iPR EX – Explosion Protected

ATEX inline Measurements

The explosion protection 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 and hygienic measurements, fully in-line with your production process.


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

Easy to Use

The 7” touch screen is individually configurable. The measured data can be output via Ethernet as a 24 V or 4-20 mA signal, or controllable relay.

For data transmission to other systems, serial RS 232, 485 interfaces, a CAN bus or UPC server are available.

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


This fully automatic process sensor is perfectly suited for direct measurement of dissolved solids, process monitoring, and control in hazardous areas. With its explosion protection, it can be employed in the automotive, aviation, petrochemical, and refinery industries.

Conformity: Zone 0 Ex II 1 G Ex ia IIC T4 Ga, ATEX 2014/34/EU, EN 60079-0 (2012) + A11 (2013), EN 60079-11 (2012).

Product in depth

The SCHMIDT + HAENSCH critical-angle refractometer with sapphire prism and high-resolution photodiode array operates consistently, independent of medium color or opacity. Stainless steel measuring head is chemical resistant, food safe, hygienic, for process temperatures up to 120 °C (with connected water cooling) and pressures up to 1 MPa. The measuring signals are routed to the non-explosive area via a special cable (maximum length 500 m) and connected to four Zener barriers. The connection to the central control system is realized with a RTU Modbus or serial RS 485 interface. Alternatively, SCHMIDT + HAENSCH offers a control unit which can also be installed outside the hazardous area.


Main specifications

StandardsATEX II 1 G Ex ia IIC T4 Ga
IEC in preparation
Measuring range1.32000 – 1.52000 nD
Resolution0.00001 nD
Precision±0.00014 nD


Ambient temperature-20 °C to +65 °C
Process Temperature-20°C to +120 °C*
Temperature resolution/precision0.01°C / ±0.2°C (0° to 70°C)
Process pressure0 to 1 MPa (145 psi, 10 bar)

Additional informationen

Wetted partsSapphire (prism), stainless steel, FKM
Protection classIP 67
Light source / wavelengthLED, 589 nm
Interface, switchesModBus, RS485 and 24V with external Zener barriers
Dimensions330mm x 149mm (length x diameter)

Control unit

OperationOne and two measuring headsets are available, connectable with built-in Zener barriers
Display7″ Touchscreen, 800 x 480 pixel
DIN rail parts (expandable)Switch inputs (24 V) and outputs (24 V / relay / 4-20 mA) / Communication (RS232 / RS485), CAN, UPC Server
HighlightsConfiguration of measuring head and outputs / Adjust switching thresholds and analog outputs /
Concentration and other scales user programmable
Power85 V … 265 V 50/60Hz


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