Inline Process Colorimeter

What is the Inline Process Colorimeter?

An inline process colorimeter continuously measures the colour or concentration of a flowing stream and outputs a signal to a control system. It is used for real-time monitoring in chemical, food and water treatment processes.

Overview

An inline process colorimeter is installed directly in a pipe or bypass line and measures the flowing sample through a fixed flow-through cell. A stable light source and filters define the measurement wavelength, and the transmitted or scattered light is detected and converted to colour or concentration units. Analogue or digital outputs such as 4–20 mA or Modbus feed a controller or distributed control system for continuous process control. The housing is sealed to the plant environment, and automatic cleaning or zeroing options reduce maintenance. Because the sample is continuously measured, trends and excursions are detected faster than with grab sampling.

How does it work?

A colorimeter passes light from a lamp or light-emitting diode through a coloured filter, then through the sample or onto the sample, and measures the transmitted or reflected intensity with a photodetector. The filter selects a band where the analyte absorbs, so the measured change follows the Beer–Lambert law for concentration work. For colour measurement, the instrument uses tristimulus filters or illumination geometry to compute colour coordinates in spaces such as CIELAB. The electrical signal is converted to absorbance, transmittance, concentration or a colour difference value against a stored reference. Because filters are fixed, only a few wavelengths are available, which limits selectivity but keeps the instrument robust and easy to operate.

What are the key features?

• Continuous measurement of a flowing process stream
• Flow-through cell sized to the pipeline
• Analogue and digital outputs for control systems
• Sealed housing for plant environments
• Optional automatic cleaning and zeroing

What are the technical specifications?

A typical inline process colorimeter configuration offers measurement principle of Transmission photometry, wavelength range of 400–700 nm, measurement range of 0–100% transmission, concentration scaled, light source of LED, detector of Silicon photodiode and output signals of 4–20 mA, RS-485/Modbus. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Inline Process Colorimeter is used in chemical and petrochemical process control, water and wastewater treatment monitoring, food and beverage production lines and pulp, paper and textile processing. Across the wider Colorimeters class, laboratories also deploy it for water and wastewater colour and ion testing, food and beverage colour grading and plastic, paint and coating colour control.

Which standards and certifications apply?

Relevant standards and methods include ISO 7887, ASTM D1209, ASTM E313, CIE 15 and USP <1061>. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Place the instrument on a level, stable surface away from strong stray light, which can bias colour readings. Keep cells and apertures clean and free of scratches, and use matched cells for concentration measurement. Verify performance regularly with reference standards, filters or certified colour tiles, and record results for trend monitoring. For reagent-based water testing, follow reagent shelf life and blanking procedures. Recalibrate or re-standardize at the interval defined by the quality system, and clean the illumination path as instructed. Protect portable units from moisture and impact.

How do I select the right Inline Process Colorimeter?

Select an inline process colorimeter for continuous, real-time monitoring of a flowing stream. Confirm the line size, flow rate and pressure suit the flow cell, and that outputs and communication match the control system. Specify the measurement range and required accuracy at the control point, and consider automatic cleaning when fouling is likely. Verify materials compatibility with the process fluid.

How does it compare with other Colorimeters variants?

Decide first whether the measurement concerns chemical concentration or surface colour. Concentration work in water, food or clinical testing suits a filter colorimeter with reagent-specific wavelengths, and pre-set calibrations speed routine testing. Colour grading of plastics, textiles, paints and packaging requires a colour difference meter with defined geometry and colour spaces. Portable models suit field and incoming inspection, while benchtop models give better repeatability for the laboratory. Check wavelength or illuminant options, measurement aperture, repeatability, data storage and connectivity, and the availability of certified colour standards for verification.