Questions and answers
[–] What happens if the product gets into the foam pipeline? Will it contaminate the foam?
The foam vessel permanently operates at 16 bars, whereas the storage tank is near atmospheric pressure. Contamination is therefore highly unlikely.
[–] In case of traditional systems we use 1 foam generator for more storage tanks. How many foam vessels are used for how many storage tanks?
It depends on the situation and on the wishes of the client. Each storage tank can be equipped with its own foam vessel. But situations where a central foam supply (one or more vessels) serves a number of storage tanks (via a distribution manifold) can be considered.
[–] What happens in heavy storm with strong wind? Shall the foam blanket close?
Because we apply the foam directly to the shell of the tank, the foam will adhere to the inner tank wall while running down to the liquid surface. The wind will then have very little effect on the foam. Foam losses due to the wind or up-draught will consequently be minimal. The minimal foam losses will be compensated anyway by the very high foam application rate, so we are confident that the foam blanket will always close.
[–] How does the system look on floating roof tanks where full coverage is required?
In case of storage tanks with floating roofs one shall consider two scenarios, i.e. a rim seal fire and a full surface fire. In this case we recommend to apply a so-called two-step system.
In case of a rim seal fire only, the isolation valve in the foam system is only opened very briefly to apply sufficient foam to cover the seal area. In case there happens to be a full surface fire the valve remains open until adequate coverage of the area is achieved.
[–] How do we apply the system on floating roof tanks in case of rim seal fires?
In case of floating roof storage tanks where the maximum fire considered is a rim seal fire TFEX applies a standard FoamFatale system with sufficient capacity to cover the seal area with foam.
[–] Have you already tested the system with 1-hour preburn time?
On the 25-meter diameter test tank we have, for financial reasons, not conducted a test with a one-hour preburn time. Our tests were done with 30 seconds preburn time. Please note that TFEX strongly recommends to install a detection system automatically actuating the FoamFatale system.
[–] Regarding the automatic detection system: What action does TFEX take to prevent a nuisance release, or false alarm, of foam?
We are fully aware of the very costly consequences of a nuisance release of foam into the product. We are generally applying a two-out-of-two or two-out-of-three voting system to minimise the probability of nuisance releases.
[–] How much time do we need to extinguish a full surface fire of a 40.000 cum storage tank?
Approximately 60 seconds are needed to extinguish such a fire.
[–] How about the reaction time of the FoamFatale system in case of a 40.000 cum storage tank?
Provided the system is equipped with an automatic detection system, extinguishing starts within 5 to 10 seconds after ignition occurred.
[–] Can we call the FoamFatale system a best available technology?
FoamFatale is a very very effective storage tank fire extinguishing technology. TFEX is not aware of the existence of a more effective system. It therefore could be considered to be BAT (best available technology).
[–] How many systems have you already installed?
We have installed FoamFatale on more, than 40 different storage tanks as yet.
[–] What is the opinion of the authorities of the FoamFatale system?
FoamFatale™ has official approval from the Hungarian Ministry of the Interior, National Fire Department to use it as sole extinguishing system on a tank.
We have been in contact with the Chairman of the NFPA Foam Committee in which he stated that NFPA does not approve or evaluate materials, products or systems. NFPA 11 states, ‘Nothing in this standard is intended to restrict new technologies or alternative arrangements, provided the level of safety prescribed by the standard is not lowered.’ The Chairman also mentioned that alternate arrangements may be considered if comparable safety levels are met.
And since Foam Fatale uses a foam application rate which is at least 5 times higher than the well-known 4.2 liter/m2/min proposed by NFPA, TFEX is fully confident that Foam Fatale exceeds the “comparable safety levels” referred to above.
[–] How long is it possible to store the foam in the vessel keeping its physical properties?
We have experience with portable extinguishers using the same concept for producing the foam. The oldest extinguisher that had not been brought in for servicing was 12 years old. When the foam was released it was in perfect condition. The foam extinguished the fire effectively.
[–] Is FoamFatale suitable to fight alcoholic fires?
Certainly yes. In this case we will adapt our foam formulation.
[–] It is a fact that we use foam concentrate and water for producing foam. What do we store in the foam vessel?
The foam vessel contains foam solution according to our recipe.
[–] What type of foam is used in the FoamFatale system (for example…AFFF)?
The FoamFatale system is a tailor made system. The type of the foam required depends on the flammable liquid stored in the tank to be protected. We will adapt our foam formulation accordingly.
[–] What size of foam vessel shall we apply compared to the size of the storage tank? What size of foam vessel and how much foam concentrate do we need for the extinguishment of the full surface fire of a 40.000 cubic metre storage tank?
We have to use one piece of 120m3 or 2 pieces of 60 m3 foam vessels and only 1,2 m3 of foam concentrate to get a safe, 30 cm thick closed foam blanket on the surface.
