1. Test description

Passive fire protection (PFP) systems are crucial in order to mitigate the consequences of fire events, which involve the equipment of the process industry. This is a crucial measure in order to prevent domino effect escalations. The utmost importance of a thorough characterization of the relevant properties of PFP materials requires a specific testing in order to fully discover their effectiveness, considering the flame impingement.

Therefore, a specific experimental device and an experimental test procedure were realized to provide necessary parameters to model the passive protection material and to test its adequacy under jet fire conditions. Other jet fire tests have been developed in the world but the most interesting characteristic of this one is that it’s been designed to reproduce real conditions in a laboratory scale.

We chose to test flat specimens; dimensions can be found above.

A direct not premixed flame is produced by a nozzle burner and realistically simulates the actual jet fire impingement. Burner is positioned perpendicularly and centrally to specimen surface; the distance between the nozzle and impinged surface is 12 cm. Diffusion flame is produced feeding a hydrogen flow rate of 2750 Nl/h and a pressure of 0.8 barg.

The length of all the trials was 30 minutes, considering the stationary jet fire conditions.

Instrumentations used to collect data useful to understand the behaviour of tested materials, are:

• infrared video camera: temperature of sample surface;
• data acquisition system and type K thermocouples: specimen surface temperature (front and back side);
• video and photo camera.

Test facility overview

2. Experimental results

2.1 Test specimens

Several tests were carried on different composition boards; all the panels were realized with a fibre‑cement matrix and Kamenny Vek basalt chopped fibres: inorganic matrix is a mixture of commercial Portland cement, cellulose fibres and a little quantity of Polyvinyl alcohol: about 200 g of different lengths chopped fibres were dispersed in about 12 kg of the mixture-water suspension.

Different specimens were tested till now.

• TEST 1: BCS-13-06-KV07 = 33% BCS-13-12-KV07 = 33% BCS-13-24-KV07 = 33%
• TEST 2: BCS-13-06-KV07 = 100%
• TEST 3: cement matrix without basalt reinforcement

2.2 Test results

In the following, the temperature registrations for the 3 tests are reported in a TEMPERATURE (°C) vs. TIME (seconds) continuous plot. The thermocouples registration was carried on the rear side of the panels, behind the flame impact zone. Thermocouple positioning on the rear of panel can be seen in the next sketch, where the item TC followed by the ID (identification number), define a measure spot. Thermocouples identification is the same used in the temperature plots.

Thermocouples relative position on panels’ rear side.

Test 1

Modified Portland (with cellulose and PVA) concrete matrix
Basalt reinforcement:
BCS-13-06-KV07 = 33% BCS-13-12-KV07 = 33% BCS-13-24-KV07 = 33%

Test 2

Modified Portland (with cellulose and PVA) concrete matrix
Basalt reinforcement: BCS-13-06-KV07 = 100%

Test 3

Modified Portland (with cellulose and PVA) concrete matrix
No Basalt reinforcement

In order to obtain a more detailed and extended temperature data set, IR camera images were acquired, reproducing the thermal history of tested panels and validating the spot measures of the thermocouples.

Examples of IR images in different moments of the sample back surface heating are reported below.

(A)

(B)

IR camera images of a central area of the back surface of the sample:
(A) a few instants after the beginning and (B) at half of the trial time.

From the IR image, heat transfer and temperature gradients can be assessed in the zone close to the flame impact: smaller the high temperature zone, higher will be the heat transferring obstacle, with a good protective effect due to the low thermal conductivity.

3. Conclusions

In this report were shown the fire tests carried on cement boards reinforced with basalt chopped strands fibres. Temperature recording via thermocouples data logging and IR camera movies were shown.

More than temperature trend recorded throughout the trials, a crucial aspect is the proper evaluation of the actual effectiveness of tested materials in flame containment.

The special basalt reinforced boards didn’t break under the jet fire action and had a fine resistance to the jet impingement (i.e. TEST 1 and TEST 2). A normal fibre-cement board, without the dispersed chopped basalt fiber (TEST 3), only resisted for few minutes under the same fire conditions: specimen rapidly broke down allowing the flame to pass through the thermal shield as ca be seen in the pictures below.

Frontal and back pictures of the almost undamaged board
(with basalt fiber reinforcement).

TEST 3: frontal and back pictures after the trial.

Much more tests are required to exactly define possible relationship between compositions, quantities, fiber lengths and screening effect capabilities.

Finally, our tests demonstrate the possibility of use this kind of materials in Passive Fire Protection (PFP) applications.

Francesco Rossi, eng.
Gabriele Landucci, eng.
Severino Zanelli, prof.
University of Pisa.
Faculty of Engineering.
Department of Chemical Engineering, Industrial Chemistry
and Materials Science.
Via Diotisalvi, 2
56126, Pisa (PI)
Italy.
e-mail: gabriele.landucci@ing.unipi.it web: http://diccism.ing.unipi.it/