Aqua designs for international projects require specialized training and knowledge.
International Codes
Many international locations have few, if any, aqua design codes or standards. So what codes should apply?
In this litigious society we live in, designers should do their best to comply with the most stringent published code. Most of those codes reside right here in the United States. The leader for commercial pool standards is the State of California.
Avoiding Litigation
If the designer is based in the United States, a reasonable line of legal questioning in foreign litigation would be:
"Are you trained to design and build projects that are compliant with the more stringent US codes and standards?"
"In the absence of local regulations or building codes, wouldn't it be prudent to design and build to those same margins of safety?"
"So, by not designing to those same US standards, you are saying that a life in this foreign country is worth less than a life in the US?"
Keep in mind that in many foreign countries, errors and omissions are often construed as criminal negligence. A designer may not just be trying to avoid financial losses, but jail as well.
Bottom Line
When designing foreign projects, it is best to design a project to be in compliance with the most stringent standards or codes that exist, unless they are in direct conflict with a local regulation.
The standards established by the ADA, IBC, NEC, ISPSC, APSP, NSF, ACI, TCNA, ANSI and VGBSA may not be the adopted code in a foreign locale. However, these standards were established for a reason - life safety and user convenience.
Don't the people in foreign countries deserve the same levels of protection?
Paolo Benedetti, SWD -
Aquatic Artist, Watershape Consultant, Expert Witness, International Aquatic Designer and Builder
Contact the author at: info@aquatictechnology.com or 408-776-8220
"Creating water as art."™
Aquatic Technology Pool and Spa©
©www.aquatictechnology.com
All rights reserved.
Showing posts with label VGBSA. Show all posts
Showing posts with label VGBSA. Show all posts
Monday, September 9, 2013
Friday, March 15, 2013
Swimming Pool Hydraulic Design Expert Witness
Swimming Pool Hydraulic Design & Plumbing
Aquatic Technology Pool & Spa expert witness Paolo Benedetti discusses proper hydraulic design and the benefits for the end user.
Safety
The paramount issue in proper hydraulic design of a swimming pool plumbing system is safety. The system must be designed to maintain low line velocities at the suction inlets. Lower line velocities result in a lessened chance of an entrapment or entanglement accident. The suction at the drain is so low that any vacuum force can easily be overcome.
Efficiency and Energy Savings
In order to lower the velocity of the water traveling through a piping system, the size of the pipes must be increased. Lowering the restrictions that the pump must overcome, allows the pump to work more efficiently. That efficiency results in a direct energy savings, as smaller pumps can be used to move more water. Sounds simple, doesn't it? But most of the swimming pool industry "doesn't get it." Larger pipes, smaller pumps! NOT larger pumps, smaller pipes!
By increasing the size of the pipes, the requisite amount of water can be circulated with a smaller pump, resulting in a saving of electricity (and money). Additionally, the pumps operate much quieter and cooler. Builders will charge more for the larger plumbing. They are actually doing the owner a favor, as the owner will quickly recover that added cost and the compounded returns on that investment, over the life of the project. And the savings will be compound even further as electrical costs continue to rise.
Hydraulically Sound Principals
The process of designing a hydraulic system is not difficult. It does however, require that one possess the basic knowledge of fluid mechanics and some simple line velocity/head loss charts.
1. Determine the required flow in GPM (to meet turnover rate or flow demands of jets, water features, etc.).
2. Layout the system design, starting with an estimate of the pipe size required. Select a pipe size on the suction side that will not exceed 6 FPS (nationwide standard/law). 4 FPS is ideal, as it will provide a margin of error and still scour collected debris from the piping.
3. Calculate the feet of pipe & number of fittings - use the head loss charts to convert & calculate the head loss of the suction piping.
4. Determine the equipment to be installed at the equipment pad (filter, heater, chemical controls, valves, etc.). From the various manufacturer's information sheets, add all of these component head losses to the total from #3.
5. Do the same for the return plumbing, as you did in #3. Aim for no more than 8 FPS (nationwide standard/law). 6 FPS is ideal on the return side. The piping size may be slightly smaller to create this slightly higher line velocity, but not always. Add the return plumbing head loss to the total from #4.
6. This grand total is the total head loss (restrictions) in the system. This is called total dynamic head (TDH). TDH really includes more than just the system loss, but we don't have time to discuss the other variables (e.g. static head, suction lift - positive or negative, etc.).
