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What makes the PDB different?

  • A market first > full aluminium sealing bar for complete protection
  • Operates off globally patented arm-controlled mechanism.
  • Offers unique security benefit
  • Globally patented design:
    • UK PCT Patent No: EP 2890857
    • US PCT Patent No: US 8,925,250 B2

Image excludes external casing and end plate.
It is a graphical representation of the PDB drop seal mechanism when activated.
Available both moritised and surface mounted.

High Performance
& Reliable
Operating Length
up to 1800mm
Easy to Install
& Adjust
Almost Zero

PDB drop seal vs traditional drop seals

The two key differences are the arm controlled mechanism and full aluminium sealing bar.

  • The arm controlled mechanism offers an unrivalled sealing pressure compared to traditional drop seals which use a flat spring mechanism originating from the 1970s.
  • The full aluminium sealing bar comprises a solid aluminium bar with rubber EPDM shrouding. This secures the entirety of the threshold gap, creating a market-leading sealed solution.

Why does the new patented arm-controlled mechanism matter?

The success of any drop seal is measured by the consistent, optimum downward sealing pressure it can generate.

In our experience, traditional flat spring mechanisms can prove problematic due to the variance in spring tension. There can also be issues with maintaining the optimum downward pressure over the performance life of the drop seal. This can lead to: the need for high door closing forces; an uneven seal coverage; and/or an actuator button indentation in the door jamb.

In comparison, the PDB drop seal provides a consistent, controlled, unilateral downward pressure across the entirety of the sealing bar.

Thanks to this unique controlled downward pressure, we are the only drop seal capable of incorporating a fully composite sealing bar of aluminium supported by EPDM rubber shrouding. This provides a market-leading, robust and resilient seal.

In addition, the PDB drop seal requires a very low closing force. Due to the arm controlled mechanism, the push back pressure on the actuator button is minimal. This ensures the door set maintains its optimum functionality.

We meet the following standards


Acoustics BS EN ISO 140 (as amended) and BS EN ISO 717-1
i. Fire – BS EN 1634-1:2014
ii. Smoke – BS EN 1634-3:2004

  • Air Infiltration Tested
  • Sound Tested – ASTM E90
  • BHMA Certified
  • Smoke Tested – UL1784
  • Fire Rated – UL10C – Positive Pressure
  • Underwriters Laboratory 4L10

PDB Drop Seals

  • Residential
  • Hotels
  • PRS
  • Student Accommodation
  • Offices / Commercial
  • All Hospitality
  • Education Facilities
  • Hospitals / Healthcare
  • Front doors
  • Interior doors

Operating Mechanism

The PDB uses a patented arm controlled mechanism. This is in comparison to the traditional flat spring mechanism adopted by the majority of the drop seal market, which has been in use for c. 50 years.

The PDB has small internal arms which provide controlled lateral and vertical forces. These apply even pressure to the sealing bar across the entire width of the door when the door is closed.

Sealing Bar

The PDB incorporates the only fully aluminium sealing bar supported by EPDM rubber inserts, which covers the entirety of the threshold gap.

This compares to the traditional drop seals which can only rely on part aluminium and part rubber strip sealing bars.

End Plates

The PDB has been designed so that the end plates are not recessed. This enables the PDB sealing bar to run the entire width of the door, ensuring optimal drop seal performance whilst not snagging on the door frame.

Downward Pressure

To be effective, the downward pressure generated by the drop seal operating mechanism needs to be controlled.

The PDB achieves this via its arm controlled mechanism. These arms create a unilateral, consistent, downward pressure of 12 lbs.sq inch (82 KN/m2) equally across the entire sealing bar.

In comparison, the downward pressure of a traditional drop seal relies on the spring strength and is generally uncontrolled.

Sealing Capabilities

The PDB arm controlled mechanism generates a unilateral downward pressure across the entirety of the sealing bar. This enables the PDB to adjust to uneven floors and fluctuations to create a complete sealed solution.

Door Closing Force

The PDB drop seal benefits from a very low closing force. Due to the arm controlled mechanism, the push back pressure on the actuator button is minimal. This ensures the door closes without the need for additional force.

Carpet Drag


The PDB drop seal offers a 2:1 release ratio that ensures highly reliable use.

Operating Length

Door widths of 450 mm to 1800 mm can be supported by mortised or surface mounted PDB drop seals.


We offer a 7 year warranty on all PDB drop seals.

No maintenance is required over the lifespan of the product.


The PDB drop seal is the only independently operating drop seal which offers this advantage.

The gap at the bottom of any door offers an opportunity to access that space. Reassuringly, the PDB drop seal secures this gap and ensures it cannot be breached until the door is opened.

What does this mean?

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Think you know door seals?
Think again!

The PDB automatic door bottom seal. Innovative, durable and globally patented. A truly all in one, sealed in place solution for doors openings.

Market tested & recognised as providing superior acoustic, sustainability, flood prevention & security performance of all door openings. Applicable across all door applications; any size; any sector.