Vest for use in polluted atmosphere

The present invention relates to a vest for use in a polluted atmosphere. The vest is intended to create a fresh air zone outside the vest. To this end, the vest has an air-permeable portion extending around at least a part of the vest, preferably around the entire vest, and a supply air connection for supplying fresh air to the interior of the vest and out through said air-permeable portion.

BACKGROUND OF THE INVENTION 
The present invention relates to a vest for use in a polluted atmosphere. 
In many industrial jobs and elsewhere workers are compelled to inhale 
pollutants of various types. A close study of the changes of indoor 
temperature for one year shows that it is often difficult to create, with 
conventional ventilation techniques, a satisfactory climate during the 
entire year. It is not possible to guarantee an acceptable climate with 
one system only. A ventilation system based upon the "cold air principle" 
with laminar air injection must comprise a complementary heating system. 
This solution is always expensive, and its practical application 
frequently is difficult. Furthermore, the result deteriorates because 
persons who are moving about in the ventilated environment themselves 
interfere with the air currents and create turbulence so that pollutants 
will enter their breathing zone. 
Protective masks of various types are often regarded as uncomfortable and 
are used only in really oppressive environments. 
Today, there is available on the market a visored helmet where air is 
injected inside the visor via a compressed air hose or by means of a fan 
mounted on the helmet. The air flowing past the wearer's face may, 
however, feel unpleasant and may irritate the eyes. 
SUMMARY OF THE INVENTION 
It is the object of this invention to provide a device capable of creating, 
in a simple, inexpensive and neat manner, a fresh air zone around a 
persons working area having a polluted atmosphere, and in a manner such 
that he will not be inconvenienced by the fresh air supplied. 
According to the invention, this object is achieved by means of a vest 
having the characteristic features stated in the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a vertical sectional view of a vest 1 according to the invention, 
said vest comprising an inner layer 3 of low permeability to air and an 
outer layer 4 having an upper air-permeable portion 5 and a lower 
air-tight portion 6. An air supply connection 7 is mounted in the 
air-tight portion 6 of the outer layer 4. A hose (not shown) from an air 
supply unit may be connected in some suitable manner to the air supply 
connection 7. FIG. 1 also shows one arm-hole 2 of the vest. 
The air-permeable portion 5 consists of a material having a high resistance 
to air, whereby the air discharged through this portion will be adequately 
distributed around the entire upper part of the body of the person wearing 
the vest. In the embodiment illustrated, the air-permeable portion extends 
around the entire upper part of the vest, which is preferable to this 
portion covering only the front of the vest. By discharging fresh air 
around the entire upper part of the wearer's body, the risk that any gases 
behind the wearer are sucked into the zone in front of him, will be 
greatly reduced. Furthermore, he can move about more quickly, especially 
turn round, if the fresh air zone established by the outflowing air 
extends around his entire body. 
The gap which is formed between the inner layer 3 and the air-tight portion 
6 of the outer layer 4 forms an air distribution zone for the air supply 
14 (FIG. 2) from the air supply connection 7. The air will thus be 
distributed around the vest before it escapes through the air-permeable 
portion 5, and it will be appreciated that the provision of the air 
distribution zone contributes to a uniform distribution of the air supply 
14 around the vest. 
Naturally, the vest will function just as well if the inner layer is 
air-tight, but a partially air-permeable layer will contribute to reducing 
excess heat between the vest and the wearer's body. 
FIGS. 2 and 3 illustrate the use of the vest in two different climates, 
FIG. 2 showing a climate where the temperature is between +16.degree. and 
+23.degree. C., while FIG. 3 shows a climate where the temperature is 
between +25 and +35.degree. C., which frequently are the winter and summer 
temperatures, respectively, in factory premises. 
In a test made with this invention, the vest was manufactured from tubular 
woven fabric of the type NORDIFA.RTM. which, at suitable places, had been 
treated with impermeable paint. 
The vest has been designed to function at excess pressures of about 
400-1800 Pa. The air supply is obtained from a unit (not shown) which is 
connected to the air supply connection 7 via a hose. The unit comprises a 
variable radial fan having a single-phase motor which provides a pressure 
increase of about 2,000 Pa and an air flow of about 40-100 liters per 
second, an air filter and an electric battery. The air flow and the 
temperature are controlled by means of knobs 10 on the air supply 
connection. 
FIG. 2 illustrates the creation of a fresh air zone 13 around the wearer 8, 
which zone is formed of air supply 14 having a temperature of +24.degree. 
C., a temperature which is considered agreeable in the context. Actually, 
the temperature and the flow rate of the supply air are selected on the 
basis of the natural convection of the human body. The temperature of the 
air 12 polluted with poisonous gases or dust is lower than +22.degree. C., 
and the air supply 14 rises from the vest due to the excess temperature 
and forms the fresh air zone 13. It is possible in this case to maintain a 
relatively low air supply flow rate, which is advantageous because the 
wearer need not be irritated by strong air currents. 
FIG. 3 illustrates a case where the temperature in the premises is higher 
than +22.degree. C. The rising power of the air supply 14 is reduced 
because the temperature difference between the supply air and the ambient 
air is reduced, for which reason the air supply flow is increased. Since 
the temperature in the premises in this case is higher, the wearer can 
accept increased air movements without feeling uncomfortable. 
The vest according to the present invention is well suited for the 
manufacture of plastic boats, for instance for work on the hull, other 
plastic industries, spray-painting plants, chemical industries, industries 
giving off dust or other air-borne particles, and temporary jobs, such as 
building sites, where use is made of hand tools with local extraction and 
where substitute air is nowadays required to maintain the dust content in 
the breathing zone at an acceptable value.