1. Water utilities are increasingly requiring premise isolation backflow prevention to protect water supplies from contamination risks on customer properties.
2. Industry standards now recognize outdoor aboveground installation as the best practice for premise isolation systems due to risks of indoor installations. Indoor vaults and in-building placements increase safety, liability and flooding risks.
3. The presentation provides details on the risks of different placement methods and argues for adopting standard details for outdoor aboveground systems to address professional liability concerns and meet recognized best practices.
2. Part 3: Placement Practices
Premise Isolation Backflow Prevention:
Best Practices & Standard Details
3. Premise Isolation: Best Practices & Standard Details
….Definitions and term use:
Isolation backflow prevention: In addition to the lavatory and water fountain, most buildings’
plumbing systems include fixtures that are designed to clean contaminated equipment,
carbonate beverages, and even infuse chemicals and detergents. Many of these processes
create dangerous and toxic substances. If these substances were allowed to reverse back into
the building’s fresh water piping, an event known as backflow, it would create serious health
hazards for the individuals on site. Building authorities deal with these risks by specifying
appropriate backflow preventer assemblies at those specific locations where contamination is a
risk. The term for this solution is “isolation backflow prevention” because a special plumbing
apparatus known as a backflow preventer isolates high-hazard fixtures and equipment at the
point of use from the rest of the on-site piping system.
4. ….Definitions and term use:
Containment or ‘Premise Isolation’ backflow prevention: For public water systems, water that
has been delivered through its water meter to a water customer is only done safely and
responsibly when there is no possibility that that water will return back from the customer to
the water system, an event (also) known as backflow. Disparate groups within plumbing,
design, and water management have devised their own favorite terms for this system. The
plumbing community prefers “Containment backflow prevention” because such systems
contain delivered water at the subscriber’s premises; On the other hand, water districts tend to
prefer “Premise Isolation”. It is important to understand that whether called Containment or
Premise Isolation, we are referring to the task of eliminating backflow at the Point of Supply
from the public water system.
This presentation is limited to the recognized best practices of these containment or premise
isolation systems.
Premise Isolation: Best Practices & Standard Details
5. Introduction
The water engineering community has been struggling with new
professional liability risk involving the location of premise isolation backflow
preventer systems; Not because of new design practices, but because of
new information about the old practices. There has been a slow trickle of
warnings for years, but in the past 3 years important organizations and
industry leaders have added new warnings with much stronger language
that not only change recognized best practices, but actually challenge the
fitness and safety of older placement methods altogether.
Premise Isolation: Best Practices & Standard Details
6. Introduction
Can we rid ourselves of the
problem by dumping the
system itself?
Sadly, we are learning
through SCADA and AMI
that there is actually more
backflow occurring at the
premise than we previously
suspected.
Premise Isolation: Best Practices & Standard Details
7. Introduction
And with this new risk realization comes a new interested party: The
insurance company. Because of this very public commentary from experts
and leading groups, casualty carriers, through subrogation, have new
weapons for damage recovery. And anytime the accused designer is able to
demonstrate that local government contributed, whether materially or
passively, to the poor design, the water district and/or building authority
may be at risk for the liability.
Premise Isolation: Best Practices & Standard Details
8. Assuming the legal rights of a person for whom expenses or a debt has been paid.
Typically, an insurance company which pays its insured client for injuries and losses then
sues the party which the injured person contends caused the damages to him/her.
Introduction
Because of subrogation, the water district needs to
demonstrate that no unsafe methods are
promoted by their plans review teams. The best
way to demonstrate that is with published
standard details and drawings that are consistent
with recognized best practices.
Premise Isolation: Best Practices & Standard Details
9. Introduction
…Meanwhile, at the 2016-17 bi-annual conference of the American Society
of Plumbing Engineers, one popular learning module titled “Let the Civil
Engineer Deal with the Containment Backflow System” suggests that
leadership is seeking reassignment of the premise isolation backflow system
design to the civil discipline. No surprise, other than how long it took to
realize… Plumbing engineers have nothing to gain and everything to lose
when they specify indoor RPZs because
• The flood risks now being realized from indoor installations of RPZs is
extraordinary;
• Designing for outdoor placement includes grading and surface contouring
for sudden flood water flows; a task that is beyond the scope of a
plumbing engineer’s training or expertise.