7. NOW, the pump can be sized. Utilizing pump flow curves, seek the desired flow in GPM at the calculated TDH (from #6). The two values should meet in the middle of the pump's curve. If they are at either extreme of the pump curve, either up or down size the pump. Choosing a pump in the middle of the curve will allow for operational variations in the system, such as a dirty filter.
8. National safety standards require that the line velocity at the suction inlets (e.g. drains) must be much lower than the line velocity in the main suction pipe (trunk line). The national standard is 3 FPS, though some states and municipalities have a more restrictive 1.5 FPS standard.
Dropping the line velocity at the suction inlets is child's play. The trunk line is merely divided into multiple balanced branch lines, until the applicable FPS standard is achieved. This can be achieved in a number of manners.
The first method, requires that the trunk line be divided as many times as it takes to get below the required FPS standard. The branch lines diameter is kept the same as the trunk line, so that the division applies evenly to all suction inlets.
The second method, is a little more complicated to plan, but easier to install. The diameter of the branch lines are increased larger than the main trunk line. Utilizing the line velocity charts, one selects the larger diameter pipe required to drop the velocity to below the required standard. Since a minimum of 2 suction inlets are required for each pump, this could greatly reduce the number of inlets required over method #1.
Prefabricated Drain Channels and Covers
The next hurdle is confusing to most swimming pool builders, designers, state and local health departments, building inspectors and even many drain manufacturers - the compatibility of GPM and FPS through an unblockable drain, suction sump or cover. Though drain sumps, channels and covers in compliance with the national Virginia Graeme-Baker Safety Act (VGBSA) list a maximum GPM flow rating, it does not mean that the pipe connections below that cover is permitted to flow at that rating.
The maximum line velocity standards still apply to the connected piping. Simply stated a 2" pipe can only flow 28 GPM at 1.5 FPS, or 43 GPM at 3 FPS where it connects to a drain sump.
What the drain cover rating does allow are the grouping of different suction systems. Multiple branch lines from different pumping systems may be grouped together under a cover, until their cumulative GPM flowrate meets the cover's rating. This allows multiple system inlets to share a drain cover.
Pre-fabricated drain channels pose another design obstacle. They are classified under the VGBSA as "unblockable" drains due to their shape and size. The VGBSA allows these drains to function as a single point suction, meaning that split drains are not required. They can be ordered with various quantities of connection points for plumbing/
Most of these channel drains only provide 2" connection ports that are limited (by law) to a mere 1.5 or 3 FPS (depending on the local standard). That equates to ONLY 28 or 43 GPM per connection!
1. Single inlet unblockable channel drains are available with 196 GPM ratings. When installed in compliance with the FPS standard, it only has a maximum flow rating of 28 or 43 GPM.
2. Dual inlet unblockable channel drains are available with 227 GPM ratings. However, when installed in compliance with the FPS standard, it only has a maximum GPM rating of 56 or 86 GPM.
3. Triple inlet unblockable channel drains are available with flow ratings of 320 GPM. Yet, when installed in compliance with the FPS standard they are limited to 84 or 129 GPM.
When you are considering the purchase of a swimming pool, require that the hydraulic calculations (head loss and line velocities) and the plumbing schematics (line drawings) be included in the plans. Require that the builder note in the plans or specifications, the pipe sizes and the maximum allowable line velocities of branch, trunk and return piping. This will ease in the verification of the system performance and compliance, by any project inspectors or consultants. The next hurdle is getting them to actually build it that way!
The design of swimming pool circulation and piping systems are not rocket science. But, it does require that one be familiar with the basics of hydraulic design, the idiosyncrasies of the codes, what component ratings really mean and the limitations of component applications.
Paolo Benedetti
Aquatic Artist, Construction & Design Consultant, Expert Witness
"Creating water as art."™
Aquatic Technology Pool and Spa
©www.aquatictechnology.com
Aquatic Technology Pool & Spa expert witness Paolo Benedetti discusses proper hydraulic design and the benefits for the end user.
Safety
The paramount issue in proper hydraulic design of a swimming pool plumbing system is safety. The system must be designed to maintain low line velocities at the suction inlets. Lower line velocities result in a lessened chance of an entrapment or entanglement accident. The suction at the drain is so low that any vacuum force can easily be overcome.
Efficiency and Energy Savings
In order to lower the velocity of the water traveling through a piping system, the size of the pipes must be increased. Lowering the restrictions that the pump must overcome, allows the pump to work more efficiently. That efficiency results in a direct energy savings, as smaller pumps can be used to move more water. Sounds simple, doesn't it? But most of the swimming pool industry "doesn't get it." Larger pipes, smaller pumps! NOT larger pumps, smaller pipes!
