions and Answers 100% Pass Head is measured in feet A plat is A map Which type of valve will prevent the collapse of a pipe Air-and-vaccume relief valve The highest degree of protection of a coated steel pipe is cathodic protection At which time of day is the age of the water stored in the distribution system the highest? In the morning One of chlorines advantages is that it has a persistent residual Chlorine gas is _____ times heavier than air. 2.5 After a water storage tank has been chlorinated, which bacteriological test must prove negative before the tank is put back into service. Coliform test Which is the best and most reliable way of finding a very small chlorine leak? Use a chlorine gas detector and place it near any area suspected of leaking. The minimum required free chlorine residual anywhere in the distribution system is a detectable level First draw samples for the analysis of lead and copper water must be collected from taps where the water has stood motionless in the plumbing for at least 6 hours Samples collected for cloakrooms are collected in plastic bottles that must contain Sodium thiosulfate The volume of a sample for coliform compliance is 100 ml If a water sample is not analyzed immediately for chlorine residual, it is acceptable to be analyzed within 15 minutes The heart of a pump is called the impeller Which device serves the same function as the packing Mechanical seal Which is used to stop air leakage into the casing around the pump shaft seals Which is at the top of a stuffing box? Packing gland Which assembly holds the lantern ring and packing? Stuffing box Why is it important to monitor the speed of a variable speed pump? To prevent cavitation from occurring Which basic electrical unit is used to measure a materials opposition of flow of electricity? Ohm The first oil change on a pump should be done After a month of operation How often should the temperature of centrifugal pump motor bearings be checked with a thermometer? Once a month All sensors that respond to liquid pressure will preform poorly if _______ enters the air sensor Air Which agency sets limits on the concentration levels of harmful contaminants in potable water distributed to costumers? United States Environmental Protection Agency Which violations are most serious? Tier 1 A positive fecal coliform test must be reported to the primacy agency within 24 hours 24 hours The number of monthly distribution system bacteriological samples is required is based on the population served Which is the approximate angle of response for average soils when using the sloping method for the prevention of cave ins? 1.0 : 1.0 At what time of day is the age of the water stored in a distribution system the lowest? Late Evening Which type of maps should not overlap each other? Sectional maps Which of the following is a joint for ductile iron piping? Flexible ball joint The amount of feet in energy required to overcome resistance to flow in a pipe is called friction head The fire insurance underwriters recommend that no main should have a diameter less than 6 inches Water velocities in a pipe should be limited to 5 ft/sec in order to minimize friction loss Which of the following is a type of joint in polyvinyl chloride piping? Bell and spigot type Which of the following is a type of joint in polyethylene piping? Thermal butt-fusion Which of the following is a type of joint for ductile iron piping? Flanged joint The height of the water in three differently shaped tanks is 22.4 feet. In which tank is the psi at the bottom the highest? It will be the same in all three tanks A water tank has a glass tube on its side showing the water level of the tank. What is its surface called? Piezometric surface Minor head losses are caused by Sudden changes in direction or velocity of flow Water mains should primarily be sized based on Adequate fire flow at a appropriate pressure The most desirable residential pressure ranges from 50-75 psi Which is pipe strength expressed in? Tensile and flexural strength The resistance of a material to longitudinal pulling forces before it breaks is called Tensile Strength Most water systems use fire hydrants with two nozzles with diameters of ______ and one nozzle with a diameter of ____ 2.5 in and 4.5 in Which type of pipe is durable and strong, has high flexural strength and good corrosion resistance, and is easily tapped? Ductile iron which of the following is a joint for concrete piping? Bell and spigot type Precipitative softening water treatment plants try to end up with distribution system water that is Slightly scale forming Which is a closed fire line? Unmetered connection for fire protection system Comprehensive maps of medium to large systems generally have scales ranging from 500 to 1000 feet to 1 inch Sectional maps generally have scales ranging from 50 to 100 ft to 1 inch Which type of centrifugal pumps are the most common? Radial flow impellers Name two types of joints for steel piping Expansion joint and rubber gasket joint The pressure during fire flow conditions should not drop below 20 psi Which type of distribution system configuration has smaller mains that generally terminate as dead ends? Tree system Which is applied to electrodes placed in the water of a water storage tank? DC current The frequent starting of distribution system pumps probably indicates inadequate distribution storage Which needs to be determined first when designing a pump station? Head requirements Which is plotted on the x axis of a pump curve? Capacity (flow rate) Hydraulics is the study of fluids in motion and at rest Which type of pipe joint consists of two machined surfaces? flanged joint Which type of pipe joint requires a movable follower ring? Mechanical joint What is the height limit to which siphoned water can be lifted at sea level? 