U.S. patent number 3,850,171 [Application Number 05/360,788] was granted by the patent office on 1974-11-26 for medical face masks.
This patent grant is currently assigned to Vickers Limited. Invention is credited to Graham John Ball, Ivor John Martin Fehr.
United States Patent |
3,850,171 |
Ball , et al. |
November 26, 1974 |
MEDICAL FACE MASKS
Abstract
A medical face mask for supplying gas/air mixture to a patient
comprising a hollow body portion adapted to cover the nose and
mouth of the patient and an inlet portion for adjustably supplying
said gas/air mixture. The body portion includes an inlet opening
and at least one outlet. The inlet portion of the mask comprises a
venturi throat in communication with the inlet opening in the body
portion and includes first and second apertured members, said
second member is mounted to the inlet portion and has a plurality
of apertures and a gas inlet means. Said first member is rotatably
mounted to said second member and has a plurality of apertures
adapted for the selective registry with said apertures in said
second member.
Inventors: |
Ball; Graham John (Basingstoke,
EN), Fehr; Ivor John Martin (Basingstoke,
EN) |
Assignee: |
Vickers Limited (London,
EN)
|
Family
ID: |
23419400 |
Appl.
No.: |
05/360,788 |
Filed: |
May 16, 1973 |
Current U.S.
Class: |
128/204.25;
128/205.11 |
Current CPC
Class: |
A62B
18/00 (20130101); A61M 16/06 (20130101); A61M
16/127 (20140204) |
Current International
Class: |
A61M
16/06 (20060101); A62B 18/00 (20060101); A61M
16/12 (20060101); A61M 16/10 (20060101); A62b
007/02 () |
Field of
Search: |
;128/203,196,195,197,199,200,205,209,210,142.3,145.5,145.8 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Recla; Henry J.
Attorney, Agent or Firm: Wettach; Thomas C. Stein; Arland
T.
Claims
We claim:
1. A medical face mask comprising a hollow body portion adapted to
fit over the nose and mouth of a patient, said body portion having
an inlet opening and at least one outlet opening, and an inlet
portion including a venturi throat in communication with said inlet
opening and having first and second apertured members, said second
apertured member being fast with said inlet portion and including a
plurality of apertured, said second aperture member including gas
inlet means for introduction of a gas into said venturi throat, and
said first apertured member being rotatably mounted to said second
apertured member and including a plurality of apertures adapted for
registry with selected apertures of said second member to permit
selectable amounts of air into said venturi throat.
2. A medical face mask as set forth in claim 1 wherein said
apertures in each of said first and second members are disposed on
a common pitch circle, said circles each being coaxial about the
axis of rotation of said first apertured member and of the same
radius as the other.
3. A medical face mask as set forth in claim 1 wherein said first
aperture member is rotatably mounted to said gas inlet means, and
said gas inlet means including biasing means for biasing said first
member against said second member.
4. A medical face mask as set forth in claim 1 wherein said second
aperture member includes at least apertures A, B, C and D and first
aperture member includes at least corresponding apertures a, b, c
and d, each of said apertures having centers positioned on
corresponding pitch circles of the same diameter and said centers
being positioned about 60.degree. apart.
5. A medical face mask as set forth in claim 4 wherein apertures b,
c and d are each slightly larger than corresponding apertures B, C
and D and where the diameters of said apertures are related as
follows: A<B = C<D and a<b<c<d.
Description
For a better understanding of the invention and to show how the
same may be carried into effect, reference will now be made, by way
of example, to the accompanying drawings, in which:
FIG. 1 is a front perspective view of a medical face mask,
FIG. 2 is a side view of the mask of FIG. 1 illustrating the
various gaseous flows that occur in use, and
FIGS. 3 and 4 are front views of details of the mask of FIGS. 1 and
2.
The mask of the Figures has a hollow body portion 1 formed of a
translucent pliable plastics material. The body portion 1 is of
appropriate configuration to be fittable to a patient's face so as
to contain the nose and mouth, the mask being fitted to the patient
utilising an elastic cord secured to holes 2 in lugs 3 extending
from the rim portion 4 of the body portion 1, this rim portion 4
extending laterally of the remainder of the body portion 1 to
facilitate close fitting of the mask to the patient's face.
An inlet portion 5 of the mask is formed by a rigid tube 6 that
extends from the body portion 1. A disk 7 is fast in the tube 6 at
its free end, that is at its end remote from the body portion 1. An
inlet jet 8 rigid with the disk 7 extends through the centre of the
disk 7 such that a venturi throat exists at the free end of the
tube 6. A further disk 9 is rotatably mounted on the jet 8 outside
the tube 6, this disk 9 being urged into face to face contact with
the disk 7 by a compression spring 10 mounted on the jet 8 and
acting between the disk 9 and a shoulder 11 on the jet 8. The outer
end of the jet 8 is formed for having connected to it a gas supply
pipe.
