Negative Pressure Applications Need a 100% Seal Too

Title Line

Plants that are processing dry powdered-type products often run their equipment under slight negative pressure to avoid product leaking out of machinery and into the plant environment.

Whilst dust leakage into the factory is avoided using negative pressure, improperly sealed flexible connections can risk contamination from air ingress.

A leaky connector can also impact on productivity if used in conjunction with pneumatic vacuum conveying as they allow air to be sucked in from outside the pipes and reduce the efficiency of the product flow.

The snap-in cuff of the BFM® fitting system keeps the connector ends locked in place and means that it is ideal to use under negative pressure applications.  

BFM® Seeflex 040E with Vacuum


Advantages of BFM® fitting with Vacuum

Title Line

BFM® fitting's 100% dust-tight seal helps you maintain your vacuum pressure, ensuring optimum product flow and hygiene.

Strong and durable material designed to handle constant negative pressure applications with ease.

The superior seal prevents any air being sucked into the system to potentially contaminate your product. Safe for use in CIP cleaning cycles.

More durable materials and fast, easy changeovers mean downtime is significantly reduced.



Connector Length & Vacuum: Why does it matter?

Title Line

As a general rule on vacuum, the maximum length of the BFM® blue band connector should be no longer than its diameter without support rings.

For instance a 100mm (4") diameter BFM® connector should be no more than 100mm (4") long.

This is because the vacuum will pull the connector walls inwards, which will eventually close the connector. 

Connectors with rings set at the recommended 100mm (4") spacing negate the effect of connector length.  TR connectors can also operate at a higher negative pressure than standard connectors. 

See the tables below for maximum negative pressure recommendations.

Title Line

The following chart shows the maximum recommended operational working negative pressure for a BFM® Seeflex 040E connector by length for standard and TR (tool release) versions (both with and without stainless steel support rings).  

BFM Negative pressure chart

Vacuum length vs pressure TR & Rings

It is also important to keep in mind when specifying a connector for use in negative pressure situations that the amount of movement, environment, temperature and nature of the pressure are all factors that should be taken into account.


BFM with support rings installed at cyclone outlet


Support Rings Help Keep Connector Walls Open

Title Line
When operating under negative pressure, the walls of a flexible connector will naturally be sucked inwards. For shorter connectors, this is not a problem, but it can become an issue for longer connectors as it narrows the available diameter in the centre of the connection, restricting product flow and potentially causing 'bridging'.
To counteract this problem, BFM® fitting connectors can be fitted with Stainless Steel Support rings to negate the effects of length. For instance, a 400mm (16") long connector will hold as much vacuum as a 100mm (4") long connector if it has three support rings (100mm (4") apart).

  • The rings also help keep the connector walls open and away from the product flow. This stops product from building up in crevices which can be hard to remove. 

  • Plastic support rings can also be used for metal detection applications.

  • BFM® Flexi connectors have a stainless steel spiral wire wrapped in urethane and can be used in light vacuum applications. 

Large Diameter Connectors in Vacuum

Large Diameter BFM® Connectors


For diameters over 650mm (26") that will encounter vacuum, it is strongly recommended that you talk with a BFM® representative

The BFM® fitting will handle vacuum at gauge pressure of up to -1000mm w.g on short length connectors, although this will depend on the application and the environment.

Explore Common Applications and Conditions Using BFM® fitting

Title Line

BFM® fitting outperform traditional hose clamp systems in virtually every processing application and condition. Here are some common process applications that are challenging for flexible connectors:

BFM® connector with milk powder feeding into a hopper

If you operate under pressure, we know keeping your product inside your process brings all sorts of challenges, usually around dust control and connector failure.

See how BFM® handles operating pressure.

BFM® connectors installed on a metal detector

Metal Detector applications can be a challenging environment for traditional clamped connector systems because steel cannot be in near proximity to the detector.

See why BFM® is used with metal detectors.

BFM® Spigots installed on product and CIP pipes

Proper cleaning of your pipes and in-line fittings is important during CIP, and having a flexible connector that can handle the chemicals and won't leak is essential.

Watch a BFM® fitting in action during CIP. 

BFM® connector and static dissipation

Static dissipative connectors like the BFM® fitting range will help reduce the chance of spark discharges occurring that can potentially ignite combustible dust explosions.

Learn more about BFM® and Electrostatic Build-Up.

Multiple BFM® connectors installed on a potato flour sifter

The constant movement on sifters puts stress on flexible connections between equipment, and often causes problems like poor sealing, leaks and failures.

Getting Started with BFM® fittings

Title Line
Get in touch with one of our local Authorized BFM® fitting Distributors to help find the right solution for you. They will help work through what you want to achieve and how BFM® fitting can improve your plant.