Hydraulics

Aquatic Technology Pool & Spa
Paolo Benedetti

Custom high-end luxury swimming pools and spas should have "engineered" plumbing systems (hydraulics). Not only infinity edge, vanishing edge, and perimeter overflow pools, but every singe vessel.

The hydraulic systems for the vessels need to be calculated, to stay below the MAXIMUM flowrates through the pipes. Flowrates (line velocities) are the most mis-understood component of swimming pools & spas.

It was estimated by the NSPI that over 95% of the swimming pools built do not comply with the industry standards for flowrates & line velocities.

This is why there have been evisceration cases, suction entrapment deaths, and hair entanglement drownings. This is not to say that these would not have occurred, but the severity of the injuries would have been significantly less, if there was merely less suction!

Now you're saying, but I need suction??!! You're correct, but a larger diameter pipe moving the same flowrate (gallons per minute) as a smaller diameter pipe, has a slower line velocity & therefore less suction.

We can still move the same amount of water (gallons per minute), but we can make the bather environment safer, ALL BY JUST USING A LARGER DIAMETER PIPE.

After the entire lengths of pipe, elbows, fittings, and equipment are calculated, the systems restriction to flow (friction) is determined. The maximum line velocities of specific pipe diameters are established by the standards & physics. However, a prudent mechanical engineer will strive for a lower line velocity than the standard. It is easier on the piping system, pumps don't have to work as hard, there is less noise, it provides a margin of safety if the system is modified, and smaller pumps can be used (ENERGY SAVINGS!).

A larger diameter pipe provides less restrictions than a smaller diameter pipe. Sized properly, the need for sweep elbows or specialty fittings to reduce restrictions are eliminated. The need for specialized anti-entrapment devices & plumbing methodology are eliminated.... merely by understanding physics.

So why don't pool builders use larger pipes??? Good question... lazy, added cost, ignorance, indifference, difficulty in plumbing - take your pick. I have had other pool builders attempt to build my designs, only to down size the pipes ("they are TOO big"), shorten beach entrances (there is a minimum design standard for a 7:1 slope), replace expensive stainless steel or galvanized rebar with regular rebar, or eliminate other details as "unnecessary" or "over-kill."

When I get a call that something wrong with my design, a gravity drain is not flowing properly (remember, it was downsized because it was "too big" ?), the beach is too steep (they shortened it & thereby increased the slope), or are experiencing rebar rusting through an element (because they deleted the corrosion resistant rebar), I point out how they chose to go with the low bidder. They were the low bidder for a reason...

The manufacturer of an anti-entrapment device (a vacuum release widgit) has been lobbying legislators in many states, trying to make it a law that their device (or ones like it) are installed on every pool. But if the legislators & building officials understood the physics & fluid dynamics of mechanical systems, these entrapment issues could be avoided with simple math.

The benefit of a properly designed system, is that the pumps are actually chosen LAST! After all of the systems' design parameters have been established, then a pump is chosen. The pump is selected to fit the need based upon the pumps' optimum efficiency range (pump curve).

An "engineered" or designed hydraulic system results in the use of smaller horsepower pumps, saves energy, moving more water, pumps make less noise, and resulting in a safer bather environment.

As you can see, a properly designed project will make the vessels operate correctly, without all of the faults that have inherently dogged the swimming pool industry.


Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool & Spa
©www.aquatictechnology.com

Plan Inclusions

Aquatic Technology Pool & Spa
Paolo Benedetti

Swimming pool plans are incomplete with merely a site plan, generic mail order structural engineering, and no plumbing schematic, electrical schematic, equipment layout, construction details, and construction specifications.

Exactly how is the project going to come together? What is the clients' level of expectation?

Without complete plans and drawings, there simply can not be ANY attention to detail.

Cross sections of the project & surrounding area are essential in establishing the proper elevations during the grading process. The grading occurs BEFORE the actual digging of the "hole." It helps to know at this stage if there are going to be inches or feet of base rock under the concrete decking.

Are the main drainage trunk lines to be installed at this time? Are there utility lines (current needs & future site expansion) that need to be installed?

Is the coping or stone on the pool bondbeam going to be 2 inches or 6 inches thick?

While this may all seem trivial, errors in establishing the correct elevations can result in water flowing towards the house, concrete above the stucco weep screed, steps of various heights, etc.

An experienced designer knows what questions to ask during the planning stage. While anyone can call themselves a designer, it is their design experience and education that are critical. Creative problem solving is the key... do they come up with solutions to conceal objects that the project must have, but that people don't NEED or WANT to see?

A true designer will be focused on BOTH the design and the clients needs. The design should work with the site & the buildings'... as if something was missing if it wasn't there.

Sometimes the clients don't know what they want. By that I mean that they might even be insistent that they have a particular feature... but they do not know WHY they want it. A good designer will be able to find out what they are "REALLY" looking for... the large grotto may have been a "must have" to block out the neighbors view of the pool or to provide a jumping platform.

The underlying WHY is so critical, as it then allows the designer to offer alternatives that will then work with the site & design. The client gets the true function of the element they were after, while the design integrity is maintained.

It DOES NOT HURT TO ASK QUESTIONS DURING THE PLANNING PROCESS.... the worst that can happen, is that the client can say "no." That's better than later hearing, "would have, could have, should have," or "why didn't anyone tell me?"

Complete plans for the permitting process may be as simple as a site plan, a few cross sections to illustrate relative elevations, and the structural engineering. In fact the least amount of details provided to the building & planning department, the better.

However, the construction plans need to be detailed.

There need to be cross sections of the spa seating, showing steps, seat, floor & water depths. Cross sections of the pool showing benches, steps, and other key elevations.

Cross sections and plan views of design details need to be provided, so that the installers can anticipate & effectively bid their scope of work. Electrical, plumbing, low voltage, data, lighting, and drainage schematics need to be provided.

The locations of the junction boxes for lighting, sound, data/communications will all need to be specified. Plumbing lines might need to be brought up above grade to provide air-gaps or loops. While absolutely necessary for the proper operation of the vessel, these elements can be placed almost anywhere with the proper amount of planning. Where are the lights going, at what elevations & angles, and what wattages?

The equipment pad and area should be laid out to scale, justifying & illustrating to the design team the need for such a large area. oftentimes, the pool equipment area is grossly undersized.... because people just don't know.

Laying out the equipment area, allows the plumbers to place the pipes in the proper location, ensuring an efficient mechanical system - both operationally & for future service needs.

What are the forms going to be made of? 3" bender board tied to rebar or dimensional lumber with stakes & kickers for support? How will the tile be installed? What are the setting materials? What standards are being followed?

What details are being incorporated? Concealed deck drains, skimmer lids, spaside remote controls??? These need to be identified, so that the client knows what is going to be delivered & how it is going to be built. What depths are the spa benches? Where will the waterline be on the clients' body? Benches & backs sloped & reclining? What are the heights of the various steps?

These and hundreds of other detail type questions are what make custom projects, truly custom.

Vessels can be made into works of art.... with the proper questions, planning & forethought.


Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool & Spa
©www.aquatictechnology.com