The Freeness Tester is a standard instrument for measuring pulp freeness (CSF, Canadian Standard Freeness). It is primarily used for test values in groundwood pulp production control, while also being widely applicable to evaluating changes in drainability of various chemical pulps during beating and refining processes. The instrument has a measuring range of 0~1000 CSF and fully complies with international standards including TAPPI T227, ISO 5267/2, AS/NZ 1301, BS 6035 part 2, CPPA C1, and SCAN C21, as well as the Chinese industry standard QB/T 1669-1992. The standard model dimensions are 300mm (L) × 1120mm (H) × 400mm (W), with a weight of 57.2 kg. A wall-mounted structure is available as an option for overseas users. It should be noted that processing can generate large amounts of fines, sometimes causing abnormally high freeness readings (false freeness), with values below 100ml, and freeness values may not directly correlate with the drainage performance on the paper machine wire. This instrument is core equipment for evaluating pulp drainage performance in the papermaking, fiber research, and quality control fields.