Saint Gobain Pure Fit SIB Hose Barb Connector System Using Barblock Retainers
A big part of today’s ever changing high purity process industry are single use products. Single use valves, needles, and even pumps are quickly becoming commonplace. When implementing a single use system, one of thing they all have is the joining of pieces through some sort of connection. A very common method of joining two pieces of tubing is through a common hose barb. Holland has been doing research on what hose barb factors create the best unions and this post will highlight key considerations to keep in mind when selecting your next fitting.
In any system, connections are going to be your weakest link. While plastic connectors are often the lowest cost of any system component, their failure can often lead to the shutdown of processes that are producing millions of dollars’ worth of product. We spend a lot of time focusing on pressures and chemical compatibility when selecting system components, but without a proper match between tubing and fitting, connections can be pulled off from vibration or tension, or blown off from a pressure spike.
A hose barb is defined as one or more continuous ridges or bumps on a fitting that are used to grip the inside diameter of a tube and seal the connection. When tubing is installed on the fitting, it expands over the barb. Grip and seal occurs as the tube (ideally an elastomer) relax to its original ID behind the barb. While some applications will require a Barblock or cable tie, often the hose barb provides 100% of the sealing.
The most important part in selecting the correct hose barb is the inside diameter of the tubing. With all of the different TPEs, silicones, and fluoropolymers on the market, differing levels of flexibility greatly affect connection style. In general, the softer the tubing, the more likely that we should use a hose barb. Softer tubing lends itself to easier installation. If the tubing does not insert easily over the fitting, not only will this make it difficult for operators to assemble, but it could also lead to the tubing not gripping the fitting properly, resulting in leaks and failure.
Another important thing to consider is the number of barbs on the fitting. While more is often better, this is not always the case with a hose barb. As tubing is pushed onto a fitting it expands. In order to seal, it must relax. The gripping and sealing occurs where the tubing relaxes to its original shape just beyond the barb. Often times, one barb allows the optimal amount of space to allow for that sealing effect. Multiple barbs are not always bad, however. For example, if the barbs are spaced so that tubing relaxes between each barb, each barb will provide additional grip. But if additional barbs are spaced so tubing can’t relax, then only the end barb is going to provide any sealing.
The next thing we need to consider when selecting a fitting is whether or not we need a clamp. Tiger clamps, cable ties, and Barblocks are all common place in industry. While these do provide a certain level of reassurance and certainly have their place in high pressure applications, if the right tubing material is selected, they may not only be unnecessary, but can also be problematic. If installed incorrectly, clamps can lead to leaks and failures. If a cable tie is cinched too tightly, soft tubing can actually be lifted away from the fitting. That being said, we do recommend the use of Barblocks in most common situations as they do provide cheap reassurance of your fluid path’s integrity.
The final consideration we’ll touch on in this post is fitting material. Do we want to use a metal or plastic fitting? A lot of this depends on application fluid and pressures. In some applications, fluids and conditions are so aggressive that our only optional is stainless. Stainless hose barbs, however, can be expensive and not practical. Polypropylene fittings are common for single use systems that are autoclaved and PVDF is recommended for applications where final assemblies are gamma irradiated. While metal is “stronger” than plastic, that doesn’t necessarily mean its barbs will grip tubing better than plastic, and many times plastic fittings will perform as well, if not better than, metal in hose barb applications.
To conclude, it’s important to understand the simple hose barb. More barbs or metal barbs don’t always mean a better connection. Optimal connection relies on the correction combination of tubing and fitting. For more help with your next flexible tubing application, contact a Holland Sales Engineer today.