Chapter 19: Backflow Prevention and Cross-
Connection Control questions with accurate answers
actual cc Ans✓✓✓ connection exists at all times
air gap requirements Ans✓✓✓ gap between supply outlet and
downstream receptacle must measure at least 2 times the inside diameter
of the outlet's tip but no less than 1 inch or 25 mm.
air gaps Ans✓✓✓ best method for protection against backflow if
correctly installed and maintained. Acceptable in all CC situations and
for all degrees of risk
Atmospheric vacuum breakers Ans✓✓✓ consists of a check valve
operated by water flow and a vent to atmosphere. when flow is forward
the valve lifts and shuts off the air vent. when flow stops or reverses the
check closes to stop water supply entry and opens the air vent. AVB's
may only be used where back pressure is not possible and must be
installed at least 6 inch or 150 mm above the highest point of the
downstream outlet.
back-flow due to back-pressure Ans✓✓✓ re-circulation of potable or
non-potable water for the purposes of fire demand or processing
requirements
Backflow Ans✓✓✓ Flow of water, foreign liquids, gases into a potable
water system.
, backflow due to backsiphonage Ans✓✓✓ caused by atmospheric
pressure, maximum height water can be siphoned is 10.3 m or 33.9 feet
sea level.
Backflow-prevention devices Ans✓✓✓ For BPD's to operate properly
for long periods of time: good quality units must be installed and
inspection and maintenance must be performed periodically.
Backpressure Ans✓✓✓ condition in which a substance is forced into a
water system due to higher pressure than system pressure
backsiphonage Ans✓✓✓ condition in which pressure in the distribution
is less than atmospheric pressure (main is under vacuum)
Barometric loop Ans✓✓✓ simple instrument that only prevents
backsiphonage. An inverted U is inserted into the supply pipe upstream
of the CC. A serious disadvantage is that the loop must extend about 35
feet or 11 m above the highest liquid level and is completely ineffective
against backflow due to backpressure.
CC category Ans✓✓✓ actual or potential
CC control Ans✓✓✓ many jurisdictions have assigned the
responsibility of CC control directly to the water supplier
Connection Control questions with accurate answers
actual cc Ans✓✓✓ connection exists at all times
air gap requirements Ans✓✓✓ gap between supply outlet and
downstream receptacle must measure at least 2 times the inside diameter
of the outlet's tip but no less than 1 inch or 25 mm.
air gaps Ans✓✓✓ best method for protection against backflow if
correctly installed and maintained. Acceptable in all CC situations and
for all degrees of risk
Atmospheric vacuum breakers Ans✓✓✓ consists of a check valve
operated by water flow and a vent to atmosphere. when flow is forward
the valve lifts and shuts off the air vent. when flow stops or reverses the
check closes to stop water supply entry and opens the air vent. AVB's
may only be used where back pressure is not possible and must be
installed at least 6 inch or 150 mm above the highest point of the
downstream outlet.
back-flow due to back-pressure Ans✓✓✓ re-circulation of potable or
non-potable water for the purposes of fire demand or processing
requirements
Backflow Ans✓✓✓ Flow of water, foreign liquids, gases into a potable
water system.
, backflow due to backsiphonage Ans✓✓✓ caused by atmospheric
pressure, maximum height water can be siphoned is 10.3 m or 33.9 feet
sea level.
Backflow-prevention devices Ans✓✓✓ For BPD's to operate properly
for long periods of time: good quality units must be installed and
inspection and maintenance must be performed periodically.
Backpressure Ans✓✓✓ condition in which a substance is forced into a
water system due to higher pressure than system pressure
backsiphonage Ans✓✓✓ condition in which pressure in the distribution
is less than atmospheric pressure (main is under vacuum)
Barometric loop Ans✓✓✓ simple instrument that only prevents
backsiphonage. An inverted U is inserted into the supply pipe upstream
of the CC. A serious disadvantage is that the loop must extend about 35
feet or 11 m above the highest liquid level and is completely ineffective
against backflow due to backpressure.
CC category Ans✓✓✓ actual or potential
CC control Ans✓✓✓ many jurisdictions have assigned the
responsibility of CC control directly to the water supplier