Premise Isolation: Best Practices & Standard Details
10. Introduction
According to a survey of 1220 U.S. civil
and plumbing engineers conducted
over a 19‐month period, 3 out of 4 say
they need local water authorities to
provide standard details for outdoor
aboveground backflow preventer
systems.
You can read more about the results of
this survey here.
Premise Isolation: Best Practices & Standard Details
11. • Water Districts NEED
Premise Isolation in
order to fulfill their EPA
mandate; and
Introduction
Bottom Line:
“…. The return of any water to the
public water system after the water
has been used for any purpose on
the customer’s premises or within the
customer’s piping system is unacceptable
and opposed by AWWA.…”
• Premise-Isolation design details and specifications need to be provided to
civil engineers because of their general familiarity with standard details
and their comparable lack of familiarity with backflow systems.
AWWA’s preamble to the Cross Connection Control Manual,
published by EPA
Premise Isolation: Best Practices & Standard Details
12. 1. Water utilities are seeking more
premise-isolation.
2. That more containment systems are
being specified as RPZ regardless of
hazard threshold.
3. AWWA, ASPE, & the legal community
recognize “outside aboveground” as
‘best practice’ for premise isolation.
This presentation will show…
Introduction
Premise Isolation: Best Practices & Standard Details
13. Above ground in an enclosure
Inside a building
Inside a vault
Placement Practices
3 options for backflow preventer placement
Premise Isolation: Best Practices & Standard Details
14. Inside a vault
Placement Practices
3 options for backflow preventer placement
A subterranean vault would have to be considered the legacy method still
widely practiced among designers today but as most of you know, an RPZ
can never be installed below grade . Beyond the issue of being unsuitable
for RPZs however, there are compelling reasons to discontinue the use of
vaults altogether.
Premise Isolation: Best Practices & Standard Details
15. Placement Practices
We’ve all seen the extraordinary measures
OSHA imposes to legally access vaults for
maintenance tasks. fresh air exchange hoses,
tents, extra men. The costs are more and more
prohibitive but frankly, the risk of serious injury
is real as well. But beyond the cost of safety for
onsite workers, liability issues persist.
Inside a vault
3 options for backflow preventer placement
1. Safety
Premise Isolation: Best Practices & Standard Details
16. Placement Practices
When a vault floods like this one, the
mandatory test cocks are submerged, and in
that event, a violation of the International
Plumbing Code has already occurred. Consider
what would typically make up the constituents
of that water. Runoff of lawn chemicals alone
make this a clear and present danger to the
water supply.
Inside a vault
3 options for backflow preventer placement
2. Liability
Premise Isolation: Best Practices & Standard Details
17. Placement Practices
In fact, it led the USC Foundation of Cross
Connection & Hydraulic Research in 2005 to
change their recommendation of even double
check BFP installation in vaults.
“The foundation’s recommendation would be
to install the double check valve above grade.”
- USC-FCCHR “Crosstalk, Summer 2005
Inside a vault
3 options for backflow preventer placement
2. Liability
Premise Isolation: Best Practices & Standard Details
18. Placement Practices
The foundation added stronger language in
2014.
“When a backflow preventer is installed below
grade, the vault or pit in which an assembly is
installed may fill up with water, The water in the
pit could create a cross-connection between the
water in the pit and the backflow preventer
through the test cocks. This may occur whether
the test cocks are opened or closed….”
- USC-FCCHR “Crosstalk, Summer 2014 .
2. Liability
Inside a vault
3 options for backflow preventer placement
Premise Isolation: Best Practices & Standard Details
19. Placement Practices
Buildings, through their normal life of changing
tenants over time, change uses with respect to
hazard levels, and hazard levels, or more
precisely, the named high-hazard threshold,
has become a moving target.
Inside a vault
3 options for backflow preventer placement
3. Changing Demands
Premise Isolation: Best Practices & Standard Details
20. Placement Practices
Around the corner from our Nashville office, I
snapped this picture. It sits in front of a
warehouse owned by an automotive dealer.
When they bought the property and erected
the building, they put a double-check BFP
down in that vault with the meter.
Inside a vault
3 options for backflow preventer placement
3. Changing Demands
Premise Isolation: Best Practices & Standard Details
21. Placement Practices
A few years later, the city changed an
ordinance that redefined their particular use to
high-hazard. When they sought a permit to
upgrade the HVAC system, the city forced them
to change to an RPZ. So after constructing this
huge vault, they now leave it almost empty
with an RPZ in an enclosure perched on top of
it. They easily paid 3X the necessary cost
because they began with a “DC-only” solution.
