iPR-EX Explosion Proof Inline Process Refractometer

The explosion proof version of the SCHMIDT + HAENSCH process refractometer consists of an intrinsically safe, single-certified sensor, which can be installed in hazardous areas. It is chemical resistant, food-safe, and delivers reliable, hygienic measurements, fully in line with your production process.

  • An explosion-proof version of the model iPR-B3
  • Suitable for all applications in explosion-proof areas
  • Certified according to the European classification ATEX II 1 G Ex ia IIC T4 Ga
  • Permanent inline real-time measurement of the concentration of dissolved solids

The iPR-EX is a fully automatic process refractometer for direct measurement of dissolved solids and for process monitoring and control. The main features of this critical-angle refractometer are a sapphire prism and high-resolution photodiode array with no influence of color or turbidity of the medium on the measuring result. The instrument enclosure is made of stainless steel making it chemical resistant, food-safe, hygienic, and allows for process temperatures up to 120 °C (with connected water cooling) and pressures up to 1 MPa.

The explosion protection consists of an intrinsically safe, single-certified sensor, which is installed in a hazardous area. The measuring signals are routed to the non-explosive area via cable (maximum length 500 m) and connected to 4 zener barriers. An RTU Modbus or serial RS 485 interface is used to communicate with the central control system.

Schmidt + Haensch also offers a process control unit for installation outside the hazardous area. The 7“ touch screen can be individually configured and the measured data can be output via Ethernet, 24 V, or 4-20 mA signal or control a relay. For data transmission to other systems, serial RS 232, 485 interfaces, a CAN bus or UPC server are also available.

Up to two measuring heads can be connected at the same time.

Main specifications

Standards ATEX II 1 G Ex ia IIC T4 Ga
IEC in preparation
Measuring range 1.32000 – 1.52000 nD
Resolution 0.00001 nD
Precision ±0.00014 nD


Ambient temperature -20 °C to +65 °C
Process Temperature -20°C to +120 °C*
Temperature resolution/precision 0.01°C / ±0.2°C (0° to 70°C)
Process pressure 0 to 1 MPa (145 psi, 10 bar)

Additional informationen

Prism Sapphire
Wetted parts Sapphire (prism), stainless steel, FKM
Protection class IP 67
Light source/wavelength LED, 589 nm
Interface, switches ModBus, RS485, and 24V with external Zener barriers
Dimensions 330mm x 149mm (length x diameter)
Weight 9600g

Control unit

Operation One and two measuring headsets are available, connectable with built-in Zener barriers
Display 7″ Touchscreen, 800 x 480 pixel
Interface Ethernet
DIN rail parts (expandable) Switch inputs (24 V) and outputs (24 V / relay / 4-20 mA) / Communication (RS232 / RS485), CAN, UPC Server
Highlights Configuration of measuring head and outputs / Adjust switching thresholds and analog outputs /
Concentration and other scales user programmable
Power 85 V … 265 V 50/60Hz
Housing IP65