Exam practice test for Texas Irrigator License

Exam practice test for Texas Irrigator License Gear rotor model B Spray with X nozzle Spray with Y nozzle Spray with Z nozzle 1" valve model Q Backflow device Mainline pipe Laterals pipe House service pipe Sleeves City main pipe City meter Controller Legend To convert psi to feet Multiply by 2.31 To convert feet to psi Multiply by 0.433 psi Precipitation Rate Formula GPM (Full Circle Head) X 96.3 -------------- = PR Head Spacing X Row Spacing (Divide) Precipitation Rate for Drip GPH (one emitter) X 231 ------------ = PR Head Spacing (inches) X Row Spacing (inches) Runtime Formula I x 60 RT ----=Runtime PR Calculating Drip Flow Zone Total Linear feet of drip /emitter spacing x GPH of emitter/ 60 = GPM for that zone Or DMDMD Slope formula Rise S = ----------- Run Triangular Head Spacing Multiply spacing by .866 to get row spacing Efficiency of System Example if 50% efficiency with 1.12 Precipitation rate Divide 1.12 by .50 to get 2.3/PR Design Pressure DP = = Recommended head pressure + total losses Actual Head Pressure AHP == Static Pressure - Total losses D - DIVIDE THE FIRST STEP TELLS YOU HOW MAY ROWS.....DIVIDE THE WIDTH BY EMITTER SPACING IN FEET (EX; 18" = 1.5 FEET) ALWAYS ADD 1 M -MULTIPLY THIS STEP TELLS YOU HOW MANY TOTAL FEET...MULTIPLY THE TOTAL ROWS BY THE LENGTH D - DIVIDE THIS STEP TELLS YOU HOW MANY TOTAL EMITTERS..DIVIDE THE TOTAL LENGTH BY THE EMITTER SPACING IN FEET M -MULTIPLY THIS STEP TELLS YOU HOW MANY TOTAL GALLONS PER HOUR..MULTIPLY THE TOTAL EMITTERS BY THE GPH GIVEN FOR EACH EMITTER D - DIVIDE THIS LAST STEP TELLS YOU HOW MANY GALLONS PER MINUTE...DIVIDE THE TOTAL GPH BY 60 TO CONVERT IT TO MINUTES Double check Assembly Backflow Preventer is suitable for? Back pressure,back siphonage,but its not suitable for high hazard applications. Reduced Pressure Principle Backflow Preventer is suitable for? Back pressure,back siphonage,and is good for high hazard applications. Backflow . . Back pressure is the irrigation side and backsiphonage is the city side. All backflow devices work for backsiphonage and only the double check and RP work for back pressure. Study what causes backsiphonage and back pressure. You have to know how to install each backflow device including air gap. Which device can stop backsiphonage? Pvb,DCA,RP,and AVB Which device can stop backpressure? DCA and RP Which device can handle constant pressure? RP,DCA,and Pvb The approved backflow devices for non-health hazards include: All devices (AVB,PVB,DCA, and RP) Which device,or devices,are approved when there is chemical applied by aspiration,injection,or emission? RP If there is an on-site sewage facility on site, which backflow is approved? RP If major Maintenance has to be performed,which backflow device has to be properly installed prior to the repair work being performed? An approved backflow device If including a master valve,where does it have to be installed? Downstream from the PVB,DCA,or RP Which devices have to be tested upon installation and annually? Devices used in applications designated as health hazards Which backflow device has to be tested upon installation? All Backflow devices If a DCA is installed below ground,what device is required? A Y-Strainer installed on inlet side of the DCA If there is an additional water source supplying water to a system being supplied by potable water supply,what device has to be used on with the potable water supply ? RP What device cannot be used when there is health hazard? DCA An AVB and PVB can be used in health hazard situations,if the following conditions are not present: Backpressure,There is pump downstream,Chemicals added An Atmospheric Vacuum Breaker Has to be installed 6'' higher than the highest head or outlet in the retracted position,will not handle constant pressure,and will stop backsiphonage What is the unwanted reversal of water flow in an irrigation system? Backflow A cross connection is any actual or potential connection between a potable water supply and: Any source that has the possibility to introduce polluted or contaminated water back into the potable water that is supplying it Backsiphonage is caused by? Negative or sub-atmospheric pressure Backsiphonage can be caused by: A break in the City Main or The fire department using water from the city fire hydrant to put out a fire.. If the pressure in the sprinkler system(or downstream side)exceeds the pressure in the supply side,what phenomenon can occur? Backpressure What can cause backpressure ? Gravity or a pump How many total ways are there to protect against backpressure and/or backsiphonage? 5 total What is the unobstructed vertical distance through free atmosphere between the lowest point of a water supply outlet and the flood level rim of the fixture or assembly into which the outlet discharges? An air gap The vertical,physical separations,of an air gap, must be: At least twice the diameter of the water supply outlet,but never less than 1 inch What is typical example of an air gap? Kitchen sink What is the maximum number of hours an AVB can have constant pressure? 12 hours How high does a pressure vacuum breaker have to be installed? 12" above the highest head or outlet in the retracted position How many test cocks does a PVB,DCA,and RP have,respectively? 2, 4 and 4 If the highest head at the site is a shrub spray on a 12" riser,how high would a PVB have to be installed if right next to that head? 24" inches Which backflow devices incorporate two check valves? DC,RP Which backflow device can be installed below grade(local regulation permitting)? DC How many test cocks are there on a DCA,RP,PVB,and AVB,respectively? 4, 4, 2, and 0