RWC 35, 50, 80, 100, 150, 200 LTR Replaceable Membrane Heating Expansion Vessel

Details

RWC Reliance Water Controls 35, 50, 80, 100, 150, 200 Litre Replaceable Membrane Heating Expansion Vessel

Features:

• Vessel with internal membrane preventing water contact with the steel shell, stopping internal corrosion.
• Vessel can be serviced without being removed due to replaceable membrane.
• Vessel has pre-charged valve for topping up air pressure.

The main purpose of an expansion vessel is to compensate for the increase in volume of water due to the varying water temperatures in hot water or heating systems. When water is heated it expands and as water is not compressible this increased volume will create a rise in pressure within the system. As an example, water being heated from 0°C-100°C will increase by approx 4.5%.

The expansion vessel allows for this extra space, as when water temperature increases the membrane inside the vessel inflates to allow the water to fill the vessel. The membrane will continue to expand until the system reaches its maximum temperature. Once this has been reached the membrane will be fully inflated and takes up the capacity of the vessel shell. Gradually the temperature will drop, which will in turn decrease the volume of water. Due to the pressure from the pressurised air surrounding the membrane, water will start to exit the vessel until the membrane is deflated.

Heating Vessel Sizing Guide:

If the system volume is known, expansion vessels can be sized with the formula:

V = eC / (1 – (p1/p2))

V    The total volume or nominal size of the expansion vessel. It is not the acceptance volume.

C    The total volume of water in the system (litres).

P1   The fill pressure of the system in Bars absolute (atmospheric or gauge pressure plus one Bar).

P2   The setting of the expansion/pressure relief valve in Bars absolute (atmospheric or gauge pressure plus one Bar).

e    The expansion factor that relates to the maximum system requirements.