24 Questions
What is the condition where the pressure of a piping system exceeds supply pressure?
Overpressure
What can cause back pressure in a closed system?
Fire department pumper connected at a hydrant
What is the minimum clearance required to the RV opening during backflow preventer installation?
10 inches
What is the required vertical clearance for a testable backflow assembly?
18 inches
Which devices have a critical level of submergence?
Double Check Valve Backflow Preventer
What type of backflow protection is required for backsiphonage only in a severe hazard application?
Air Gap
What is the hazard rating of a Trap Primer?
Severe hazard
What loads the relief valve on a RP to the closed position?
Spring force
What is the required protection for make-up water to a plating tank?
Reduced Pressure Zone Assembly (RPZA)
What is the disadvantage of Premise Isolation?
Higher cost
What can increase a hazard assessment?
Connection of a boiler system
What is the requirement for bypass installations in backflow prevention systems?
Bypasses are prohibited except where an equivalent backflow preventer is installed
What is the minimum clearance required for backflow preventers installed above grade?
30 inches
What happens to ΔP as zone pressure increases on a gauge?
ΔP increases
Which backflow prevention devices cannot be used in a closed system?
Atmospheric Vacuum Breaker
An Air Gap is sized based on what?
Vertical distance between the flood level rim and the critical level
What is the first step when testing a Reduced Pressure (RP) Backflow Assembly?
Verify the proper installation of the assembly
What is the minimum distance required between a backflow preventer and a wall or obstruction?
5 feet
What is the required back clearance to any backflow assembly?
10 inches
What is the hazard classification of a situation where an RPBA is installed but no air gap is present?
Severe
What is the minimum pipe size required for a backflow preventer installation?
3/4 inch
What is the purpose of a cross-connection control method?
To prevent backflow into the potable water supply
What type of backflow prevention device is typically used in a high hazard situation?
RPBA with air gap
What is the purpose of a backflow preventer?
To prevent the flow of contaminated water into the potable water supply
Study Notes
Backflow Prevention
- Bypasses are prohibited except where an equivalent backflow preventer is installed on the bypass.
Clearance Requirements
- Minimum clearance to RV opening is 30".
- Clearance in front of a backflow assembly is 30" or 1500mm.
- Back clearance to any backflow assembly is 3/4" or 20mm.
- Required vertical clearance for a testable assembly is 12" or 300mm.
Hazard Ratings
- A heat exchanger with double wall leak path requires severe protection.
- Required potable water protection in a Waste Water Treatment Plant is RPBA + Air Gap.
- If refused entry to a premise, the hazard rating becomes severe.
- The hazard rating of a Trap Primer is severe.
- A plating tank is hazard rated as severe.
- Required protection for make-up water to a plating tank is RPBA.
- The required protection for a pressurized tank make-up water with a severe hazard rating is RPBA.
Backflow Prevention Devices
- RPBA is required for backflow protection in a Waste Water Treatment Plant.
- A backflow preventer on a boiler is defined as a device that prevents backflow from occurring.
Testing and Maintenance
- Before initial installation of a backflow preventer, ensure proper clearance and installation.
- To test a RPBA, put CV1 under backpressure, then test the relief valve.
- If the relief valve on a RPBA opens at less than 2 psi, the spring is weaker than required.
- The check valve requirements for PVB (SRPVB) are critical.
- The first step on PVB testing is to ensure proper installation and clearance.
Backflow Conditions
- Backpressure can be caused by a Fire pumper truck or a closed system.
- Backsiphonage can occur due to a drop in system pressure.
- A closed loop can be created by a PRV, but not a check valve.
- High velocity flow in a pipe can cause erosion and damage.
Other Concepts
- Auxiliary water sources include elevated customer tanks, onsite wells, and cisterns, but not municipal water.
- A common feature of test cocks and Shut-off valves is that they are used for testing and maintenance.
- An AVB cannot be used on a severe hazard application.
- Supply water protection on a Commercial/Industrial Boiler system with chemicals requires RPBA protection.
This quiz covers essential concepts and regulations related to backflow prevention, bypasses, and parallel installations in plumbing systems.
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