Water distribution practice test Exam D1 /D2 with Complete Solution

The only absolutely reliable method of backflow prevention is the use of - ANSWER Air Gap The bubbles formed in a positive multiple tube fermentation test are - ANSWER Carbon Dioxide The maximum rate of withdrawal of gas from a 150lb chlorine cylinder in 24-hours is - ANSWER 40 lbs If you encounter a liquid chlorine leak in a one tone container, what action should you take first, to reduce the severity of the leak? - ANSWER Rotate the container to place the leak at the top The most commonly used water disinfectant in the United States is - ANSWER Chlorine When collecting a distribution system sample, the water should be allowed to run for a period of time prior to sample collection. How long - ANSWER As long as necessary to permit cleaning of service line Sample bottles wich are furnished by a certified laboratory for collection of bacteriological samples - ANSWER Are ready to use The difference between water pressure upstream and downstream of a pump when it is not in operations is know as the - ANSWER Total static head A device that automatically shuts off flow in an elevated storage tank when the water level in the tank reache a preset level is termed a - ANSWER Altitude valve In an occupied trench requiring personal egress what is the maximum allowable distance between a worker and an exit letter - ANSWER 25 feet A water bearing formation in the soil is referred to as - ANSWER An aquifer The distance between the static water level and the pumping water level is termed the - ANSWER Drawdown To prevent the entry of surface contamination into a well is the purpose of - ANSWER Sanitary seal The presence of coliform bacteria in a distribution system - ANSWER Indicates that pathogenic organisms may be present also The most common valve type in water distribution system is the - ANSWER Gate valve A Venturi is a device used to - ANSWER Measure water flow Backspin is occurring after well shut down this indicates - ANSWER A faulty check valve A ph reading of 6.0 units indicates the water sample is - ANSWER Slightly acidic Chlorine gas - ANSWER Is heavier than air The change in what're demand during the course of a day is called - ANSWER Diurnal variation Catholic protection is a system used for - ANSWER Metallic corrosion inhibition The elevation of the free surface in a water table well wich is not running is called - ANSWER Static water level The maximum momentary load placed on a water supply system is known as - ANSWER Peak demand Most below ground level storage tanks are constructed of - ANSWER Concrete Hey bacteriological sampling bottle should be - ANSWER Filled carefully to leave a small air space When fully open, wich of the following will have the lowest friction loss - ANSWER Gate valve Enclosed, open, and smi closed are terms used for the designation and selection of - ANSWER Impellers The process by wich water changes from the gas to the liquid form is called - ANSWER Condensation Sleeve type and victaulic couplings are the most common forms of - ANSWER Mechanical couplings The most commonly used meter on a small diameter domestic service is the - ANSWER Mutating disc meter If a pump sounds like it's pumping rocks, the most likecly cause is - ANSWER Cavitation "Backflow Device" is termedused to describe a device that - ANSWER Prevents back flow of potentially contaminated source in to drinking water Which is a devices used to measure flow - ANSWER Weir When closing a hydrant, it should be - ANSWER Closed slowly to reduce surges A bacteriological test that measures only the presence or absence of Califorms is - ANSWER Colilert A compound meter is a device which - ANSWER Provides accurate reading over a wide range of flows The rotating element in a centrifugal pump is commonly called the - ANSWER Impeller The packing gland serves many functions in a centrifugal pump. Among these is - ANSWER Keep gritty material from entering the packing box What are the names of positive displacement pumps - ANSWER Reciprocating and rotary What is the practical maximum suction lift for a centrifugal pump in good working condition - ANSWER 15 to 25 feet Residual chlorine refers to - ANSWER The amount of chlorine in the chlorinated water after a selected time