U.S. patent number 3,830,256 [Application Number 05/306,184] was granted by the patent office on 1974-08-20 for fluid mixing.
This patent grant is currently assigned to The British Oxygen Company Limited. Invention is credited to Lawrence Alfred Cox.
United States Patent |
3,830,256 |
Cox |
August 20, 1974 |
FLUID MIXING
Abstract
An apparatus for mixing two or more fluids including a series of
passages into each of which each fluid to be mixed can be passed at
a chosen rate so that each passage can supply a chosen mixture, and
valve means operable to select which of the passages is used to
supply the mixture.
Inventors: |
Cox; Lawrence Alfred (London,
EN) |
Assignee: |
The British Oxygen Company
Limited (London, EN)
|
Family
ID: |
27431583 |
Appl.
No.: |
05/306,184 |
Filed: |
November 14, 1972 |
Current U.S.
Class: |
137/599.04;
137/606 |
Current CPC
Class: |
A61M
16/12 (20130101); B01F 3/026 (20130101); F16K
19/00 (20130101); Y10T 137/8729 (20150401); Y10T
137/87684 (20150401) |
Current International
Class: |
A61M
16/10 (20060101); A61M 16/12 (20060101); B01F
3/00 (20060101); B01F 3/02 (20060101); F16k
019/00 () |
Field of
Search: |
;137/599,607,606 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Nilson; Robert G.
Attorney, Agent or Firm: Dennison, Dennison, Townshend &
Meserole
Claims
I claim:
1. A gas mixing apparatus including:
a. at least two gas inlet passages for the gases to be mixed;
b. a gas pressure regulator in each inlet passage;
c. a plurality of gas mixture distribution passages;
d. a plurality of flow rate control passages, each flow rate
control passage being connected between an inlet passage and a gas
mixture distribution passage, and each gas mixture distribution
passage being connected by flow rate control passages to both of
said at least two gas inlet passages;
e. a calibrated flow impedance in each flow rate control passage,
for passing gas at a chosen flow rate to the gas mixture
distribution passage downstream thereof, whereby gas mixtures of
different chosen compositions are able to be formed in the gas
mixture distribution passages;
f. a common outlet to which all the gas mixture distribution
passages are connected, and from which a gas mixture can be
supplied; and
g. valve means operable to close selected gas mixture distribution
passages, whereby the composition of the gas mixture supplied from
the common outlet depends on which of the gas distribution passages
is left open to the passage of gas therethrough.
2. Apparatus as claimed in claim 1, in which each flow impedance is
in the form of an orifice.
3. Apparatus as claimed in claim 1, in which each flow impedance
has associated with it a non-return valve for each of the fluids
passed to it.
4. Apparatus as claimed in claim 1, in which the cross-sectional
area of at least one of the orifices is adjustable.
5. Apparatus as claimed in claim 1 including a pressure regulator
located in the outlet line.
6. Apparatus as claimed in claim 5, including an outlet switch in
the outlet line downstream of the pressure regulator.
7. Apparatus as claimed in claim 5, including an orifice of reduced
cross-sectional area downstream of the pressure regulator in the
outlet line.
8. Apparatus as claimed in claim 5, including a demand valve
downstream of the pressure regulator in the outlet line.
Description
The present invention relates to fluid mixing, and particularly to
apparatus for mixing gases for medical purposes.
In order to provide a comprehensive gas supply service for
respiratory purposes it is necessary to be able to provide a
mixture of two different gases in which the constituent gases may
be present in any one of several different ratios. It has been
customary to provide such a mixture by using a gas mixing apparatus
which can provide continuous variation in the composition ratio of
the mixture over a considerable range. This apparatus is relatively
complex, and hence, expensive.
It is an aim of the invention to provide a fluid mixing apparatus
which is relatively simple in construction. Accordingly the present
invention provides an apparatus for mixing two or more different
fluids which is as claimed in the appended claims.
