US 2284054 A
Description (OCR text may contain errors)
S. HERMANN May 26, 1942.
GAS MASK Fil ed Sept. 9, 1941 INVENTOR m m m m wnz M fin m ATTORNEY Patented May 26, 1942 UNITED STATES PATENT OFFICE GAS MASK Siegwart Hermann, New York, N. Y. Application September 9, 1941, Serial No. 410,131
This is a continuation in part; of patent application, Ser. No. 394,835, filed May 23, 1941.
My invention relates to improvements in gas masks. The object of my invention is to improve the effect of gas masks by increasing the filter capacity of the device without increasing respira tory difiiculties, but decreasing even the breathing resistance of gas masks.
This is to be performed, according to this invention, by forcing accessory air into the gas mask through a respiratory system comprising a series of filters namely a pre-cleamng filter and a main filter, both of them containing substances e. g. activated charcoal; suitable for the filtering of the air to be inhaled. The filters of the respiratory system are separated by a length of tubing. A bellows pump, to be operated preferably by the wearer of the gas mask, is placed before the pre-cleaning filter for .forcing the air through the system. Supplementary means for giving access to air from without are provided in the connection with the main filter, said means being active even if the pumping of air through the system is stopped.
I am aware of the fact that it has been already suggested to provide gas masks with devices designed to force the air into the masks in order to overcome breathing difficulties due to the resistance of accumulated filtering material. However, in the known devices of this kind, the pumping can never be stopped because there are no other possibilities for the air from without to pass through the respiratory system in the mask. Therefore, the person using the mask will suffocate when the pumping in of air cannot be maintained.
Now, according to this invention, not only the air to be forced into the respiratory system, but also supplementary air, flows through the gas mask, the latter even when the device forcing the air in does not work.
In the annexed drawing several forms of the invention are shown diagrammatically. Like numbers denote like parts.
Fig, 1 is a View of a gas mask provided with a respiratory system according to this invention.
Fig. 2 is a partially sectional View of the filtering part and a part of the hose of the device according to Fig. 1 showing the supplementary air supply.
Fig. 3 shows a modification of the device according to Fig. 2.
Fig. 4 shows a modification of a part of Figs. 2 and 3, when valves are used.
Fig. 5 is an enlarged section through Fig. 4 on the line 55.
The gas mask l is provided with a regular main filter 2 and a length of hose 3 connecting filter 2 with an additional pre-cleaning filter 4. The bellows 5 are designed to supply air to the respiratory system comprising said main filter 2, hose 3 and pre-cleaning filter 4.
Means for supplying additional air from without to the main filter of the respiratory system are shown in Figs. 1, 2 and 3, respectively.
According to the performance of this invention, as shown in Figs. 1 and 2, a rubber hose 3 is connected with the main filter 2 by means of an, extension 2 of the filter 2 over which hose 3 is drawn. A funnel or cone 6 inserted in the upper part of hose 3 extends into filter 2 permitting the air pressed through the system to enter this part of the gas mask. Corresponding holes 8 in the extension 2 and holes 9 in the rubber hose 3 form a supplementary connection between the main filter and the air from without.
In the device as shown in Fig. 3 a relatively thin hose l3 connects the filters 4 and 2. This hose is attached by means of a connection l2 to a rigid tube ll extending into the main fi1ter'2. A jacket l0 connected with extension 2' surrounds tube ll. Corresponding holes H1 in the jacket l0, and 8 in the extension 2 are giving access to the air from without to this modification of the respiratory system. I
I have found that by forcing air through a respiratory system as described, air filtered in the pre-cleaningfilter as Well as in the main filter will flow through the system. If the user of the gas mask is forced to stop the pumping, sufiicient air can still be sucked through the breathing holes forming the supplementary air supply,
Figs. 4' and 5 show a modification of the device, according to this invention, comprising valves closing the breathing holes while an is forced through the respiratory system by the bellows and opening them when the pressure stops. The valves consist of aring I d inserted in extension 2'. To the ring I4 are attached small thin blades, e. g. of rubber, for the purpose of closing the holes 8 of the extension. When the air forced through the device meets the blades l5, they are pressed against the holes 8-, thus closing them. When the pressure stops by the suction of breathing, a vacuum is created 'sufiicient to open the valves and to give access to the air from without.
I have described preferred embodiments of my invention but it is understood that changes and omissions may be made without departing from the spirit of my invention.
What I claim is:
In a gas mask a respiratory system, comprisingv a main filter provided with an extension, a rubber hose drawn over said in the upper part of said rubber hose extending in the main filter, said extension and rubber hose being provided with holes forming a connection between the main filter and the air from without, a supplementary filterbeing connected with the main filter by said rubber hose and a pump for pressing air through the system placed before said supplementary filter.
extension. a funnel inserted