[–] What is the working temperature range of the FoamFatale system?
It is suitable to operate in the range between minus 40 and plus 60 degrees Centigrade.
[–] Will the Continuous Linear Nozzle on a cone roof tank remain in position or be damaged as a result of an explosion?
The Continuous Linear Nozzle is made out of standard steel piping. Its mechanical strength is high. Its mass makes it unlikely to be dislodged as a result of an explosion. It could be made an integral part of the tank, thus reinforcing the tank itself. It is not likely to be damaged by an explosion.
[–] Can we use our existing foam concentrate in the FoamFatale system?
We have to know the composition of the existing foam concentrate. If it is suitable, we can use it. In many cases we will be able to adapt the foam to the needs of FoamFatale.
[–] What happens in a case where the tank frequently changes product and where contamination of the product with some of the previous product is not acceptable ? The Continuous Linear Nozzle plus its upstream piping could act as condenser. Condensed product vapours could collect in the dead ends of the upstream piping.
For such a tank the configuration of CLN plus piping will be such that at the highest point a rupture disc will be installed to ensure that any condensate will flow back into the main tank.
[–] The foam solution pipes are usually made of mild steel, attacked by inside corrosion. I worry about the nozzles of the foam generators plugged by the scale detached in high flow conditions. Is your installation more reliable?
Yes it is. We do not use any aspirating type foam generators; there are no aspirating holes, orifices or bottlenecks in our foam pipes. We use a large size steel pipe which leads the foam, and not the foam solution to the storage tank. Scaling can not block the foam flow, the system is highly reliable.
[–] When the fire rages for hours, the shell of the tank and the foam inlet devices become destroyed by the heat. How do you let the foam in then?
One of the advantages of the FoamFatale technology is the very fast response to the ignition. The delay between the breakout the fire and the actuation of the system is only 8-10 seconds. After the actuation the extinguishment is done in about 1-2 minutes at all sizes of tanks. There is simply no time to heat up the tank shell and to destroy the foam inlet device, the Continuous Linear Nozzle.
[–] The ring shape nozzle will be damaged by any explosion similarly to the foam chambers. How will it work then?
The thorus of the Continuous Linear Nozzle is fixed to the tank shell by clamps. It serves also as reinforcement of the upper edge of the tank. In case of explosion the whole device is inside the space, where the pressure is increased. The well dimensioned steel tube of the CLN is attacked by the forces of the explosion from all directions, therefore there is no reason to move or brake.
[–] I guess the foam will submerge when using it by extraordinary high foam flow rate you recommend. How will the generated turbulence affect the closing of the foam blanket?
The total foam flow rate is really very high, but the total cross section of the foam inlet is also large. This results in gentle application, makes no turbulences on the surface of the liquid. The continuous Linear Nozzle provides a curtain-like foam introduction pattern along the circumference of the tank.
[–] What happens to the foam if the liquid level is low in the tank and the foam has to flow down to the depth of 15 meters?
The foam gets out of the ring-shaped continuous linear nozzle (which is located inside the tank, at the height of the wind girder) with a relatively high velocity. It hits the inside surface of the tank shell, and flows down stuck to the shell. The foam begins the intensive cooling of the shell, and keeps it in safe against the heat convection and radiation of the fire. The total volume of the foam to cover the liquid surface shall be introduced to the tank in 2 minutes, so the flow rate on the shell is high. When the foam riches the liquid surface it turns to horizontal direction and moves towards the center of the surface, until the foam blanket closes. Then the fire is put out. The foam will suffer no damages. During the short extinguishing period the fire has no chance to destroy the foam.
[–] In a working system (as opposed to test rigs) the feeder pipelines would probably need to be left empty. This adds to the potential risk of internal descaling but also provides an opportunity for significant water hammer (especially in systems for large tanks) during automatic actuation.
The problem of hydraulic shock in the pipes as a result of actuation of the system of course has to be addressed during the detailed engineering. The pipe between pressurized foam storage and the tank to be protected in case of our test tank is about hundred meters. During our tests however we did not notice any pressure surges in that line.
[–] The system supply piping problem is internal corrosion scale that detached in high flow conditions, plugging the pourer nozzles. Whilst your system feeds a slot rather than an orifice, with consequent reduction in any risk of plugging, scale could inhibit system efficiency. One solution might be galvanized feeder piping but I have also seen application nozzles plugged with flakes of galvanizing. The next option would be 304 stainless steel but since this is a more stringent code than most companies currently apply, it may be unacceptable, since it would add to installation costs even though life cycle costs would be less.
We fully share your concern of failing equipment running alongside the walls of a tank. In particular foam chamber type systems are vulnerable since they have an air-aspirating device somewhere in the vertical part of the foam supply line. Insects and birds love these places to build their nests. And in particular in humid climates where the air humidity passes through the dew point one gets condensation inside the pipelines which results in corrosion and within a decade in failure of the pipeline.
