BRAE-337 Landscape Irrigation Final
Exam 2 Latest Updated Graded A+
How much wire resistance is allowed if the controller output is 26 volts, the valve
requires 22 volts, the total length including snaking is 773 feet, and the inrush current is
0.47 amps? - ANSWER-5.5 ohms/1000 ft. Wire Resistance (size) = [(Allowable Voltage
Loss * 1000)/(Inrush Current * Length * 2)]
**If a sprinkler requires an average sprinkler pressure of 60 psi, what is the pressure
that will be required at the POC? - ANSWER-Something much higher because of the
friction through the pipe and components
**The problem with the early basic controllers was that: - ANSWER-The systems would
run for the same amount of time all year
**What is the equation for weekly (gross) irrigation water requirement computation? -
ANSWER-Plant Water Use (net)/(Distribution Uniformity * (1 - Losses))
**What is the gross amount to apply (inches), if the net irrigation required is 0.23 inches,
the DU is 0.8, and the losses are 9%? - ANSWER-0.32 in. Gross = Plant Water Use
(net) of 0.23/(Distribution Uniformity of 0.8 * (1 - Losses of 0.09))
**What is the run time required if the gross to apply is 0.30 inches and the precipitation
rate is 1.21 in/hr? - ANSWER-15 min. 0.3 in * 1.21 in/hr = 0.248 hr. 0.248 hr * 60 min =
15 min
**When determining irrigation frequency, or when to irrigate, how do you determine the
correct number of days? - ANSWER-Use the result from the equation SMDmax / ETL
and round down
After using the 3 rules to calculate pressure and flow available, which result should be
used for design purposes? - ANSWER-The smallest value
Assuming a standard AWWA meter, what is the maximum flow rate that you should
design for through a 1-1/2 inch water meter for irrigation purposes? - ANSWER-75 gpm.
This is 75% of the max meter capacity, and the maximum flow before velocities go over
5 fps
Assuming the same throw diameter and the same flow rate, what happens to the
precipitation rate as the spacing is INCREASED. - ANSWER-decreases
Having a tight sprinkler spacing typically equates to a higher DU. It also means: -
ANSWER-higher maintenance costs
, Head-to-head spacing means: - ANSWER-The throw diameter from head #1 reaches
head #2
How many gallons per minute does a 360 degree Hunter MP2000 nozzle discharge at
40 psi? - ANSWER-~1.5 gpm
How would you actually compute the flow rate available at the point of connection? -
ANSWER-Record the time to fill a container of a known volume
Ideally, each individual zone should: - ANSWER-have the same equipment, pressure,
and spacing
If the available pressure is not enough for the system requirements, what can you do as
a designer to fix this issue? - ANSWER-Add a booster pump
If the average ET rate for a landscape is 0.14 in/day and the maximum SMD is 0.8
inches, how often should you irrigate to prevent any deficit? - ANSWER-Every 5 days
If the gross irrigation requirement is 1.8 in/week and the precipitation rate is 0.58 in/hr,
how many hours must the irrigation system run each week if there are 4 identical
zones? - ANSWER-12.4 hr/week. Gross irrigation req. of 1.8/ PR of 0.58 = 3.1 for each
zone. Multiply by 4 to get 12.4 hr/week.
