English Instructor Manual (PDF) - Metric Version - National ...

Swimming pools = 6 hours
Spas = 30 minutes
Wading pools = 1 to 2 hours
Waterparks/specialty pools = 1 to 2 hours
Hospital/health club pools = 3 hours
Flow rate is the amount of water passing through the circulation system at a given time.
It is measured in litres per minute (lpm) or cubic metres per hour (m 3 /h).
Activity: Using the Calculation Formulas handout, do several turnover rate and fl ow rate
calculations. Have the students practice using the following two formulas:
1. Turnover rate (hr) = volume ÷ fl ow rate ÷ 60 min/hour
2. Flow Rate (lpm) = volume ÷ turnover rate ÷ 60 min/hour
Using the following values, what is the turnover rate?
Volume = 756,000 litres, fl ow rate = 1,750 lpm
What should the fl ow rate be to attain a 6 hour turnover rate?
Key Points: Discuss that circulation is the movement of water and is infl uenced by many factors.
These include:
Pool shape and contour
Surface and main drain water removal
Inlet placement and design
Circulation pumps
Piping and fi ttings
Other system components such as heating systems and chemical feeders
Key Points: Discuss the various components of a circulation system. These include:
Main drains
Drain covers
Skimmers or overfl ow gutters
Hair and lint strainer
Pump and motor
Filters
Heaters
Chemical feeders
Gauges and meters
Valves, piping and return inlets
Key Points: Discuss the various aspects of suction-side components. These include:
Main drains (located on the pool fl oor) and skimmers or overflow gutters (located on
the surface) are designed to pull water into the circulation system.
Each component should be designed to accommodate 100% of the fl ow required to
meet the turnover standards.
Because of the possibility of suction entrapment, pools and spas should not be open
if drain covers are missing or damaged. Many regulations require multiple main drains
and skimmers
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© 2014 National Swimming Pool Foundation®