Definition
A percussion meter is a laboratory instrument used to determine the water filtration properties of fibrous materials under specific conditions. The instrument indirectly reflects the fiber morphology and bonding state of the material by quantifying the water filtration time or water filtration amount of the suspension, and its measurement results are usually expressed in the value of percussion resolution, which is widely used in papermaking, textile and plant fiber research.
Principle
The instrument works on the Schober-Rigler principle, which measures the filtration characteristics of a fiber suspension through a standard screen. In a suspension with a fixed concentration and volume, the specific surface area, flexibility and filamentation of the fibers affect the water filtration resistance. The higher the degree of fiber bonding, the slower the water filtration speed, and the measured knock degree value increases accordingly. The process follows the basic laws described by Darcy's law for fluids to pass through porous media.
The water filtration rate relationship can be expressed as: Q = k · ΔP · A / (μ · L), where Q is the filtrate flow, ΔP is the pressure difference, A is the filtration area, μ is the fluid viscosity, L is the thickness of the filter layer, and k is the coefficient related to the permeability of the fiber layer.
Measurement method
The standard measurement process includes sample preparation, instrument calibration, test execution, and result calculation. First, the fiber sample is dispersed into a suspension at a specified concentration and injected into the instrument measurement room. Under standard temperature and pressure conditions, the time it takes for a certain volume of filtrate to pass through a standard screen or the volume of filtrate collected in a fixed time is recorded. The measured values are converted into standard units of percussion through formulas, usually averaged three times to ensure the reliability of the results.
Influencing factors
Measurement results are influenced by a variety of factors. The variety, preparation process and degree of pulping of fiber raw materials will change the fiber morphology. The concentration, temperature and pH value of the suspension may affect the viscosity of the fluid and the dispersion of the fibers. The specifications, sealing properties and calibration status of the instrument screen have a direct impact on the measurement accuracy. The stirring speed, injection method and reading timing in operation also need to be strictly standardized.
Applications:
This instrument is mainly used in production control and research and development in the paper industry to monitor the pulp pulp degree and predict the physical properties of paper. In the textile sector, it is used to evaluate the processing properties of natural fibers. It is used in agricultural research to analyze the fiber quality of plant stems. In the field of environmental protection, the principle can be used to evaluate the dewatering performance of sludge. The relevant test methods are specified in detail in the ISO 5267 series, GB/T 3332 and other standards.
Key points of selection
When choosing an instrument, consider whether the measurement range and accuracy meet the relevant standard requirements. The material of the instrument needs to be corrosion-resistant and thermally stable, and key components such as screens should meet standard specifications. The degree of automation affects the operation efficiency and human error control, and the data interface and software functions need to be adapted to the laboratory management system. Verify that the instrument has auxiliary functions such as temperature compensation and automatic calibration. After-sales service and reference material supply channels are also guarantee factors for long-term use.