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ASSESSMENT OF THE FIRE RESISTANCE PERFORMANCE OF CIRCULAR VENTILATION 

DUCTS WITH FIRE ATTACK FROM OUTSIDE THE DUCT

Assessment Report Number: 17/13647‐221 

Prepared for:

S.A.CO.P. SRLVia Maestri del Lavoro, 2212100 MADONNA DELL’OLMO (CN)Italy

Date:14th February 2017

Reproduction of this document is authorized only if made in full. Reports digitally signed in digital format, and all its digital copies, are considered original documents. Paper copies have no legal validity. This document consists of 14 pages.

Page 1

Assessment Report Number: 17/13647‐221  Page 2 of 14

Table of contents

1 Objective .........................................................................................................................................22 Fire resistance test evidence ..........................................................................................................32.1 Summary of test reports supporting this assessment ............................................................3

2.2 Test report Nº 12/5570‐1559 .................................................................................................3

2.3 Test report Nº 12/5931‐1823 Part 1.......................................................................................8

3 Appraisal  of  the  contribution  of  cladding with  “Isolquilt”  blankets  to  the  fire  resistance  of circular steel ventilation ducts..............................................................................................................113.1 Assessed performance..........................................................................................................14

1 Objective

This report provides an appraisal of the fire resistance performance of a ventilation duct assembly

that is part of an air distribution system to resist the spread of fire from one fire compartment to

another with fire attack from outside the duct. Horizontal and vertical protected duct sections are

considered. The ducts are required to provide 120 minutes integrity performance, thermal insulation

and smoke leakage, if subjected to a fire resistance test in accordance with EN 1366‐1:1999.

This assessment is based in fire performance demonstrated by ventilation ducts in fire resistance

tests carried out according to EN 1366‐1:1999: “Fire Resistance tests for service installations. Part 1:

Ducts".

Assessment Report Number: 17/13647‐221  Page 3 of 14

2 Fire resistance test evidence

2.1 Summary of test reports supporting this assessment

2.2 Test report Nº 12/5570‐1559

2.2.1 Short description of tested duct assembly

Steel duct insulated with “ISOLQUILT” blankets.

Internal section of the duct: 1000 mm x 500 mm.

Each metal section is fixed with the next with a screw in each corner, three ventilation duct clips on 

each long side and another ventilation duct clip on each short side.

Thickness of metal duct: 0,8 mm.

Thickness of insulation: 50 mm. The duct is insulated with “ISOLQUILT” blankets composed by fabric

with aluminium on its external face + ceramic wool (25 mm) + aluminium sheet + ceramic wool (25

mm) + fire proof fabric with aluminium on its external face.

Figure 1. “ISOLQUILT” blankets.

Testing Laboratory Sponsor Report Number Date of test Test Standard

LGAI Technological Center, S.A.

SACOP PEANO s.r.l. S.U. 12/5570‐1559 28/09/2012 EN 1366‐1:1999

LGAI Technological Center, S.A.

SACOP PEANO s.r.l. S.U. 12/5931‐1823 09/11/2012 EN 1366‐1:1999

Assessment Report Number: 17/13647‐221 Page 4 of 14

The blankets are fixed with Kevlar thread (Ø2,7 mm) every 100 mm. In addition, on the exposed side

it is fixed with fire proof belts every 200 mm. The metal piece of these belts is protected with fire

resistant fabric.

Figure 2. Fire proof belts and Kevlar threads used to attach the blankets to the duct.

Figure 3. Metal pieces of the belts used to attach the insulation blankets to the duct.

Each insulating blanket is 400 mm overlapped on the following element. This overlapping is sealed 

with ceramic wool.

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Figure 4. Detail of overlapping sealing between elements.

An 800 mm overlap is used longitudinally (see figure 5).

Figure 5. Detail of overlap is used longitudinally.

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Method of support of the duct

At the unexposed side, the duct is directly supported on bearers formed by C‐shaped profiles and 

M8 threaded rods. These threaded rods subject themselves directly to the supporting construction.

The distance between bearers can be seen in Figure 6.

Figure 6. Distance between supports.

At the exposed side, the duct is directly supported on bearers formed by L‐shaped profile and M16 

threaded rods. These threaded rods subject themselves directly to the supporting construction.

Figure 7. Supporting bearers.

The distance between hangers can be seen  in Figure 6.