Designers need to contemplate these latter-day
retrofits as they make design decisions.
Inside a vault
3 options for backflow preventer placement
3. Changing Demands
Premise Isolation: Best Practices & Standard Details
22. Above ground in an enclosure
Inside a building
Inside a vault
Placement Practices
3 options for backflow preventer placement
If the double check valve is commonly installed in a vault, then equally
common is that the RPZ is installed in an indoor location.
Premise Isolation: Best Practices & Standard Details
23. Inside a building
Placement Practices
3 options for backflow preventer placement
1. Space allocation/Accessibility
The space provided for an indoor BPA is
routinely inadequate as provided by the
architect. That’s because giving up space that
would otherwise add value is being allocated
as non-revenue space. Non-revenue space is
the enemy of every development project.
Premise Isolation: Best Practices & Standard Details
24. Inside a building
Placement Practices
3 options for backflow preventer placement
The BPA pictured cost tens of thousands in
property value. Even a mere 3” indoor BPA
will cost a developer $6,000 to $9,000 more
than an outdoor installation in a heated
enclosure. A separate presentation discusses
the real costs of indoor backflow preventer
installation in detail.
1. Space allocation/Accessibility
Premise Isolation: Best Practices & Standard Details
25. Inside a building
Placement Practices
3 options for backflow preventer placement
2. Professional liability: indoor flooding
Here’s what the American Society of Plumbing
Engineers advise about indoor RPZs.
“Before an RPZ is located, consideration should be
given to both how much water will be discharged,
and where it will drain. Consideration must be given
to the drain system to assure the drainage system
can handle the load. If a drain is not capable of
accepting the flow, other choices as to the location
of the valve, such as outside in a heated enclosure,
should be made.”
-2006 ASPE Plumbing
Engineering Design Handbook, vol 2, p 70
Premise Isolation: Best Practices & Standard Details
26. Inside a building
Placement Practices
3 options for backflow preventer placement
This flood occurred
in a hospital
mechanical room
causing over $1M
in damage.
2. Professional liability: indoor flooding
Premise Isolation: Best Practices & Standard Details
As we have
illustrated, an RPZ,
behaving as
designed, creates
a sudden flood.
27. Inside a building
Placement Practices
3 options for backflow preventer placement
This is two sides of
1 wall. On the left,
we see that the
sudden water flow
and volume moved
the wall into the
next room (right
photo), which
happened to be a
telephone and low-
voltage wiring
room.
2. Professional liability: indoor flooding
Premise Isolation: Best Practices & Standard Details
28. Inside a building
Placement Practices
3 options for backflow preventer placement
The insurer sought
recovery from all
the risk holders
including the
engineer, architect,
contractor,
subcontractor, and
even the most
recent recorded
tester;
2. Professional liability: indoor flooding
Premise Isolation: Best Practices & Standard Details
29. Inside a building
Placement Practices
3 options for backflow preventer placement
While the details of
who paid what
were not made
public, we do know
that the property
insurer was made
whole by one or
more of the listed
defendants.
2. Professional liability: indoor flooding
Premise Isolation: Best Practices & Standard Details
30. Inside a building
Placement Practices
3 options for backflow preventer placement
In times past, this
event would have
been seen as an
unforeseeable
casualty, a pipe
burst. But insurers
have been listening
to the next part of
the discussion. This
commentary from
experts changed
everything.
2. Professional liability: indoor flooding
Premise Isolation: Best Practices & Standard Details
31. Inside a building
Placement Practices
3 options for backflow preventer placement
So if an RPZ is designed to dump water, then drain
capacity is the issue. The chart on the right is from
the manufacturer of the BPA seen in the previous
flood photos. It illustrates the anticipated flow rate
from the relief valve at various pipe sizes and at
various pressures. Here is a link to the this chart for
Watts devices. Note that the assembly shown will
flow 375 GPM at 85 PSI. A 4” drain pipe with a 1%
fall rate evacuates clean water at a maximum rate of
93 GPM. If that device is flowing at 375 GPM and
your clearing 93, then you are flooding at a rate of
282 GPM.
2. Professional liability: indoor flooding
Premise Isolation: Best Practices & Standard Details
32. Inside a building
Placement Practices
3 options for backflow preventer placement
An article published June 2013 in
the Chicago chapter of the
American Society of Plumbing
Engineers written by David
DeBord, a former president of
that organization, and current
Education chair of the national
ASPE, states all these facts better
than I can.
