Plumbing Africa June 2019 | Page 35

HEALTH AND SANITATION c. 33 Float switch installation o The float switch shall be tethered to a rigid freestanding object, such as a vertical section of pipe or the pump, that: • permits the float switch to rise and fall without any obstructions; and • is located in an area where it is easily accessible and can be withdrawn from the tank without requiring entry into the tank. o To set the operating parameters of the float switch: • to maximise rainwater collection, the tether length should be as short as possible: 75mm [3 in.]. Refer to the manufacturer’s installation instructions for details; • to maximise rainwater collection, the tether point should be as low as possible (so that the float is 50mm [2 in.] above the pump intake when in the down position); and • if using a dual float switch configuration, the float switch controlling the solenoid valve should be located a minimum of 75mm [3 in.] above the float switch controlling the pump. d. Other water level sensors shall be selected and installed in accordance with applicable National/Provincial/ Local codes and regulations, and all electrical connections must be made by a licensed electrician in accordance with the manufacturer’s instructions. Solenoid valves and shut-off valves a. Select the type and size of solenoid valve and/or shut-off valve. • All valves must be suitable for potable water and pressure applications. • Valve openings must be the same size as the piping where the valves are located. • Top-up systems typically use an N/C solenoid valve. • Solenoid valves with a ‘slow close’ or ‘soft close’ are recommended. b. Electrical requirements • Solenoid valves must be wired into a power supply in conjunction with a water level sensor. c. • • Solenoid valve and shut-off valve installation Solenoid valves and shut-off valves used as part of a top-up system shall be installed on the potable water supply pipe upstream of the air gap. Solenoid valves must be installed by a licensed plumber and electrician in accordance with the manufacturer’s instructions. d. Water hammer protection • If a ‘slow close’ or ‘soft close’ solenoid valve is not used, a water hammer arrester shall be installed on the potable water supply piping upstream of the solenoid valve, in accordance with applicable national/provincial/ local codes and regulations. June 2019 Volume 25 I Number 4