Publicly Available Specification (PAS) 121 has sparked some confusion as regards the difference between an insulated fire curtain and an insulated zone fire curtain. Read more.

1. Insulated Fire Curtains and PAS 121 - In the Zone?
Publicly Available Specification (PAS) 121 has sparked some
confusion as regards the difference between an insulated fire
curtain and an insulated zone fire curtain. Hopefully in this blog
and whitepaper we will be able to remove the confusion from the
subject.
The Test
EN1363-1 provides guidelines on fire resistance testing. After
thermocouples have been attached to the fabric and around the
perimeter of the fire curtain the unit is exposed to temperatures
as detailed on the chart below.
The curtain can now be classified with time against integrity or insulation. For example, a curtain with
integrity for 30 minutes would be “E30”, a curtain with integrity and insulation for 60 minutes would
“EI60”.
© Colt UK

2. Insulation
EN 1363-1 describes insulation as “the ability to restrict the temperature rise of the non fire exposed
surface to the following levels”
1. An average increase of temperature above the initial average temperature of more than 140
degrees C; or
2. An increase at any location above the initial average temperature by more than 180 degrees
C.
When conditions greater than items 1 or 2 are achieved, the time is recorded and the curtain is
classified to the length of time it kept within the parameters, for example EI "XX".
The Problem
EN1363-1 is very specific on the type, fixing, and location of the thermocouples. During testing the
flexible fabric intumesces, which means that the surface temperature of the fabric cannot be
accurately measured, therefore the curtain cannot be categorised as having insulation properties in
accordance with EN1363-1.
The Insulated Zone
There has been a recent attempt to solve to this testing problem by holding the thermocouples at a
distance away from the fabric. These tests are detailed in the Publicly Available Specification (PAS)
121. This curtain is being called an insulated zone fire curtain.
In effect all this test proves is that if you go far enough away from an insulated zone fire curtain the
temperature limits above will be met, i.e. outside the insulated zone. It has not been tested as
described in EN 1363-1, therefore it cannot be classified as an insulated fire curtain.
Whitepaper
For further information on this subject download our “Fire Curtains and PAS 121 whitepaper” which
explains why the PAS 121 guidance needs to be handled with care.
Graeme Clark is a Senior Consultant for Colt UK and specialises in the design and
product application of energy efficient HVAC and smoke control systems.
© Colt UK

3. Colt UK LinkedIn
F-
Gas Colt UK Pinterest
regul
ation
s are
Colt UK Google+
finall
y
bitin
g Colt UK Twitter
Colt UK YouTube
Colt UK Facebook
Colt UK Slideshare
© Colt UK