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Overlap with support construction

Overlap with support construction: 150 mm. Penetration sealing is built using “ISOLQUILT” blankets

screwed to the supporting construction, PROMAT ceramic wool and “INTUMEX” intumescent joints

are used as shown in figure 8.

Figure 8. Overlap with supporting construction.

More detailed information of the tested sample is included in test report Nº 12/5570‐1559 Part 1.

2. Test results

Integrity:

The integrity was maintained during the entire test. Leakage at the end of the test is 9,28 m3/h m2 

(127,1 m3/h). Leakage limit value: 15 m3/(m2h). Leakage limit value for tested sample: 205 m3/h.

Thermal insulation:

Thermal insulation was maintained during the entire test, 120 minutes.

Smoke leakage:

The smoke leakage was maintained during the entire test 120 minutes. Leakage at the end of  the 

test is 9,28 m3/h m2  (127,1 m3/h). Leakage limit value: 10 m3/(m2h). Leakage limit value for tested

sampler: 137 m3/h.

3. Classification:

According  to  test  report Nº  12/5570‐1559  Part  2,  the  classification  obtained  for  the metal  duct 

insulated with “Isolquilt” blankets is: EI 120 (ho o→i) S.

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2.3 Test report Nº 12/5931‐1823 Part 1

2.3.1 Short description of tested duct assemblies

Metal Duct type A insulated with “ISOLQUILT” blankets. Internal section of the duct: 1000 mm x 500

mm. Thickness of steel sheets: 0,8 mm. Thickness of insulation: 50 mm.

Each metal section is fixed with the next one with a screw in each corner, two clips on each long side

and another clip on each short side.

The duct is insulated with “ISOLQUILT” blankets composed by fabric with aluminium on its external

face + ceramic wool (25 mm) + aluminium sheet + ceramic wool (25 mm) + fire proof fabric with

aluminium on its external face.

The blankets are fixed with Kevlar thread (Ø2,7 mm) every 100 mm. In addition, on the exposed side

it is fixed with fire proof resistant belts every 200 mm. The metal piece of these belts is protected

with fire resistant fabric.

Each insulating blanket is 400mm overlapped on the next element. This overlapping is sealed with

ceramic wool. And 800mm overlapped on itself.

Method of support of the duct

The duct is just supported on the furnace floor (Figure 9).

Figure 9. Rectangular vertical duct tested (view from inside the furnace).

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Penetration sealing using “ISOLQUILT” blankets screwed to the supporting construction, PROMAT

ceramic wool fixed with metal clamps at the non‐exposed side (Figure 10) and steel plates at the

exposed side (Figure 11), sealed by means of and “INTUMEX” intumescent joint (Figure 12).

Figure 10. Penetration seal outside the furnace.

Figure 11. Penetration seal inside the furnace.

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Figure 12. Penetration sealing construction.

2. Test results

Integrity:

The integrity was maintained during the entire test. Leakage at minute 120 is 1.98 m3/h m2 (12,87

m3/h). Leakage limit value: 15 m3/(m2h). Leakage at the end of the test is 2.85 m3/h m2 (18.53 m3/h).

Leakage limit value for tested sample: 97.5 m3/h.

Thermal insulation:

The thermal insulation was maintained until minute 121.

Smoke leakage:

The smoke leakage criteria was maintained during the entire test. Leakage at minute 120  was 1,98 

m3/h m2  (12,87 m3/h). Leakage at the end of the test was 2,85 m3/h m2  (18,53 m3/h). Leakage limit

value: 10 m3/(m2h). Leakage limit value for the tested sample: 65 m3/h.

3. Classification:

According to test report Nº 12/5931‐1823 Part 2, the classification period for the metal ducts type A, 

insulated with “Isolquilt” blankets is: EI 120 (ve o→i) S.

Assessment Report Number: 17/13647‐221 Page 11 of 14

3 Appraisal of the contribution of cladding with “Isolquilt” 

blankets to the fire resistance of circular steel ventilation ducts

This assessment is based on two test reports on tests according to EN 1366‐1 on protected

rectangular steel ducts with fire exposure from outside (duct type A). One test was carried out with a

vertical duct and the second one was conducted on an horizontal duct. A general description of the

tested samples and the results obtained are included in Section 2 of this report.

The two tests have been conducted with the same insulation method, cladding with “ISOLQUILT”

blankets, 50 mm thick. The “ISOLQUILT” blankets is composed by fabric with aluminium on its

external face + ceramic wool (25 mm) + aluminium sheet + ceramic wool (25 mm) + fire proof fabric

with aluminium on the external face.

