Equipping a water purification system for electrochemical machining with process instrumentation

Application Report | Machinery & Apparatus

  • Measurement technology for a turnkey membrane filtration system
  • Vast range of measurement requirements including flow, level, pressure, temperature and analysis


ECM Technologies engineers and supplies solutions for electrochemical machining (ECM), which is a method to precisely cut angles, gaps, edges or other shapes into electrically conductive metals. An ECM process requires an electrolyte to be injected into the workpiece so as to function as a medium between the tool and the workpiece, dissolving the desired parts by way of electrolysis without direct mechanical contact. Through the process of ECM demi water with heavy metal ions is discarded as a waste product which has to be purified using a membrane filtration system. Electrolyte cleansing technology removes the toxic particles from the electrolyte. In order to operate such a purification system properly, a whole range of parameters such as flow, level, temperature, pressure, pH, turbidity or conductivity have to be controlled on a regular basis

Measurement requirements

For a customer in northern Europe ECM Technologies tailored a water purification system for electrochemical machining processes. As the whole installation had to be delivered as a turnkey solution, ECM Technologies required process instrumentation for the various measurement tasks.

Customer benefits

ECM benefited from the synergy of a single source supplier. KROHNE was able to meet all measurement requirements ranging from flow and flow control, to level, temperature up to analysis for turbidity and conductivity.

Products used


Electromagnetic flowmeter for general applications with conductive liquids

  • Economical flow measurement of liquids (≥5 μS/cm) with solid content (≤10%)
  • -25…+120°C / -13…+248°F
  • Wafer-style design: DN10…150 / ⅜…6", max. PN40 / ASME Cl 300
  • 4…20 mA, pulse, frequency, status, HART®

DWM 2000

Electromagnetic insertion-type flowmeter for flow monitoring of conductive media

  • Ideal for liquids, pastes and slurries (≥20μS/cm), suitable for immersed applications (IP68)
  • -25…+150°C / -13…+302°F; up to 25 barg / 360 psig
  • For pipes DN25…400 / 1…16", optional >DN400 / 16"
  • 3-wire, 4…20 mA


Guided radar (TDR) level transmitter for basic liquid applications

  • Continuous level measurement in buffer, storage, collecting or recycling tanks
  • Intuitive quick setup procedure
  • Measuring range: 0.7…20 m / 2.3...65.5 ft
  • -50…+100°C / -58…+212°F; -1…16 barg / -14.5…232 psig


Potentiometric pH sensor for wastewater, surface and process water applications

  • For use with analytical transmitter
  • Process connection: PG13.5
  • 0…14 pH; Max. +70°C / +158°F; 10 bar / 145 psi
  • Glass sensor with PTFE diaphragm and optional Pt100 for temperature compensation


Conductive conductivity sensor for water, wastewater, process water or pure water

  • For use with analytical transmitter
  • Process connection: G½, G¾, G1, ¾ NPT (male)
  • 0.05 μS/cm…20 mS/cm; Max. +135°C / +275°F
  • With two stainless steel, titanium or graphite electrodes and Pt100 for temperature compensation


Inductive conductivity sensor for water, wastewater and chemical applications

  • For use with analytical transmitter
  • Process connection: G1½ union nut and immersion versions
  • 1…2000 mS/cm; Max. +100°C / +212°F
  • Electrodeless conductivity sensor with Pt1000 for temperature compensation


Optical turbidity sensor for water and wastewater applications

  • For use with analytical transmitter
  • For immersion or insertion
  • 0…4/40/400  NTU/FNU; Max. +50°C / +122°F; 6 bar / 87 psi
  • 90° scattered light (NIR-LED) measurement acc. to ISO 7027


Resistance (RTD) temperature assembly for higher flow velocities and pressures

  • Thread connection
  • DIN-style based on form 8, welded multipart thermowell with straight tip
  • -40…+600°C / +1100°F


Coriolis mass flowmeter for universal applications and process control

  • For mass, density and volume flow of liquids and gases up to +130°C / +266°F
  • Also certified for hygienic use
  • Flange: DN15…100 / ½…4", max. PN100 / ASME Cl 600; many hygienic fittings
  • 3 x 4…20 mA, HART®, Modbus, FF, Profibus-PA/DP


Pressure transmitter for standard pressure and level applications

  • Compact design with recessed stainless steel diaphragm and optional display
  • 0.5…200 bar / 7…2900 psi; 0.2…200 barg / 3…2900 psig
  • Thread: G½; ½ NPT (male, female)
  • 2-wire 4…20 mA