Control of liquids

Pneumatic controllers

L-27 DS

Intended use:

The pneumatic level controller is used to control 2 levels in liquids at atmospheric pressure. Model with 2 electrical microswitch output and with 2 signals of control (second signal adjustable).
Besides liquids can control fluid mixtures that allow the tube to be cleaned after the level of mixture downs.

The liquid or mixture that is controlled must not emit vapours that rarify the entrapped air inside the tube. This could be provoke a misfunction of the device. 


The controllers bases their function on the pneumatic outline. The controllers have an electric microswitch activated due to a membrane sensitive to pressure.
The action on the microswitch is carried out by the pressure of the air column entrapped inside the tube and the pressure chamber. Depending on the model, a water height of 40 mm.w.c. is sufficient to trigger the switch.

There are models with a micro pneumatic valve and there are other models that activate the switch due to a depression.
The models with sensitivity adjustment “SR”, the models with double signal “DS”and the models with “A99” switch have a regulation system with a spring that allows the adjusment of the sensitivity. Tightening the regulation nut to reduce the sensitivity and increase the strain of the liquid to activate the microswitch. 

Mechanical connection:

Make a hole wide enough to introduce the tube or fix it with the mounting accesory usuable.

Ensure of the water-tightness of the unions. Do not use tow or Teflon tapes, only screw the tube to the housing up to the base gasket.

In lateral mounting, ensure of a minimum height of the tube of 200 mm minimum after the elbow. 


Aproximate measures are given in mm. 




Technical data:

Name Pneumatic controller  
Type L-27 DS ref: 2401-5
  L-27 DS VITON ref: 2402-5
Type of signal Dobule signal  
Actuating pressure    
L-27 First signal +80 mm WG above the tube inlet; ±20 mm WG and Second signal +300 mm WG adjustable  
L-27 DS VITON First signal +100 mm WG above the tube inlet; ±20 mm WG and Second signal +330 mm WG adjustable  
Tank pressure Atmospherical  
Maximum pressure +0.5 bar  
Cable entry M20x1.5  
Electric microswitch:    
Switching voltage 250 V AC  
Switching function 2x(1 NO + 1 NC)  
Capacity of the contact 15 A / 250 V AC
(for resistive loads)
For inductive or capacitive loads reduce at 50%
Ambient temperature -5 °C ... +60 °C  
Type of protection IP53 According DIN EN60529  
Weight 1.50 kg  
Housing and cap Aluminium, RAL 7001 coated
(Under request Plastic: Glass reinforced Polypropylene)
Pressure chamber (base) Glass reinforced Polyester
(Under request Aluminium)
Membrane NBR
(Under request Viton)
Base gasket EPDM  
Xicle antiturbulence (under request) Brass  
Tube connection screw G 1 " female