What is the p-value and why is it measured?

The p-value (phenolphthalein alkalinity) describes the buffering capacity of water against acid input. It measures the hydroxide ions (OH-) and carbonate ions (CO₃²-) dissolved in the water, which are converted into water (H₂O) and hydrogen carbonate (HCO₃-) during titration. The measurement result is given in mmol/l.

Without a sufficient p-value, water has hardly any buffering capacity – even small amounts of acid can shift the pH value into the acidic range. In practice, the p-value is therefore a decisive parameter for corrosion protection: in steam boiler systems, cooling water circuits and industrial treatment plants, the alkalinity of the water must be continuously monitored in order to prevent corrosion on pipes, heat exchangers and boiler components.

What is the SYCON P?

The SYCON P from RLS Wacon is a fully automatic online titration device for the quantitative determination of the p-value in process water. It is based on the proven SYCON platform and offers the full range of functions of the Premium series: two programmable limit values, four relay outputs, an RS485 interface with Modbus RTU and an analog output 0/4-20 mA.

With two Reagents (P25-5 and P25-20), the device covers a measuring range of 0.2 to 20 mmol/l and is therefore suitable both for the fine monitoring of low-alkaline water and for highly alkaline applications.

How does the SYCON P work?

The SYCON P works according to the colorimetric titration method. The dye phenolphthalein contained in the Reagent is colorless below pH 8.2 and intensely pink to violet above this level. During the measurement, an alkaline water sample (pH > 8.2) is automatically fed into the measuring chamber and titrated step by step with the Reagent. An optical sensor detects the color change at the pH 8.2 point and calculates the p-value.

The analysis time is approx. 3 minutes. The indicator consumption is only 0.05 to 0.6 ml per analysis, depending on the measured p-value.

Advantages of the SYCON P

• Exact determination of measured values by titration method

  Quantitative determination of the p-value with ± 5 % accuracy and ± 2.5 % repeatability

• Continuous online monitoring of a critical corrosion parameter

  Protects boilers, pipes and heat exchangers from acid-induced corrosion

• Two measuring ranges for different applications

  P25-5 (0.2-5 mmol/l or 0.01-0.5 ppm) for low alkaline water, P25-20 (0.8-20 mmol/l or 0.2-6.0 ppm) for highly alkaline applications

• RS485 interface with Modbus RTU

  Direct query of measured values and device parameters by a PLC – seamless integration into the system automation

• Two freely programmable limit values

  Pre-alarm and main alarm or monitoring of a bandwidth with lower and upper threshold value

• 4 potential-free relay outputs

  Limit value 1, limit value 2 / indicator level, device fault, analysis active / cooling water valve

• Self-calibrating full color sensor

  No manual calibration – automatic compensation for ambient light, contamination and turbidity

• Very low indicator consumption

  0.05-0.6 ml per analysis – one 500 ml bottle is sufficient for numerous analyses

• 9-language graphic display with SD card

  Complete logging, installation wizard, software updates via SD card

Der Beitrag SYCON P erschien zuerst auf RLS Wacon analytics.