Selecting a static mixer for two-part fluids

Static mixers represent an efficient, cost effective and reliable method of mixing these materials, yet there are a number of factors that make selecting the best mixer a daunting task.

Nordson EFD has developed an interactive Static Mixer Selection Quiz that walks you through a series of questions to find the perfect mixer for your specific application. In this article Stephen Suchanek discusses some of those questions that bring you closer to the perfect match.

Cartridge type

First look at your current dispensing process. What is your mixer attached to? Will it be meter mix equipment or a cartridge? Options at EFD include our DIY dual syringes, Side x Side cartridges, u-TAH Universal cartridges, coaxial cartridges, and meter mix systems.

1.    DIY dual syringes: Designed for packaging and applying two-component materials for home improvement projects, automotive, and other small-scale applications. This type of cartridge is perfect for dispensing small amounts of material. Sizes range from 4mL to 30mL. The most common applications are epoxies with some specialised use of acrylics. The housing outlet on the mixer will either be blunt tip or needle. Select sizes can be paired with DIY Twist-Lock mixers.

2.    Nordson EFD offers a comprehensive selection of high-quality Side x Side cartridges for dispensing two-component materials used in automotive, construction, industrial, medical, and dental applications. These cartridges work with a wide variety of materials including acrylics, epoxies, silicones, polysulfides, and polyurethanes.

·         Side x Side cartridges: A rugged, one-piece design that resists bulging to ensure on-ratio dispensing. Available in 200mL, 300mL, 400mL, 600mL, and 1500mL sizes. These cartridges can be used with standard bell or integral nut mixers.

·         Bayonet cartridges: Available in 50mL and 160mL. These are most commonly used in electronics manufacturing, hoof care, and more precise industrial applications. In the hoofing industry, our bayonet cartridges help apply glue to seal splits on hooves. These cartridges accept only bayonet-style mixers.

·         Ratio-Pak: A snap-together version of a Side x Side cartridge that allows for a wide variety of mixed ratios all the way up to 25:1. These are available with 7/8-14 thread outlets on all sizes and 7/8-9 thread outlets on select sizes. These cartridges can be used with standard bell or integral nut mixers.

·         Film-Pak: A collapsible film-based Side x Side cartridge that reduces packaging waste volume by 87% when compared with standard rigid cartridges. These cartridges can be used with standard bell or integral nut mixers.

1.    u-TAH Universal cartridges: These allow two-component materials to be dispensed using commonly available 1/10th gallon or 310mL caulking guns. The outlet features the 7/8-9 thread found on a wide range of our integral nut mixers.

2.    Coaxial cartridges: This cartridge-in-cartridge features a robust neck outlet to prevent cracking and large outlet valve bore for efficient flow. Like the u-TAH, this cartridge features a 7/8-9 thread outlet.

3.    Meter mix: These valves are designed to bring the reactive adhesives and sealants into the static mixer and engineered for easy disassembly and cleaning. We have options for adhesives and sealants, abrasive urethanes, and high-viscosity mix ratios. All standard meter mix valves are compatible with standard bell housing outlets. Jackets are available for select mixers in high pressure and precision applications.

Material type

Our mixers work with a wide variety of materials including acrylic, epoxy, polysulfide, polyurethane, PU foam, and silicone. The fluid type will determine the number of elements you’ll need since different fluids require varying amounts of mixing. The typical number of elements for each material type are:

·         Acrylic: 8-10 elements

·         PU Foam: 10-24 elements

·         Epoxy: 15-24 elements

·         Silicone: 20-30 elements

·         Polysulfide: 24-32 elements

·         Polyurethane: 24-36 elements

Note: Materials that are a 1:1 mix ratio will tend toward the lower end of the range above while higher mix ratios will tend toward the high end of the range.

Mixed viscosity

Element diameter is influenced by three primary things: the viscosity of the material, the backpressure required for a proper mix, and the required flow rate. Generally speaking, the thinner the material is the smaller the diameter of the element.

Flow rate comes into play based on how quickly you’re dispensing the fluid you’re working with. If you’re dispensing material quickly, then you’ll need a larger diameter. Conversely, dispensing a material more slowly would require a smaller diameter.

Housing outlet

Housing outlets are important because they impact the dispense pattern you’re trying to achieve. The most common outlets include luer lock adapters for use with a variety of dispense tips for fine dispensing to slip luer and stepped outlets for more industrial applications. There are also a variety of more specialised outlets including barbed, H-tapered (for adding luer lock adapters), and Pro-Tip on select mixers.

Choosing the best static mixer for your application is a process but looking at your type of cartridge or valve, what material you’re working with, your mixed viscosity of both fluids, and what housing outlet you’ll need for what deposits you’re aiming for will help with this process. As always, these are guidelines and it’s important to consult your local sales rep for proper testing. Nordson EFD’s 2K Static Mixer Selection Quiz will help you select an apropriate mixer:

Visit: [email protected]. For more details about Nordson EFD’s 2K dispensing systems, download this guide.

Stephen Suchanek is a global product line manager at Nordson EFD. He manages the two-component product line. He joined Nordson EFD in 2018 and has more than 25 years of product management experience.

www.nordsonefd.com