SX Type Cross-Bar Static Mixer

Product Overview

The SX type cross-bar static mixer is the most versatile model in the ywmixing catalog. Where the SV is the precision specialist and the SK is the heavy-industrial workhorse, the SX sits in the middle and handles roughly 60% of the static-mixing duties we encounter. Its internal element is a set of flat bars — typically four per element — arranged in an X pattern, rotated 90° between successive elements. The result is a series of intersecting flow channels that split, rotate, and recombine the stream in a way that achieves 2-5 μm dispersion precision while keeping the pressure drop moderate and the channel free-section around 70% of the pipe bore.

The 70% open area is the SX's defining operational advantage over the SV. In practical terms, the SX can pass suspended particles up to 3-5 mm without clogging — a level of solids tolerance that makes it the default choice for partially filtered process streams, polymer melts with trace gel particles, and food products that contain pulp or fibre inclusions. The mixer will also tolerate gas-liquid two-phase flow and modest slug flow without waterhammer-style pressure excursions, which is not true of the plate or single-X geometries.

Viscosity-wise, the SX covers 1 cP to 10,000 cP — a band that includes the vast majority of industrial chemicals, polymers, food products, and pharmaceuticals. Above 10,000 cP, the bar geometry starts to act as a complete obstruction rather than a mixer, and the SK or SH becomes the appropriate choice. Below 100 cP, the SV or SL is preferred for finer dispersion or heat-transfer enhancement respectively. Within its viscosity window, the SX delivers σX ≤ 1-5% with 4-6 elements, which is the same uniformity band as the more expensive SV plate mixer — at a meaningfully lower pressure drop.

Working Principle

An SX element is a fabricated assembly of four rectangular bars welded or mechanically fastened at the centerline to form an X when viewed along the pipe axis. The bar width is typically 0.1-0.15 times the pipe diameter, and the bar thickness is 3-6 mm for SS316L or 5-10 mm for carbon steel. The element length is normally 1.0-1.5D. Six to ten elements are stacked in a cylindrical housing, with each element rotated 45° or 90° relative to its neighbor depending on whether the design intent is X-on-X (intersecting channels) or X-on-plus (offset channels).

As fluid enters an SX element, it meets the four bars and is split into four quadrants. Each quadrant stream then has to flow around the outside of the bar and re-merge with its neighbor on the other side. The 90° rotation of the next element forces each of these quadrant streams to be split again — but in a different geometric orientation. Over 4-6 elements, the original fluid has been divided and recombined 4ⁿ times (where n is the element count), so by the sixth element the fluid has experienced 4,096 split-and-recombine events. This is the mathematical basis of the SX's σX ≤ 1-5% performance.

The hydrodynamic regime matters. In the turbulent regime (Re > 10,000), the bar wakes contribute additional mixing through eddy shedding, and the effective dispersion is finer (2-3 μm) than the laminar case. In the laminar regime (Re < 2,300), mixing is purely by stream-tube splitting and folding, giving 3-5 μm dispersions. For transitional flow, the SX still performs well but the element count should be increased by 50% to maintain the same uniformity — an adjustment that we apply during the selection process when the operating Re falls in the 2,300-10,000 range.