Backflow training
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Backflow Training. Introduction to Backflow For Irrigation Systems. Agenda. Backflow definitions Hydraulics Degree of Hazard Types of Backflow Preventers Product Selection Approvals Installations. What is Backflow?.

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Backflow Training

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Backflow training

Backflow Training

Introduction to Backflow

For Irrigation Systems


Agenda

Agenda

  • Backflow definitions

  • Hydraulics

  • Degree of Hazard

  • Types of Backflow Preventers

  • Product Selection

  • Approvals

  • Installations


What is backflow

What is Backflow?

  • The undesirable reversal of flow of water or mixtures of water and other liquids, gases, or other substances into the potable water supply from any source or sources.


Normal flow

Normal Flow


What is a cross connection

What is a Cross Connection?

  • Any unprotected actual or potential connection between a public or a consumer’s potable water system and any other source or system through which it is possible to introduce into any part of the potable water system any used water, industrial fluid, gas, or substance other than the intended potable water with which the system is supplied.


What is a cross connection1

What is a Cross Connection?

  • A direct cross connection is subject to both back-siphonage and back-pressure.

    • Usually a hard piped connection

  • An in-direct cross connection is subject to back-siphonage only.

    • Can be a potential cross connection


Hydraulics

Hydraulics

  • Back-pressure

  • Back-siphonage

  • Head

  • Barometric loop

  • Continuous vs. non-continuous pressure


Back pressure

Back-Pressure

  • Any elevation of pressure in the downstream piping system above the supply pressure at the point of consideration which would cause a reversal of the normal direction of flow.

  • Causes

    • Change in elevation of the downstream piping.

    • High pressure piping interconnect


Back pressure1

Back-Pressure


Back pressure2

Back-Pressure


Back siphonage

Back-Siphonage

  • Any decrease of pressure that causes a negative or sub-atmospheric pressure to exist in the upstream piping ahead of the point of consideration which would cause a reversal of the normal direction of flow.

  • Causes

    • Undersize piping

    • Line breaks

    • High water withdrawal rates


Back siphonage1

Back-Siphonage


Back siphonage2

Back-Siphonage


Backflow training

Head

  • The term “head” is used to describe pressure.

  • One foot of head equals .433 pounds per square inch.

  • In the backflow industry, the pressure loss through the valve is called “head loss”.

  • All manufacturers express the head loss of their valves in units of pounds per square inch.


Backflow training

Head

27 3/4” of water generates a pressure of one pound per square inch (psi)

27 3/4”

1 psi


Barometric loop

Barometric Loop

  • A barometric loop is a horseshoe-shaped loop in a water line, that has a height greater than 33.9 ft.

  • A very effective means of preventing backflow due to back-siphonage.

  • Impractical due to physical size.


Pressure

Pressure

  • Non-continuous

    • System cannot realize more than 12 hours of continuous pressure per 24 hour period.

  • Continuous

    • Anything that is not non-continuous!


Degree of hazard

Low Hazard

Non-Health Hazard

Pollution

High Hazard

Health Hazard

Contamination

Degree of Hazard


Types of backflow preventers used in irrigation systems

Types of Backflow Preventers used in Irrigation Systems

  • Atmospheric Vacuum Breaker

  • Pressure Vacuum Breaker

  • Double Check Assembly

  • Reduced Pressure Principal Assembly


Types of non mechanical backflow preventers

Types of Non-Mechanical Backflow Preventers

  • Air Gap

    • A physical separation between the free flowing discharge end of a potable water supply pipeline and an open or non-pressure receiving vessel.

    • An “approved air gap” shall be at least double the diameter of the supply pipe measured vertically above the overflow rim of the vessel.

    • Never less than 1 inch.


Air gap

Air-Gap


Atmospheric vacuum breaker

Atmospheric Vacuum Breaker

  • Contains a float-check, a check seat, and an air inlet port.

  • Water flow causes the float to close the air inlet port.

  • When the flow of water stops...

    • The float falls and forms a check valve against back-siphonage

    • The air inlet port opens to allow air to enter and satisfy the vacuum.


Atmospheric vacuum breaker avb

Atmospheric Vacuum Breaker (AVB)

  • Protects against a health hazard

  • Back-siphonage condition only.

  • Non-continuous pressure application.