If the reference ET is 1.43 in/week and the landscape coefficient is 0.7, what is the
water requirement of the landscape? - ANSWER-1.00 in/week. ETL = reference ET
(1.43) * KL (0.7)
If you have two valves on the same circuit, the inrush current: - ANSWER-Needs to
double
If you were to decrease the nozzle size, what happens to the radius of throw? -
ANSWER-decreases
In general, the maximum flow rate through the water meter for the irrigation system
should not exceed: - ANSWER-75% of the safe meter flow
More stations, small flow rates, and smaller pipe sizes means: - ANSWER-fewer
sprinklers per lateral
Name the specific location where the pressure versus flow rate data is recorded. -
ANSWER-Point of Connection
On the pipe friction loss chart, the shaded area represents an excess of which factor? -
ANSWER-Velocity limit
Exam 2 Latest Updated Graded A+
How much wire resistance is allowed if the controller output is 26 volts, the valve
requires 22 volts, the total length including snaking is 773 feet, and the inrush current is
0.47 amps? - ANSWER-5.5 ohms/1000 ft. Wire Resistance (size) = [(Allowable Voltage
Loss * 1000)/(Inrush Current * Length * 2)]
**If a sprinkler requires an average sprinkler pressure of 60 psi, what is the pressure
that will be required at the POC? - ANSWER-Something much higher because of the
friction through the pipe and components
**The problem with the early basic controllers was that: - ANSWER-The systems would
run for the same amount of time all year
**What is the equation for weekly (gross) irrigation water requirement computation? -
ANSWER-Plant Water Use (net)/(Distribution Uniformity * (1 - Losses))
**What is the gross amount to apply (inches), if the net irrigation required is 0.23 inches,
the DU is 0.8, and the losses are 9%? - ANSWER-0.32 in. Gross = Plant Water Use
(net) of 0.23/(Distribution Uniformity of 0.8 * (1 - Losses of 0.09))
**What is the run time required if the gross to apply is 0.30 inches and the precipitation
rate is 1.21 in/hr? - ANSWER-15 min. 0.3 in * 1.21 in/hr = 0.248 hr. 0.248 hr * 60 min =
15 min
**When determining irrigation frequency, or when to irrigate, how do you determine the
correct number of days? - ANSWER-Use the result from the equation SMDmax / ETL
and round down
After using the 3 rules to calculate pressure and flow available, which result should be
used for design purposes? - ANSWER-The smallest value
Assuming a standard AWWA meter, what is the maximum flow rate that you should
design for through a 1-1/2 inch water meter for irrigation purposes? - ANSWER-75 gpm.
This is 75% of the max meter capacity, and the maximum flow before velocities go over
5 fps
Assuming the same throw diameter and the same flow rate, what happens to the
precipitation rate as the spacing is INCREASED. - ANSWER-decreases
Having a tight sprinkler spacing typically equates to a higher DU. It also means: -
ANSWER-higher maintenance costs
, Head-to-head spacing means: - ANSWER-The throw diameter from head #1 reaches
head #2
How many gallons per minute does a 360 degree Hunter MP2000 nozzle discharge at
40 psi? - ANSWER-~1.5 gpm
How would you actually compute the flow rate available at the point of connection? -
ANSWER-Record the time to fill a container of a known volume
Ideally, each individual zone should: - ANSWER-have the same equipment, pressure,
and spacing
If the available pressure is not enough for the system requirements, what can you do as
a designer to fix this issue? - ANSWER-Add a booster pump
If the average ET rate for a landscape is 0.14 in/day and the maximum SMD is 0.8
inches, how often should you irrigate to prevent any deficit? - ANSWER-Every 5 days
If the gross irrigation requirement is 1.8 in/week and the precipitation rate is 0.58 in/hr,
how many hours must the irrigation system run each week if there are 4 identical
zones? - ANSWER-12.4 hr/week. Gross irrigation req. of 1.8/ PR of 0.58 = 3.1 for each
zone. Multiply by 4 to get 12.4 hr/week.
If the reference ET is 1.43 in/week and the landscape coefficient is 0.7, what is the
water requirement of the landscape? - ANSWER-1.00 in/week. ETL = reference ET
(1.43) * KL (0.7)
If you have two valves on the same circuit, the inrush current: - ANSWER-Needs to
double
If you were to decrease the nozzle size, what happens to the radius of throw? -
ANSWER-decreases
In general, the maximum flow rate through the water meter for the irrigation system
should not exceed: - ANSWER-75% of the safe meter flow
More stations, small flow rates, and smaller pipe sizes means: - ANSWER-fewer
sprinklers per lateral
Name the specific location where the pressure versus flow rate data is recorded. -
ANSWER-Point of Connection
On the pipe friction loss chart, the shaded area represents an excess of which factor? -
ANSWER-Velocity limit