The present invention will now be described by way of example with
reference to the accompanying drawing which is a schematic flow
diagram of apparatus for producing an air-oxygen mixture for a lung
ventilator.
Referring to the drawing, oxygen and air are passed along their
respective inlet lines 1 and 3 to regulators 2 and 4 respectively
at a pressure of 0.4N/mm.sup.2. These regulators are designed and
fluid loaded to ensure that the oxygen and air leave their
respective regulators at a constant pressure of 0.28N/mm.sup.2.
The oxygen passes from regulator 2 along the inlet line and is
directed into four separate flow lines, 6, 8, 10 and 12. The air
leaves the regulator 4 and is directed along the inlet line 3 into
four flow lines 14, 16, 18 and 20. All the flow lines are connected
to an outlet line 21 at a common outlet point 22.
Before reaching the outlet point 22, the oxygen lines 6, 8, and 10
are joined to the air lines 16, 18 and 20 respectively. Flow
impedances in the form of calibrated orifices 26 are located in the
flow lines 6, 8, 10, 16, 18 and 20. These orifices (or throttles)
are dimensioned so that their flow impedances have such relative
magnitudes as to be able to give from the pairs of flow lines 6 and
16, 8 and 18 and 10 and 20, mixtures containing 25 percent, 35
percent and 60 percent by volume of oxygen, respectively. It will
be appreciated that there will be 100 percent and approximately 20
percent of oxygen in the flow lines 12 and 14 respectively because
the line 12 is an oxygen line and the line 14 is an air line.
Push button on/off switches 28, 30, 32, 34 and 36 are located in
the flow lines as shown in the drawing. The switches 30, 32 and 34
control the mixed pairs of flow lines 6 and 16, 8 and 18, and 10
and 20 respectively.
Non-return valves 38 are located in all the flow lines downstream
of the on/off switches to prevent reversed gas flow.
The outlet line 21 leads from the outlet point 22 to the lung
ventilator (not shown). An outlet regulator 40 is located in the
outlet line 21. An off/on switch 42 and a calibrated orifice 44 are
located in the outlet line 21 downstream of the outlet regulator
40. The bore of the orifice 44 defines the gas flow rate to the
ventilator.
The operation of the apparatus is as follows:
The oxygen and air supplies are turned on, and the switch 42 is
switched off. The appropriate one of the on/off switches 28 to 36
is pressed to select a gas of the required composition.
At the start of each inspiratory phase of the ventilator, the
switch 42 is switched on by the flow mechanism of the ventilator.
This allows the selected gas to pass through the orifice 44 to the
ventilator.
At the end of each inspiratory phase, the switch 42 is switched off
by the ventilator flow mechanism thereby shutting off the
inspiratory gas supply to the ventilator until the start of the
next inspiratory phase.
The composition of the gas being fed to the ventilator can be
changed simply by pressing the appropriate one of the switches 28
to 36 so as to open the required flow line or pair of flow lines.
The action of pressing one of these on/off switches automatically
releases a previously pressed switch so as to close the previously
opened flow line or pair of flow lines. This prevents two flow
lines or pairs of flow lines from being open at the same time so as
to pass a gas of incorrect composition.
In this particular apparatus, the gas is fed from the outlet
regulator 40 at a pressure of 0.2N/mm.sup.2. Although non-return
valves 38 are included in this described apparatus, it is to be
understood that apparatus according to the invention may operate
efficiently without non-return valves.
The orifices 26 and 44 may be replaced by orifices of adjustable
cross-sectional area. The calibrated orifice 44 may be replaced by
either a demand valve, or a fine adjustment valve which allows a
preset adjustable gas flow. The fine adjustment valve may be used
either with or without a flowmeter.
In a modified apparatus provision may be made for two or more of
the on/off switches to remain on at the same time. This increases
the number of gas composition ratios which can be selected by an
operator.
* * * * *