Frequently Asked Questions

There are so many different BFM® fitting materials and connectors available. Our FAQ section below may help provide answers you have about your application.

Frequently Asked Questions


Is it possible to use the Teflex connector with a small horizontal vibration (+/- 10 mm)?

The Teflex will work on vibration as long as the movement is not too much, too fast. Up to 10 mm is fine.

Can we use Morris couplings rather than welding the spigots to our pipework?

It is possible. However, Morris couplings need a straight length equivalent to 1.5x the coupling length, so there would need to be enough space. You would want at least an inch of the spigot to remain to get enough clamping area.

How do you properly size a connector sleeve?

When installing the BFM® fitting you need to weld the spigots in place so that the correct Installation Gap (IG) is created for your connector length. The connector length will depend on how much space is available for the installation, what length needs to be covered, and if there is movement. The tails of the BFM® spigot can be cut back by up to 40 mm which allows flexibility to create the correct IG. In most applications, the best solution is to pick a standard (stocked) item that is 100 mm – 200 mm long. If there is movement (such as with a sifter) or an offset installation, having a longer connector is always preferable. As a rule the connector length should be no less than 1.5x the diameter in these applications. A calculator is available to help size the IG correctly. Contact BFM® for more information.

What’s the best way to connect a BFM® fitting to a square pipe?

Square-to-round transition adaptations are easily achieved. See the examples below:


What is the smallest gap a BFM® connector can fit into?

The smallest gap you can have between the BFM® spigots is 65 mm (2.5″) for an 80 mm (3″) long BFM® connector. Note that this gap may not be suitable for frequently changed connectors or where there is more than just a slight vibratory movement.


How can we ensure no CIP chemicals get into the internal gap during the wash process?

While there is potential for CIP chemicals to get into the internal gap during the wash process, the BFM® fitting is still far superior to any other type of connector in this situation. We always recommend the BFM® connector is removed and wiped clean after the CIP process to ensure no residual chemicals.

Can BFM® fittings be washed?

Yes, both CIP and manual washing are possible. Refer to the washing guidelines for Seeflex and Woven connectors.

What is the best way to clean an FM1 breather bag?

Although you can wash the FM1 breather bags, it is not recommended. The media has a dust release surface which aids efficiency and dust release. Washing will deteriorate this surface making it less effective. The best method is to blow an air gun through (in reverse and not too close), use a vacuum, or shake/brush any dust away.


Is it possible to get a copy of the FDA certification for BFM® fittings?

The FDA do not actually specifically certify products unless manufactured in and exported from the US. We are, however, FDA compliant as it is not possible to get 3A certification without FDA compliance.

What is the difference between FDA certification and 3A compliance?

The FDA and 3A are closely linked. In order to get a 3A certificate a company must prove to an independent assessor that their product is on the FDA approved list of substances, and that the manufacturing facilities, procedures and procurements meet strict standards. There are also a large number of other administrative and traceability requirements that must be met, making conformance with 3A an exceptional indicator of quality. A 3A certificate proves FDA compliance.

Do BFM® fittings have ATEX compliance?

Yes. The BFM® fitting has been independently tested through the IBExU institute in Germany. The tests encompass several different products and sizes. Refer to this document for more information: BFM® Declaration of Compliance – ATEX. Copies of the actual reports are available on request.

Do BFM® fittings have an ECCN (Export Control Classification Number)?

The BFM® fitting does not export using any of these numbers as this is an American export classification system. Although some of the parts of a BFM® connector are imported from the US, the majority of product cost is incurred in New Zealand. Hence, the product is classified as “New Zealand origin.”

Is the Seeflex 040E connector ATEX compliant for use in all dust and gas zones?

Seeflex 040E has been confirmed by IBExU as ATEX compliant for all Dust Zones  Please refer to the BFM® Declaration of Compliance – ATEX document for more information. A copy of the testing report is available on request.

Is the Seeflex 040AS ATEX compliant?