2. Professional liability: indoor flooding
Premise Isolation: Best Practices & Standard Details
33. Inside a building
Placement Practices
3 options for backflow preventer placement
He uses the Manufacturer’s data
supplied by a different
manufacturer, and he uses a 65
PSI instead of my 85, but he
actually does the math in the
article and offers FLOOD rates or
219 GPM for 2 1/2 and 3”; and
flood rate of 482 GPM for 4”
and above.
2. Professional liability: indoor flooding
Premise Isolation: Best Practices & Standard Details
34. Backflow Failure
Placement Practices
Inside a building
3 options for backflow preventer placement
Watch this video showing a
check valve failure and the
resulting flood water flow.
2. Professional liability: indoor flooding
Premise Isolation: Best Practices & Standard Details
35. Above ground in an enclosure
Inside a building
Inside a vault
Placement Practices
3 options for backflow preventer placement
Premise Isolation: Best Practices & Standard Details
36. Above ground in an enclosure
Placement Practices
3 options for backflow preventer placement
In 1996, the American Society of
Sanitary Engineers (ASSE) developed a
quality and safety standard for
aboveground enclosures as a product
class. It’s known as ASSE-1060 and it
addresses 5 concerns.
• Freeze protection to −30°
• Vertical load strength of 100 PSF,
• Full flow drainage capacity, etc.
• Reliable Access
• Keyed Security
1. Quality, 2. Safety, 3. Security
Premise Isolation: Best Practices & Standard Details
37. Above ground in an enclosure
Placement Practices
3 options for backflow preventer placement
Moreover, they took the guidance
further by identifying all possible
climate conditions and defining
appropriate guidance for Freeze-
prone areas (Class I); Frost-only areas
(Class II); and warm areas where no
climate control of any kind is required
(Class III).
1. Quality, 2. Safety, 3. Security
Premise Isolation: Best Practices & Standard Details
38. Above ground in an enclosure
Placement Practices
3 options for backflow preventer placement
“An outdoor, aboveground BFP installation may be the best way to
1) reduce the owner’s exposure to damage caused by flooding
and the corresponding water contamination caused by a cross-
connection; and
2) reduce the legal liability of the design engineers, the installers,
and the certified testers whose professional actions, in part, may have
otherwise caused the flooding harm. The water industry has a
nationally accepted design criteria in ASSE’s Standard-1060 to
protect these installations. It’s a win-win-win ‘insurance policy’.
Douglas Cregor, Esq.
4. Legal endorsement
Premise Isolation: Best Practices & Standard Details
Indianapolis attorney, Doug Cregor has been the leading
attorney in the U.S. specializing in cross-connection control
litigation and advocacy. He is quoted in Plumbing Standards
Magazine as follows…
39. The public water supply is unprotected from returning water without a
premise isolation system. RPZs are only fail-safe solution.
The duties of the building/plumbing authority and the plumbing code do not
wholly satisfy the duties of the water utility.
Indoor RPZs 3” and larger are perpetual floods risks.
The need to address sudden on-site water flows disqualify MEPs from outdoor
premise isolation design, even if within MEP halo.
Civil engineers are unfamiliar with BPA installations and need standard
details from water authorities.
Take-Aways
A broadly adopted region-wide set of guidelines would save cities 000s of
hours in plans-review time.
Premise Isolation: Best Practices & Standard Details
40. Safe-T-Cover's blog: Updated weekly with articles on backflow prevention,
standard details, and best practices.
Enclosure Design eBook: Learn the 5 design considerations for
aboveground enclosures
Recent story on decision to add standard details by the city of Arlington, Texas
Trends in Backflow Preventer Installation: A downloadable guide to the latest
trends in backflow best practices.
Additional Resources
Premise Isolation: Best Practices & Standard Details
The Eng commty: struggling w/ new professional liability risk involving the location of PremISO Backflow preventer systems.
not because new design practice,
but because of new information about the old practices.
Slow trickle of warnings for years,
* past two years: imp orgs and ind’ry leaders have added new warnings, much stronger lang:
not only change recognized best practices,
but actually challenge the fitness and safety of older placement methods altogether.