33.9 ft How many feet of water will equal the atmospheric pressure at sea level? 34 ft Which type of impeller is best to use for pumping water with low volumes of solids? Closed Which type of pump has the ability to rotate its discharge 360 degrees End suction pump How many times higher than the normal operating pressure should the pressure rating of distribution piping be? 2.5 to 4.5 times Which type of piping has been banned from the water industry? Asbestos cement Which type of piping comes in diameters as large as 168 inches (14 feet)? Reinforced concrete Which type of pipe has the highest normal maximum working pressure? Ductile iron Which type of pipe has the lowest normal maximum working pressure Polyvinyl chloride Ductile iron piping using flex ball joints is most appropriate for river crossings and rugged terrain Ductile iron piping using push on or mechanical joints is most appropriate for where flexibility is required Polyvinyl chloride piping using solvent weld joints is most appropriate only for small lines Concrete piping using bell and spigot type joints is most appropriate for all locations Which type of piping is available is both bolted and boltless flexible pipe joint designs? Ball and socket joint Which type of pipe joint permits flexible pipe alignment, is inexpensive to manufacture, and is easy to assemble? Push on joint Which type of pipe joint has machined ends? Shouldered joint New polyvinyl chloride pipe has a C value of about 150+ Do you think an emergency storage tank is likely to contain potable water? No Which type of valve is used on hydraulic lines connected to valve actuators? Needle valve Which type of valve would be particularly useful for throttling the flow of corrosive liquids? Pinch valve Water meter pits are usually used in cold climates A horizontal load, parallel to a pump shaft is called a thrust load Manufacturers typical design pumps such that the first critical speed is at least ____ higher or lower than rated speed 20% Regarding fire flow, mains smaller than 6 inches should only be used to complete a grid Which type of pipe requires special external protection in high chloride soils? Reinforced concrete Which type of pipe is most likely to collapse or become distorted under partial vacuum? Steel piping Casing pipe used to house a large water main under a railroad crossing should have a diameter that is ___________ larger than the outside diameter of the water main bells. 2 to 8 inches Data manipulations using the basic elements of an automatic mapping system would include modeling and analysis Which data category for water utility data sets includes the following map layers: Control information, planimetric features, and hydrology features? Base data Which is the chlorine species called HTH Calcium Hypochlorite Which is the proper detention time for disinfecting a water storage tank that is filled with already chlorinated water such that the free chlorine residual is 10 mg/L after the proper detention time is completed? 6 hours Which is the proper detention time for disinfecting a water storage tank with water that is mixed with hypochlorite already in the tank such that the free chorine is 10 mg/L after proper detention time is complete? 24 hours The disinfectant residual in treated water entering the distribution system must not be less than o.2 mg/L for more than 4 hours during periods where the system is serving water to the public The chemical formula for hypochlorous acid is HOCL Usually the best disinfectant to use in large diameter pipes or very long pipelines is chorine gas Which method for controlling nitrification problems in a distribution system would result in a temporary increase in trihalomethanes super chlorinating reservoirs and storage tanks Which is the available chlorine concentration used for disinfecting a water storage tank using a method that involves spraying or painting all of the interior tank surfaces? 20 mg/L When following a two step process for disinfecting a water storage tank, the initial dosage of 50 mg/L available chlorine should be held in a partially filled tank for at least six hours Why are altitude valves used on water storage tanks? To stop the flow of water into the tank when it is full If iron bacteria are causing corrosion problems in the distribution system, which is the most probable solution? Use a corrosion chemical as treatment Which type of chlorine gas feeder is most commonly used? Vacuum When concentration cell corrosion occurs in iron pipes the electrons will move through the iron pipe from the anode to the cathode Which type of corrosion occurs when two types of dissimilar metals are electrically connected and immersed in a common flow of water, where one metal becomes the anode and the other the cathode? Galvanic corrosion