Standard Seeflex 040AS connectors up to a maximum of 650 mm diameter are confirmed as ATEX compliant. There are maximum length restrictions depending on the zones and processes involved.  Please refer to the following document for more information: BFM® Declaration of Compliance – ATEX.

Do you still need to install a grounding strap when using Seeflex 040AS (anti static) connectors?

Yes. Seeflex 040AS has anti-static properties to ensure static does not build up through product flow (friction). The anti-static strap is required for any occurrence of electricity through the system. This could be caused by any unexpected current/charge. No connector will allow a large/sudden electrical charge to pass so the strap is required to ensure a spark does not pass between pieces of equipment.


What is the maximum connector length for larger diameter connectors?

For standard Seeflex 040E connectors from 700 mm (27.5″) to 1,000 mm (39.5″) in diameter, a maximum length of 500 mm (20″) applies. For connectors from 1,050 mm (41″) up to 1,650 mm (65″) in diameter, a maximum length of 200 mm (8″) applies. Under certain circumstances and depending on the application, a slightly longer length may be possible. However, this would need to be discussed with BFM®.

What type of metal are the rings in your ringed connectors made of?

The wire used for the rings and kevlar/blackout cover holders is 6 mm, 304 g stainless steel with a tensile strength of approximately 800 MPa.

What is the minimum distance a ring should be from a spigot?

For a 150 mm connector, the minimum distance is 75 mm. For all other lengths, it is 100 mm. A 250 mm connector can have 2 rings that are 75 mm from the spigots (and therefore 100 mm apart from each other).

Is the silicon seal in the snapband of the connector food grade?

Yes, the silicone is post-cured which makes it food grade.

What kind of BFM® connectors are there?

BFM® fittings are available in many industry approved medias, and a whole range of sizes. Most of the BFM® standard range is 3A approved and conforms with FDA, EC and ATEX regulations. The Seeflex 040E is used on a majority of applications, but there is also a lightweight version and other application specific medias. The BFM® connector can also be manufactured with stainless steel rings, with tapers and many sizes to suit. Please ask a distributor for more information on which connector will suit you.

What is the most appropriate connector media for abrasive products?

Seeflex 040E is very strong and has been used with sugar, crystallized lactose, aggregates and more. Installing an internal flow correction system is an additional way to improve the system and avoid abrasion.

What pH levels can the BFM® Seeflex fittings be used with?

pH levels between 3 and 9 are generally acceptable. Outside of this range, it is largely dependent on concentration, application and duration of contact. It’s important to remember that the pH scale alone doesn’t determine the resistance of the materials. Product type, concentrations and temperatures are far more important. Our woven Teflex is an excellent alternative for use with acids or alkalis. This is a pure PTFE media which can be used on most products up to very high temperatures. It is best to double check with us if there are any concerns regarding media compatibility.

Can BFM® fittings be used with acids such as sulphuric or hydrochloric acid?

The resistance of the connector materials to chemicals is very dependent on the strength (concentration) of the chemical, the process and how the system is maintained (cleaned). The LM4 is a 100% polyester woven fabric so its capability with either chemical is limited. Seeflex 040E is also limited with these chemicals. Teflex is the optimum material for use with chemicals as it is resistant to acids.

Can you use BFM® fittings with oils?

It depends on the type of oil. Some oils are very aggressive and would degrade the polyurethane. The tight seal of the spigot connections can also be adversely affected by oils.

Can the BFM® fittings be used for the transport of nitrogen?

Yes. Seeflex 040E is used by many companies around the world who regularly use nitrogen to purge lines without issue. It should be noted, however, that we have not performed gas leak testing to a specified industry leak rate standard. We have completed air leak testing (a 600 mm connector held a low vacuum pressure for more than 10 minutes). The BFM® is not certified or recommended for gas sealing in safety of life or mission critical applications.

Is there an option available for light sensitive applications?

Yes. Our “Blackout Cover” fits on the outside of a BFM® connector and will cut out 100% of the light.

How can you stop the connector sleeve from “shrinking” under negative pressure (vacuum)?

