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3.4 DISCHARGE
3.4.1 The discharge outlet from the Pressure (expansion) Relief Valve must
be connected to a discharge pipe. It is recommended that a tundish
be installed in the discharge pipe to give a visible indication that the
valves are operating.
3.4.2 The discharge pipe must fall continuously from the valve outlets and
be unobstructed and in a frost-free environment.
3.4.3 The pipe from the valves to the tundish should be 15mm o/dia
minimum. From the tundish to the point of discharge the pipe should
be 22mm o/dia minimum and have a resistance to flow equivalent to
9 metres of straight pipe. Long discharge pipe runs should have an
increased internal diameter.
3.4.4 The water may drip from the discharge pipe of the pressure relief
device and this pipe must be left open to the atmosphere. The pressure
relief device is to be operated regularly to remove lime scale deposits
and to verify that it is not blocked.
3.4.5 The pipe material should be capable of conveying water/steam at
100°C.
3.4.6 The final discharge point should be in a safe, visible position.