“ISOLQUILT” blankets.

The blankets were  fixed with Kevlar  thread  (Ø2,7 mm)  every  100 mm  fire  resistant belts  located 

every 200 mm along the duct.

Fire proof belts and Kevlar threads used to attach the blankets to the duct.

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A metal piece of these belts is protected with fire resistant fabric.

Metal pieces of the belts used to attach the insulation blankets to the duct.

Each insulating blanket is 400 mm overlapped on the following element. This overlapping is sealed

with ceramic wool. An overlap of 30 % of the perimeter of the duct section is used longitudinally. A

minimum overlap of 400 mm shall be maintained. If the perimeter of the duct is below 400 mm,

then an overlap with the length of the perimeter shall be used.

For horizontal ducts, at the penetration sealing consist there is an overlap with support construction

of 150 mm. The penetration sealing is built using “ISOLQUILT” blankets screwed to the supporting

construction, PROMAT ceramic wool and “INTUMEX” intumescent joints are used as shown in the

following figure.

Overlap with supporting construction for horizontal ducts.

Assessment Report Number: 17/13647‐221 Page 13 of 14

For vertical ducts, at the penetration sealing is carried out using “ISOLQUILT” blankets screwed to

the supporting construction, PROMAT ceramic wool fixed with metal clamps at the top side of the

supporting construction and fixed with steel plates at the bottom side. The system is sealed by

means of and “INTUMEX” intumescent strips.

Penetration sealing for vertical ducts

The purpose of this report is to assess the fire resistance of circular steel ventilation ducts, vertical

and horizontal, protected with “ISOLQUILT” blankets, considering fire exposure from the outside

(Type A). According to our experience, the fire resistance of circular ventilation ducts is usually equal

or better than rectangular ducts if they are built following similar construction, components,

penetration sealing method, etc.

The rectangular insulated steel ducts fire tested in tests Nº 12/5570‐1559 and Nº 12/5931‐1823

demonstrated a successful behaviour regarding integrity, thermal insulation and smoke leakage

criteria during a period of 120 minutes.

The ducts fire tested were made of steel sheets, 0,8 mm thick. Internal section: 1000 mm x 500 mm.

Each metal section was fixed with the next one with one bolt in each corner, three clips on each long

side and another clip on each short side. The horizontal duct was supported on bearers formed by L‐

shaped profiles (50 mm x 50 mm x 5 mm) and M16 threaded rods.

Assessment Report Number: 17/13647‐221 Page 14 of 14

The construction of the proposed circular ventilation ducts follows the same construction as the

rectangular ones, made of steel plates, 0,8 mm thick. Maximum internal section: Ø800 mm. Flanges,

40x5 mm the duct sections shall be fixed to the flanges using self‐tapping screws per c/c 150 mm.

The horizontal circular ducts shall be supported on bearers connected to M16 threaded rods.

In order to provide the thermal insulation with “ISOLQUILT” blankets, the cladding shall be carried

out exactly as in the rectangular ducts tested. The description is given above. The penetration

sealing must be carried out exactly as for the rectangular ducts tested.

According to our experience in Applus+ Fire Laboratories, it is expected that under the conditions of

assembly described in the previous paragraphs, the circular ventilation ducts (maximum internal

diameter: 800 mm) protected with “ISOLQUILT” blankets, 50 mm thick should be capable of

maintaining the required 120 minutes performance regarding integrity, thermal insulation and

smoke leakage, if subjected to a fire resistance test in accordance with EN 1366‐1 with fire exposure

from outside (ducts type A).

The proposed vertical and horizontal circular ventilation ducts protected with “ISOLQUILT” blankets,

50 mm thick, may therefore be positively appraised.

3.1 Assessed performance

It can be concluded that The proposed vertical and horizontal circular ventilation ducts (maximum

internal diameter: 800 mm) protected with “ISOLQUILT” blankets, 50 mm thick, should be capable

of maintaining the required 120 minutes performance regarding integrity, thermal insulation and

smoke leakage, if subjected to a fire resistance test in accordance with EN 1366‐1 with fire exposure

from outside (ducts type A).

Digitally signed by:

Dr. Leandro Barrera RollaFire Safety Engineering Department 

LGAI Technological Center S.A.