The pinch valve is normally closed. Before filling begins, it must be released by pressing a button. The use of the system can thus also be signalled remotely by means of a control lamp or similar device provided by the customer.

If the fill level reaches the maximum probe, a signal to be set up by the customer (horn or similar) is triggered. Pumping must be stopped immediately. The signal can be switched off at the control box. After a certain (adjustable) time, the pinch valve closes automatically, preventing further filling of the silo. If the pinch valve has closed at full delivery, it can be opened again by responsible operating personnel using the key switch in order to flush the residual material out of the filling pipe with air. The valve must then be closed again. (Caution! The safety device is ineffective while the key switch is actuated).

A magnetic switch is fitted to the filling pipe coupling. When the dummy coupling fitted with magnets is removed, the vibration motor of the silo venting filter is switched on for 10 - 20 seconds by a pulse. Once filling is complete when the dummy coupling is fitted, the jogging process is repeated. A version without automatic filter shaking is also available as an option. If the final surge causes a high injection pressure or if the filter elements are contaminated, an overpressure may occur in the silo that exceeds the set value of the overpressure flap. To prevent this risk, a pressure switch can be installed in the silo roof. If the set pressure is exceeded, the pinch valve closes automatically, the filter is cleaned, then the pinch valve opens again and the filling process can continue until the max. probe is reached