Plumbing Africa August 2018 - Page 88

86 TECHNICAL DEAD LEGS! SANS 10252-1 (7.7.1.3) states: Unless stated otherwise, the length of an unheated pipe (dead leg) conveying hot water directly from a fixed water heater to a terminal water fitting, or from a point of take-off from a hot water circulating system (ring) to a terminal water fitting, shall be such that the internal volume of that pipe does not exceed four litres. Example 15mm copper (litres per metre: 0.150): 4ℓ divided by 0.150 equals a length of 26.66m Volume of pipe (internal diameter) = π × r2 × length Exposed hot water pipes must always be lagged. The reason for this is obvious: to save water and energy. August 2018 Volume 24 I Number 6 Weight/mass Water possesses a specific weight (mass). A cubic metre of water at a temperature of 4°C weighs and therefore has a mass of 1 000kg. (Water has a specific gravity of 1.) Practical application This will remind you that the structure supporting any tank or hot water cylinder having a mass in excess of 300kg shall be designed and signed off by an engineer. It will also remind you that when installing geysers, the structure supporting the weight of the cylinder must be done in accordance with SANS 10254. (See article on page 43 of the May 2018 issue of Plumbing Africa). PA www.plumbingafrica.co.za