For vacuum, the best way to keep the connector open is to use stainless steel rings (this is generally only possible with connectors over 100 mm long). Another option is to use fabric connectors, such as the LM3 or LM4 which “breathe” and filter air into the system. Refer to the BFM® Limitations: Negative Pressure document for more information.

Does BFM® have a product that can withstand 500ºF?

Absolutely. There are two options for high temperatures. Our Teflex NP (non-permeable) material can handle 300ºC / 572ºF, and surges of up to 316ºC / 600ºF. Our other pure Teflon material, Teflex, can handle 260ºC / 500ºF as an operating temperature, and surges up to 280ºC / 536 ºF. It is a permeable material but woven quite tightly.

Will the BFM® connector affect the accuracy of a metal detector?

There are Seeflex 040E fittings running through a number of metal detectors around the world without issue. Metal detectors have an arc in which there can be no metal so you just need to ensure the spigots are welded outside of this arc (i.e. welded to the pipe both above and below the metal detector). The BFM® connector then runs right through the metal detector. In the very unlikely event Seeflex 040E were to have any problems with false results, then Seeflex 040AS could be used. For further guidance, the metal detector specs will often tell you what ohm resistance the material needs to be within.

What BFM® connector would work best with a laundry soap product?

This may depend on what is in the laundry soap. In general, the Seeflex 040E will work perfectly well. However, if there are sodium carbonate or sodium salt ingredients, the Seeflex may start to break down over time. Unilever in New Zealand run the BFM® fitting on soap products without issue.

Have Seeflex connectors been successfully used with ground coffee and are there any effects of the coffee oils on the materials?

We have BFM® fittings running with coffee in a number of plants around the world. There is no difference in terms of connector life when compared to any other general application. There have been no problems with oils from coffee affecting the media.

Can you provide connectors with different materials such as rubber or silicon?

No, it is not possible to manufacture a BFM® fitting using silicon or other such materials.

What are the largest and smallest diameter BFM® connectors that can be manufactured?

1,650 mm (65″) is the largest diameter, and 100 mm (4″) is the smallest.

What is the maximum diameter connector BFM® can produce with stainless steel or plastic rings?

The maximum for stainless steel (SS) rings is 500 mm (20″). For plastic rings, we can do any diameter up to 1,000 mm (39.5″).

Do all BFM® connectors with a diameter greater than 800 mm have finger loops as a standard?

Yes. These loops are designed to aid installation from one side.

What is the minimum length for a connector with a ring?

The minimum length for a connector with a ring is 150 mm. If it is any shorter, the ring stops you from being able to snap the connector into the spigot.

Does Seeflex contain cyanuric acid, latex, melamine, nonylphenols, oleamide, silicone or any other phthalates?

No. To the best of our knowledge, BFM®’s material suppliers do not use or intentionally incorporate any of the following agents into Seeflex 040E, 040As or 020E:

bisphenol A (BPA)
bis (2-ethylhexyl) phthalate (DEPH)
dibutyl phthalate (DBP)
benzyl butyl phthalate (BBP) or any other phthalates
cyanuric acid
Please refer to the Seeflex Materials Safety Declaration.

Can the BFM® fitting be used with liquids?

Yes, but keep in mind that BFM® fitting is designed to provide a 100% seal on powder applications and we do not make this statement about liquids. With that said, the Seeflex 040E works very well for liquids and is used in a number of applications (there may be the occasional small leak or drip). The composition of the liquid should be checked to ensure compatibility with Seeflex.

What is the maximum pressure and vacuum applicable for each type of connector?

This varies greatly. Please refer to the BFM® Limitations: Pressure and BFM® Limitations: Negative Pressure information sheets.

How do you calculate the connector material permeability?

The air permeability quoted on our spec sheets is tested by the material manufacturer. It is the amount of air that will pass through the material at a given pressure. 125 Pa (0.5 iwg) is a standard testing pressure. Whether a product will pass through depends on the product, its particulate size and the amount of pressure.


Can BFM® spigots be connected to aluminum pipes?