Can we rid ourselves of the problem by dumping the system itself?
More backflow is occurring than was previously believed
And with this new risk realization comes a new Interested Party. The insurance company.
Because of this very public commentary from experts, they now have new weapons for damage recovery.
And anytime the designer is able to demonstrate that local government was causal to the poor design,
they, through the magic of subrogation,
have at least one more pocket to pick.
* The Local Water Authority.
MEANWHILE, In the October Bi annual conf of the ASPE,
Plumbing engineers are seeking reassignment of the Prem-Iso BP system design to the civil discipline due to
1. the flood risks now being realized from indoor installations of RPZs;
2 .the realization that designing BPAs for outdoor placement includes grading and surface contouring for
sudden flood water flows which are beyond the scope of a plumbing engineer’s expertise.
According to a survey of 1220 civil and plumbing engineers in North central Texas
conducted over a 19‐month period, 3 out of 4 say they need local water authorities to provide standard details for outdoor aboveground backflow preventer systems.
The bottom line: Water districts need premise isolation, and
Premise isolation design specifications need to be provided for civil engineers.
Consider these facts.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
So let’s look at the considerations.
Safety, Liability, and changing demands
* We’ve all seen the extraordinary measures OSHA imposes to legally access vaults for maintenance tasks. fresh air exchange hoses, tents, extra men. The costs are more and more prohibitive but frankly, the risk of serious injury is real as well.
* But beyond the cost of safety for onsite workers, liability issues persist.
* When a vault floods like this one, the mandatory test cocks are submerged, and in that event, a violation of the International Plumbing has likely already occurred. The water may look clean, but consider what would typically make up the constituents of that water. Runoff of lawn chemicals alone make this a clear and present danger to the water supply. In fact, it led the USC Foundation of Cross Connection & Hydraulic Research in 2005 to change their recommendation of even double check BFP installation in vaults.
* (READ)
Finally, Changing demands. Engineers are obviously preoccupied with new construction.
But buildings, through their normal life of changing tenants over time, change uses with respect to hazard levels, and hazard levels, or more precisely, the named high-hazard threshold, has become a moving target.
Around the corner from our office in Nashville, I snapped this picture. It sits in front of a warehouse owned by an automotive dealer. When they bought the property and erected the building, they put a double-check BFP down in that vault with the meter.
A few years later, the city changed an ordinance that redefined their particular use to high-hazard. When they sought a permit to upgrade the HVAC system, the city forced them to change to an RPZ. After constructing this huge vault, they now leave it almost empty with an RPZ in an enclosure perched on top of it. They paid three times for a single solution.
Now this enclosure – This is what happens all too often when tenants or hazard thresholds change in areas where no guidelines or Standard Details exist.
So let’s look at the considerations.
Safety, Liability, and changing demands
* We’ve all seen the extraordinary measures OSHA imposes to legally access vaults for maintenance tasks. fresh air exchange hoses, tents, extra men. The costs are more and more prohibitive but frankly, the risk of serious injury is real as well.
* But beyond the cost of safety for onsite workers, liability issues persist.
* When a vault floods like this one, the mandatory test cocks are submerged, and in that event, a violation of the International Plumbing has likely already occurred. The water may look clean, but consider what would typically make up the constituents of that water. Runoff of lawn chemicals alone make this a clear and present danger to the water supply. In fact, it led the USC Foundation of Cross Connection & Hydraulic Research in 2005 to change their recommendation of even double check BFP installation in vaults.
* (READ)
Finally, Changing demands. Engineers are obviously preoccupied with new construction.
But buildings, through their normal life of changing tenants over time, change uses with respect to hazard levels, and hazard levels, or more precisely, the named high-hazard threshold, has become a moving target.
Around the corner from our office in Nashville, I snapped this picture. It sits in front of a warehouse owned by an automotive dealer. When they bought the property and erected the building, they put a double-check BFP down in that vault with the meter.
A few years later, the city changed an ordinance that redefined their particular use to high-hazard. When they sought a permit to upgrade the HVAC system, the city forced them to change to an RPZ. After constructing this huge vault, they now leave it almost empty with an RPZ in an enclosure perched on top of it. They paid three times for a single solution.
Now this enclosure – This is what happens all too often when tenants or hazard thresholds change in areas where no guidelines or Standard Details exist.
So let’s look at the considerations.
