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Expansion vessels



Expansion vessels preloaded with replaceable membranes suitable to be installed in heating closed circuits. Manufactured according European Directive 97/23/CE for pressure vessels, two dish ends joined by welding process and procedures by homologated staff. Models s DP/VR y DP/VRV, are manufactured, tested, checked and verified by Mecalia.

ApplicationsExpansion vessels models DP/VR and DP/VRV are designed for heating installations which allows absorbing the volume rise caused by the increase of temperature of heating fluid.On heating installations when water is heated , his volume increase, this can be


Working Pressure: 8 bar
Max. Working Temp.: -10ºC up to +140ºC
Membrane: EPDM Replaceable
Marked: CE according Directive PED 97/23/CE.
Composition: Galvanized steel flange with internal polypropylene protection in the area in ​​contact with water.
Mixing: Water
Colour: Red RAL 3000
Operation: There is a full air chamber under pressure between the membrane and the tank plate. Once connected the expansion vessel to the circuit to which is intended, the temperature rises and also does the volume of water (image 1) When membrane is filled with water, the air is pushed and it's compressed. the water volume keeps expanding until the maximum working temperature water is reached. At this state, the membrane occupies almost all the space of the tank(image 2). Once the effort stops, the temperature of the installation goes down gradually and also the water volume. The water starts to come out of the tank due to the pressure of the air found in the pressurized chamber. The air pushes the membrane till it gets the original pressure back. Finally, when the vessel reaches its initial position, a new cycle begins (image 3). At the moment of setting up the vessel in a heating installation, the following points must be kept in mind: * Before proceeding to the installation, make sure that the expansion vessel volume has been calculated by authorized staff. * The expansion vessel will be placed preferably in the return piping in order to avoid the water temperature and damage the membrane. The expansion vessels will be mandatory assembled between the boiler and the mixing valve, preferably in the return piping to the boiler. * The expansion vessel will be installed in such a way that airbeds cannot be produced. * Avoid radiations near the expansion vessel to protect membrane against possible increases of temperature. * It is not allowed any valve that could be closed and insulate the own circuit of the expansion vessel. * Fit the inflating pressure of the vessel to the network pressure. (PINFLATING=PNETWORK+0,2bar).
Maintenance: Maintenance must be carried out exclusively by authorized staff. At least once every six months, check through the inflating valve that pressure is correct, with the precaution of doing so by contrasting values ​​at the same temperature and with the installation depressurized. Never disassemble the vessel without having previously depressurized the installation. Standard pressure should be regular and adjusted according installation. When filling with water, make sure that the pressure indicated on the pressure gauge is slightly higher than the static pressure of the installation. Keep the installation at the maximum working temperature for half a day, remove the air from the system replacing it with water. Protect the vessel from weather inclemences. To prevent internal corrosion in the expansion vessels, it is recommended to purge the closed circuit regularly.
Advantages: Water hammer decrease. Reduction of the consumption of water and electrical energy, due to the safety group, avoiding water leaks.