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70 Cards in this Set
- Front
- Back
Shut off valves for backflow prevention SB |
Resilient seated shut off & full flow characteristics - Full port Ball valves - Resilient wedged gate valves |
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Bypass arrangement, Jumper connections, removable sections swivel or change over devices, hoses and hose bibs or the presence of an abundance of piping that cannot be traces. Are examples of ? |
A Potential Cross-Connection sitiuatioin |
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*** Physical location of CC protection devices (plateforms for the testable devices) Measured from Centerline Heigh above floor: PVB / SPPVB No more then ____ SCVAF / DCVA / DCVAF _____ RP / RPF |
PVB / SPPVB No more then 5 ' (1500mm) SCVAF / DCVA / DCVAF 2 1/2 - 5' &750-1500) RP / RPF 2 1/2 - 5' &750-1500) |
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AG, AVB, PVB, DCVA These protect against? |
BACKFLOW MODERATE CONDITION |
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AVB , DCAP protect in what applications |
BACKFLOW MINOR |
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LFVB Application, Lab Faucet Vacuum Breaker |
-Protect against Back siphonage only
- NOT to be used under constant pressure conditions - Used to isolate MINOR hazards * Used for Moderate, Severe hazards area or Premise isolation |
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Provision for Electrical currents on back flow protection devices |
If a backblow prevention assembly is to be removed from the line. Provide a jumper wire to by-pass strong electrical currents |
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Test cocks need to be what type |
SB Resilient seated test cocks w full flow charteristics: ball valves plug valves port needle valves |
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Generally speaking 3 authorities which concern themselves directly/individually with the quality & safety of water as it relates to health they are: |
Perveyor or the Water Utility Plumbing Inspector Medical Officer of Health |
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Where should an approved Backflow protection assembly be installed? |
Installed at the Service Connection to any premises where there is an auxiliary water supply even though there is not connection or cross connection. |
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Backflow - Severe Hazard what is used * Backflow not necessarly back pressure |
AVP PVB RP AG * Backflow not necessarly back pressure |
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DUC / DCV how to know the difference |
DUC, Duel Check vavle non testable DCV, Double Check valve, Testable |
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Barometric Loop, is it good CC protection? (Using the principle that a perfect vacuum can only lift water approx 10.4m or 34ft. A loop rising 107m or 35ft above the highest fixture on the premise being served. SB inspected yearly) |
Not recommended, backflow protection because: - Cumbersome - Difficult to protect from freezing - Can be easily nulified through tie-ins or bypass arrangements |
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AG, Air Gap what size |
- 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"
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What is Back Siphonage |
- 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. |
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Where would an Air Gap not be installed |
- 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. |
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What is a Severe Hazard Level |
A Cross Connection (or potential) involving any substance iin sufficient concentration to cause death, spread disease or illness |
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What is a Minor Hazard condition |
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. |
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How do repairs contribute to Cross-Connection |
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. |
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Back Pressure |
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 |
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An Atmosheric vacuum breaker, Dual check valve Hose connection VB Dual check valve with Atmospheric ports are: |
Non Testable devices |
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Are Plumbing Permits required to install Cross Connectio 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* |
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Area Protection |
Protection provided for a piping system section with potable and non-potable connections downstream of a back flow preventer |
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Can strainers be used on RP's used for Fire Protection |
- No, strainers SNotB used in Fire supression system as they reduce the flow characteristics - ULC could approve but must inquire. |
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Can a RP be by-passed? |
- 24 hrs of uninterrupted service a by-pass or parallel arrangement SB installed. - By pass must have the same degree of backflow protection. |
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What is an Auxiliary Water Supply |
Any water supply source or system other than the public water supply, that maybe available in a building or on a premise. |
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What is a Moderate Hazard |
A cross connection (or potential) involving any substance which has a low probability of becoming a severe hazard and would constitute a nuisance. |
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What is a Critical Level |
Level of submergence at which the back siphonage preventer ceases to prevent Back siphonage. |
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RP is constantly leaking |
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 |
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*** Where must an AIR Gap be used |
Air Gaps must be used - Sewage equipment - Non-potable or auxiliary water systems - Any lethal substance |
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Potential toxicity or probabiltiy of back flow what is of more concern? |
The Rick factor due to potential toxicity is of greater concern when selecting a backflow preventor than probability of backflow |
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What can happen with a pump as they pertain to back siphonage |
Back siphonage is the result of reduced water system pressure on the suction side of an in-line booster pump |
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What is a Backflow Preventer |
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. |
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AVB Installation requirements |
- No operation > the 12 hours continous pressure - Installed min of 6" above FLR - Vertically & where spillage is not objectionable - Effective against Backflow Only |
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*** PVB Installation requirements |
- Installed min of 12" above FLR - Vertically & where spillage is not objectionable - Effective against Backflow Only |
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*** Inplant or Premise isolation, what is better |
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. |
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Can pumps pose a contamination issue |
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 |
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What is Backflow & What causes backflow |
- 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 |
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Anti-siphon breaker (Device containing a shut-off valve followed by a valve body containing disc float assembly, a check seat and an air inlet port allowing water to drain) |
- 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. |
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Area-Isolation |
- 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. |
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Centreline Height above floor? (platforms for the testable devices |
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) |
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How long does a customer have to fix a failed device |
Testable cross connection control device repaired or replaced & retested within 5 working days. |
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RF opening pressures |
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 |
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What needs to happen if a failed device if found |
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. |
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RPF ? Parts ? |
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 |
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What is the minimum check valve differential of a DCVAF? |
Minimum check valve differential of a DCVAF is 3.4 kPa or 0.5 psi |
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Shut off #2 close and RP leaking |
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. |
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HCDVB flow function position of valves in normal flow pressure limitations |
- 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. |
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What si the minimum check valve differential of a DCVA? |
Min check valve differential of a DCVA is 6.9 kPa (1psi) |
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Shut off assemblies install after Jan 1, 1987, with metal to metal shut off valve or test cocks will be considered Unapproved |
Unapproved |
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HCVB Host connection Vacuum Breaker |
Force loaded check valve biased to NC position and an atmospheric vent that is NO Normally Open. |
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HCDVB Hose connection duel check Vacuum breaker |
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 |
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How many hours is a testin course? What mark do I need to on the exam |
- Testers course of instruction shall be 30 hours - Need a mark of 75% on the exam |
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Protection required for single story clinic Multi Story Clinic |
- 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 |
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Alarm Check what is it and is it an approved back flow preventer ? |
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 |
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What should happen if both shutoffs are closed & test cock #2 is open |
I both shutoffs are closed & test cock #2 is open, water should begin to discharge from the relief valve port |
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LFVB Installation: Back siphon / Back pressure? location |
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. |
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Is a permit required for a DUC? Dual check valve assembly |
No, not a testable device |
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Tester Recertificaiton requirements? |
Tester recertifationcause 9 hours min 3 hours ot Theory Min of 6 hours of practical 75 % on written exam Satifactory completion of practical exam |
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HCDVB test pressure & time? |
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. |
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LFVB Laboratory Faucet Vacuum Breaker |
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. |
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LFVB Function: Normal flow, no flow |
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. |
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LFVB Function Back siphonage |
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.` |
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RP Installation |
- 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 |
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SCVAF Function & Installation |
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 |
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1-SCVAF single check valve assembly for Fire Systems 2- Application? |
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 |
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What happens when RP supply pressure drops? |
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 |
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HCDVB / HCVB Installation |
- 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 |
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RP doesn't open after by passing water from High side to low side, what could be there reason |
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. |
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HCVB Function: normal backsiphonage |
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. |