Want to optimize a fire system? Instead of blindly following the norms, run expert field tests. A polyurethane foam manufacturer invested EUR 2,500 in tests. Their savings reached several times that amount compared to the total project estimate!
(Yet another) manufacturing plant came to us with a problem of false activation of a fire suppression system. Unfortunately, such incidents are quite common in industry. They cause dozens of thousands of euro-worth losses every year (cost of cleaning, lost product, etc.). In plants where such situations occur even several times a year, costs can easily reach several hundred thousand euro.
No wonder, then, that the idea of turning off a “hypersensitive” system for the sake of savings seems all too tempting. However, what about the fire hazard? In case of a real fire emergency not only do you risk serious losses, but your insurer can refuse compensation. So is there anything you can do to make the system respond only in the event of actual threat?
It takes two types of detectors to properly detect fire
This time, the problem of an oversensitive fire detection system involved a polyurethane foam plant. The “culprit” was a system based on aspirating smoke detectors (ASD). This type of sensor samples air in various inaccessible places without depending for detection on the convective movement of smoke.
These detectors are known for their effectiveness where the highest sensitivity of detection is a must. They detect fire hazard in fraction of a second. This makes them extra useful in facilities with hindered access and detection – for example, in high-storage warehouses, industrial sites or landfills.
It would seem, therefore, that the aspiration detectors in this warehouse were a good choice. After all, quick detection of a polyurethane foam fire is critical because it is very fast, with high power, and toxic.
Moreover, when plastic elements burn, temperature rises rapidly. A convection column is formed, which carries the products of combustion up to the ceiling. The farther from the ceiling, the more detector power is needed to detect a fire. And this is what distinguishes aspiration detectors. So what could possibly go wrong?
False activations of fire suppression systems are all too common industrial incidents. Losses amount from tens to hundreds of thousands of euros.
Źródło: www.tbsgmbh.com
Aspirating detectors trigger false fire alarms in a warehouse
When the high sensitivity of aspiration detectors brings as many problems as benefits, the instinctive thing is to improve the current solution. Unfortunately, this was not possible in this case. First, the aspiration detectors had three levels of sensitivity, but even at the lowest level they still picked up minimal amounts of smoke. Apparently, they were so effective that they could sense the smoke of a barbecue from nearby homes (!).
Well, how about turning the bothersome solution off then? Indeed, this seems tempting, indeed, but what if there is actual fire? The plant may burn down, and the insurer could refuse to acknowledge the insurance claim. Unfortunately, such situations happen all too often. So, how to solve this puzzle then?
In the case of our client, there was no point in replacing an otherwise expensive solution. A better approach was to enhance it with detectors of a different type. The existing system is responsible for the warning signal, while the new detectors are to confirm it. When both of them are activated (coincidence), information about the fire is confirmed.
Example: linear smoke detector to complement aspirating detector
Linear smoke detector is especially fit for large-area facilities, or when installing a large number of classical detectors is difficult (for example, a high ceiling). The transmitter emits narrow band infrared beam at the receiver. The alarm is triggered when smoke particles are found in the beam field.
A “tailor-made” fire detection system for a foam manufacturer
But how to choose a complementary fire detection system and not fall into the same trap again? Vendors offering a limited number of solutions are keener on convincing the client to choose their own product rather than on solving their problem. Meanwhile, each detection method has its advantages, but also limitations that the you should be aware of.
There is another factor, which complicates the selection of optimal fire detection system: in industrial setting, the list of factors that affect the selection of an effective solution is very detailed. While public buildings are similar and somewhat repetitive in terms of structure, industrial plants differ from one to another. They are densely packed spaces, with different types of machinery and a huge number of potential ignition sources, or byproduct gases that can be interpreted as a fire signal. This means that even extensive experience of the fire protection system provider cannot guarantee 100% effectiveness.
Therefore, in particularly difficult cases, it is advisable to perform tests. Our experience shows that an empirical approach does not have to be expensive, and, most importantly, it can drastically reduce the costs associated with both the purchase of a detection system and false activations, as proven by the following case of our client.
Instead of blindly following standards when selecting a fire system, opt for expert tests. Your savings can reach several times the amount invested!
Źródło: www.tbsgmbh.com
How to select a fire protection system: don’t guess, just investigate!
