Chapter 1

Question 1

Define: Back Pressure

Answer 1

Pressure, regardless of source, against outlet side of backflow prevention device. exceeds supply pressure against the inlet side of device. example: Pressure from gravity due to elevation differences.

Question 2

Back Siphonage:

Answer 2

A form of backflow due to negative or sub-atmospheric pressure within a potable water system.

Question 3

Backflow:

Answer 3

Undesired reversal of the flow of water in a piping system. caused by back pressure or back siphonage.

Question 4

backflow prevention:

Answer 4

the mechanical prevention of reverse flow, or back siphonage, of non-potable water from an irrigation system into the potable water source.

Question 5

Backflow prevention ASSEMBLY:

Answer 5

Any assembly used to prevent backflow into a potable water system. The type of assembly used is based on existing or potential degree of health hazard and backflow condition.

Question 6

Dynamic Pressure:

Answer 6

The pressure of water as it is moving through the system. or “Working Pressure”.

Question 7

Precipitation Rate meaning + Formula used to figure:

Answer 7

AKA- “Application Rate” The rate at which water is applied by the irrigation system. Measured in inches per hour. Formula:
GPM (full circle head) x 96.3
_____________________
head spacing x row spacing

or
total GPM x 96.3
____________
Total area

Question 8

Reduced Pressure Principle Backflow Prevention Assembly (RPPA, RP, RPZ)

Answer 8

The assembly containing two independently acting, approved check valves together with hydraulically operating, mechanically independent, pressure differential relief valve located betweeen the two check valves below the first check valve. MUST BE USED IF CHEMICALS ARE TO BE ADDED TO THE SYSTEM.

Question 9

Define Slope & it’s formula:

Answer 9

A measure of the rate of change in elevation over a prescribed distance.
Can be expressed as a RATIO, a GRADE, or as a PERCENT. ie: a ratio of 1ft vertical to 4ft horizontal is the same as grade of 0.25, and equal to a percent slope of 25%.

Slope= Rise divided by Run

Question 10

Static Pressure:

Answer 10

The measured pressure of water when it is not moving. (Remember, “stagnant” sounds like static)

Question 11

Transpiration:

Answer 11

The process of plant material giving off water vapor from the leaves.

Question 12

Triangular Head Spacing & Formula:

Answer 12

Spacing in which the heads of each row are offset so that they form an equilateral triangle.
Row spacing = Head spacing x 0.866

Question 13

Soil & it’s types:

Answer 13

3 types include: Sand, silt and clay. Most soils are a combo of the types.
Water moves HORIZONTALLY through soil by means of “capillary action”. Water moves DOWNWARD through soil by means of capillary action AND gravity.

Question 14

PVC is the abbreviation for?

Answer 14

Polyvinyl Chloride

Question 15

SDR is the abbreviation for?

Answer 15

Standard dimension ratio. (wall thickness of Class pipe) S.D.R. 26 equals Class 160;
S.D.R. 21 equals Class 200; S.D.R. 13.5 equals class 315. No wall thickness can be less than .060 inches.