Because a stainless steel spigot will not directly weld to aluminum, another technique will need to be used. One such option would be to weld a flange to the spigot and then attach it by bolt or rivet to the pipe. Alternatively, a Morris coupling could be used.

Can BFM® spigots be manufactured so specific sizes, like 630 mm or 920 mm?

BFM® spigots are only manufactured in 50 mm (2″) increments. The best way to fit the spigot to the pipework is to taper or flange it to suit the standard sizes.

Is it possible to get BFM® spigots manufactured in different thicknesses?

Our spigots are only available in standard thicknesses. They are all 2 mm thick except for the 100 mm spigots which are 1.5 mm thick. The 100 mm spigots are sized to fit standard tube which is measured externally. Other BFM® spigot diameters are measured internally to accommodate nominal bore standard pipe.

Which type of stainless steel are BFM® spigots available in?

We make spigots in both 304L SS and 316L SS.  They are also available in C22 Hastelloy.

What is the wall thickness of BFM® spigots?

100 mm diameter spigots are 1.5 mm thick. All other sizes are 2 mm thick.

What size BFM® spigot do I need?

BFM® spigots come in a range of exact sizes, eliminating the imprecise nature of current connector widths and ensuring a perfect fit with the BFM® connector. Simply choose the spigot that closely matches your pipe size.

What is the interior finish of the spigots?

The internal finish is 0.8Ra micro-meters (32Ra micro-inches).

What is the maximum diameter spigot you can use with a pneumatic monitoring system?

We have currently tested a single pneumatic monitoring system on spigots with a diameter up to 350 mm. For spigots 400 mm and over, we advise installing additional sensors.


What is the maximum diameter available for BFM® blanking caps and bins/socks?

The maximum diameter available is 1,650 mm.

Is it possible to get BFM® blanking caps in LM3, LM4 or Teflex?

Unfortunately not. We only produce actual connectors out of these fabrics, not caps.

Tool Release

Are all connectors available in TR (Tool Release) versions?

Yes. Our entire standard connector material range is available in TR versions.

Is there a maximum diameter that TR (Tool Release) connectors can be made to?

The maximum available diameter for a TR (Tool Release) connector is 650 mm (25.5″).

Tapered Connectors

What is the minimum length a tapered Seeflex 040E connector can be produced with 150 mm diameter & 250 mm diameter bands?

For these diameters, the minimum connector length is 150 mm long. Refer to the BFM® Guidelines: Tapered Connectors information sheet for guidance.

Is it possible to have a tapered connector with rings?

Unfortunately, we are unable to manufacture with rings on tapered connectors.

Can you get tapered connectors made in Seeflex 060ES?

Absolutely. You can order tapered Seeflex 060ES connectors up to 800 mm (31.5″) in length. If you have a requirement for anything over this length, please contact us first as we may be able to help.

What is the maximum length for tapered connectors?

For connector diameters of 300 mm or less, the maximum length for tapered spigots is 800 mm. Please contact us to discuss any tapered connectors with diameters over 300 mm.

Flexi Connectors

Is the spiral of the Flexi connector made from stainless steel?

Yes, the spiral is made from stainless steel

What maximum vacuum can Flexi connectors handle?

100 mm (4″): 0.10 bar, 150 mm (6″): 0.07 bar, 200 mm (8″): 0.06 bar, 250 mm (10″): 0.06 bar, 300 mm (12″): 0.02 bar

What is the shortest length of Flexi connector available?

200 mm (8″) is the shortest length for a Flexi connector.

What is the distance between the cuff and the start of the Flexi Wire in a Flexi connector?

There is 50 mm (2″) from the edge of the cuff to the start of the Flexi Wire.

What is the minimum length for a Flexi-Earthed connector?

Minimum length for a Flexi-Earthed connector is 250 mm (10″).

What is the minimum length for a Flexi or Flexi-Light connector?

Minimum length for the Flexi and Flexi-Light connectors is 200 mm (8″).  The Flexi-Earthed connector has a slightly longer minimum length of 250 mm (10″).

