Beating & Freeness Tester

Beating and Freeness Tester is a filter testing equipment, designed to determine the rate of drainage of a dilute pulp suspension and deliver it in the terms of the Schopper- Riegler (SR) value. The SR value is the inverse of the volume of collected water divided by 10. The rate of drainage is associated with the work done on the fiber during the process of beating and refining.

When the stock or pulp under evaluation undergoes any kind of treatment, such as mixing and dispersion, work is done on the fibers, which changes their structure. Some of the physical changes that occur are -

• Fibrillation of the secondary walls of the fiber
• Fiber shortening (occurs mainly during beating or refining)
• Formation of cellulose debris (occurs mainly during beating or refining)

Now days, the equipment is primarily used in various aspects of stock control and is one of the prime tests used for the determination of property development during the evaluation of pulps.

Specification
On the basis of operating principle, the equipment is similar to the Canadian Standard Freeness Tester and consists of a drainage chamber and a rate-measuring chamber. The drainage chamber is fabricated using a corrosion resistant material with a base that comprises of a phosphor bronze wire screen. This is sealed with an internal cone, which, when freed, rises through the dilute pulp sample thereby mixing the stock in the process.

Features
Some of the general features and characteristics of Beating and Freeness Testers that are available in industry are -

• Design and calibration as per industry standards and specifications
• Simple and easy to operate
• High accuracy
• Heavy construction and durability
• Stand models are constructed using corrosion-resistant stainless steel, while wall models are made using brass

Applications
Based on the Schopper-Riegler value, the beating and freeness tester was the first drainability test equipment to be designed. While the test is suitable for testing the various kinds of pulp in aqueous suspension, the test delivers acceptable results only if an adequately dense mat of fiber of the correct weight is deposited on the wire screen. Care should therefore be taken when pulps contain a higher percentage of debris or fines and in cases where the SR value lies outside the range of 10 - 90 SR.