Setting Personal Standards
‘I’ve had the pleasure of teaching hydraulics to watershapers in a variety of classroom settings,’ noted Dave Peterson in opening his Currents column in the May 2010 edition of WaterShapes. ‘These courses . . . ask a lot of the students who sign up for them . . . [and] I find it enormously encouraging that so many people are focused on spending the time and energy required to improve their skills and raise their levels of expertise.
‘At the same time, unfortunately, my classroom experience has exposed me to some unsavory ways of thinking and leads me to conclude that the watershaping industry hasn’t done a particularly good job through the years in reaching its practitioners with core technical education.’ He continued:
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‘In many cases, the people attending my classes have spent years or even decades in building pools, spas and other watershapes. With distressing consistency, however, they tell me that their education in hydraulics . . . has almost entirely come to them in the course of listening to sales pitches from suppliers or their representatives.’
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‘Of all the observations I’ve gleaned from my classroom ventures, perhaps the most significant have to do with my growing understanding of the impact codes have on watershapers’ daily lives. . . . Take, for instance, the six-feet-per-second maximum velocity for suction-side plumbing. As I see it, standards such as this are not unlike speed limits: They represent allowable maximums, and to exceed them at all involves breaking the law.’
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‘So why on earth would anyone ever use the six-feet-per-second threshold as a design standard? I know lots of people do, because I see so many of them in my classrooms. And the thinking apparently has it that the standard is what might be termed “best practice” when in fact it is nothing more than what is minimally acceptable. The problem is, if you use the standard as a design criterion, you essentially leave yourself no leeway, no buffer against “breaking the law.” ‘
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‘I preach instead that you should never aim above a four-and-a-half-feet-per-second velocity on the suction side. With that as my target, I’m comfortable with six feet per second being the minimum standard – and I understand that if I really want to optimize system performance and safety, four-and-a-half feet per second is better.’
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‘This gives me the room for variation that comes only from having leeway if I must exceed my own standard. If, for example, the pump I select isn’t exactly optimal for the application and I end up with a velocity of five feet per second, the system will still function well within the limit. If, by contrast, I’ve designed right up against six feet per second, then I’d find myself in violation of the code.’
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‘In my work in the classroom as well as the field, I’m [also] startled to discover how many people think they should select the pump first before developing any other part of a design. . . . This is generally a sign of rote behavior: You pick a one-and-a-half-horsepower pump simply because that’s what you’ve always done – and then you size the plumbing and develop various system features based on the pump’s performance.’
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‘It should go the other way around: The first thing you do is establish a flow rate based on turnover, the performance requirements of a desired water effect, the desired flow over a vanishing edge or the constraints of some other form of water-in-transit detail. Thus, you start with the performance need for X gallons per minute, then design your plumbing to handle that flow rate, then calculate the total dynamic head of the plumbing system. Only with the flow rate and head loss numbers in hand should you go about selecting a pump.’
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‘My point here is that each of us must set his or her own standard for excellence. In this process,’ Dave concluded, ‘we can be informed by codes and industry benchmarks, but we shouldn’t let observing minimums or hand-me-down practices determine how we work. Instead, we should consciously strive to observe standards we know will create outstanding end products.’
Have you ever been a victim of the kind of rote thinking that Dave discussede about five years ago? If so, has your approach to these issues changed? If not, how did you avoid the trap? Please share your experiences by commenting below!
Dave Peterson is president of Watershape Consulting of San Diego, Calif. He’s been part of the watershaping industry since 1994, starting his own firm in 2004 after stints with an aquatic-engineering firm and a manufacturer. A registered civil engineer, he now supports other watershape professionals worldwide with design, engineering and construction-management services and may be reached via his web site, www.watershapeconsulting.com.