Safety, Liability, and changing demands
* We’ve all seen the extraordinary measures OSHA imposes to legally access vaults for maintenance tasks. fresh air exchange hoses, tents, extra men. The costs are more and more prohibitive but frankly, the risk of serious injury is real as well.
* But beyond the cost of safety for onsite workers, liability issues persist.
* When a vault floods like this one, the mandatory test cocks are submerged, and in that event, a violation of the International Plumbing has likely already occurred. The water may look clean, but consider what would typically make up the constituents of that water. Runoff of lawn chemicals alone make this a clear and present danger to the water supply. In fact, it led the USC Foundation of Cross Connection & Hydraulic Research in 2005 to change their recommendation of even double check BFP installation in vaults.
* (READ)
Finally, Changing demands. Engineers are obviously preoccupied with new construction.
But buildings, through their normal life of changing tenants over time, change uses with respect to hazard levels, and hazard levels, or more precisely, the named high-hazard threshold, has become a moving target.
Around the corner from our office in Nashville, I snapped this picture. It sits in front of a warehouse owned by an automotive dealer. When they bought the property and erected the building, they put a double-check BFP down in that vault with the meter.
A few years later, the city changed an ordinance that redefined their particular use to high-hazard. When they sought a permit to upgrade the HVAC system, the city forced them to change to an RPZ. After constructing this huge vault, they now leave it almost empty with an RPZ in an enclosure perched on top of it. They paid three times for a single solution.
Now this enclosure – This is what happens all too often when tenants or hazard thresholds change in areas where no guidelines or Standard Details exist.
So let’s look at the considerations.
Safety, Liability, and changing demands
* We’ve all seen the extraordinary measures OSHA imposes to legally access vaults for maintenance tasks. fresh air exchange hoses, tents, extra men. The costs are more and more prohibitive but frankly, the risk of serious injury is real as well.
* But beyond the cost of safety for onsite workers, liability issues persist.
* When a vault floods like this one, the mandatory test cocks are submerged, and in that event, a violation of the International Plumbing has likely already occurred. The water may look clean, but consider what would typically make up the constituents of that water. Runoff of lawn chemicals alone make this a clear and present danger to the water supply. In fact, it led the USC Foundation of Cross Connection & Hydraulic Research in 2005 to change their recommendation of even double check BFP installation in vaults.
* (READ)
Finally, Changing demands. Engineers are obviously preoccupied with new construction.
But buildings, through their normal life of changing tenants over time, change uses with respect to hazard levels, and hazard levels, or more precisely, the named high-hazard threshold, has become a moving target.
Around the corner from our office in Nashville, I snapped this picture. It sits in front of a warehouse owned by an automotive dealer. When they bought the property and erected the building, they put a double-check BFP down in that vault with the meter.
A few years later, the city changed an ordinance that redefined their particular use to high-hazard. When they sought a permit to upgrade the HVAC system, the city forced them to change to an RPZ. After constructing this huge vault, they now leave it almost empty with an RPZ in an enclosure perched on top of it. They paid three times for a single solution.
Now this enclosure – This is what happens all too often when tenants or hazard thresholds change in areas where no guidelines or Standard Details exist.
So let’s look at the considerations.
Safety, Liability, and changing demands
* We’ve all seen the extraordinary measures OSHA imposes to legally access vaults for maintenance tasks. fresh air exchange hoses, tents, extra men. The costs are more and more prohibitive but frankly, the risk of serious injury is real as well.
* But beyond the cost of safety for onsite workers, liability issues persist.
* When a vault floods like this one, the mandatory test cocks are submerged, and in that event, a violation of the International Plumbing has likely already occurred. The water may look clean, but consider what would typically make up the constituents of that water. Runoff of lawn chemicals alone make this a clear and present danger to the water supply. In fact, it led the USC Foundation of Cross Connection & Hydraulic Research in 2005 to change their recommendation of even double check BFP installation in vaults.
* (READ)
Finally, Changing demands. Engineers are obviously preoccupied with new construction.
But buildings, through their normal life of changing tenants over time, change uses with respect to hazard levels, and hazard levels, or more precisely, the named high-hazard threshold, has become a moving target.
Around the corner from our office in Nashville, I snapped this picture. It sits in front of a warehouse owned by an automotive dealer. When they bought the property and erected the building, they put a double-check BFP down in that vault with the meter.
