Control of solids

Rotary blade indicators


Intended use:

Rotary blade level indicator for lateral mounting used in maximum, intermediate or minimum levels with reinforced shaft extension and with a wide range of type varities depending on each application.

The rotary blade level indicator FDF observes the filling level as a limit switch. It can be used as indicator for dusty and powdery, granulated and grainy bulk goods and are appropriated due to the range of models and blades to control the level of bulk solids like dust, flour, grain, sand, plastic, etc. with a bulk density between 0.01 to 2 t/m3. Although the characteristics of the product, humidity, conductivity, grain size, etc. change, any adjustment is needed

These devices are used to control the level in silos, containers, bunkers and they can be installed horizontally or vertically. They are versatile and universal usable because of their wide range of type varities. For vertical mountings there are rope shafts up to 10 m could be made depending on the product to control. 


The rotating measuring blade, projecting into the silo or container, is driven by a gearmotor. If the bulk material reaches the measuring blade, the rotation will be hindered and it will be stopped. The return torque turns the pivoted motor from its end position and actuates the signal switch. A second switch turns off the motor off.
If the filling level of the bulk material sinks, the blade becomes freely again and a spring will turn the motor back into its original end position. Thereby the motor will be turned on again and the signal switch will be switched back. 

Mechanical connection:

There are models that can be mounted horizontally or vertically into the silo.

The standard form is mounting the device with a flange, drilling holes on the silo to allow the mounting of the controller using screws, rods, fasteners or nuts. If the flange was not requested, the thread can be, for example, G 1 " 1/4 and can be fixed using 1 or 2 nuts or introducing it into a threaded socket with a maximum of 25 mm length. If it is larger, the bulk goods have the possibility to deposit in the thread socket. This could provoke that the device becomes useless.

After the mounting is done, the housing could be turned in order to face the cable gland correctly. 


Approximate measures are given in mm. 




Technical data:

Name Rotary blade indicator  
Type and ref. FDF23  
Switching voltage Standard 230 V AC (50 ... 60 Hz)
(Under request 115 V AC, 48 V AC, 24 V AC, 24 V DC, 12 V DC due to a converter)
Power consumption 4 VA in AC; 4 W in DC  
Density of the product 0.01 t/m3 ... 2 t/m3  
Cable entry 2 of M20x1.5  
Maximum voltage of contact 4 V DC ... 250 V AC  
Contact function 1 NO + 1 NC  
Capacity of the contact 1 mA / 4 V DC ... 2 A / 250 V AC
(for resistive loads)
For inductive or capacitive loads reduce at 50%
Ambient temperature -20 °C ... +70 °C  
Protection IP66 according DIN EN60529  
Weight 1.2 kg ... 5 kg depending on the model  
Other characteristics Depending on requested options