Silverwing produces a range of vacuum boxes suitable for both new build inspection and in-service inspection. Unlike some vacuum boxes that rely upon a vulnerable vacuum gauge the Silverwing range have calibrated vacuum relief valves fitted as standard. The use of a calibrated (recalibration required annually) vacuum relief valve ensures that not only do they meet the requirements of applicable international standards but the box cannot be damaged by drawing too great a vacuum.
The vacuum is generated by the use of an electric vacuum pump or by use of an Air Vacuum Generator (AVG) and external compressor. The vacuum boxes are rated to either 20 inch Hg (10psi/0,7bar) or 10 inch Hg (5psi/0.37bar) depending on usage. Inspection companies tend to use the electric pump with the vacuum boxes due to its greater flexibility while construction companies tend to use the AVG based systems.