A few years later, the city changed an ordinance that redefined their particular use to high-hazard. When they sought a permit to upgrade the HVAC system, the city forced them to change to an RPZ. After constructing this huge vault, they now leave it almost empty with an RPZ in an enclosure perched on top of it. They paid three times for a single solution.
Now this enclosure – This is what happens all too often when tenants or hazard thresholds change in areas where no guidelines or Standard Details exist.
So let’s look at the considerations.
Safety, Liability, and changing demands
* We’ve all seen the extraordinary measures OSHA imposes to legally access vaults for maintenance tasks. fresh air exchange hoses, tents, extra men. The costs are more and more prohibitive but frankly, the risk of serious injury is real as well.
* But beyond the cost of safety for onsite workers, liability issues persist.
* When a vault floods like this one, the mandatory test cocks are submerged, and in that event, a violation of the International Plumbing has likely already occurred. The water may look clean, but consider what would typically make up the constituents of that water. Runoff of lawn chemicals alone make this a clear and present danger to the water supply. In fact, it led the USC Foundation of Cross Connection & Hydraulic Research in 2005 to change their recommendation of even double check BFP installation in vaults.
* (READ)
Finally, Changing demands. Engineers are obviously preoccupied with new construction.
But buildings, through their normal life of changing tenants over time, change uses with respect to hazard levels, and hazard levels, or more precisely, the named high-hazard threshold, has become a moving target.
Around the corner from our office in Nashville, I snapped this picture. It sits in front of a warehouse owned by an automotive dealer. When they bought the property and erected the building, they put a double-check BFP down in that vault with the meter.
A few years later, the city changed an ordinance that redefined their particular use to high-hazard. When they sought a permit to upgrade the HVAC system, the city forced them to change to an RPZ. After constructing this huge vault, they now leave it almost empty with an RPZ in an enclosure perched on top of it. They paid three times for a single solution.
Now this enclosure – This is what happens all too often when tenants or hazard thresholds change in areas where no guidelines or Standard Details exist.
So let’s look at the considerations.
Safety, Liability, and changing demands
* We’ve all seen the extraordinary measures OSHA imposes to legally access vaults for maintenance tasks. fresh air exchange hoses, tents, extra men. The costs are more and more prohibitive but frankly, the risk of serious injury is real as well.
* But beyond the cost of safety for onsite workers, liability issues persist.
* When a vault floods like this one, the mandatory test cocks are submerged, and in that event, a violation of the International Plumbing has likely already occurred. The water may look clean, but consider what would typically make up the constituents of that water. Runoff of lawn chemicals alone make this a clear and present danger to the water supply. In fact, it led the USC Foundation of Cross Connection & Hydraulic Research in 2005 to change their recommendation of even double check BFP installation in vaults.
* (READ)
Finally, Changing demands. Engineers are obviously preoccupied with new construction.
But buildings, through their normal life of changing tenants over time, change uses with respect to hazard levels, and hazard levels, or more precisely, the named high-hazard threshold, has become a moving target.
Around the corner from our office in Nashville, I snapped this picture. It sits in front of a warehouse owned by an automotive dealer. When they bought the property and erected the building, they put a double-check BFP down in that vault with the meter.
A few years later, the city changed an ordinance that redefined their particular use to high-hazard. When they sought a permit to upgrade the HVAC system, the city forced them to change to an RPZ. After constructing this huge vault, they now leave it almost empty with an RPZ in an enclosure perched on top of it. They paid three times for a single solution.
Now this enclosure – This is what happens all too often when tenants or hazard thresholds change in areas where no guidelines or Standard Details exist.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
So if these things are designed to dump water, then drain capacity is the issue. The chart on the left is from Wilkins. It’s the Relief Valve Discharge Rate chart of its top of the line, 375 RPZ. It illustrates the flow rate of that device in various sizes and at various pressures.
Note that a 2 1/2 inch device will flow 375 GPM at 85 PSI. If you remember your fluid volume tables, you’ll recall that a 4” drain pipe with a 6 inch fall per 100 horizontal feet evacuates clean water at a rate of 93 GPM. If that device is flowing at 375 GPM and your clearing 93, then you are flooding at a rate of 282 GPM.
The chart on the right is a Drain Requirements chart created by the city of Columbus, OH. It’s importance cannot be overstated. It reveals that unless you intend to utilize 8” drain pipes at a 6” per 100 horizontal feet fall-rate all the way to the sewer, you cannot justify anything larger inside than a 2” RPZ inside.
