EMCO 4-electrode Conductivity Sensor series 711 for Concentration Measurement



The EMCO conductivity Sensor Series 711 is designed to measure medium and higher conductivity ranges to determine concentration of common acids and lays, such as: Sulphuric Acid, Nitric Acid, Hydrochloric Acid, Sulphur Tri-Oxide (Oleum), Hydrofluoric Acid, NaOH.
The conductivity must either increase or decrease with the concentration. See fig. 1
The fluid must only contain one single electrolyte - or at least the electrolyte of interest must be the major supplier to the conductivity.


Petro,/-Chemical, Metal refining, Sulphuric Acid Processing, Pulp & Paper. Chemical, Steel Processing, Fertilizer industries, and other corrosive liquid handling industries.


The EMCO sensor element has a 4 electrode design for higher accuracy and wider measuring range over the 2 electrode design.

The electrodes are internal for use in smaller pipes – less than 75 mm. For larger pipes, use series 721.

The sensor has an accurate temperature element with low response time for fast temperature compensation. For the corrosive fluids wetted parts are in porous free PTFE with electrodes in tantalum or platinum
The cable to connect to the Analyzer is specially selected to ensure high accuracy and long distance between sensor and analyzer.
The cable is a part of the supply of the sensor.

A selection of electrode and sensor element materials is available to suit the specific application.

Our many years in instrument design guarantees a roughed design, but still allows the possibility to solve customers´ special requirements.

Principle of Measurement

Electrical conductivity is the ability of a liquid to carry a current.
The conductivity is equal to the conductance of the liquid times the cell constant.
The conductance is the reciprocal of the electrical resistance of the liquid measured.
The cell constant is equal to the distance between the electrodes divided by the effective area of the electrodes.

Cell Constant

The cell constant is equal to the distance in cm between the electrodes divided by the effective area in cm² of the electrodes.
The applicable value of the cell constant depends on the conductivity of the solution being measured.
Low conductivity requires low cell constant and high conductivity requires high cell constant

Factory determined cell constant ensures highest accuracy. The cell constant is marked on the sensor. The dedicated analyzer is programmed with this specific cell constant ensuring the highest accuracy


Extremely resistant to wear | Applicable for very corrosive fluids | Rugged design | Resistant to scaling | Easy to install | Cable mounting via connector

Technical Specification

Measure range  0- 1500 mS/cm 
Process connection  Flange according to ANSI B 16.5, EN 1092-1 or DIN 
Pressure ratings  150 lbs, 300 lbs, PN 40 
Sizes  1½”, 2”, DN 32, DN 40, DN 50. 
Pressure max.  10 bar 
Temperature max.  150°C 
Material. sensor body  PTFE, AISI 316 
Material. electrodes  Tantalum, platinum or AISI 316 
Material. electrode support PTFE
Insertion length 140 mm
Temperature element Pt1000 Class A IEC 751
Cell constant Individually determined, marked on sensor
Accuracy better than 2 % (1 % per decade)
Protection IP 65
Sensor cable 9 pole
Cable lengths 3 m, 5 m, 10 m, 20 m, 30 m.
Suitable Analyzer model 570


The sensors can be calibrated in one or several points documented at reference temperature of 25°C


Dimensional drawing
Material certificate according to EN 10204-3.1
Pressure test certificate
Calibration certificate
Instruction manual

Overall Dimensions



With our fully equipped machine shop including welding EMCO Controls can supply mechanical parts including flow tubes, by-pass systems etc.

Quality Assurance

EMCO Controls is certified according to ISO 9001- 2008,
Pressure Equipment Directive PED Module H,
and welding quality certificate to EN 3834-2.

Sensor Coding



Concentration sensor with DN 40 PN 40 flange, internal electrodes in tantalum, sensor body in PTFE, insertion length 140 mm and 5 meter cable has following code: