Single Use Connections- As Simple or as Complicated as You Want to Make It

December 4, 2013

For stainless steel guys, the rapid emergence of single use technologies can be pretty scary. At Holland, we saw the life sciences process market changing right before our eyes. Fading are the days gigantic stainless tanks and expensive cleaning systems. In their place, plastic bags and tubing assemblies that are thrown away after each use. At Holland, instead of hiding from industry trends, we’ve embraced them. We’re able to offer a full compliment of single use components and product offerings and will focus on sharing some information about single use technologies in upcoming posts. The first topic we’ll focus on is how you connect all of this stuff together.

In the rapidly changing biopharmaceutical market, single use technologies are quickly coming to maturity. As process conditions and demands escalate, engineers find themselves looking for ways to maintain scalability, reduce costs, and maintain process security and product reliability. While future posts will focus on tubing material selections and specific product offerings, this post will take a look at how we’re going to put it all together.

While there are a wide variety of connectors available from industry heavyweights such as Sartorius, Saint-Gobain, Colder, and Millipore, ranging from general purpose to sterile connectors, the most common connector (the tri clamp of the single use world, if you will) is the hose barb. These barbed fittings are inserted into the terminations of tube ends and come in a wide variety of flavors. Ranging from wyes to reducers to elbows, almost anything is the single use world can be connected. The topic of this post, however, we focus on how we secure those fittings, and in the single use world, there are three main ways.

Cable Ties
Also known as the hose tie, zip tie, or tie wrap, the cable tie is a type of fastener traditionally used for bunching and organizing electric cables or wires.  Cable ties have been used in a wide variety of applications and have even been used as makeshift handcuffs (not that this writer has any experience with that or anything). In the single use bio process connector world, they’re an excellent low cost choice for securing hose barbs. The reliability of cable ties is a function of the dimensions and material properties of the tubing, hose barb, and cable tie, as well as the process used to create the assembly.

Some advantages to cable ties are the widespread availability and material selections. Despite not being a product contact surface, cable ties are subject to stresses such as autoclave, steam treatments, and gamma irradiation. Other factors to consider when selecting the zip tie material are process pressure and temperature. Cable ties are widely available in nylon, polypropylene, and PVDF, making them well suited for a variety of processes. They also come in a wide variety of sizes and are “adjustable”, lending them to usage for a variety of tube diameters and wall thicknesses.

While cost effective, cable ties are not as secure as other sealing options and are suggested for medium to low value product handling applications.

The BarbLock technology is based upon a sleeve/collet combination for 360 degree sealing. The collet provides a 360 degree radial seal that mimics a cable tie. The collar provides a compression seal over the barb that guarantees the collet is secured in place. Manufactured by Saint-Gobain, BarbLocks are more sensitive to tubing size and dimensions. Because the sleeve and collets have specific combinations and are pre-manufactured, they are limited to manufacturing specified tubing sizes.

When properly applied, BarbLocks exhibit a higher working pressure than other connection types. They do, however, require a special tool to position and crimp the sleeve over the collet. Manual, as well as semi automatic and fully automatic tools are available.

Barblock VS. Cable Tie

Barblock VS. Cable Tie

BarbLocks are available in both polypropylene and PVDF/Kynar, allowing them to be used in a wide variety of applications and withstand both gamma irradiation and autoclave.

While more expensive, BarbLocks are an excellent choice for mid to high value products.

Overmolded Connections
Overmolding allows for the removal of the hose barb all together. The interior of a molded connection provides a smooth inner surface and a seamless transition for continuous, consistent, leak-proof flow. Molded manifolds reduce the risk of loss of a valuable batch of product.
Available in wyes, tees, crosses, reducers, as well a triclamp connections, molded connections reduce the total number of connecters that must be kept in inventory. Molded connections are available in both USP Class VI platinum cured silicone and thermoplastic elastomers or TPEs. Molded assemblies are generally sold as complete manifolds, assembled and packaged in a clean room. Premanufactured assemblies reduce downtime and virtually eliminate cleaning costs.

Bio-Simplex Connections

Bio-Simplex Connections

While the over molded connection and manifold style is the most robust and clean, it is also the most costly. Also, because they are injection molded and premanufactured, in-field flexibility is limited. Overmolded assemblies are ideal for the highest value products and are often used in conjunction with downstream processing equipment, such as TFF filters and filling machines.

To conclude, hopefully this post gives a good overview of the rapidly maturing single use connection industry. If you are looking to explore new ways to cobble together your single use manifolds, contact a Holland Sales Engineer today for additional information.
Holland Applied Technologies