3 Steps to the Right Fluid Connectors

Flow requirements: When determining the flow requirements of an application, the inner diameter (ID) of the tubing should probably be the first consideration. Consult flow charts for different diameter tubing, and select the size that will deliver the flow needed at expected operating pressures. Also bear in mind that flow may be reduced slightly by inline components such as connectors, valves, and filters. Pressure drops across components vary by manufacturer, with some designs producing less turbulence and resistance to flow than others. Once the tubing ID has been determined, choose a connector or valve design that provides the greatest flow with the least pressure drop.

Media effects: Whether the connector is made of metal or plastic, it needs to be compatible with the media being transferred. Air and water are commonly used media and are fairly simple to evaluate for chemical compatibility. Others, however, can be more difficult to evaluate due to their combinations of ingredients. Examples of this type of media include IVD reagents and inks used in printing applications. Reference materials can help to narrow down the material choice, but testing may be required to evaluate the effect of some media.

Temperature and pressure: In addition to the range of application temperatures and pressures, consider the temperatures the connectors may be subjected to in storage or shipping, which may be outside the range the connector may encounter in use.

Termination type: Connectors are joined to plastic tubing using a variety of terminations: hose barb, compression fittings, push-to-connect, and more. Connectors with multiple well-made barbs (featuring sharp edges and free of parting lines) provide a secure connection over a wide range of tubing styles and materials. Single-hose barbs work well with softer tubing such as silicone rubber. For stiffer tubing materials like reinforced PVC and harder plastics, however, the ID of the tube may not sufficiently relax around the barb to form a tight seal and require multiple, sharp barbs to seal and provide adequate pull of resistance.

Valve options: Connectors with integral valves create a cleaner and safer connection, eliminating the need for clamps and secondary shutoff valves, and enhancing the overall perception of the device or equipment. Valved connectors prevent spills upon disconnection, as well as the entry of air into the system. There are many styles of valves, with varying flow rates and pressure drops. Integral valve types include poppet and flush-face styles that allow completely dripless disconnections that may be required to protect the user from hazardous media.

Mounting options: In some applications, a connector is mounted to the back, side, or front panel of a machine or enclosure. For cases like these, some suppliers offer panel mount and/or pipe thread options to securely mount to the device. In these configurations, using an elbow as the mating connector may provide a distinct advantage. Why? If a connector mounted on the front panel of a chemical analyzer includes a 90-degree elbow, for example, the tubing can be easily routed down the face of the machine, eliminating unwieldy tubing loops that take up extra space and detract from the appearance of the installation.