../s3_ae.gif 1940. Ventilation of the fortifications
Document carried out by E. and R. Cima starting from various technical documents. Autoédition Cima ©1998-2010

Introduction - Warning

Not to confuse ventilation and air-conditioning

- To ventilate a room is to renew its air. In the case of the fortification it is a question, above all, of making the buildings respirable for their occupants.

- To air-condition a room is primarily to maintain, with a wanted degree, its temperature and its hygroscopy.

For the originators of underground permanent fortifications, the first concern is to be able to ventilate correctly the buildings, their air-conditioning being secondary; except… for the services of maintenance! Indeed, temperature and moisture corrode as well the materials as the installations. A fortification created to last in time will be very expensive in term of maintenance if it is not air-conditioned: degradation of the wall linings, the fixtures, the materials of communication and transport of energy, the stored weapons, etc

Common point between ventilation and air-conditioning

The common point is that of the atmosphere of the places to treat, also can it be trying to air-condition via the ventilation systems; vast subject, badly solved by the CORF and which we will not approach in this document. We will thus be satisfied, here, to study the ventilation of an underground quartering.

Extraction of the foul air

Extraction of the foul air

The buildings of quartering which produce foul air are primarily the latrines, the kitchen, the generating power station, the infirmary and the reserves with food.

It is thus necessary, for these casemates, to establish a special network of sheaths leading the foul air outside the fortification. Electromechanical extractors activate this elimination.

To differentiate these sheaths from others which traverse the galleries, the standard adopted by the CORF is that they are painted in yellow.

ge24_sa_airvicie.jpg Sheaths of evacuation of the foul air of the kitchen (Holy Agnes SFAM). The valve is used to avoid the external air intake, when the extractor is with the stop.
After war, by preoccupation with economies, all the repainted sheaths received a color gray aluminum and only their collars and valves were painted in yellow.
Recycling of the interior fresh air

Recycling of the interior fresh air

The mixing of the air, in the totality of the fortress, can be really assured only by one system of sheaths distributing the fresh air, in light overpressure, in each casemate.

A room of ventilation ensures this role. The air, drawn from the principal gallery, is brewed by a centrifugal electromechanical ventilator, then led in each room. The sheaths leading the fresh air are of red color.

salle_vent_1.png Diagram (outline) of the room of ventilation. ventil_cas_1.jpg Large air intake (vertical) in quartering (Holy-Agnes SFAM). ge24_fr_airpur.jpg Room of troop with Fressinea (SFAM) with its sheath for fresh air.
External fresh air

External fresh air

Time with other the air must be renewed, would be this only for replacement the expelled foul air.

A sheath, with air intake armor-plated, is thus added to the already existing network and leads the air, since outside to the room of ventilation. The sheaths leading of the air drawn outside are of green standardized color.

salle_vent_2.png Diagram (outline still) of the room of ventilation. ge24_bichel_facade.jpg The air intake is in frontage. Here it is under the flagstone, with the top on the left of the central crenel (Shelter of the Bichel-south. SF Thionville).
f24_b6_gfm.jpg The air intake can also be with the top of the flagstone, under armoured bell. Here it in the foreground, is protected by a light envelope from concrete, not far from a GFM (Galgenberg. SF Thionville).
Gassed air

Gassed air

In the event of bombardment by toxic machines one of the solutions would be (possibly and as in open country) to make carry to the men the masks with which they are equipped. The ventilation system could then remain such as it is.

But the masks are not easy use and, at the cost of some installations, the ventilation system can be transformed into anti-gas system; it is enough to seal off all the openings giving on outside and to filter the entering air.

The room of ventilation, become room of neutralization, thus receives filters activated carbon able to regenerate the air.

The filters can be easily clogged; it is thus important to spare them. Each one of them can be disconnected from the circuit what allows, in the event of attack by poison gas, to use only one minimum number of it.

salle_vent_3.png Diagram (outline still) of the room of ventilation.

The important pressure loss, at the time of the passage of the air in the filters, requires the installation of a powerful ventilator “gassed air”. The engine of this last, more powerful than the other, is coupled with the ventilator by a set of belts.

ventil_cas_2.jpg Here the two ventilators are one with the top of the other, “fresh air” in top, “air gassed” in bottom, with its engine with belts (Fressinea. SFAM). The doubling amongst ventilators, quasi imposed by the presence of the filters, is also a pledge of safety.


A last improvement makes it possible to use the powerful ventilator “air gassed” to propel the air drawn outside without passing by the filters. It is enough to shunt the filters with a short sheath, of course equipped with a valve. One can thus increase the speed of renewal of the air of quartering, if the need were felt some, and, especially, to mitigate a breakdown of the ventilator “fresh air”.

The standardized color of this small circuit is the white.

Note: the position of the shunt varies from one fortification to another (see the alternatives below). Its implementation is easier in the case number 2 where it is independent of the sheath supplying the filters.

salle_vent_4b.png Diagram, final, of the room of neutralization.
ge24_fressin.jpg Fressinea (SFAM). The filters, repainted after war, are not red any more. On the other hand the vertical shunt, in front of the two filters, has its valve with standardized white color.
ge24_bambesch.jpg Bambesch (SF Faulquemont). The filters do not have a standardized color but have, all the same, their gray color of origin (One finds this gray color in several works of the RF of Metz). The shunt is of white color, with the back of the filters, the wall.
Model of room of neutralization

Model of room of neutralization


From the final diagram of a room of neutralization of quartering, we did not resist emulously to create the model 3D below (which took an unquestionable time to us!)

The passage of the mouse animates the image

ge26-074.jpg Model
Various modes

Various modes

The room of neutralization can thus function, upon request, under four quite distinct modes. The whole is to open or close the good valves. They are the specialists “Z” who undertake some!


1-l' air can be simply recycled;

2-l' air, taken outside, and not gassed, can be pulsated in normal ventilation by the not very powerful ventilator of the circuit of recycling;

3 it even air, not gassed, can be pulsated in ventilation with high banc by the other ventilator, more powerful than the precedent;

4-enfin, in the event of attack by poison gas, the gassed air can be filtered before being distributed to the casemates.


Teachware on the modes of a room of neutralization

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