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I. Different definitions: 1. Phenolphthalein alkalinity: It is caused by all the hydroxide ions in water and half of the carbonate content; the alkalinity is measured at pH 8.3. 2. Total alkalinity: The total amount of substances in water that can neutralize strong acids. Second, alkalinity calculation: Alkalinity refers to all substances in water that can undergo neutralization with strong acids; in other words, it is the total amount of substances that can accept protons H+. Alkalinity in water is primarily composed of three types of substances: strong bases, such as sodium hydroxide and calcium hydroxide ； Weak bases, such as ammonia, aniline, etc ； Strong-base weak acid salts, such as carbonates, acidic carbonates, phosphates, silicates, etc. The alkalinity of circulating water is primarily expressed by the following formula: M=2++ +++2+. Under normal conditions, the concentrations of the last four components in the circulating water are very low; therefore, only these three components are considered, and the total alkalinity M is given by: M=2++. The determination of alkalinity in industrial cooling water has traditionally relied on the neutralization titration method. Alkalinity is measured using phenolphthalein as an indicator, and this value is referred to as phenolphthalein alkalinity, denoted by the symbol P. Alkalinity measured using methyl orange as an indicator is called total alkalinity, denoted by the symbol M. For different water quality conditions, the methods for calculating alkalinity vary slightly. To better reflect the actual condition of the water, it is necessary to choose an appropriate method for calculation. Determination methods: 1. Total alkalinity: Using methyl orange as an indicator, a standard solution of hydrochloric acid or sulfuric acid is used for titration until the stoichiometric point A is reached at a pH value of 4.5; at this point the solution changes color from yellow to orange-red, and the titration is stopped at that point to obtain the result. 2. Phenolphthalein alkalinity: Alkalinity is determined by titrating to the endpoint (pH 8.3) using phenolphthalein as an indicator. It is usually used in combination with the methyl red endpoint alkalinity. As a manufacturer of water quality analysis instruments, Jensprima Jep provides the PACON4900 – an online analyzer that is compact, easy to operate, and offers accurate measurements. It is used for the automatic online detection of phenolphthalein alkalinity as well as for quality control of boiler water. The principle of the drop colorimetric method allows for the measurement of high/low ranges by selecting different reagents. Low maintenance and low reagent consumption, allowing for long-term continuous operation. Standard 4-20mA and RS485 Modbus outputs, which can be easily integrated into your existing control systems. Measurement parameters: · Phenolphthalein alkalinity (p-value). Typical applications: boiler water, cooling water, wastewater. Product features: · Special material measurement tank – condensation does not accumulate on the optical components. · Automatic zero adjustment for each measurement, ensuring more stable results. · 4-20mA/RS485 Modbus output. · 4 programmable relay outputs. · External signal input function (able to be connected to external devices). · Compact design for easy installation. · Low maintenance requirements and minimal reagent consumption. · Durable design with accurate analysis capabilities. · Automatic online monitoring; only one reagent is required. Measurement range: 0.2 – 5 mmol/L, 0.8–20 mmol/L. Accuracy: ±5% of the upper limit of the selected reagent. Repeatability: ±2.5% of the upper limit of the selected reagent. Measurement method: Titration colorimetry. Reagent consumption: 0.05–0.6 ml per analysis. Validity period of reagents: 2 years from manufacture. Analysis time: Approximately 3 minutes, depending on the phenolphthalein alkalinity concentration and the set flushing time. Measurement interval: 5–360 minutes, selectable. Automatic cleaning: The instrument automatically cleans itself after each measurement. Calibration: Manual calibration via the service menu. Operating temperature: 10–45°C. Water sample temperature: 5–40°C. Water sample pressure: 0.5–5 ba; 1–2 bar is recommended. Water quality requirements: Clear, colorless, free of suspended particles and bubbles, with pH > 8.2. Power supply: 100–240VAC. Power consumption: 20 W (during operation), 3.5 W (in standby mode). Input/output: 6 mm hoses; water discharge is open without backpressure. Current output: 0/4–20mA. Relay outputs: 4 passive NC/NO relay outputs, 250VAC/1A. External inputs: 2 programmable input contacts. Protection rating: IP65. Dimensions: 300 x 300 x 200 mm. Weight: 4 KG