Pressure indicator particularly for respirators

A pressure indicator, particularly for respirators, comprises a housing which has a pressure chamber, is connectable to a pressure source, for example a respirator gas pressure and includes a plurality of individual indicator chambers which is connected to the pressure chamber with an indicator piston member slidable in each of the chambers and biased by individual springs in a direction which brings a feeler portion of the indicator piston member within the housing. The feeler portion extends out of the housing in an indicating position which position is arrived at by pressure in the pressure chamber acting on the indicator piston to force it out of the housing. Each indicator piston member is biased by a biasing force, for example, produced by a selected spring so that it will be in a non-indicating position until a distinct pressure acts on the indicator piston member to force it in a position in which the feeler portion thereof extends out of the housing. The individual feeler portions of the indicator piston members are advantageously covered by a flexible covering which is provided with individual projecting portions which provide housings for the feeler members. The covering is such that the individual feelers may be sensed as being present in the projecting portions of the covering when the pressure chamber of the device has reached a predetermined pressure and forces this particular feeler into the projection.

BACKGROUND OF THE INVENTION 
Field of the Invention 
This invention relates, in general, to respirators and, in particular, to a 
new and useful pressure indicator for respirators which provides a 
pressure indication which can be sensed in darkened conditions. 
Respirators with pressure gas tanks containing the ventilating gas are 
equipped with a pressure measuring instrument to monitor the pressure in 
the tanks, and thus also the supply of the ventilating gas. This 
monitoring must also be possible in dark rooms or in great depth in water. 
A known pressure indicator for respirators contains in the same housing in 
addition to a pointer, another pointer admitted by the same pressure. It 
is a displaceable piston which is under spring pressure and which has an 
outwardly protruding indicating pin. The indicating pins are provided with 
elevations or depressions, like grooves, which correspond to the pressure 
stages. They can be recognized by feeling. This is also possible in the 
dark or under water. Since the stroke of the indicating pin is small, 
however, the markings are so close together that a reliable recognition is 
not possible, and errors cannot be excluded. This is particularly true 
when working with gloves (German Pat. No. 1,299,533). 
SUMMARY OF THE INVENTION 
The invention provides a pressure indicator for respirators which makes it 
possible to reliably recognize, by feeling, the pressure in the pressure 
gas tank, even in the dark. 
In accordance with the invention, the pressure indicator includes a 
pressure chamber which is connected to a plurality of individual indicator 
chambers each of which has an indicator piston member which is movable 
therein. The individual indicator pistons are biased by pressures, for 
example, produced by a combination of the sizing of the piston and the 
size of a biasing spring which permit them to move in a direction away 
from the pressure chamber so as to project out of the housing into an 
indicating position only when the pressure chamber reaches the distinct 
pressure at which the biasing means are set. Thus, when an individual 
pressure is arrived at in the pressure chamber which corresponds to the 
biasing of the particular indicator piston member, it will be moved in its 
associated chamber so as to project with a portion out of the housing. 
This portion comprises a feeler which enters into a protuberance formed by 
a covering on the exertior of the housing so that it may be felt by a 
person to show the pressure at which the indicator is connected. 
The feelers provided in the pressure stages permit a completely reliable 
feeling by the user with gloves, even in the dark. The user determines 
which feelers have already entered the housing, and knows then the 
pressure gas supply. Even great contaminations do not interfere with this 
determination. 
Accordingly, it is an object of the invention to provide a pressure 
indicator which may be used to indicate pressure and which may be sensed 
in darkened conditions. 
A further object of the invention is to provide a pressure indicator which 
includes a plurality of feeler members which are moved out of a pressure 
housing which is connectable to the pressure source and which are set to 
move out of the housing at distinct pressures and which may be felt as an 
indication of the pressure which is connected to the indicator. 
A further object of the invention is to provide a pressure indicator which 
is simple in design, rugged in construction and economical to manufacture. 
For an understanding of the principles of the invention, reference is made 
to the following description of a typical embodiment thereof as 
illustrated in the accompanying drawings.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings, in particular, the invention embodied therein 
comprises a pressure indicator having a housing 1 with a pressure chamber 
3 therein which is connectable to a pressure course through a connection 
tube. A plurality of individual indicator chambers 4 are provided in the 
housing which communicate with the pressure chamber 3 and, in accordance 
with the invention, an indicator piston member 7 is slidable in each of 
the individual chambers. The indicator position member 7 has a feeler 
portion 9 which, in an indicating position, extends out of the housing 1 
and in a non-indicating position is located inside the housing. The 
indicator piston member 7 includes an end portion 11 which is exposed to 
the pressure of the pressure chamber 3. Biasing means, such as spring 6, 
in combination with a selected piston size of the piston member 7, bias 
each respective indicator piston member 7 at a distinct pressure in a 
direction to urge the member toward a non-indicating position at which the 
feeler portion 9 extends entirely within the housing as indicated in the 
upper portion of FIG. 1. Each of the indicator piston member 7 is movable 
against the biasing means to an indicating position, such as shown at the 
lower portion of FIG. 1 in which the feeler portion 9 extends out of the 
housing in a position at which it may be felt by a person's finger. This 
shows that the chamber 3 has arrived at the pressure corresponding to the 
biasing means associated with the particular feeler and a selected 
pressure has been achieved, such as indicated to the left-hand side of 
FIG. 2. 
Housing 1 contains a pressure chamber 3 to be connected over a connection 2 
with the pressure tank. Connected to pressure chamber 3 are piston 
pressure meters 4 for the pressure stages to be determined. The meters 4 
include a cylinder 5 in which a pressure piston 7 is sealingly guided and 
is movable against the biasing force of a calibrated compression spring 6. 
The pistons 7 are sealed with the cylinder by sealing rings 8. Each piston 
has a feeler 9 which is completely retracted into housing 1 by the 
compression spring 6 in a relaxed condition, but which protrude out of the 
housing when the compression spring 6 is compressed. The path of pressure 
piston 7 is limited by an extension (10) bearing against housing ledge 1a 
in the indicating position and by a stop 11 in a non-indicating position. 
A hood 12 of elastic material protects piston pressure meters 4 against 
fouling and and has covering projections or knobs 13 which receivers 
feelers 9. 
A throttle 14 in connection 2 limits the amount of pressure gas when 
housing 1 is not tight. The pressure stages, hence the pressure values to 
be monitored, are determined either by different size pistons 7 or 
different force compression springs 6 exerting the counterpressure. The 
spring forces are adapted to the respective lower and upper limit value of 
the pressure stage to be monitored. At a pressure of 250 bar, e.g. feeler 
9 of pressure piston 7 for pressure stage 250 to 300 bar is thus 
completely retracted into housing 1, with compression spring 6 relaxed, 
until it is stopped by stop 11. At the same time, pressure piston 7 for 
pressure stage 200 to 250 bar, with compression spring 6 compressed, is 
limited in its path by extension 10, is still completely forced into 
cylinder 5 and feeler 9 has completely emerged from housing 1 and the 
feeler 9 is contained in knob 13. By feeling and pressing knobs 13, it is 
readily possible to determine the presence of feelers 9 by the carrier of 
the respirator. 
While a specific embodiment of the invention has been shown and described 
in detail to illustrate the application of the principles of the 
invention, it will be understood that the invention may be embodied 
otherwise without departing from such principles.