Due to the extremely difficult conditions of a foam fire, we analyzed three solutions possible for use in the client’s warehouse:
CO & HCN smoke detector
Installed at up to 15 m (according to the manufacturer’s guidelines), sensitivity of 1-200 ppm.
Gas detectors with sensitivity of several ppm are as sensitive as aspirating detectors, but are not certified (insurer should agree on using them).
Linear heat detector
Installed at up to 7.5 m (up to 11 m in special cases), detected firepower: approx. 2000 kW).
In a hall 15 m high and in a polyurethane foam fire, the linear detector will detect a fire only when it is developed. Therefore, delayed automatic activation of the fire system can be ineffective.
Linear smoke detector
Installed at up to 25m, detected firepower: approx. 200kW, two levels of detection.
The linear smoke detector will detect fire much earlier than the linear heat detector, with a slight delay compared to the aspirating and gas detector.
Why a linear self-leveling detector?
In the case of this warehouse, we proposed a newer generation of linear smoke detection technology. The FireBeam Plus self-positioning optical linear smoke detector allows effective and yet cost-effective fire protection of large-volume facilities, in which vibration-generating equipment operates, such as overhead cranes. The detector allows automatic correction of deflection up to 15° over a distance of 100 m. This is particularly important in the case of a building such as a warehouse, which is subject to high thermal expansion.
To confirm the effectiveness of the proposed solution, we conducted tests at the accredited Baltic Fire Laboratory. The tests lasted one day and cost EUR 2,500.
In the case of the foam warehouse, the height of the hall was 16.31 meters. Therefore, we applied an additional detection level, according to standards. At this additional detection level, the smoke cones should overlap, leaving no “blind spots,” so the cone of smoke would be detected even at the most unfavorable position of the fire.
Eight degrees of difference yields tens of thousand euro of savings
It turned out that using research in the design of a fire installation simply pays off! In fire standards applied globally, two models of convection cone formation appear: with an angle of 14° (VdS) and 22° (NFPA).
According to VdS 2095, when designing a fire alarm system based on linear detectors, 14° should be adopted, which is a more stringent value. Nevertheless, for the calculations we adopted the cone opening angle of the convection column of 22° (as recommended by the NFPA). Such a decision was based on our own experience, the TF4 (polyurethane foam burning) test fires described in the sources, and the agreement with the fire protection expert. Tests at the Baltic Fire Laboratory confirmed our approach.
Using an wider angle of 22° instead of the recommended 14° did not affect the effectiveness of the system. Moreover, changing the angle by just 8° allowed us to deploy detectors less frequently and thus reduce the total number of detectors in the entire system by 37.5%. And since the cost of the project is essentially the cost of the detectors, the research reduced the cost of the project by tens of thousand euros.
Testing costs are a fraction of the total savings
“Desensitization” of the fire system solves the problem of aspiration detectors responding too quickly and eliminates the risk of significant losses. The use of an additional system based on a different type of detection allows making the best of both systems.
What is more, this case shows that blindly applying general, often vague standards and norms can lead to oversizing of fire protection systems. Therefore, we recommend selecting a solution based on precise calculations, and, in justified situations, also run field tests.
In the case of this foam manufacturer, the cost of the procedure was a fraction of the savings that they had obtained in the project.
| SAMPLE CALCULATION OF SAVINGS | |
|---|---|
| Initial quote of the project | EUR 115 000 |
| Cost of the fire detector test | EUR 2 500 |
| Hardware savings (fewer detectors) | 37.5% |
| Adjusted project quote | EUR 73 000 |
| Expected savings | EUR 42 000 |
We also ran tests in other projects, to precisely match the technology to customers’ needs.
In other projects, we also conducted tests that allowed us to precisely match the technology to the customers’ needs.
For a manufacturer in the food industry, we performed tests of pyrometric detectors for extinguishing wafers on a fast-moving production line. The tests were run both on a custom test installation prepared by the WOLFF GROUP, as well as live, in the investor’s plant. The results were positive, successfully solving the basic problem: very fast and evident detection of a fire on an object that moves with high speed (1m/s).
For the power industry, we performed tests to find an alternative to detection based on sensor cables. Although the existing solution worked well, the client’s workers frequently damaged the cable. The tests are ongoing.
We also use tests to design explosion safety systems for industrial plants in various industries. Find out more about explosion protection for your plant.
