Silos that are filled directly from a pressurised tanker need to incorporate suitable mechanisms to allow displaced air within the silo to escape during filling. If these mechanisms are insufficient for the pressures created within the silo, or if the equipment is poorly maintained and becomes inefficient, dangerously high pressures can build up within the silo. This can lead to a catastrophic blow out, damaging plant and equipment, dispersing possibly toxic silo contents over a wide area and endangering the lives of employees.