W.S. Tyler SS-31 Ro-Tap® Mechanical Sieve Shaker

Overview

The W.S. Tyler SS-31 Ro-Tap® Mechanical Sieve Shaker is a precision-engineered, ASTM-compliant dry sieve analysis instrument designed for reproducible particle size distribution (PSD) determination in quality control, R&D, and regulatory testing laboratories. It operates on the standardized Ro-Tap® motion principle—combining horizontal circular oscillation (278 cycles/min) with vertical tapping (150 taps/min)—to simulate hand-sieving while eliminating operator variability. This dual-motion profile ensures uniform particle stratification and efficient separation across stacked sieves, particularly critical for cohesive, fine, or irregularly shaped materials. The SS-31 accommodates up to four full-height 12-inch (305 mm) test sieves or eight half-height sieves, delivering over twice the effective screening area of its 8-inch counterpart (SS-30), thereby enhancing throughput and statistical robustness for coarse-to-fine PSD characterization.

Key Features

• ASTM E11-23 and ISO 3310-1 compliant mechanical agitation mechanism with calibrated 278 rpm oscillation and 150 rpm tapping frequency
• Rugged cast-iron base and reinforced steel frame engineered for continuous operation and long-term dimensional stability
• Digital electronic timer with 0.1-second resolution and programmable duration up to 99 minutes for precise test repeatability
• Quick-adjust sieve support plate system enabling rapid configuration for full-height, half-height, or intermediate-height sieve stacks
• 1/4 HP permanently lubricated induction motor with thermal overload protection for consistent torque delivery under load
• Optional bench-mounting capability via pre-drilled base holes to minimize vibration transmission and improve measurement fidelity
• Compatibility with both ASTM-standard and ISO-standard 12-inch (305 mm) test sieves—including stainless steel, brass, and nylon mesh variants

Sample Compatibility & Compliance

The SS-31 is validated for dry granular, powdered, and friable solid samples within the nominal particle size range of 0.5 inch (12.5 mm) down to No. 500 (25 µm). It supports standardized sieve analysis per ASTM C136/C136M (aggregates), ASTM D6913 (soils), ASTM D5758 (plastics), USP (pharmaceutical powders), and ISO 9276-2 (representation of particle size distributions). All mechanical components meet CE marking requirements for machinery safety (2006/42/EC), and electrical configurations comply with IEC 61000-6-3 (EMC) and IEC 61000-6-2 (immunity). When integrated into GLP/GMP environments, the device supports audit-ready documentation through external data logging systems.

Software & Data Management

While the SS-31 is a standalone electromechanical shaker without embedded firmware or onboard software, it is fully compatible with industry-standard laboratory data management workflows. Its repeatable timing and fixed motion parameters enable seamless integration with LIMS platforms via external digital timers equipped with RS-232 or USB output. For 21 CFR Part 11 compliance, users may pair the shaker with validated third-party timing controllers featuring electronic signatures, audit trails, and user-access controls. Calibration records—including periodic verification of oscillation/tapping frequency using certified tachometers—and maintenance logs are maintained externally in accordance with ISO/IEC 17025 requirements.

Applications

• Quality assurance of bulk pharmaceutical excipients and active ingredients per USP monographs
• Aggregate gradation testing in civil engineering and asphalt mix design laboratories
• Particle size profiling of catalysts, metal powders, and battery electrode materials
• Food ingredient consistency validation (e.g., flour, sugar, spices) per AACC and AOAC methods
• Geotechnical soil classification and sediment analysis in environmental and mining labs
• Validation of milling and micronization processes in chemical and polymer manufacturing

FAQ

What sieve diameters and configurations does the SS-31 support?
The SS-31 accepts 12-inch (305 mm) diameter test sieves in full-height, half-height, or intermediate-height formats. Maximum stack capacity is four full-height sieves + pan, six intermediate-height sieves + pan, or eight half-height sieves + pan.
Is the SS-31 suitable for wet sieving applications?
No. The SS-31 is strictly a dry-sieving instrument. For wet sieving, W.S. Tyler offers the Hydro-Sieve® series or ultrasonic dispersion-assisted systems.
Can the SS-31 be used in regulated pharmaceutical environments?
Yes—when operated within a documented SOP and paired with traceable calibration and timing verification, the SS-31 meets foundational requirements for USP , EP 2.9.31, and ISO 13320-aligned particle sizing protocols.
What voltage options are available for international deployment?
Three electrical configurations are offered: 115 V / 60 Hz (North America), 230 V / 50 Hz (Europe, Asia, Australia), and 230 V / 60 Hz (Japan, parts of Latin America); all models maintain identical mechanical performance specifications.
How is mechanical calibration verified?
Calibration requires periodic verification of oscillation frequency (278 ± 2 rpm) and tap rate (150 ± 2 rpm) using a non-contact optical tachometer traceable to NIST standards; W.S. Tyler provides calibration check kits and service documentation templates.