Rub­ber Bladder 

The JÄGER Group saves lives in sec­onds with the rub­ber bladder 

Safe­ly on the move with our fire extin­guish­ing expert 

Tak­ing the bus to work, kinder­garten or sports? For many peo­ple this is every­day life. None of the pas­sen­gers think about a pos­si­ble fire in the bus. But we are aware of this dan­ger and, togeth­er with our part­ners, are devel­op­ing solu­tions for greater safe­ty when dri­ving by bus – even with com­pact engine com­part­ments in the vehicle. 


Accord­ing to analy­ses by the DEKRA expert orga­ni­za­tion, 75 per­cent of all bus fires occur in the engine com­part­ment. The spe­cial­ist for fire pro­tec­tion and ear­ly fire detec­tion, the com­pa­ny Pro­tec­fire from Lue­beck, has devel­oped a new space-sav­ing extin­guish­ing sys­tem with just one line espe­cial­ly for the pro­tec­tion of bus­es and trucks. 


The com­pa­ny turned to Jäger Gum­mi und Kun­st­stoff GmbH with the chal­lenge of being able to pump the extin­guish­ing agent pre­cise­ly into the pipeline, regard­less of its position.

Help in seconds 

Since the patent­ed „detex­line“ extin­guish­ing sys­tem, unlike con­ven­tion­al sys­tems, works with just one line, both fire detec­tion and extin­guish­ing take place via this line. Dur­ing nor­mal oper­a­tion, the sys­tem is depres­sur­ized and only becomes active in an emer­gency. In the event of a fire, how­ev­er, the extin­guish­ing agent must be able to enter the line pre­cise­ly from the open­ing of the stain­less steel extin­guish­er with­in sec­onds. For a posi­tionin­de­pen­dent and fast extin­guish­ing process, Jäger Gum­mi und Kun­st­stoff togeth­er with Pro­tec­fire devel­oped the so-called rub­ber bladder. 


In case of fire the fol­low­ing hap­pens: The con­trol head in the extin­guish­ing sys­tem receives a com­mand and releas­es the gas pres­sure car­tridge in the blad­der. The blad­der inflates – start­ing from the bot­tom – in the extin­guish­ing agent tank. In this way, the exist­ing extin­guish­ing agent is suc­cess­ful­ly pressed in one direc­tion towards the extin­guish­ing line, which dis­trib­utes the extin­guish­ing agent via sev­er­al noz­zles. There­fore it does not mat­ter how the extin­guish­er is positioned.

High­est demands on an extin­guish­ing sys­tem ready for use 

The spec­i­fi­ca­tions are high: the mate­r­i­al must fit the require­ments for extin­guish­ing agents and be resis­tant accord­ing to use – at ambi­ent tem­per­a­tures of ‑30 °C to +80 °C. The wall thick­ness­es must be thin so that there is enough space in the extin­guish­er for the pro­pel­lant gas car­tridge (with nitro­gen) and the extin­guish­ing agent, the blad­der can be inflat­ed and the expan­sion dur­ing infla­tion begins even­ly from the bot­tom of the extin­guish­er. Con­se­quent­ly, the rub­ber blad­der must be reli­ably man­u­fac­tured with a con­stant wall thick­ness in order to be able to press the extin­guish­ing agent even­ly from all sides in the direc­tion of the out­let open­ing to the extin­guish­ing pipe. 

From the right com­pound to the right tool 

Togeth­er with its sis­ter com­pa­ny Artemis, Jäger devel­ops a tool con­cept and a suit­able mix. The require­ments are high and must be met over a long peri­od of time. The Pro­tec­fire sys­tem is designed to be main­te­nance free for ten years and must func­tion at all times in the event of an emergency. 


The com­pound­ing experts at Jäger Gum­mi und Kun­st­stoff and Artemis are devel­op­ing a mix­ture of extreme­ly elas­tic nat­ur­al rub­ber (NR) and styrene- buta­di­ene rub­ber (SBR) to meet the required mate­r­i­al resis­tance at sub-zero tem­per­a­tures. In addi­tion, a thread­ed met­al ring is vul­can­ized on for the con­nec­tion to the extin­guish­ing line. 


The rub­ber blad­der is man­u­fac­tured using an injec­tion mold in the injec­tion mold­ing (IM) process. Ini­tial­ly, there are still devi­a­tions in the wall thick­ness, as the core cen­ter­ing can­not be held per­ma­nent­ly. Jäger reworks the tool imme­di­ate­ly and sub­se­quent­ly real­izes reli­able core cen­ter­ing. Now the prod­uct is per­fect – it can be deliv­ered to Protecfire.

Save Case Study now! 


Put to the acid test 

To with­stand the rig­ors of a fire, Pro­tec­fire car­ries out exten­sive test­ing on the fin­ished prod­uct. Jäger‘s rub­ber blad­der has proven itself suc­cess­ful­ly in tests with extin­guish­ing agents, tests under con­di­tions sim­i­lar to those of fire, tests in a cli­mat­ic cham­ber – for approval in cold regions – as well as in the state-approved test meth­ods SP4912 and UNECE R107 for engine protection.


This also involves check­ing how much extin­guish­ing agent is pressed out of the extin­guish­ing con­tain­er and over what peri­od of time. The results show: More extin­guish­ing agent is pressed out of the con­tain­er by the rub­ber blad­der – hard­ly any reserve of extin­guish­ing agent has to be tak­en into account. Even a small con­tain­er with only 7 liters of extin­guish­ing agent can extin­guish a fire even­ly and com­pre­hen­sive­ly with­in 25 sec­onds – this applies to an engine com­part­ment vol­ume of up to 8 cubic meters.

Trav­el safe­ly into the future with us 

Since Jan­u­ary 1, 2019 all new tourist coach­es and dou­ble-deck­ers in the Euro­pean Union (reg­u­la­tion UNECE R107) must have a per­ma­nent­ly installed extin­guish­ing sys­tem in the engine compartment. 


From 2021 this will also apply to region­al and city bus­es. Protecfire‘s extin­guish­ing sys­tem and the Jäger rub­ber blad­der for fire­fight­ing guar­an­tee safe trav­el in the new decade! 


Are you inter­est­ed in fire pro­tec­tion tech­nol­o­gy? Vis­it also our cus­tomer:

Your con­tact per­son for the rub­ber bladder

Loca­tion Hamburg

A. Fröh­n­er

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