Can a Flexi connector operate to the same temperatures as a Seeflex 040E connector?

No. The maximum operating temperature is 85ºC (185ºF). The material used to make Flexi connectors is lighter and uses a different manufacturing process to the 040E/020E. The metal rings also add temperature.

FM1 Breather Bags

Is there a breather bag available in the BFM® fitting range?

Yes. Our FM1 breather bag is used when you have a vessel that you are trying to fill and need to vent air. The LM4 or LM3 connector can also be used if you require your BFM® fitting (connector) to breath due to pressure. The LM3 breathes more air than the LM4, but may also bleed more product. This will depend on pressure, product, application and conditions.

What is the maximum length an FM1 breather bag can be made to?

The maximum length FM1 breather bags can be made to is 1 m (3’3″). The smallest length is 100 mm (4″).

Does the FM1 breather bag conform to the filter classification standard EN779:2012, classification F9?

The EN779 classifications are a standard for ventilation filters. These are intake filters on buildings, in hospitals and the like. Breather bags are made from a dust filter media, which are tested and specified differently. However, for a rough comparison, the FM1 is 97% efficient at 3 microns, or F7. If the airflow or pressure is low the efficiency will increase. This depends on surface area, particle size and type, etc.


Does an LM3 connector remain flexible at -94ºF?

Yes. The LM3 is made from pure polypropylene and works well in very low temperatures. We have many connectors currently operating in low temperature applications and they remain flexible.

Can LM3 be used for processing freeze-dried coffee?

Yes. LM3 is perfect for this application as it can operate comfortably down to -70ºC (-94ºF). However, we recommend a separate FM1 breather bag installation to handle venting. In other words, although the LM3 is air permeable, it needs to act as a connector so it does not become clogged.

What is the surface resistance of LM4?

LM4 (100% polyester) has a surface resistance of 109 ohms.

Can you get rings inserted into LM4 woven connectors?

Yes, although this is an additional cost.

Is LM4 okay to use with caustic soda?

Yes. LM4 is fine with caustic soda in concentrations of up to 5%.

Seeflex 020E

Is it possible to make Seeflex 020E in an even thinner material (e.g., 0.10 or 0.15 mm)?

No, 020E is the thinnest available.

Seeflex 040AS

Does Seeflex 040AS have USDA and 3A certification?

Yes. Seeflex 040AS is FDA and USDA compliant, and has 3A certification.

What is the maximum length for a Seeflex 040AS connector with stainless steel rings?

Due to the specialized nature of the 040AS material, 1,000 mm (39.5″) is the longest we can manufacture a Seeflex 040AS connector with rings.

Can you make a 040AS connector with plastic rings?

Yes. The rings may have a maximum diameter of 1,000 mm / 39.5″.

Seeflex 040E

Is Seeflex 040E suitable for outdoor use?

Seeflex 040E can be used outdoors. It has been proven for use in both the sun and water. Extended exposure to UV will cause the Seeflex 040E to turn a little yellow, but the media will not lose any strength or integrity.

What is the maximum pressure Seeflex 040E can withstand?

Seeflex 040E can be used at 5 psi on a standard connector up to 200 mm long. Above this, we recommend using a stainless steel support ring or Seeflex 060E. Please contact a BFM representative for more information.

Why is my Seeflex 040E going yellow?

There a number of reasons the Seeflex 040E could go yellow. It could be due to use with chemicals, oils, fats or exposure to UV light. In most of these situations this is purely staining of the media, and there is no loss of strength or integrity. Please contact one of our representatives if you have any concerns. If you are using with a CIP (clean in place) solution you simply need to ensure that you thoroughly wash all the chemicals off the BFM spigot and connector before you start up again. If there is any caustic or acid left on the cuff area, it will go yellow over time.

Will Seeflex 040E work with an ethanol application?

If the contact with the ethanol is permanent, Seeflex 040E is not suitable. If it is sporadic and low temperature, then you should have no problem. You may need to run a few tests on the media to check the suitability as it will depend on time and temperature of contact. Please contact one of our representatives to discuss this further.

