top of page

Finding the Right Fitting for Fluid Management Systems

The Component Checklist: Finding the Right Fitting for Fluid Management Systems


Fluid management components join flexible tubing assemblies, allowing the flow of valuable media to be easily regulated. With the thousands of available connectors out there, it can be tough to find the right one.

Correctly defining all the details of a desired connector and understanding the options available can help in the selection of the right fitting and also save OEMs significant time and money. This article provides a detailed checklist of the items to be considered when choosing the best fitting to ensure a product’s success.

✓ 1. INTENDED USE:

Identify the intended use of the product or assembly and how the component will be used in the application. While defining what the fitting needs to do, determine what the user interface will be like and what the mating requirements are. Fittings must be intuitive for users and safe for patients. Describe certain aesthetics.

✓ 2. TOLERANCES:

Determine sizes, like the critical dimensions of the assembly and the required fitting. A reasonable tolerance range for a plastic component is typically + or - .005 inches and + or - .002 inches for critical dimensions, depending on the actual size and the amount of plastic around the feature. Be aware that specifying tight tolerances where they’re not needed can significantly drive up costs.

✓ 3. TYPE OF FITTING:

Specify the type of component needed for the assembly. Explain any desired features such as product family, threads, barbs, connection type, configuration, etc. Does it need to be a straight through connector, elbow, Y, tee, multiport connector, or panel mount?

✓ 4. MATERIALS:

Describe what is being connected, so the appropriate material can be determined. Will the material need to be solvent bondable or weldable? To ensure product integrity, consider assembly methods. Some materials weaken upon exposure to solvents or crack under stress. Others may not weld well. COMMONLY USED PLASTIC RESINS:

  • Polyethylene: Chemically resistant, opaque thermoplastic that can withstand reasonably high temperatures.

  • Polycarbonate: Hard, transparent thermoplastic with moderate chemical resistance that provides good impact resistance and superior dimensional stability. Gamma irradiation stable and can be tinted to prevent color change.

  • Polypropylene: Soft thermoplastic with high chemical resistance to solvents and chemicals in harsh environments, and gamma irradiation stable.

  • Polyamide (Nylon): Thermoplastic with good wear and chemical resistance, low permeability to gases, and sufficient performance at elevated temperatures.

  • Acetal: Strong and lightweight thermoplastic that provides high strength and rigidity over a wide range of temperatures.

  • PTFE: Fluoropolymer that is resistant to most chemicals and solvents, with stability at high temperatures.

  • PVDF: Thermoplastic that is mechanically strong with good ductility over a broad temperature range, and has excellent chemical resistance.


TYPES OF TUBING:

Soft & Flexible

  • Polyurethane

  • Thermoplastic Elastomer (TPE)

  • Silicone

  • Polyvinyl Chloride (PVC)

SEMI-RIGID

  • Linear Low Density Polyethylene (LLDPE)



✓ 5. MEDIA COMPATIBILITY:

Ensure that the chosen material will not react to the fluids exposed to it. What kind of media will be going through the component – water, air, lipids, blood, chemicals, etc.? The type of media flowing through the connector can affect the strength, appearance, color, and performance. Define toughness, ductility, lubriciousness, etc.

✓ 6. BIOCOMPATIBILITY & REGULATORY REQUIREMENTS:

Are there any requirements that the product must meet, such as ISO 10993, animal derivative-free, BPA-free, USP Class VI, RoHS and REACH? Many of these assessments are conducted for materials used in medical devices to minimize any potential hazards to patients.

✓ 7. TEMPERATURE RANGE:

Determine temperature requirements. Very low temperatures or freezing and thawing can cause certain materials to become brittle, while high temperatures may cause deformation. Humidity also needs to be considered.

✓ 8. PRESSURE RANGE:

Determine minimum, maximum, and working pressures that the connector will be expected to tolerate. The strength and durability of a material needs to be evaluated in high pressure applications.

✓ 9. FLOW RATE:

Assess the required flow rate, volume requirements, and the effect of any fluid pulsation for connect and disconnect forces.

✓ 10. STERILIZATION:

Not all plastics are suited for all sterilization methods. It’s important to identify what sterilization processes and parameters apply, if any, and that the chosen material will perform appropriately with that sterilization method.

✓ 11. TUBING DETAILS:

Define the material, size, wall thickness, and durometer of the tubing that will be connected. This will help define the barb style and size that’s right for the application.

✓ 12. LIFE CYCLE:

Is the product single-use or will it be exposed to cleaning solutions? Anticipate maintenance, changeability, and the expected longevity of the whole system.

✓ 13. MANUFACTURING:

Define expectations for cost, volume, minimum order quantities, and lead times.

Fluid management components are a critical piece in the transfer of valuable media in medical equipment, laboratory, analytical instrumentation, and industrial applications. By following the steps outlined in this article, engineers can ensure the selection of the appropriate fitting and the success of their delivery systems.

NOTE:

The data presented here is for reference only. The particular conditions of your use and application of our products are beyond our control. Please test our products in your specific application to determine suitability.

bottom of page