By increasing the size of the pipes, the requisite amount of water can be circulated with a smaller pump, resulting in a saving of electricity (and money). Additionally, the pumps operate much quieter and cooler. Builders will charge more for the larger plumbing. They are actually doing the owner a favor, as the owner will quickly recover that added cost and the compounded returns on that investment, over the life of the project. And the savings will be compound even further as electrical costs continue to rise.
Hydraulically Sound Principals
The process of designing a hydraulic system is not difficult. It does however, require that one possess the basic knowledge of fluid mechanics and some simple line velocity/head loss charts.
1. Determine the required flow in GPM (to meet turnover rate or flow demands of jets, water features, etc.).
2. Layout the system design, starting with an estimate of the pipe size required. Select a pipe size on the suction side that will not exceed 6 FPS (nationwide standard/law). 4 FPS is ideal, as it will provide a margin of error and still scour collected debris from the piping.
3. Calculate the feet of pipe & number of fittings - use the head loss charts to convert & calculate the head loss of the suction piping.
4. Determine the equipment to be installed at the equipment pad (filter, heater, chemical controls, valves, etc.). From the various manufacturer's information sheets, add all of these component head losses to the total from #3.
5. Do the same for the return plumbing, as you did in #3. Aim for no more than 8 FPS (nationwide standard/law). 6 FPS is ideal on the return side. The piping size may be slightly smaller to create this slightly higher line velocity, but not always. Add the return plumbing head loss to the total from #4.
6. This grand total is the total head loss (restrictions) in the system. This is called total dynamic head (TDH). TDH really includes more than just the system loss, but we don't have time to discuss the other variables (e.g. static head, suction lift - positive or negative, etc.).
7. NOW, the pump can be sized. Utilizing pump flow curves, seek the desired flow in GPM at the calculated TDH (from #6). The two values should meet in the middle of the pump's curve. If they are at either extreme of the pump curve, either up or down size the pump. Choosing a pump in the middle of the curve will allow for operational variations in the system, such as a dirty filter.
8. National safety standards require that the line velocity at the suction inlets (e.g. drains) must be much lower than the line velocity in the main suction pipe (trunk line). The national standard is 3 FPS, though some states and municipalities have a more restrictive 1.5 FPS standard.
Dropping the line velocity at the suction inlets is child's play. The trunk line is merely divided into multiple balanced branch lines, until the applicable FPS standard is achieved. This can be achieved in a number of manners.
The first method, requires that the trunk line be divided as many times as it takes to get below the required FPS standard. The branch lines diameter is kept the same as the trunk line, so that the division applies evenly to all suction inlets.
The second method, is a little more complicated to plan, but easier to install. The diameter of the branch lines are increased larger than the main trunk line. Utilizing the line velocity charts, one selects the larger diameter pipe required to drop the velocity to below the required standard. Since a minimum of 2 suction inlets are required for each pump, this could greatly reduce the number of inlets required over method #1.
Prefabricated Drain Channels and Covers
The next hurdle is confusing to most swimming pool builders, designers, state and local health departments, building inspectors and even many drain manufacturers - the compatibility of GPM and FPS through an unblockable drain, suction sump or cover. Though drain sumps, channels and covers in compliance with the national Virginia Graeme-Baker Safety Act (VGBSA) list a maximum GPM flow rating, it does not mean that the pipe connections below that cover is permitted to flow at that rating.
The maximum line velocity standards still apply to the connected piping. Simply stated a 2" pipe can only flow 28 GPM at 1.5 FPS, or 43 GPM at 3 FPS where it connects to a drain sump.
What the drain cover rating does allow are the grouping of different suction systems. Multiple branch lines from different pumping systems may be grouped together under a cover, until their cumulative GPM flowrate meets the cover's rating. This allows multiple system inlets to share a drain cover.
Pre-fabricated drain channels pose another design obstacle. They are classified under the VGBSA as "unblockable" drains due to their shape and size. The VGBSA allows these drains to function as a single point suction, meaning that split drains are not required. They can be ordered with various quantities of connection points for plumbing/
Most of these channel drains only provide 2" connection ports that are limited (by law) to a mere 1.5 or 3 FPS (depending on the local standard). That equates to ONLY 28 or 43 GPM per connection!
1. Single inlet unblockable channel drains are available with 196 GPM ratings. When installed in compliance with the FPS standard, it only has a maximum flow rating of 28 or 43 GPM.
2. Dual inlet unblockable channel drains are available with 227 GPM ratings. However, when installed in compliance with the FPS standard, it only has a maximum GPM rating of 56 or 86 GPM.
