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Silo overfill protection


Silo overfill protection

Application area:

The silo overfill protection is suitable for preventing overfilling for silos to be filled pneumatically. It consists of a pneumatic pinch valve with electric solenoid valve in the filling line and a switch box. For the function, a maximum fill level limit switch must be provided by the customer on the silo and compressed air (approx. 6 bar) free of oil and water must be constantly available. The switch box is connected to 380 V, 50 Hz power supply.

Electrical wiring and compressed air supply must be provided by the customer. The system must be switched on before the filling. Blowing in is not possible without electrical voltage.

Electrical equipment:

The pinch valve is closed in the normal state. It must be released by pressing a button before starting the filling. The use of the system can be signalled remotely by local equipment such as indicator lamp or similar.

A signal to be set up by the customer (horn or similar) is triggered if the fill level reaches the maximum sensor. The delivery must be stopped immediately. The signal can be switched off at the switch box. After a specified (configurable) time, the pinch valve then closes automatically whereby any further filling of the silo is prevented. If the pinch valve has closed for full delivery, it can be opened again using a key switch by responsible operating personnel to flush out the fill tube with air to clear residue material. The valve must be closed again afterwards (Attention! The protection is not effective during actuation using the key switch!).

A magnetic switch is attached to the fill tube coupling. The vibration motor of the silo ventilation filter is switched on by a pulse for 10 - 20 seconds when the blank coupling populated with magnets is removed. The vibration process repeats after completion of the filling when attaching the blank coupling. A version without automatic filter vibration is also optionally available. At high air injection pressure due to the final sloshing or in the case of soiled filter elements, overpressure in the silo can occur which exceeds the setting value of the overpressure valve. A pressure switch can be installed in the silo roof to prevent this risk. If the setpoint pressure is exceeded, the pinch valve closes automatically, the filter is cleaned and then the pinch valve opens again and the filling process can be continued until the maximum sensor is tripped.