Foam nozzle
Foam nozzles are nozzles specially designed for the production of extinguishing foam and are therefore part of the water-bearing fittings for water delivery in the fire service . In the foam pipe , the water- foam compound mixture from the proportioner is mixed with air and ejected as extinguishing foam. Until 2014 they were standardized in DIN 14366, which basically differentiated between 2 types: heavy and medium foam nozzles. In addition, there are also combination foam nozzles that combine both variants in that the low-foam nozzle is attached to the center foam nozzle. A lever is used to switch between the two functions. While foam nozzles can only produce medium and heavy foam, high-expansion foam generators are required for the production of high- expansion foam .
Standardized foam pipes
Foam nozzle types according to DIN (until 2014)
The nozzles according to the DIN standard differ in their parameters:
| designation | Type | Volume flow liquid
[L / min] |
Minimum VZ according to DIN ( MBS ) | resulting amount of foam
[m³ / min] |
Minimum throw distance
[m] |
|---|---|---|---|---|---|
| S2 | Heavy foam pipe | 200 | 10 | 2 | 10 |
| S4 | Heavy foam pipe | 400 | 10 | 4th | 20th |
| S8 | Heavy foam pipe | 800 | 10 | 8th | 25th |
| M2 | Middle foam tube | 200 | > 40 | 8th | 6th |
| M4 | Middle foam tube | 400 | > 40 | 16 | 7th |
| M8 | Middle foam tube | 800 | > 40 | 32 | 10 |
| M2W | Middle foam tube | 200 | > 20 | 4th | 12 |
| M4W | Middle foam tube | 400 | > 20 | 8th | 20th |
| M8W | Middle foam tube | 800 | > 20 | 16 | 25th |
Medium foam pipes with the suffix W have a particularly high throw, but less foaming . The flow rates refer to an inlet pressure of 5 bar on the foam tube. Heavy foam pipes must also achieve a foaming factor of at least 5 with AFFF and protein foaming agent .
Foam nozzles consist of a housing with a fixed coupling and handle, a nozzle, an air intake opening and - for all heavy foam pipes of the old design and medium foam pipes - a refiner screen. The housing, which is mostly made of sheet steel, is slim and tubular in the case of heavy foam pipes, while it is rather short and stocky in the case of medium foam pipes. The air intake openings are located near the nozzle; their diameter depends on the type of foam pipe.
During use, the water flows through the nozzle (s) and is finely distributed; foam bubbles form when air enters ( injector principle ). A constant pressure (usually 5 bar) should be ensured, otherwise the quality of the foam will decrease.
The basic functional principle of the foam nozzle goes back to the Berlin patent attorney Clemens Wagner, who invented an air foam nozzle in 1923, which became known as the Kometrohr . In 1932 Wagner registered his patent. However, the Kometrohre used a nozzle assembly consisting of 3 nozzles, today's foam pipes usually only use one nozzle.
This was the last status of the German foam device standards:
- DIN 14366: 2011-01 Portable foam nozzles PN 16
- DIN 14384: 2011-01 Foam compound proportioner PN 16, self-priming
- DIN 14819: 2011-01 D-suction hose for extinguishing agent additives
Foam nozzle types according to DIN EN (from 2015)
The above German foam device standards were replaced in 2015 by the following European standards:
DIN EN 16712-XX Portable devices for discharging extinguishing agents that are conveyed by fire pumps - Portable foam devices ...
… Part 1: proportioner PN 16; German version EN 16712-1: 2015
... Part 2: suction hose; German version EN 16712-2: 2015
... Part 3: Heavy and medium foam nozzles PN 16; German version EN 16712-3: 2015
... Part 4: Light foam generators PN 16; German version EN 16712-4: 2018
The standard for high-expansion foam generators has been added. In practice, the performance data of the foam pipes according to DIN EN largely correspond to those of the previously explained DIN.
In the last published version of DIN 14384: 2011-01 Foam compound proportioner PN 16, self-priming, proportioners with a volume flow of less than 200 L / min were also included in the standard at the request of the user. This has been incorporated into the European standard: the overall spectrum now ranges from Z0.5 to Z8 with admixing rates in the range between 0.1% and 6%.
Marking of the volume flow of the foam devices according to DIN EN 16712
In the course of European standardization, the volume flow of the most widespread foam devices with volume flows of 200, 400 or 800 L / min has been specified since 2015. We recommend attaching these labels to the 65 respective devices at a later date. If the identification color corresponds to that of the fitting (e.g. red band on Z4), it can be omitted. Unfortunately, this marking has so far not established itself in Germany either for new devices or for used devices.
| Nominal volume flow according to EN
[L / min] at 6.5 bar outlet pressure of the proportioner |
Identification color (banderole or similar) according to DIN EN 16712 |
|---|---|
| 200 | yellow |
| 400 | red |
| 800 | blue |
Non-standardized foam tubes
Foam gun
The foam gun is a combination of foam pipe, proportioner and foam compound container that is not standardized according to DIN. The foam concentrate is in a plastic bottle that is attached directly to the foam gun. The foam gun is only suitable for small operations. The water is released either by means of a lever, similar to that of a hollow jet pipe , or by means of a trigger attached in front of the handle, which must be kept depressed at all times. With the filling of a plastic bottle you can lay a foam carpet of approx. 5 m² at a height of approx. 30 cm. The throwing distance is about 1 to 1.5 m.
literature
- Holger de Vries: Use of special pipes: Training and practice - Basics - Functionality - Hydraulics - Standardization - Requirements - Foam pipes - Powder pipes - Monitors - Extinguishing lances . (Expertise Fire Brigade) Paperback - August 14, 2018, ISBN 978-3-609-69401-6
- Lutz Rieck: Die Rote Hefte, Booklet 6 - fire extinguishing fittings . 11th, revised edition. Kohlhammer, Stuttgart 2000, ISBN 978-3-17-015171-0 , pp. 94-98 .
- Diverse: Hamilton - Handbook for the fire brigade . Boorberg Verlag, 21st edition 2012. ISBN 978-3-415-04560-6
Individual evidence
- ↑ a b DIN 14366 portable foam nozzles
- ↑ a b "Fire fighting with water and foam" from the series "Einsatzpraxis", Holger de Vries, ecomed Verlag 2008
- ↑ VZ stands for foaming rate .
- ↑ Beuth Verlag - Buy Norms, Standards & Specialist Literature | since 1924. Retrieved April 6, 2019 .