3. Triple inlet unblockable channel drains are available with flow ratings of 320 GPM. Yet, when installed in compliance with the FPS standard they are limited to 84 or 129 GPM.
When you are considering the purchase of a swimming pool, require that the hydraulic calculations (head loss and line velocities) and the plumbing schematics (line drawings) be included in the plans. Require that the builder note in the plans or specifications, the pipe sizes and the maximum allowable line velocities of branch, trunk and return piping. This will ease in the verification of the system performance and compliance, by any project inspectors or consultants. The next hurdle is getting them to actually build it that way!
The design of swimming pool circulation and piping systems are not rocket science. But, it does require that one be familiar with the basics of hydraulic design, the idiosyncrasies of the codes, what component ratings really mean and the limitations of component applications.
Paolo Benedetti
Aquatic Artist, Construction & Design Consultant, Expert Witness
"Creating water as art."™
Aquatic Technology Pool and Spa
©www.aquatictechnology.com
Saturday, January 26, 2013
Expert Swimming Pool and Spa Advice from International Designer
The causes of most construction defects are directly attributed to one of 2 causes - failure to follow instructions, plans or project specifications and/or the lack of qualified supervision.
Failure to Follow Instructions
Most defects in construction projects are directly attributed to someone not taking the time to READ instructions. Whether they be the product usage insert, manufacturer's installation manual or the engineer's plans and notes... failing to take the time to read AND understand the instructions results in errors.
Sometimes these errors can be huge - incorrect strength or diameter of steel, walls that are too thin, pipe diameters that are too small or electrical systems that are incorrect. These types of errors can result in a project that may be structurally unstable or dangerous to swimmers.
When these instructions refer to another code or standard, it is the installers responsibility to seek out and understand those codes as well.
In the plans if the structural engineer states, "Shotcrete must be installed in compliance with ACI 506R-05," then the installer must understand what those standards require.
The structural engineer does not need to reprint the entire referenced standard in the plans. Why? Because anyone who installs shotcrete as a part of their business should already be aware of, possess a copy of, and be following the requirements of ACI 506.
If the instructions that are enclosed with electrical components are not read and adhered to, a potentially life threatening situation can be created. The failure to properly bond metallic components can result in a fatal electrical shock. Though most electrical components clearly state how they are to be installed, many will also refer to NEC 680 & 682. Again, anyone who builds swimming pools or fountains should have a copy of these codes and be intimately familiar with them.
The Lack of Qualified Supervision
Note the word "qualified?" Just because a project has on-site supervision does not mean that the supervision is worth anything. The supervisor may just be directing the progress and may "no nuthin' 'bout da details uf da wurk." Therein lies the problem... the blind leading the blind.
The person who supervises the work of others, needs to know how that work is to be performed. The person supervising the design, planning and construction needs to be familiar with:
structural engineering
soils
excavation
building forms
hydraulics
plumbing
electrical
reinforcing steel
shotcrete (wet or dry mix methods)
tile
masonry
plaster
concrete
mechanical (venting)
fuels (approved piping, venting, shut-offs)
automation and controls
This is not to say that they need to be a licensed expert in each of these fields. But, it is saying that they need to know enough about each topic to question what others are telling them is right. Anyone can make a mistake, even experts that the contractor may hire.
The contractor needs to understand that pools with diving boards must comply with various floor contour and shape requirements, and which diving boards can be safely used in each. They must ensure that the project design and engineering complies with these codes and minimum dimensional shapes.
The swimming pool contractor needs to be able to recognize differential soils or buried trash during an excavation. They need to be smart enough to have the structural and soils engineers weigh in on the discovery. It may mean nothing or it may be a big deal - but they need to let the experts decide which!
The contractor needs to understand the basics of hydraulics and the Virginia Braeme-Baker Safety Act, in order to deliver a swimming pool that is safe from entrapment hazards, unwarranted restrictions, high energy consumption and cavitation. The need to ensure that the suction point sumps are the correct size, are compatible with the flow rate ratings of the drain covers and if sumps are field fabricated, that they meet the requirements of the VGBSA.
The supervisor on the project needs to know what each of the sub-trades are required to do. Whether it is the electrician, plumber, mechanical, masonry or concrete sub-contractor - they need to know the codes and standards that apply to each. And they have a duty to ensure that these codes are followed and complied with - even if the local inspectors do not enforce the codes.
Because when the client has any doubts about the project, an expert will come in and dissect the project. Each component of the pool that is found non-compliant may be required to be corrected. Tearing out completed work to repair underlying defects can quickly consume any project profits.