* An article published this summer in the Chicago chapter of the American Society of Plumbing Engineers written by David DeBord, a former president of that organization, states all these facts better than I can.
He uses the Manufacturer’s data supplied by the Watts Corporation and he uses a 65 PSI instead of my 85, but he actually does the math in the article and offers FLOOD rates or 219 GPM for 2 1/2 and 3”; and flood rate of 482 GPM for 4” and above.
* He concludes that regarding indoor RPZs, : (READ)
So if these things are designed to dump water, then drain capacity is the issue. The chart on the left is from Wilkins. It’s the Relief Valve Discharge Rate chart of its top of the line, 375 RPZ. It illustrates the flow rate of that device in various sizes and at various pressures.
Note that a 2 1/2 inch device will flow 375 GPM at 85 PSI. If you remember your fluid volume tables, you’ll recall that a 4” drain pipe with a 6 inch fall per 100 horizontal feet evacuates clean water at a rate of 93 GPM. If that device is flowing at 375 GPM and your clearing 93, then you are flooding at a rate of 282 GPM.
The chart on the right is a Drain Requirements chart created by the city of Columbus, OH. It’s importance cannot be overstated. It reveals that unless you intend to utilize 8” drain pipes at a 6” per 100 horizontal feet fall-rate all the way to the sewer, you cannot justify anything larger inside than a 2” RPZ inside.
* An article published this summer in the Chicago chapter of the American Society of Plumbing Engineers written by David DeBord, a former president of that organization, states all these facts better than I can.
He uses the Manufacturer’s data supplied by the Watts Corporation and he uses a 65 PSI instead of my 85, but he actually does the math in the article and offers FLOOD rates or 219 GPM for 2 1/2 and 3”; and flood rate of 482 GPM for 4” and above.
* He concludes that regarding indoor RPZs, : (READ)
So if these things are designed to dump water, then drain capacity is the issue. The chart on the left is from Wilkins. It’s the Relief Valve Discharge Rate chart of its top of the line, 375 RPZ. It illustrates the flow rate of that device in various sizes and at various pressures.
Note that a 2 1/2 inch device will flow 375 GPM at 85 PSI. If you remember your fluid volume tables, you’ll recall that a 4” drain pipe with a 6 inch fall per 100 horizontal feet evacuates clean water at a rate of 93 GPM. If that device is flowing at 375 GPM and your clearing 93, then you are flooding at a rate of 282 GPM.
The chart on the right is a Drain Requirements chart created by the city of Columbus, OH. It’s importance cannot be overstated. It reveals that unless you intend to utilize 8” drain pipes at a 6” per 100 horizontal feet fall-rate all the way to the sewer, you cannot justify anything larger inside than a 2” RPZ inside.
* An article published this summer in the Chicago chapter of the American Society of Plumbing Engineers written by David DeBord, a former president of that organization, states all these facts better than I can.
He uses the Manufacturer’s data supplied by the Watts Corporation and he uses a 65 PSI instead of my 85, but he actually does the math in the article and offers FLOOD rates or 219 GPM for 2 1/2 and 3”; and flood rate of 482 GPM for 4” and above.
* He concludes that regarding indoor RPZs, : (READ)
Video showing a #1 check valve failure and debris in the relief valve holding it open.
See this video now at
https://www.youtube.com/watch?v=d7MjJuZQoYo
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
There are three options for backflow preventer placement.
3 possibilities, all three are widely practiced.
1.
2. Strong nat’l migration toward RPZ, away from DC with many standard details that have ceased to iteratively improve. That’s a business school way of saying Best practices are now evident because as time continues, cities are defining the same methods.
3. Indoor RPZ 2 ½” and larger cause floods and feed insurers. It’s not enough to say that some large indoor systems are poorly designed. If your building has a flange-sized RPZ inside and does not have at least an 8” drain system all the way to the sewer, then it fails the flood liability test and should not be there.
4. MEP engineers cannot stamp anything that is to be installed beyond 6’ of the building envelope so how can they design flange-sized RPZ systems at all?
5. Civil Engineers are not plumbers and need standard details provided by water authorities in order to properly design these systems.
6. Water authorities are driving these devices inside because “that’s the way everyone knows how to do it.” Continuing to direct and favor methods that are unsafe, or even less safe, expose the jurisdiction to liability risk.