See how buhler tank level sensor looks and its principle 👇👇👇

Buhler Technologies GmbH (german company)
NS 25/25-AM-K7,5-SK661/1200
L1=1200 mm
analogue output 4-20mA/ resolution 7.5
max oil pressure 25bar / temperature 120°C

These types of  devices mounted externally on the tanks or housings for monitoring the liquid level

This magnetic level sensor can be used where the oil pressure is from 12 bar to 25 bar only. Bühler company makes sensors ranging from 10 to 360 bar

The level switches are not designed for cycling

During pressure testing, the level switches are pressurised with the below-following test pressure:

Level switch with transducer tube (4-20mA output)

If the level switch is equipped with a transducer tube for continuous liquid level monitoring, the solenoid switches can only be installed on the left side of the indicator scale. 

The transducer is factory set and must not be changed.

4mA = empty tank 
20mA = full tank

Working of the magnetic level indicator

As you saw above in the figure. It is provided with a flange to connect the transducer with the tank. This will connect the flange to the tank, then the oil of the tank pumped into the tube of the sensor via top flange or bottom flange. Just as there will be oil filling in the tank in the same way, the oil will be filled in the tube of this sensor. there is a cylindrical floating magnet under the sensor tube, the same magnet moves when the level of the oil rises up or down.

Following outputs in this transducer

Analogue output using transducer tube (4-20mA)

Digital output using MKS 1/W magnetic level switches

both the above outputs will be considered as inputs to the PLC.

Transducer tube is known as level transmitters also. The level transmitters are mounted on the outside of a bypass level indicator. This level transmitter works on the magnetostrictive principle. high-resolution measuring principles are used for continuous level measurement of liquids tanks and are based on determining the position of a magnetic float following the magnetostrictive principle.

 

Type                                  MKS 1/W

Function                            Changeover contact   

Max. voltage                     230 VAC/DC

Max. switching current     1 A

Max. contact load             50 VA

Connector                         M3 (DIN EN 175301-803)

                                          3-pin + PE 

IP class                              IP 65

Item no.                            2889999

MKS 1/W is a contact changeover switch for the level switch, The contact changeover of this switch will be at which point, in which direction are you mounting it, as the above picture you can see if you mount that switch on the left side of the sensor 1 and 2 points are normally NC and if you mount this on right side 1 and 3 points are normally NC. This switch has a magnet sensing contact change over. 

If the magnet is sensed from the UP direction, then NO gets changed to NC. That NC contact remains NC, when the magnet crosses in the DOWN direction then it changes to the normal NO contact

Types of contact changeover switches (Buhler make)

MKS 1/K

MKS 2/K

MKA 1/W (above explain)

MKS 1/W-L 24V