Nabic Fig 503

Features

• Boiler connection permanently open
• Minimum water loss on change over
• Inline Servicing
• Dezincification resistant materials
• Cassette Construction
Applications

Applications

The Fig 503 Three Way Valve has been designed for use on vented hot water systems, to ensure there is a permanent connection from the boiler or calorifier to atmosphere.

Fitting a Fig 503 allows the use of a single common vent pipe, and permits continued operation of the system whilst maintenance is carried out on an individual unit.

Construction

The Fig 503 is of gunmetal construction, with all wetted parts manufactured from dezincification resistant materials. Cassette construction allows for the valve to be inspected and serviced without removal from the system. The internal design keeps loss of water on change over to a minimum, and is such that boiler isolation is impossible. End connections have female threads to BS 21, and the DN65 size is also available with flanged boiler and vent connections. For other design conditions please consult NABIC technical department.

• Body Material: Gunmetal
• Maximum Pressure: 7 bar
• Maximum Temperature: 93°C

Sizing

To provide adequate emergency steam relief capacity, vented hot water systems require the fitting of a suitably sized vent pipe in addition to a safety relief valve (Fig 542). The following sizes are specified in BS 779, BS 853 & BS 855.