Cross Connection

Resilient seated shut off & full flow characteristics

- Full port Ball valves

- Resilient wedged gate valves

A Potential Cross-Connection sitiuatioin

PVB / SPPVB No more then 5 ' (1500mm)

SCVAF / DCVA / DCVAF 2 1/2 - 5' &750-1500)

RP / RPF 2 1/2 - 5' &750-1500)

BACKFLOW MODERATE CONDITION

BACKFLOW MINOR

- NOT to be used under constant pressure conditions

- Used to isolate MINOR hazards

* Used for Moderate, Severe hazards area or Premise isolation

If a backblow prevention assembly is to be

removed from the line.

Provide a jumper wire to by-pass strong electrical currents

SB Resilient seated test cocks w full flow charteristics:

ball valves

plug valves

port needle valves

Perveyor or the Water Utility

Plumbing Inspector

Medical Officer of Health

Installed at the Service Connection to any

premises where there is an auxiliary water supply even though there is not connection or cross connection.

AVP

PVB

RP

AG

* Backflow not necessarly back pressure

DUC, Duel Check vavle non testable

DCV, Double Check valve, Testable

Not recommended, backflow protection because: - Cumbersome

- Difficult to protect from freezing

- Can be easily nulified through tie-ins or bypass arrangements

- Unobstructed vertical distance between the

lowest opening from any pipe/fauchet conveying

water or waste to a tank, fixture AND the Flood Level Rim (FLR) of the receptable.

- 2 x Pipe D or 1"

- Never less than 1"

- Reversal of the normal direction of flow, due to Negative Pressure (Vacuum) being created in the system.

- This reduction in pressure causes atmospheric pressure to force polluted water up through a submerged fixture inlet.

- An Approved Air Gap SNotB installed in an

environment where the atmosphere maybe

contaminated i.e Fumehood

- For this reason Air Gaps SB included in yearly inspections.

A Cross Connection (or potential) involving any substance iin sufficient concentration to cause death, spread disease or illness

Existing condition, or potential connection

between the domestic water pipe and any pipe, vat or tank intended for holding potable water which has a low probability of becoming a

Moderate Hazard.

Whenever a distribution system is shutdown to accomidate repairs, a negative or reduced

pressures will occur at all locations within the

affected system which lie at the hight elevation then the break.

A pressure higher then the supply pressure

- Booster pump w/o backflow protection

- Potable water connections to boilers / other pressure devices w/o prevention devices

- Interconnection with other system operated at a higher pressure i.e. fertilzer injection system

- Water main break or Pumping for a Fire

Non Testable devices

-Yes, permits are required to install RP's, Double Check valves and Pressure Vacuum breakers

- No premits reqired for testing/repairing

*These are testable devices and must be

registered upon installation*

Protection provided for a piping system section with potable and non-potable connections

downstream of a back flow preventer

- No, strainers SNotB used in Fire supression

system as they reduce the flow characteristics

- ULC could approve but must inquire.

- 24 hrs of uninterrupted service a by-pass or

parallel arrangement SB installed.

- By pass must have the same degree of backflow protection.

Any water supply source or system other than the public water supply, that maybe available in a building or on a premise.

A cross connection (or potential) involving any substance which has a low probability of

becoming a severe hazard and would constitute a nuisance.

Level of submergence at which the back siphonage preventer ceases to prevent Back siphonage.

To a point it is doing its Job however

- Either the 1st check valve, the 2nd check valve or the Relief valve has failed.

The check valves SB cleaned of possible debris & rubber seat checked for damage

Air Gaps must be used

- Sewage equipment

- Non-potable or auxiliary water systems

- Any lethal substance

The Rick factor due to potential toxicity is of greater concern when selecting a backflow

preventor than probability of backflow

Back siphonage is the result of reduced water system pressure on the suction side of an in-line booster pump

An assembly or device which prohibits the

backflow of water into the potable water supply

* If it is open to atmosphere SNotB located where it could contaminate the water supply & the opening to atmoshere could be submerged & spillage from opening undersirable.

- No operation > the 12 hours continous pressure

- Installed min of 6" above FLR

- Vertically & where spillage is not objectionable

- Effective against Backflow Only

- Installed min of 12" above FLR

- Vertically & where spillage is not objectionable

- Effective against Backflow Only

Wherever possible, provide inplant isolation

(fixture and/or zone) because inplant personnel are protected and in most cases the back flow preventer can be siged smaller due to smaller

inplant piping.

Considerable case must be exercised to prevent the use of the suction side line to pumps for

sanitary, laboratory or industrial uses on lower floors.

Polutants or contaminants from equipment

supplied by take-off from the suction side line may easily be pumped through out the upper floors

- Flowing back/reversal of the normal direction of flow, allowing waste to enter a building through the drainage system.

- Causes: Unusual heavy rains, overloaded public sewers (undersize) blocked public sewers

- A device installed on a line that is designed to prevent a vacuum from forming in a piping system.

- Device can be under continous pressure.

* Don't confuse with a Atmospheric vacuum breaker.

- Confinement of sources of pollution or

contamination, existing/potential, within a

specified area

- Each source of pollution or containment within the controlled area maybe required protection.