Can Seeflex 040E be used in an application with animal fat?

Yes. Although the fat may stain Seeflex 040E and cause it to go a little yellow, the strength of the media will not be greatly affected.

Is Seeflex 040E suitable in an application with sodium sulphate?

Yes, sodium sulphate has a pH of 7 and is suitable for use with Seeflex 040E.

Would a Seeflex 040E connector with rings or a Flexi connector be more appropriate for dust collection on a Sweco with a vacuum?

A Seeflex 040E connector with rings will be more resilient to the vacuum than a Flexi connector. You could also use TR for extra resistance. Try to keep the connector as short as possible and small gaps between rings.

Can you operate a 150 mm diameter Seeflex 040E connector in -0.5 bar pressure?

Although we have tested the TR version of the BFM® Seeflex fittings under vacuum to over 0.8 bar, we would not recommend a Seeflex connector for that much pressure (refer to the ‘BFM® Limitations: Negative Pressure’ document). However, depending on the length of the connector and the type of vacuum (i.e., gradual increases vs continuous vs sudden) it may be possible with the insertion of rings in the connector. The length is the most critical element as greater lengths will cause the walls to suck in further, potentially placing them in the product flow and increasing the chance of abrasion. If having a non-transparent connector is an option, the LM4 connector is a good option. Because it is a woven fabric, the LM4 will suck in outside air which is filtered through the material.

Is Seeflex 040E FDA compliant?

Yes. Seeflex 040E complies with the following regulations: FDA CFR 177.1680 and 177.2600, USDA and 3A (20-).

Are phenol (bisphenol A) or phthalates used in the manufacturing of the Seeflex 040E?

No. BFM® Global Ltd certifies that in the manufacturing of our products we do not intentionally use any of the below mentioned substances and it is not foreseen that they could be produced: bisphenol A (BPA), bis (2-ethylhexyl) phthalate (DEPH), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP). Refer to the Seeflex Safety Declaration for more information.

Does Seeflex 040E contain any by-products of animal substances?

Seeflex 040E is a synthetic organic material that does contain substances derived from tallow sources. Our suppliers have assured us that processing conditions used in the production of this tallow derivative product are in compliance with the minimum conditions described below for the processing of rendered fats listed in Annex XIII, Chapter XI of the EU Regulation 142/2011/EC, and the Notes for Guidance EMA/410/01 Rev 3. Additionally, this tallow derivative product is compliant with the U.S. Food and Drug Administration regulations regarding the use of prohibited cattle materials in food (21 CFR § 189.5) and cosmetics (21CFR § 700.27), as prohibited cattle materials do not include tallow derivatives.

Our current connector thickness is 1.2 mm but the Seeflex 040E is only 0.9 mm. Is that thick enough for passing heavy powder?

Absolutely. Seeflex 040E is one of the strongest flexible connector materials available with abrasion and tear resistance in both directions. This extra strength in comparison to other materials means it does not need to be as thick yet offers greater flexibility.

Seeflex 060ES

What is the maximum operating pressure for Seeflex 060ES?

Although it has been tested at much higher pressures, the upper limit we recommend for the Seeflex 060ES is 1.3 bar. This number was derived from tests undertaken on a 250 mm diameter connector, 200 mm long, at ambient temperature. Connector diameter, length and operating temperature will affect maximum operating pressures. Please refer to the ‘Operating Pressure Guide’ document.

Is there a maximum connector length for Seeflex 060ES?

Yes. The maximum connector length for Seeflex 060ES connectors is 1,000 mm (39.5″). For tapered connectors, the maximum length we recommend is 800 mm. Please contact us for any requirement over this length. We may be able to help depending on the application.

Can I get Seeflex 060ES with rings?

Unfortunately not. We can not make a Seeflex 060ES connector with rings.

Teflex NP

What is the maximum pressure Teflex NP can be used with?

The maximum continuous operating pressure we recommend for Teflex NP is 3 psi, and short surges to 5 psi. Teflex NP is not recommended for use in negative pressure/vacuum operations.

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