SX Type Precision Mixing Element

Product Overview

The SX type precision mixing element is the small-diameter, tight-tolerance version of the standard SS316L SX element. The cartridge is built to the same crossed-bar geometry but with bar cross-sections as small as 1.5×4 mm in the DN4-DN15 range, and with positional tolerances of ±0.05 mm on the bar centers rather than the ±0.2 mm of the standard SX element. This precision is required in laboratory, pilot, and small-scale production service where the flow rate is below 1 L/min and the residence time inside the element must be predictable to within 5%.

Material Properties

The precision element uses SS316L bar stock to the same UNS S31603 specification, but with a tighter chemical composition — phosphorus and sulfur are both limited to 0.025% max to improve weldability on the small tie-rod joints, and the inclusion rating is ASTM E45 Class A (thin, sparse). The bar surfaces are electropolished to Ra ≤ 0.4 μm as standard, which eliminates the micro-crevices that would otherwise trap process fluid and contaminate the next batch. The mechanical strength specification matches the standard SX element (yield 200 MPa, Charpy 60 J at -20°C), but the small bar cross-section means the rated flow velocity is limited to 4 m/s to keep bar deflection within tolerance.

Compatible Housings

The precision element fits a dedicated precision housing in DN4-DN50, supplied with Swagelok, compression-fitting, or 1/4-28 UNF threaded end connections. The housing interior is electropolished to the same Ra ≤ 0.4 μm finish. End retention is by a split-ring retainer that engages a groove machined into the housing's outlet bore. The element can also be installed in standard SX housings in the same size range, with the only restriction being that the standard housing's larger bore clearance will reduce the mixing efficiency by 10-15%.

Installation & Replacement Guide

Precision elements must be handled with clean nitrile gloves to avoid fingerprint contamination. Depressurize the housing, vent both ends to atmosphere, and remove the outlet split-ring using the supplied non-marring pick. Slide the element out by the central tie-rod extension. Clean the housing with HPLC-grade isopropanol and dry with filtered nitrogen. Fit a new FFKM (perfluoroelastomer) O-ring (Kalrez or equivalent), insert the element, and re-install the split-ring. The full replacement takes 5-10 minutes, but the cleanliness requirements add 20-30 minutes for the cleaning and drying steps.

Technical Specifications

Parameter	Value
Material	SS316L (UNS S31603), bar stock, electropolished Ra ≤ 0.4 μm
Element Geometry	Crossed bars 45°/90° rotation, 4-8 bar layers, central tie-rod
Bar Cross-Section	1.5×4 mm (DN4-DN15); 2×6 mm (DN20-DN32); 3×10 mm (DN40-DN50)
Dimensional Tolerance	±0.05 mm on bar position; ±0.1 mm on length
Pipe Diameter Range	DN4 to DN50
Pressure Rating	PN16 standard; PN40 available
Temperature Range	-50°C to +250°C
Viscosity Range	0.5 cP to 5,000 cP
Flow Rate Range	0.001 to 50 L/min (model and size dependent)
Pressure Drop	ΔP = 0.8-1.5 × empty-pipe ΔP at Re = 1,000-10,000
Mixing Precision	Coefficient of variation σX ≤ 3% at L/D = 7, 6 bars
Connection Types	Swagelok, compression fitting, 1/4-28 UNF, 1/8 NPT, 1/4 NPT
Mass (DN25, L/D=7)	0.08 kg per element

Applications

The precision SX element is the standard replacement for laboratory and pilot-plant service. Pharmaceutical R&D uses the element in continuous-flow reactor feed lines (DN4-DN15 handling 1-100 mL/min of reagent in solvent) for kinetic studies. Analytical instrument manufacturers integrate the element in sample-conditioning skids (DN6-DN10) where the residence time must be predictable to within 1% for chromatographic calibration. Micro-reactor developers use the element in numbering-up arrays (16-64 parallel channels at DN2-DN4 each) for catalyst screening. Other typical services include cosmetic active-ingredient blending, fragrance compounding, fine-chemical process development, and high-purity solvent blending for semiconductor清洗 lines.