DUCT SEALING TIMES - 'Sealing the correct way, using FiloSeal+HD'​

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DUCT SEALING TIMES - 'Sealing the correct way, using FiloSeal+HD'​

DUCT SEALING TIMES - 'Sealing the correct way, using FiloSeal+HD'​

Over the past 15 years Duct Sealing has become an important factor when designing and constructing new buildings; however, it remains both a task and a product that a lot of companies overlook and underestimate the time required to effectively seal ducts. The majority of end users & specifications of duct seal products require a quick & simple installation, with a re-enterable seal that can cope in extreme circumstances. Water & Waste Treatment plants, areas where hydrocarbons are present, buildings within high water tables areas, and oxygen suppression systems in data centres are just a few examples (and there are many more) where difficult circumstances are encountered requiring a specialised product to be utilised. Filoform designs and manufactures specially formulated products where one product can cover all requirements.


  • Last minute actions to seal the ducts
  • Incorrect products used – EXPANDING FOAM FROM A CAN - A BIG NO NO!
  • Rushed installations
  • Overpriced solutions
  • Difficult to source and long lead times
  • Overcomplicated product selection
  Filoform can make it easy for you.
We can help you select the correct product; our experienced technical team with over 30 years knowledge of sealing cable ducts are available to provide support. All our systems are ex-stock and we have a large variety of duct sealing systems readily available, that can effectively seal 99% of any openings or cable configurations, in most environments.

Illustrated below is a common duct sealing problem where the incorrect products have been used. 

A typical Installation using expanding foam from a can. This will always FAIL.

While the expanding foam is a quick and cheap method of sealing a duct, the soft large cell structure will inevitably break down over a short period of time leading to an expensive exercise trying to dig the old foam out and replace with a suitable and sustainable replacement from Filoform.

Mastics and other putty products are sticky and tricky to install and ultimately will always FAIL over time.

This is the same story as expanding foam, although most putties become hard and difficult to handle in cold situations. Installation is more difficult with an increased risk of water or gas breaking through the ducts quicker than normal.


Sealing cable ducts in different industries require slightly different specifications, which over the years have changed due to the different environments encountered with chemicals and gases that are used or naturally present.

Although most industries require different resistances, the most common problems arising from open or poorly sealed ducts can result is rust, corrosion, and humid environments, which in turn contribute or cause damage to support structures, metalwork, and electrical components, all of which are very costly to maintain and repair.

Using Filoform's sealing products, we can accommodate all industrial sealing requirements whether you need to seal against high levels of hydrogen sulphide or fire resistance.


Ducts containing cables are what first springs to mind when trying to seal; however if the project has been designed to be future-proof, it is likely that there will be ducts ready for future utilisation that will be left empty and these must be temporarily plugged to ensure the tightness/soundness of the structure.

Illustrated above are temporary bungs that for whatever reason are allowing water penetration and corroding badly.

A quick but un-effective system for blank ducts!

Mechanical bung removed from a leaking duct.....

This will defiantly fail over time.


The FiloSeal+HD system covers all aspects of sealing to meet specific requirements, providing resistance to water, gases, hydrocarbons, rodents, termites and possible fire. With varying sizes and number of cables in the ducts, the FiloSeal+HD system seals against everything mentioned and more. If you are currently using a duct sealing system that does not meet your full expectations or wish to upgrade from using expanding foams then FiloSeal+HD should be your choice as the most effective and highly performing duct sealing system.

FiloSeal+HD is an industry recognised duct sealing system with many test reports to testify to the performance and spec and many satisfied users. This system has 2 'off the shelf' part sizes which accommodate the most popular duct sizes ranging from 50mm up to 160mm, however, larger sizes can easily be arranged.

FiloSeal+HD provides a strong support system using the hexagonal tubes which builds up like a honeycomb structure. FiloSeal+HD is suitable for sealing any cable configuration or pipes contained in one duct and also allows for easy re-entry of the seal to add or remove cables or pipes as required.

The Filoform duct sealing system FiloSeal+HD uses our MD+ sealant which is easily applied from a skeleton gun. The high quality, one component, flexible sealant “MD+” is based on a silicon compound that cures with air (Humidity).

After application and full curing the thixotropic MD+ forms a plastic elastomer mass with special qualities effectively sealing and bonding, while providing a high level of durability.

FiloSeal+HD is very easy to apply regardless of the type of cable scenario in the ducts as it uses strong, but flexible hexagonal tubes to support the cable and provide a strong backing for the seal.

Trefoil Cables

Trefoil cable arrangements can be difficult to seal with most of the sealing systems available, however, FiloSeal+HD duct sealing system manages them very easily. The cables are carefully separated using the FiloSeal+HD hexagonal tubes which are being separated and supported by the hexagonal tubes - note the central positioning of the hexagonal tubes to establish the required cable separation and allow maximum flow of the duct sealant into the trefoil cable formation. The hexagons separating the cables must have the smaller hexagonal tubes nested in the large one to create additional strength.

FiloSeal+HD Prevents water ingress and gas migration into a 33kV substation through LV-HV cable ducts using FiloSeal+HD Reenterable LV HV Power Cable Duct Seal System - the sequence of images above show the installation of the cable duct seal system into ducts providing underground cable protection to 33kV single core cables (trefoil formation) and multiple LV armoured power cables.

The unique design of the hexagonal tubes makes positioning and separation of the cables very simple while also providing a strong backing for the MD+ to be applied upon.

RODENTS & TERMITES - Mastotermes Darwiniensis

Filoform has heavily invested in finding out if our sealing system FiloSeal+HD can resist rodents & termites. We decided to test our seals against the most destructive termite (white ant) in the world which is called Mastotermes Darwiniensis. These termites are found in Northern Australia and cause millions of dollars of damage per year, and it's estimated that 2 in every 3 properties will suffer from a termite infestation.

We can confidently say that FiloSeal+ & FiloSeal+HD can resist rodents & termites.


Filoform can offer full on-site training on how to install our duct seals, whilst also offering valuable tips & tricks that we have learned over the past 30 years of sealing ducts.


•	Flexible, one component,
•	adhesive and sealing compound in a cartridge - (310ml)
•	High levels of Gas and Water tightness
•	Excellent adhesion, to all common building materials
•	Resistant against Water, Alkaline, Chemical agents
•	Resistant to Hydrogen Sulphide/Methane, Chlorine, Hydrocarbons and many more
•	Resistant to rodents and termites
•	Non corrosive
•	Solvent free
•	Shock absorbing
•	Non toxic
•	Complies with ATEX regulations
•	Suitable for any shaped duct / bore hole / opening
•	Quick and easy installation
•	Seals all know materials, PVC & PE sheathed cables, PILC, (HD) PE pipes
•	Suitable for renovations, can be installed retrospectively

2018-11-16 00:00:00 2869 viewed