Bagaimana cara menentukan apakah konsentrasi asam dalam tangki acar perendaman melebihi standar?

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 mungkin tidak mencukupi) . kertas uji konsentrasi asam (kertas uji khusus) Beberapa produsen menyediakan kertas uji untuk asam spesifik (seperti Kertas Konsentrasi Asam Hidroklorat), yang akan mengembangkan warna setelah direndam dalam asam, secara langsung sesuai dengan kisaran konsentrasi (seperti 10%~ 15%, 15%~ 20%, {{6 {6 {6 {6 {6 {6%{6%{6%{6%, {6%{6%{6%{6%{6%{6%, Diperlukan) Semakin tinggi konsentrasi asam, semakin besar konsentrasi ion dan semakin tinggi konduktivitas . kurva "konsentrasi-konduktivitas" adalah pra-dikalibrasi, dan ketika nilai yang diukur menyimpang dari kurva dengan ± 10%, itu menunjukkan bahwa konsentrasi yang abnormal . 4. mengesampingkan fenomen reaksi fenomen yang abnormal {{12} obson. workpiece and the acid will change significantly, which can be used as a preliminary basis for judgment: Insufficient concentration (low) phenomenon: The rate of bubble generation on the surface of the workpiece slows down (the metal reacts with the acid to generate less hydrogen). The time for rust removal or descaling is significantly extended (e.g., Acar yang awalnya diselesaikan dalam 30 menit masih gagal untuk memenuhi standar setelah lebih dari 1 jam) . Perubahan warna larutan asam tidak jelas (e . g . dalam konsentrasi yang diperkirakan) {22 {22 {konsentrasi {22 {{{20} {pHo {22 {{{20 {20 {{{20 {{{20 {{{20 {{{20 {{{20 {{20 {{20 {{20 {{20 {{20 {{20 {{20 {{20 {{20 {{20 {{20 {{22, dan solusi asam, dalam konsentrasi. (exceeding the standard): the reaction is violent, a large number of bubbles are generated, and acid mist is volatilized (e.g., when the hydrochloric acid concentration is too high, obvious white mist appears above the tank). The surface of the workpiece is excessively corroded, and "blackening" and "holes" or abnormal weight Kehilangan muncul (peningkatan risiko embrittlement hidrogen) . Suhu larutan asam meningkat secara abnormal (jika operasinya tidak tepat ketika mengencerkan asam sulfat terkonsentrasi, ia dapat mendidih karena pelepasan panas yang intens). v . frekuensi dan rekor persyaratan persyaratan persyaratan {22 {22 kali {2 kali {22 kali {22 kali {2 kali {22 kali. 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" to record the detection time, concentration value, tester and whether it exceeds the Standar . Dalam hal kelainan, langkah-langkah pengobatan (seperti menambahkan asam, mengencerkan atau mengganti) harus ditandai . 6. tindakan pencegahan yang aman: sarung tangan dan kacamata yang tahan asam selama pengujian untuk menghindari percikan asam; Tuang sampel asam secara perlahan untuk mencegah percikan . pengaruh suhu: Ketika pengujian kepadatan atau konduktivitas, suhu asam harus diperbaiki ke suhu standar (seperti 20 derajat), jika tidak akan menyebabkan kesalahan (suhu kenaikan dan kepadatan cairan berkurang) . faktor kompleks: jika asam mengandung sejumlah besar logam (seperti logam (seperti fe - fe³+Faktor kompleks: jika asam tersebut mengandung sejumlah besar logam (seperti logam (seperti fe - fe - feó+Feon+Feon+Feon (seperti jumlah besar (seperti jumlah logam (seperti jumlah besar (seperti jumlah besar (seperti jumlah logam (seperti jumlah besar (seperti feon+ Metode titrasi harus digabungkan untuk memperbaiki hasil . melalui penilaian komprehensif dari metode di atas, konsentrasi asam abnormal dapat ditemukan pada waktunya untuk menghindari efek aspar yang tidak memenuhi syarat karena konsentrasi yang tidak mencukupi, atau kecelakaan keamanan yang disebabkan oleh konsentrasi yang berlebihan (seperti korosi yang berlebihan, eksplosion hidrogen) {46