Video: The Vulcano hose and the Bridge-W2 hose clamp – a perfect vacuum duo

You’ve chosen the right vacuum hose. Spiral-reinforced, food-grade and sized for the vacuum pressure. The nozzle is secure and the system is drawing a vacuum as it should. Everything suggests that the assembly is sound. But what actually determines whether the hose will last over time is often the smallest component in the assembly: the hose clamp.  

At a glance, a hose clamp looks just like any other hose clamp. But on a vacuum hose with a steel spiral, it is the geometry of the edge that determines which hose clamp is the right choice. 

Whilst in our latest video on vacuum fittings we focused on the joints in a vacuum system, here we go one step further: to the transition from hose to nozzle, where the hose clamp is what ensures the seal. Our Account Manager, Ajnur Hrnjic, gives you an overview of the perfect vacuum duo. 

The duo consists of two components: a flexible vacuum hose and a hose clamp tailored to its geometry. Individually, they are good components. It's the interaction between them that makes all the difference. 

Among our PU hoses, you’ll find the Vulcano hoses – transparent polyurethane hoses with a built-in, PU-coated steel spiral that counteracts vacuum forces and keeps the cross-section open under negative pressure. 

Three key features make it a solid choice for vacuum applications in the process industry:

1. Transparent wall and smooth inner surface: You get a full view of the flow under vacuum, and the smooth surface minimises friction and build-up, helping to prevent blockages and loss of vacuum. 
2. Robust in wet environments: The hose is resistant to hydrolysis and microorganisms, allowing you to use the vacuum safely in food processing involving fatty substances and in the pharmaceutical industry. 
3. Wide temperature range and strict regulatory requirements: With a temperature range from -40 °C to +90 °C and negative pressures of up to 0.40 bar, you can ensure a stable vacuum even when the process fluctuates significantly. The hose complies with regulations EC 1935/2004, EU 10/2011 and FDA requirements, ensuring your documentation is in order for both your customers and regulatory authorities. 

The  Bridge W2 is a stainless steel (AISI 430) hose clamp with rounded edges and a bridge design, specifically engineered for spiral-reinforced vacuum hoses. Whereas a traditional hose clamp is often flat and sharp-edged, the W2 follows the contour of the hose.  

On the outside of the steel spiral, the Vulcano hose forms a series of ridges with small grooves in between – indentations that run all the way round the hose. It's precisely where the rounded edge of the Bridge W2 fits in. Instead of resting on top of the coil’s ridge as a sharp line, the clamp distributes the clamping force evenly 360 degrees around the hose wall. 

 In day-to-day operation, this geometry offers three specific advantages: 

• Uniform surface pressure: The force is spread across the entire contact surface against the nozzle. It's a stable and reliable vacuum seal with no weak spots. 
• Mechanical relief of the spiral: There is no point load that, over time, could work its way into the polyurethane or deform the spiral. 
• Hygienic fit: The even tension leaves no pressure marks or creases where product residues and moisture might otherwise accumulate. 

The mistake is often made with the best of intentions. A technician or operator needs to fit a new vacuum hose and grabs a traditional hose clamp from the shelf because the diameter seems to fit straight away. The joint is tightened, holds a tight seal at start-up and appears to be working perfectly. The problem is simply that a traditional hose clamp with sharp, right-angled edges works against the spiral’s construction from the very first hour of operation. 

Every time the hose is subjected to vibrations and pressure fluctuations, the sharp edges gnaw a little deeper into the polyurethane. The material becomes pinched between two hard surfaces and loses its elasticity precisely where the clamp is fitted. 

Over time, this develops into a full-scale cut, with the hose cracking along the coils long before the end of its intended service life. In a vacuum system, this wear rarely manifests as drips on the floor. Quite the opposite. The negative pressure draws in ambient air, moisture and particles through the microscopic cracks. The consequence is oxidation, microbiological contamination or a compromised batch, which is only detected during subsequent quality control. 

As we have previously mentioned, a steel spiral does not guarantee trouble-free vacuum operation if the hose material is not suitable for the process. The same logic applies to the connection: even the most wear-resistant hose will fail prematurely if the wrong hose clamp cuts into it from the outside. 

To ensure that the connection remains completely leak-free over time, it pays to take a thorough approach during assembly.  

Here are 3 things you should bear in mind to achieve the perfect fit. 

1. Select the size based on the hose’s external diameter: Choose the hose clamp’s diameter range based on the hose’s external diameter measured across the spiral, not on the nominal internal diameter. The Bridge W2 hose clamp covers ø40–330 mm and fits all our Vulcano hoses.  
2. Position the rounded bridge correctly: The edge must sit precisely in the groove between two spiral windings – not on top of the spiral itself. Then tighten evenly all the way round using a controlled torque, without overtightening. 
3. Ensure correct earthing: The Vulcano hose has an antistatic wall material that dissipates static electricity. However, the charge must be discharged from the system; otherwise, sparks may occur, particularly when conveying dry materials and powders. Expose the steel spiral at both ends of the hose and connect it to the plant’s earth connection to ensure static dissipation.

A vacuum system is a chain. The hose, the couplings, the hose clamps – everything is interconnected. And as with any chain, the weakest link determines how durable the whole system is. Vulcano and Bridge W2 are a well-thought-out combination because the belt’s geometry is adapted to the hose’s spiral. Tight, hygienic and gentle all at once. 

That’s why the most important thing to remember is: don’t choose hose clamps based on diameter alone. Choose the one that suits the hose’s construction. 

Are you considering this setup for your production line? Call us on +45 7020 0422 or email inquiry@alfotech.eu, and we’ll help you find the right solution. 

It works initially, but it rarely lasts. A standard hose clamp has flat, sharp edges, and even when tightened gently, daily vibrations, pressure fluctuations and handling will, over time, cause the edges to cut into the polyurethane along the spiral. You should therefore choose a hose clamp that matches the hose’s external geometry. 

Inspect the hose immediately adjacent to the hose clamps’ edges. If you observe discolouration in the polyurethane, deep indentations or incipient cracking along the spiral, the structure of the hose wall has been compromised and the hose should be replaced. 

The geometry of the edges. A standard clamp has flat, right-angled edges that lie on top of the hose’s surface as a sharp line. A vacuum clamp such as the Bridge W2 has rounded edges and a bridge-like shape that nestles into the groove between the spiral coils. The difference may be difficult to see with the naked eye, but in operation you get a joint that holds up over the long term. 

The hose is supplied with full traceability, a batch number and a declaration of conformity in accordance with EC 1935/2004, EU 10/2011 and FDA CFR 21-177.2600. The material is free from plasticisers, nitrosamines and phthalates, so you can safely use the hose for sensitive food and pharmaceutical processes.