Our configuration however comprises a pipeline without any openings in it.
The probability of internal corrosion for untreated steel piping can of course not be excluded.
Even if rust flakes would come loose inside the pipeline it would possibly result in negligible blockage of the Continuous Linear Nozzle (CLN) due the nature of the CLN.
This all is the reason why we no reason to advise to use galvanized or stainless piping.
[–] What kind of foam do you use?
The formula of the foam material, stored in the Self Expanding Foam vessel under pressure is a part of our patented technology. We produce it ourselves and fill it to the SEF pressure vessel at the site.
[–] You say that one of the exceptional advantages of your system is using ready-made foam. It can be some sort of premix, I guess. What is the life span of that? Changing in every 5 years can generate high maintenance costs.
Our experience shows that the parameters of our pre-mixed foam change less than 10% compared to the original values during 10 years duty in the pressurized foam storage tank. If one changes the content of the foam pressure vessel every ten years, it still results in very low costs.
Please take into account that we are able to put out the fire by using a very small quantity of foam concentrate compared to the traditional fire fighting methods.
Example: with the FoamFatale technology the full surface fire of a 6000 m3 tank can be extinguished by the use of 200 liters of foam concentrate, and a tank of 80 000 m3 requires only 3 m3. The cost of this foam material, when changed every ten years, does not play a significant role.
Note that the foam concentrate to be kept in stock when one uses a conventional foam system is considerably larger than the foam one stocks in the pressurized foam vessel as pre-mix.
Also note that we currently recommend changing the pre-mix foam every 10 years. We picked the figure 10 because we have the experience that after 10 years the foam is still in tip-top condition. Since the pre-mix foam is stored under pressure in an inert gas environment we are confident that the foam will just as well stay in good condition for much longer, but at this moment we simply do not have the experience so we do not want to stick our neck to extend the period between foam changes.
[–] Whilst it is true that vast potential savings could be realized in event of a large storage tank fire involving a tank that is protected with the FoamFatale system, expenses entailed in protecting a tank farm of 100 or more tanks with either “conventional” methods or the TFEX technology are significant.
When more tanks are equipped with our foam application system, one can reduce cost by providing a common foam supply to a group of individual tanks.
The foam supply tanks should be intelligently located at a reasonable distance from the storage tanks to be protected. This solution reduces the cost per storage tank.
During the Basis of Design phase of the project one should determine the most cost- effective system configuration for the storage tanks to be protected.
If one uses a common foam supply system the capacity of the supply unit must match to the largest tank in the group. So when the dominant tank is for instance 40 000 m3 (diameter 58 m), the required self-expanding foam quantity is 175 m3.
We agree with you that on the basis of risk assessment one cannot economically justify a full surface extinguishing system for a floating roof tank.
A number of interested parties however are seriously considering a full surface extinguishing capability. Their reasoning is often strategic, i.e. when the entire income of a country passes through one tank farm and escalation of a tank fire to adjacent tanks cannot be excluded (because the tanks are relatively close to each other) they want the “belt and braces” solution, because the consequences for the country of a full surface fire are really dramatic.
[–] What do statistics show? is the fixed system protection against full surface fire a cost-effective investment?
The current most up-to-date database for tank fire incident in storage tanks was made as part of LASTFIRE 1 in the late nineties.
Lastfire is very clear that when one manages a tank properly the probability of that tank being involved in a fire is very low. But a low probability still means that it cannot be excluded entirely.
Despite all the knowledge gathered during that Lastfire project the World is still faced with a number of large fires in storage tanks.
Conventional systems to tackle tank fires are complex. Foam proportioning equipment is complicated, and therefore prone to failure.
Fire-trained personnel is generally a problem. Personnel reduction is an ongoing action in the Oil Industry, so at a certain moment one comes below the critical number of (volunteer) firemen. Conventional systems to become successful require well-organized logistics and above all half an army of well-trained personnel.
But unfortunately “success” in conventional fire fighting of a tank fire is only relative; since the end result is always that the fire is out, but also that the tank is completely lost.
Our system is set up during quiet periods. During a fire all that is needed is to open one valve (or a few valves in case of a common foam supply system). Our system is highly reliable. It is so simple that the probability that it fails because a component fails is very low, simply because there are hardly any components. It works perfect since it does not require any external water or power source and can be triggered remotely or automatically.
We do not claim to offer the one and only solution to all tank fire problems. But we are confident that our system, due to its unconventional approach of the typical fire extinguishing one faces these days, offers a revolutionary solution to many of these problems.
We can imagine that huge refineries with a full-time company fire brigade and an army of technical personnel to fall back on as assistant- firemen do not need our system. But a not around-the-clock manned marketing terminal in the suburbs of a city do need our system, since they cannot afford to have a tank fire lasting some time and endangering the population living in the vicinity.