Pressure switch covers do not have a bearing structure but are entirely made of PVC membrane and supported by an overpressure of air generated inside.
The use of balloons or pressure switches is permitted in the facilities where there are spectators, practitioners and staff – no more than 50 persons.
These covers must be made with materials of fire reaction class not exceeding level 2 and approved according to the decree of the Home Office of 26 June 1984; an adequate support must be provided to prevent the risk of sudden falls in the event of pressure drop. Alternatively, sound and light alarms can be installed to communicate any abnormalities, pressure drops, and / or wind or snow loads above the design limits of the area under consideration.
Maintaining structural pressure is essential to a Pressure Structure. The system to control and increase the internal pressure are indispensable prerequisites in which they works: for the first is the emergency group, mandatory, which activates itself when the pressure drops, while for the second is to point out that the most important stress to which a “pressure static” structure has to overcome is that generated by the wind. Consequently, there is a need for an anemometer that signals its speed and orders the emergency unit to function when a certain value is exceeded, making harder the PVC membrane and hence warranting proper stability of the structure.
In fact, the characteristics of resistance to traction and tearing of the PVC membrane, combined with the internal pressure, ensure that the pressurized cover maintains its stability.
As with tensile structures, the cover can be made in single or double membrane. In terms of running costs compared to the fixed structures, the Pressostatic system presents some enhancements regarding: the electric part to maintain internal pressure (since ventilation works 24 hrs and consumption depends on fan power) and logistics, because we must considered throughout the year disassembly and assembly operations; finally, the need to deliver each year to the Municipality a certificate of static eligibility, signed by a qualified technician attesting the verification of the cover material and the devices.
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