Any installation with a > centreline measurement shall be proveded witha fixed Platform under assembly

PVB/ SPPVB no more than 5' (< 1500mm)

SCVAF/DCVA/ DCVAF 2.5-5' (750-1500mm)

RP / RPF 2.5-5f (750-1500 mm)

Testable cross connection control device repaired or replaced & retested within 5 working days.

Relief valve shall open at a minimum pressure differential of 13.8 kpa or an RP back flow preventer or 6.9 kPa for a RPF backflow preventer, as measured across check valve 1

An approved tester must submit a report in writing to the Director of Water Resources on as approve form within 2 business days where not repaired.

Same components as a RP & is designed specifically for use in Fire Protectiopn systems.

The min relief valve opening point is 6.9 kPa (1psi)

* RP opening point is 13.8 kPa or 2 psi

Minimum check valve differential of a DCVAF is

3.4 kPa or 0.5 psi

If shut off valve #2 on a RP is closed water begins to discharge from the relief valve port, check valve #1 is probably leaking. The check valve should be cleaned if possible debris & rubber seat checked for damage.

- No flow through the device the check valves are closed and the vent is open

- Designed for pressure only on water demand for short intermittent periods of time.

Min check valve differential of a DCVA is 6.9 kPa (1psi)

Unapproved

Force loaded check valve biased to NC position and an atmospheric vent that is NO Normally Open.

Consits of 2 independently acting check valves, force loaded to NC position.

Between the 2 checks is a means of venting to atmoshere force loaded to NO position

- Testers course of instruction shall be 30 hours

- Need a mark of 75% on the exam

- Single-story clinic, a double check valve will be adequate in most cases

- A reduced Pressure princble assembly for hospitals, mortuary, morque autopsy or any multi-storied clinic

A single, soft seated check valve which may or may not be internally loaded will sound an alarm when the check valve opens.

Shall have suitable connections for testing the water tightness & operation

* NON Approved backflow Preventer

I both shutoffs are closed & test cock #2 is open, water should begin to discharge from the relief valve port

Shall not be installed in a vent hood or wherre toxic / objectionable fumes occur.

- Installed on the Discharge side of the last control valve.

- Installed on a typical lab faucet goose neck.

No, not a testable device

Tester recertifationcause 9 hours min 3 hours ot Theory

Min of 6 hours of practical

75 % on written exam

Satifactory completion of practical exam

When back pressure equivalent to 3m of Heat is applied DS checkvalve on a HCDVB device, it shall not leak for 6 seconds or more this is normal

> 6 seconds however indicates the atmospheric vent if faulty and that the HCDVB device should be repaired.

2 independently acting check valves, force loaded or biased to a normally closed position, and between the check valves there is a means of automatically venting to atmosphere that is forced loaded or biased to a NO position.

Normal flow, primary check valve opens & the atmosheric vent is closed off by the deflection of a diaphram seal. The second check valve opens permitting flow throught the device.

- No flow (under pressure but not flow)

Primary check valves seats against the diaphram which in turn seals the atmosheric vent & the secondary check valve closes.

When back siphonagfe occurse the secondary check valve closes & the primay check valve seals / c;pses agaomst the diaphram.

The atmospheric vent is open permitting air to enter.

In the event that the secondary check valve fails, leakage would be vented through the atmospheric vent.`

- RP installed readily accessible

- Protectedfrom freezng & > from 43C (110F)

- Not be installed in a Pit/ or below ground level

- Relief valve port must have approved AB or max Flood Level (greater of two)

- If not for Fire Protection, a strainer ahead of preventer insome localities.

Horizontal Position

No Corrosive Fumes

Normal operation, the check valve opens permitting flow - Upon Backflow the check would close highly,preventing contamination of supply.

Install: readily accessible with adequate space

- No Pits unless drainage provided

On test cocks removed & plugged

- Horizontal Positioin

One internally loaded check valve installed between 2 tightly clising, resilient seated, shut off valves, complete with test cocks

2- Designed for use in Fire Protection systems that are constructed of acceptable potable water system materials, and that would only consitute a MINOR hazard

If the supply pressure drops, the relieve valve will maintain a minimum pressure in the zone between the 1st and 2nd check valves of approximently 13.8 kPa (2psi) & Lower that the supply pressure by releasing suffienient water to maintain the required differance in pressure. If supply pressure becomesa < 2 psi & the relief valve opens & discharges the reduced pressure zone the atmosphere

- Installed on hose threaded outlets i.e hose bibs, service sinks and wall hydrants

- installed on the discharge side of control vlve

- so air vent are not submerged

- not be subject to continous pressure

- Drainage type & it > 43C or above HW type required

- no toxit fumes

- where spillage is not objectionable

The Differential pressure relief valv doesn't open after by -passing water from hight to low side this could indicate either the relief valv e is falulty or shout off 2 is leaking

- If it the relief valve pressure will drip to 0Kpa

- If the shut off valve #2 the lower guage will need to be opened more than 1/4 open.

Normal flow the force leaded check valve opens and the atmospheric vent closes allowing water to flow thought the device

- No flow or with Back siphonage occurs the foruce leaded check valve will close, opening the atmospheric vent, allowing aire in the downstream.