    • No more than 12 hours of pressure per 24 hour period

AVB


Atmospheric vacuum breaker1

Atmospheric Vacuum Breaker


Anti siphon valves

Anti-Siphon Valves

  • Non-Testable

  • Not USC Approved

  • Usually not inspected


Pressure vacuum breaker pvb

Pressure Vacuum Breaker (PVB)

  • Contains...

    • Independently-acting, internally-loaded check valve.

    • Independently-acting, loaded air inlet valve located on the discharge side of the check valve.

    • Two resilient-seated test cocks.

    • Two resilient-seated isolation valves.


Pressure vacuum breaker

Pressure Vacuum Breaker

  • Protects against a health hazard.

  • Back-siphonage condition only.

  • Continuous pressure application.

    • Can realize pressure for 12 hours or more per 24 hour period.

PVB


Pressure vacuum breaker1

Pressure Vacuum Breaker


Pressure vacuum breaker2

Pressure Vacuum Breaker


Double check valve assembly dc

Double Check Valve Assembly (DC)

  • Contains two independently-acting approved check valves.

  • Four resilient-seated test cocks.

  • Two resilient-seated isolation valves.


Double check valve assembly

Double Check Valve Assembly

  • Protects against a non-health hazard.

  • Back-pressure condition.

  • Back-siphonage condition.

  • Continuous pressure applications.

DC


Double check assembly small

Double Check Assembly - Small


Double check assembly large

Double Check Assembly - Large


Reduced pressure principal backflow preventer rp

Reduced Pressure Principal Backflow Preventer (RP)

  • Contains two independently-acting approved check valves.

  • A hydraulically-operating, mechanically independent differential pressure relief valve located between the two check valves.

  • Four resilient-seated test cocks.

  • Two resilient-seated isolation valves.


Reduced pressure principal backflow preventer

Reduced Pressure Principal Backflow Preventer

  • Protects against a health hazard.

  • Back-pressure condition.

  • Back-siphonage condition.

  • Continuous pressure applications.

  • The Ultimate in mechanical protection.

RP

Rules


Reduced pressure assembly small

Reduced Pressure Assembly - Small


Reduced pressure assembly large

Reduced Pressure Assembly - Large


Operation of an rp device

Operation of an RP Device


Backflow training

No-Flow Condition


Backflow training

Normal Flow


Backflow training

Backpressure with 2nd Check Fouled


Backflow training

Backsiphonage with 2nd Check Fouled


Troubleshooting an rp assembly

Troubleshooting an RP Assembly

  • Turn off number 2 shutoff valve

  • If discharge stops, problem is in 2nd Check


Troubleshooting an rp assembly1

Troubleshooting an RP Assembly

  • If discharge continues, induce flow by opening number four testcock

  • If discharge stops or slows dramatically, problem is in first check


Troubleshooting an rp assembly2

Troubleshooting an RP Assembly

  • If discharge continues with no change, problem is in relief valve


Product selection guide

Product Selection Guide


Specify the proper device for the application

Specify the Proper Device for the Application

  • We can communicate industry standards for degree of hazard, hydraulic and backflow conditions.

  • Up to authority having jurisdiction to make the final decision.


Approvals and listings

Approvals

FCCC&[email protected]

FM

Listings

ASSE

UPC

UL

CSA

AWWA (Voluntary Standard - Certified to)

Approvals and Listings


Installation requirements

Installation Requirements

  • Hydraulics

  • Accessibility for testing and repair

  • Indoor vs. Outdoor

  • Freeze protection

  • Vandal protection

  • Relief valve discharge


Pressure vacuum breaker installations

Pressure Vacuum Breaker Installations


Double check assembly installations

Below Grade

Above Grade

Double Check Assembly Installations


Rp assembly installations

RP Assembly Installations


Irrigation systems issues

Irrigation Systems Issues

  • Quick closing solenoid valves

    • Create water hammer

    • Cause RP to discharge

      • Soft seated check valve between solenoid and RP

    • Cause noise

      • Install water hammer arrestor


Water hammer devices

Soft Seated Check

Water Hammer Arrestor

Water Hammer Devices


Key terms

Accessible

Approved Assembly

Approved Check Valve

Isolation

Backflow program

Administrative Authority

Annual test

Certified Tester

Containment

Point of use

Key Terms


Thank you

Thank You


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