The two co-operating disks 7 and 9 constitute air inlet means
positioned to permit air to be drawn into the mask by the action of
gas entering the mask through the venturi throat. To this end, and
referring to FIGS. 3 and 4, the disks 7 and 9 are apertured. The
disk 7 has four apertures A, B, C and D, equi-angularly
spaced-apart on the same pitch circle diameter but of different
diameters. In the illustrated example shown the diameters are A =
0.1470 inch, B = 0.2130 inch, C = 0.2130 inch and D = 0.28125 inch
spaced at 60.degree. apart on a pitch circle diameter of 3/4 inch.
The disk 9 has four corresponding apertures a, b, c and d which, in
one position of the disk 9 relative to the disk 7, align with the
apertures A, B, C and D respectively. To ensure that air flow
through the apertures that are in line with one another is, in most
positions of the disk 9 relative to the disk 7, determined by the
sizes of the apertures A, B, C and D, the apertures b, c and d are
each of slightly larger diameter than the corresponding apertures
B, C or D. In the illustrated example a = 0.1285 inch, b = 0.234375
inch, c = 0.28125 inch and d = 0.34375 inch in diameter.
In addition to the apertures A, B, C and D the disk 7 is provided
with a pip 12 directed towards the disk 9 and disposed on the same
pitch circle diameter as the apertures A, B, C and D for engagement
with either one of two closed bores 13, 14 in the disk 9 on the
same pitch circle diameter as the apertures a, b, c and d and
equi-angularly spaced apart therefrom and from each other. In the
illustrated example the pip 12 is 0.125 inch in diameter and the
bores 13, 14 are each 0.134 inch in diameter. The pip 12 can
alternatively be engaged in the aperture a or in the aperture b as
discussed below.
The mask is used as follows. The particular example illustrated is
intended to have its jet 8 connected to an oxygen source supplying
oxygen at a flow rate within the range of 8 to 14 litres per
minute, and to operate within acceptable limits up to a flow rate
of 19 litres per minute. Oxygen entering the mask through the jet 8
(dotted lines 15 in FIG. 2) causes air to be drawn in through
whichever of the apertures in the two disks 7 and 9 are in
alignment (chain dot lines 16). The thus oxygen-enriched air enters
the mask body portion 1 to be inhaled by the patient. The length
and inner diameter of the tube 6, and the diameter of the orifice
of the jet 8, are such that the jet of oxygen entering the tube 6
breaks up within the tube 6 before entering the body portion 1 and
the resultant turbulent gas flows within the tube 6 (illustrated in
FIG. 2) prevent oxygen not inhaled by the patient, and exhaled air,
re-entering the tube 6. The excess oxygen and exhaled air is
permitted to leave the mask through apertures 17 in the mask body 1
(chain lines 18). In this illustrated example the tube 6 is 37/8
inches long, its inner diameter is 1 inch, and the jet orifice is
0.144 inch in diameter.
The desired oxygen concentration in the gas stream entering the
mask body portion 1 is selected by adjusting the position of the
disk 9 relative to the disk 7, percentage concentrations of 50
percent, 60 percent, 70 percent and 80 percent, within .+-. 1
percent at oxygen flow rates of from 8 litres per minute to 14
litres per minute being obtainable with the illustrated mask by
setting the disk 9 as follows:
Pip 12 engaged in bore 13, apertures a, b, c and d respectively
aligned with apertures A, B, C and D - 50 percent oxygen
concentration.
Pip 12 engaged in bore 14, apertures b, c and d respectively
aligned with apertures A, B and C, apertures a and D blanked off -
60 percent oxygen concentration.
Pip 12 engaged in aperture a (blanking this aperture off),
apertures c and d aligned with apertures A and B, apertures b, C
and D also blanked off - 70 percent oxygen concentration.
Pip 12 engaged in aperture b (blanked off), apertures a and d
aligned with apertures D and A, apertures c, B and C also blanked
off - 80 percent oxygen concentration.
In the last position (80 percent oxygen concentration), although
the pip 12 is a very loose fit in the aperture b, the relative
sizes of the apertures a and D and d and A are such that the
apertures A and a are always open throughout the range of movement
permitted to the disk 9 in this position.
It will be appreciated that the various settings described above
are obtained by positive locations of the pip 12 in either the bore
13, the bore 14, the aperture a or the aperture b, the setting
being altered by withdrawing the disk 9 against the action of the
spring 10, rotating the disk 9 and releasing it again. Appropriate
scale markings carried by the disk 9 line up with a fiducial line
on the disk 7 for each of these settings.
* * * * *