Hvordan bestemmer man, om syrekoncentrationen i nedsænkningstanken overstiger standarden?

To determine whether the acid concentration of the immersion pickling tank exceeds the standard, a comprehensive analysis needs to be conducted in combination with the process standards, detection methods and actual reaction phenomena. The following are specific methods: 1. Concentration threshold based on process standards Each pickling process (such as steel rust removal, metal surface activation, etc.) has a clear acid concentration range, and the process documents or formula requirements need to be confirmed in advance. For example: Hydrochloric acid pickling: The commonly used concentration in the steel industry is 10%~20% (mass fraction). If the measured concentration is greater than 25% or less than 8%, it is considered to exceed the standard. Sulfuric acid pickling: The concentration is usually controlled at 15%~25%. Exceeding 30% may accelerate metal corrosion and produce a large amount of hydrogen. If it is less than 10%, the rust removal efficiency will be significantly reduced. Mixed acid (such as hydrochloric acid + hydrofluoric acid): It needs to be controlled according to a specific ratio (such as HCl:HNO₃=3:1). If the concentration of a single acid deviates from the formula by ±10%, it will be judged as abnormal. 2. Laboratory test method (precise quantification) The most reliable way to judge is to analyze the concentration of acid by sampling: Titration method (chemical analysis) Principle: Titrate the acid with a standard alkali solution (such as NaOH) and calculate the acid concentration by the amount of alkali consumed. Operation steps: Accurately draw 10mL of acid with a pipette, inject it into a conical flask, and add 2~3 drops of phenolphthalein indicator. Titrate with a known concentration of NaOH standard solution (such as 0.1mol/L) until the solution is slightly red and does not fade for 30 seconds, and record the consumed volume V (mL). Judgment standard: If the calculated result exceeds the process allowable range (such as ±5% fluctuation), it is considered that the concentration exceeds the standard. Density method (applicable to strong acid) Principle: The concentration of acid is linearly related to density (such as the higher the concentration of concentrated sulfuric acid, the greater the density), and the density is measured by looking up the table for comparison. Operation steps: Use a densitometer (or hydrometer) to directly immerse in the acid, read the scale value, and measure the temperature at the same time (need to be calibrated to the standard temperature of 20℃). Refer to the "Acid Concentration - Density Comparison Table" (e.g., hydrochloric acid at 20°C, 20% concentration corresponds to a density of about 1.09g/mL). If the measured value deviates from ±0.02g/mL, the concentration may be abnormal. pH detection method (applicable to dilute acid or mixed acid) principle: acid concentration is negatively correlated with pH value (the higher the concentration, the lower the pH), but it should be noted that strong acids (such as hydrochloric acid and sulfuric acid) have a dissociation℃close to 100% at high concentrations, and may not be sensitive to pH changes (e.g., 20% hydrochloric acid pH≈-0.3, 15% hydrochloric acid pH≈-0.1), and need to be used in combination with titration. The pH of weak acids (such as hydrofluoric acid) is nonlinearly related to concentration and needs to be converted through a standard curve. 3. On-site rapid detection method (convenient qualitative) is suitable for real-time monitoring or scenarios without laboratory conditions: pH test paper/test strips Use a glass rod to dip acid and drop it on the test paper, compare the pH value with the standard color card, and combine process experience to determine whether the concentration is abnormal (for example, in steel pickling, hydrochloric acid pH>1 kan være utilstrækkelig) . syrekoncentrationstestpapir (specielt testpapir) Nogle producenter leverer testpapir til specifikke syrer (såsom saltsyrekoncentrationstestpapir), som vil udvikle farve efter at være nedsænket i syre, direkte svarende til koncentrationsområdet (såsom 10%~ 15%, 15%~ 20%osv. Konduktivitetsmåler krævet) Jo højere syrekoncentration er, jo større er ionkoncentrationen og jo højere ledningsevne . "koncentrationskontrol" -kurven er forudkalibreret, og når den målte værdi afviger fra kurven med ± 10%, indikerer det, at den koncentration er abonormal . 4. observerer reaktionen til at hjælpe med at dømme, når den dampe er den koncentration, den er i den koncentration, den er en koncentration. Unormal, reaktionen mellem emnet og syren vil ændre sig markant, hvilket kan bruges som et foreløbigt grundlag for vurdering: utilstrækkelig koncentration (lavt) fænomen: hastigheden af ​​boblegenerering på overfladen af ​​arbejdsemnettet bremser (metal reagerer med syren til at generere mindre hydrogen) . tidspunktet for rust -fjernelse eller descaling er betydelig udvidet. (e.g., the pickling that was originally completed in 30 minutes still fails to meet the standard after more than 1 hour). The color change of the acid solution is not obvious (e.g., in the pickling of steel, the Fe²+ concentration increases slowly, and the acid solution does not turn light green as Forventet) . Fænomenet med overdreven koncentration (overskridelse af standarden): Reaktionen er voldelig, et stort antal bobler genereres, og syretåge er flygtigt (e . g ., når hydrochlorinsyre -koncentrationen er for høj, åbenlyst hvid tåge fremhæves over tanken) {{}}}} lesrochlorinsyreconcentrationen er for høj, åbenlyst hvid tåge fremhæves over tanken) {{}}}}} lerochlorinsyreconcentration Arbejdsstykket er overdrevent korroderet, og "sorte" og "huller" eller unormalt vægttab forekommer (øget risiko for brintforbrydning) . Temperaturen på den syreopløsning stiger unormalt (hvis operationen er forkert, når der fortynder koncentreret svovlsyre, og det kan koges på grund af intens varmefrigivelse) . v {{{}}}}} frekvens og registrering af optagelser og registrering af optagelser og efter at have kogt på grund af intens varmefrigivelse) {. v {{{}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}} frequency: In regular production, 1~2 times per shift (8 hours). If the process stability is poor or continuous operation, it is necessary to inspect once every 2~4 hours. After preparing a new acid solution, adding acid solution, or changing the workpiece material, the concentration must be tested immediately. Record and traceability: Establish an "Acid Concentration Detection Ledger "for at registrere detektionstiden, koncentrationsværdien, tester og om den overstiger standarden . I tilfælde af abnormalitet skal behandlingsforanstaltningerne (såsom tilsætning af syre, fortynding eller udskiftning) markeres . 6. Forholdsregler Sikker drift: slid syrebosættelsesglader og gasgles under testning af at undgå at syre syre; pour the acid sample slowly to prevent splashing. Temperature influence: When testing density or conductivity, the acid temperature must be corrected to the standard temperature (such as 20℃), otherwise it will cause errors (temperature increases and liquid density decreases). Complex factors: If the acid contains a large amount of metal ions (such as Fe²+, Fe³+), it may affect the density or conductivity, and Titreringsmetoden skal kombineres for at korrigere resultaterne . gennem den omfattende vurdering af ovennævnte metoder, den unormale syrekoncentration kan opdages i tide til at undgå ukvalificerede pickling -effekter på grund af utilstrækkelig koncentration, eller sikkerhedsulykker forårsaget af overdreven koncentration (såsom overdreven korrosion, hydrogen eksplosion) .}}}}}}}}}}}}}}}}}}}}}}}}}}}