Kids Study Adjustable Desk,Drafting Table Adjustable,Sit Stand Desk,Standing Desk Electric Shaoxing contuo Transmission Technology Co.,Ltd , https://www.contuodesk.com
How to correctly test the degree of pulp release
[Chinese Packaging Network News] In the papermaking industry, a widely known saying is: "Three parts of papermaking, seven parts of beating." Understanding this phrase highlights the crucial role of beating in the pulping process. However, in actual production, many inspectors tend to overlook how significantly the pulping process affects the final product quality.
The degree of beating, also known as the freeness, is a key indicator that reflects how easily the pulp slurry can be filtered. Simply put, the higher the freeness, the easier it is for water to pass through the pulp; the lower the freeness, the more difficult it becomes. In other words, the freeness is inversely proportional to the filtration speed of the pulp suspension.
In China, the current standard for measuring freeness is GB/T 3332-2004, which outlines the method for determining the freeness of pulp using the Shöber-Rygler technique.
To accurately test the freeness of pulp, it's essential to understand the testing procedure. The process involves taking 2 grams of dry pulp and diluting it to 1000 ml with water. After thorough mixing, the diluted slurry is poured into the filter bucket of the freeness tester. It then passes through a standard 100-mesh copper mesh. The amount of water discharged through the side tube during a specific time period is measured using a graduated cylinder.
Taking the QZ-SDJ Freeness Tester as an example, a properly functioning device must meet several basic technical specifications:
1. Measurement range: 0–100° SR (Shoer degree).
2. The rising speed of the sealing cone should be 100±10 mm/s.
3. Flow rate of the bottom hole: After removing the umbrella frame, block the side flow tube with a stopper, cover the bottom hole with your finger, pour 20±0.5 mL of distilled water at 20±0.5°C into the separation chamber, and record the drainage time. This time should be 149±1 seconds.
4. Remaining volume: Block the bottom hole with your finger, pour 20 mL of 20±0.5°C distilled water into the separation chamber. After all excess water has drained through the side tube, release the bottom hole and collect the remaining water. The volume should be between 7.5 and 8.0 mL.
When using the QZ-SDJ freeness tester, it’s important to pay attention to several key factors beyond just meeting the technical parameters. First, maintaining the correct temperature of both the sample and the water is critical, as temperature variations can significantly impact filtration performance. Additionally, regular cleaning of the instrument is necessary. Inspect the filter bucket, separation chamber, and copper mesh for any fiber buildup. If present, clean them promptly using a soft brush and acetone—without damaging the copper mesh. A blank test using distilled water after cleaning can help verify the effectiveness of the cleaning process. If the blank test result exceeds 4°SR, the copper mesh should be replaced immediately.
Understanding the principles behind the testing process and being aware of these operational details ensures accurate measurement of the pulp freeness using the QZ-SDJ freeness tester. This knowledge not only improves the reliability of the results but also contributes to better quality control in the papermaking industry.