Soap foam flowmeter | Precautions for using gas chromatography

『Soap foam flowmeter』Related information(v cone flow meter|rotary gas meter|gallon meter|gear meter|metal tube rotameter|glass tube rotameter|nutating disk meter|transit time ultrasonic flow meter|wedge flow meter|pd meters|hydraulic flow meter|ultrasonic water flow meter|water flow meter|air flow meter|magnetic water flow meter|oxygen flow meter|gas flow meter|argon flow meter|air velocity meter|gasoline flow meter|fuel flow meter|ultrasonic water meter|digital water meter|nitrogen flow meter|solid flow meter|Oxygen tank flow meter|digital water flow meter|diesel fuel flow meter|steam flow meter|02 flow meter|compressed air flow meter|oil flow meter|liquid flow meter)

1. The first method of GB/T18204.26-2000

1. Principle: Formaldehyde in the air reacts with phenolic reagents to form pyrazine, which is then oxidized by high-speed iron ions in an acidic solution to form a blue-green compound. According to the depth of color, the colorimetric quantification is carried out. The water used in this method is either distilled water or deionized exchange water; The purity of the reagents used is generally analytical grade. 2.1 Absorbent solution: Weigh 0.10g of phenol reagent [C6H4SN (CH3) C: NNH2 · HCl, abbreviated as NBTH], dissolve it in water, pour it into a 100ml stoppered measuring cylinder, and add water to the mark. Store in the refrigerator and keep stable for three days

2.2 Absorption solution: Measure 5ml of absorption solution and add 95ml of water to obtain the absorption solution. When sampling, use freshly prepared 2.3% ammonium iron sulfate solution: Weigh 1.0g of ammonium iron sulfate [NH4Fe (SO4) 2 · 12H2O] and dissolve it in 0.1mol/L hydrochloric acid, then dilute to 100ml. 2.4 Iodine solution [C (1/2I2)=0.1000mol/L]: Weigh 30g of potassium iodide and dissolve it in 25ml of water, then add 12.7g of iodine. After the iodine is completely dissolved, dilute to 1000ml with water. Transfer to a brown bottle and store in the dark. Weigh 40g of sodium hydroxide solution, dissolve it in water, and dilute to 1000ml. Take 28ml of concentrated sulfuric acid and slowly add it to the water. After cooling, dilute to 1000ml. Sodium thiosulfate standard solution [C (Na2S2O3)=0.1000mol/L]: Standard reagents purchased from reagent stores can be used, or prepared according to Appendix A. Mix 0.5g of soluble starch with a small amount of water to form a paste, then add 100ml o

f boiling water and fry. Boil for 2-3 minutes until the solution is clear and transparent. After cooling, add 0.1g salicylic acid or 0.4g zinc chloride and store. 2.9 Formaldehyde standard storage solution: Take 2.8ml of formaldehyde solution with a content of 36-38% and place it in a 1L volumetric flask. Dilute with water to the mark. 1ml of this solution is equivalent to 1mg of formaldehyde. The accurate concentration is calibrated using the following iodometric method. Calibration of formaldehyde standard storage solution: Accurately measure 20.00ml of formaldehyde standard storage solution to be calibrated and place it in a 250ml iodine volumetric flask. Add 20.00ml of [C (1/2I2)=0.1000mol/L] iodine solution and 15ml of 1mol/L sodium hydroxide solution, let it stand for 15 minutes. Add 15ml of 0.5mol/L sulfuric acid solution and let it stand for another 15 minutes. Titrate with [C (Na2S2O3)=0.1000mol/L] sodium thiosulfate solution until the solution turns pale yellow. Add 1ml of 5% starch solution and continue titration until the blue color fades. Record the volume of sodium thiosulfate solution used (V2), ml. Simultaneously, use water as a reagent for blank titration, and record the volume (V1) of the standard solution of sodium sulfate sulfide used for blank titration, in ml. The concentration of formaldehyde solution can be calculated using the formula

(1): C=(V1-V2) × N × 15/20......

(1) with observation: C - concentration of formaldehyde solution (mg/ml) V1- consumption of reagent blank [C (Na2S2O3)=0.1000mol/L] volume of sodium thiosulfate solution, ml; V2- consumption of formaldehyde standard storage solution [C (Na2S2O3)=0.1000mol/L] volume of sodium thiosulfate solution, ml; N - accurate equivale

Soap foam flowmeter | Precautions for using gas chromatography

1. The first method of GB/T18204.26-2000

『SILVER Official Website SERVICE』