APHA/PT-Co (Hazen) Color Analyzer (ASTM D1209)

This test method describes a procedure for the visual measurement of the color of light colored liquids. It can be referred to by several different names: APHA, Platinum-Cobalt, or Hazen. The measurement was originally developed to detect contamination of water supplies as detected by a slight yellow color. Today it finds use in many industries to measure slight yellowness to determine product quality (either degradation or impurities).

The APHA/Platinum-Cobalt color scale is described in ASTM D1209 “Standard TestMethod for Color of Clear Liquids (Platinum-Cobalt Scale)”. This ASTM method is an off-line manual laboratory method. The original test design required an observer to compare the color of a product to a known standard, and then judge the “color.” The APHA/Platinum-Cobalt color scale ranges from 0 to 500. The lowest value of 0 is referred to as water white. value of 500 is distinctly yellow.

Using a Guided Wave APHA/Platinum-Cobalt Color Analyzer system to automate this measurement within a process eliminates the visual judgment of a technician and delivers online real-time process control information to the process operators.

General Purpose, Zone 1 and Zone 2 Ex Enclosures

APHA Analyzer System Configuration

The Guided Wave Saybolt Color Analyzer system is a complete solution. The “ready-to-go” analytical system includes:

  • Analyzer – ClearView® db filter photometer technology
  • Fiber optic cables
  • Sample interface – insertion probe or flow cell
  • Control software and Saybolt application calibration
  • Accurate, Real-time Reliable Results

The APHA/Platinum-Cobalt Color Analyzer system utilizes a Guided Wave multi-wavelength ClearView db filter photometer analyzer platform. It may be configured for either one (1) or two (2) independent sample monitoring points. The ClearView db analyzer is configured with application-appropriate wavelengths to measure the APHA/Platinum-Cobalt color of the sample. The analyzer employs a dual-beam design – meaning; the system has an continual internal optical reference check that allows it to self-compensate for signal variation due to non-sample conditions. This ultimately provides the system with long term stability. The final product is a total APHA/Platinum-Cobalt Color System that measures the color variation without interference from other factors.

Figure 1 shows an initial calibration chart showing the measured values as compared to laboratory standard values.

The Smart Color Analyzer Choice

Complete APHA/Platinum-Cobalt (Hazen) Color Analyzer System:

  • Unique dual beam optics – for long term, stable operation
  • Up to two (2) independent measurement points –  for added analytical flexibility at reduced cost per point
  • High efficiency yet rugged fiber optics – analyzer electronics can be located away from a hazardous sample point
  • In-door touch screen or Ethernet (Modbus TCP) – easy local or remote analyzer operation and control
  •  Analytical calculations are all encoded in the software – answers and alarms are clearly reported

Guided Wave’s APHA/Platinum-Cobalt Analyzer system delivers accurate, real-time process measurement results. Its linearity and repeatability, as well as its low maintenance requirements make it a cost effective, smart choice to help optimize production, improve yields, ensure consistent product quality and enhance profitability.

Options for a Custom Color Analyzer

Another advantage of the Saybolt Analyzer system is that is can be customized in many ways. For more information about specifications and analyzer operations contact us.

Specifications: APHA/Pt-Co (Hazen) Color Analyzer – Photometer

Analyzer TechnologyFiber optic dual-beam ClearView db photometer (see also document #1033)
Fiber Connectors SMA 905
Light Source Tungsten-Halogen, >4000 hours typical
Photometric Noise<50 µAU 450-2100 nm 1 minute rms
Photometric Drift <500 µAU rms/ °C
Response Time 1 second, minimum. User settable
Measurement Range0-500 APHA/Platinum-Cobalt units (Pathlength can be optimized to increae sensitivity)
Measurement AccuracyComplies with ASTM method D1209
Power 24 VDC, 3 A; 72 watts
Environmental 0 – 45°C, 0 – 90%, sun and rain sheltered
Channels Up to 2 (two) sample channels and optional turbidity monitoring
Outputs (analog)Up to 6 for a one channel unit, Up to 4 per channel for a two channel unit, 4 – 20 mA, customer powered
Outputs (discreet)Up to 6 for a 1 channel unit, Up to 4 per channel for a 2 channel unit, contact closures
Inputs (analog) 4 (optional) 4 – 20 mA, isolated grounds
Local Display LCD touch screen, color QVGA
CommunicationsEthernet (TCP Modbus) standard
Enclosures General Purpose NEMA 4 unclassified, Z-Purge, NEMA 4x, CI D2, X-Proof, ICEEx, ATEX, CI D1