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The purpose of this document is to give guidance to approved contractors and suppliers who are engaged in the fire stopping of service penetrations in walls and doors using the Astro Eco Telescopic Letter Box System FX. All service holes through floors and compartment walls must be fire stopped to prevent the passage of fire, smoke and hot gases. The key points for intumescent passive fire protection products are to:

Prevent the spread of fire, smoke and hot gases through a building by containing it in the compartment of origin.

Maintain the integrity of escape routes from a building.

Reduce loss or damage to property from the effect of fire and smoke.

Maintain pressure differential between compartments and ventilation channels.

The Astro Eco Telescopic Letterbox FX

The Astroflame Telescopic Letterbox range is specially designed to increase the safety and security of occupants against fire.

The ECO range is Fire & Smoke rated for 30 minutes. Where relevant, particularly for multiple occupancy residential buildings, letterboxes have been fire tested to BS 476 PART 22 & 31.1 for 30 minutes fire & smoke rating.


Please note that the maximum tested height from the floor to the letterbox is 1050mm to stay within the tested criteria.

The letterboxes are adjustable to suit door thickness of 40mm - 65mm for 30 minute rated doors only. Fixing screws supplied

To install

1. Measure the external dimensions of the central telescopic section (including the fitted intumescent liner) to ascertain the aperture cut out.

2. Carefully cut an aperture in the fire door leaf up to 1050mm from the bottom of the door. Please ensure that the aperture is a tight fit to allow the fixing of wood screws into the corner of the face plates.

3. The face plate fitted with the integral draught excluders should be located to the internal face of the door.

4. Locate the letter box into the cut aperture and secure using 4no.steel wood screws into each face plate.

5. To maintain the fire proof integrity of the fire door ensure any gaps between the letter box and the door aperture are sealed using Astro Intumescent Mastic Sealant.


Astro Eco Telescopic Letter Box FX is manufactured in the EU, meeting the highest quality standard in compliance with ISO EN 9001:2000 . For fire test certification contact Astroflame Fireseals technical department.

Test Results

Fire tested for 30 minutes to BS 476 Part 22
Smoke tested to BS 476 part 31/1
Acoustic tested to BS EN ISO 140-3. Achieving 32dB Rw
Security tested to BS EN 13724 Clause 6.6.5 (PAS 23/24)

Storage and disposal

Astro Eco Telescopic Letter Box FX should be stored indoors. No shelf life is given as this product will not deteriorate in storage.For additional testing, certification or technical information please contact




Astroflame (Fire Seals) Ltd. Intumescent House
Unit 8, The IO Centre, Stephenson Road, Segensworth
tel 0800 023 2482
(01329 844500)
fax 0800 023 2483
(01329 844600)
tel +44 1329 844500
fax +44 1329 844600


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