And anyone in construction will agree... it is cheaper to do it right the first time!
Take the time to READ and UNDERSTAND the plans and installation instructions.
Employ QUALIFIED project supervisors or go get educated... there are some excellent programs on swimming pool construction available. The $3,000 spent on one of these programs, will save you much more than that, if an expert is ever hired to evaluate one of your projects.
Paolo Benedetti
Aquatic Artist, Consultant & Construction Defect Expert Witness
"Creating water as art."™
Aquatic Technology Pool and Spa
©www.aquatictechnology.com
Failure to Follow Instructions
Most defects in construction projects are directly attributed to someone not taking the time to READ instructions. Whether they be the product usage insert, manufacturer's installation manual or the engineer's plans and notes... failing to take the time to read AND understand the instructions results in errors.
Sometimes these errors can be huge - incorrect strength or diameter of steel, walls that are too thin, pipe diameters that are too small or electrical systems that are incorrect. These types of errors can result in a project that may be structurally unstable or dangerous to swimmers.
When these instructions refer to another code or standard, it is the installers responsibility to seek out and understand those codes as well.
In the plans if the structural engineer states, "Shotcrete must be installed in compliance with ACI 506R-05," then the installer must understand what those standards require.
The structural engineer does not need to reprint the entire referenced standard in the plans. Why? Because anyone who installs shotcrete as a part of their business should already be aware of, possess a copy of, and be following the requirements of ACI 506.
If the instructions that are enclosed with electrical components are not read and adhered to, a potentially life threatening situation can be created. The failure to properly bond metallic components can result in a fatal electrical shock. Though most electrical components clearly state how they are to be installed, many will also refer to NEC 680 & 682. Again, anyone who builds swimming pools or fountains should have a copy of these codes and be intimately familiar with them.
The Lack of Qualified Supervision
Note the word "qualified?" Just because a project has on-site supervision does not mean that the supervision is worth anything. The supervisor may just be directing the progress and may "no nuthin' 'bout da details uf da wurk." Therein lies the problem... the blind leading the blind.
The person who supervises the work of others, needs to know how that work is to be performed. The person supervising the design, planning and construction needs to be familiar with:
structural engineering
soils
excavation
building forms
hydraulics
plumbing
electrical
reinforcing steel
shotcrete (wet or dry mix methods)
tile
masonry
plaster
concrete
mechanical (venting)
fuels (approved piping, venting, shut-offs)
automation and controls
This is not to say that they need to be a licensed expert in each of these fields. But, it is saying that they need to know enough about each topic to question what others are telling them is right. Anyone can make a mistake, even experts that the contractor may hire.
The contractor needs to understand that pools with diving boards must comply with various floor contour and shape requirements, and which diving boards can be safely used in each. They must ensure that the project design and engineering complies with these codes and minimum dimensional shapes.
The swimming pool contractor needs to be able to recognize differential soils or buried trash during an excavation. They need to be smart enough to have the structural and soils engineers weigh in on the discovery. It may mean nothing or it may be a big deal - but they need to let the experts decide which!
The contractor needs to understand the basics of hydraulics and the Virginia Braeme-Baker Safety Act, in order to deliver a swimming pool that is safe from entrapment hazards, unwarranted restrictions, high energy consumption and cavitation. The need to ensure that the suction point sumps are the correct size, are compatible with the flow rate ratings of the drain covers and if sumps are field fabricated, that they meet the requirements of the VGBSA.
The supervisor on the project needs to know what each of the sub-trades are required to do. Whether it is the electrician, plumber, mechanical, masonry or concrete sub-contractor - they need to know the codes and standards that apply to each. And they have a duty to ensure that these codes are followed and complied with - even if the local inspectors do not enforce the codes.
Because when the client has any doubts about the project, an expert will come in and dissect the project. Each component of the pool that is found non-compliant may be required to be corrected. Tearing out completed work to repair underlying defects can quickly consume any project profits.
And anyone in construction will agree... it is cheaper to do it right the first time!
Take the time to READ and UNDERSTAND the plans and installation instructions.
Employ QUALIFIED project supervisors or go get educated... there are some excellent programs on swimming pool construction available. The $3,000 spent on one of these programs, will save you much more than that, if an expert is ever hired to evaluate one of your projects.
Paolo Benedetti
Aquatic Artist, Consultant & Construction Defect Expert Witness
"Creating water as art."™
Aquatic Technology Pool and Spa
©www.aquatictechnology.com
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