U.S. patent number 3,834,682 [Application Number 05/264,314] was granted by the patent office on 1974-09-10 for mixing column for medical humidifier and method of humidifying inhalable gases.
This patent grant is currently assigned to American Hospital Supply Corporation. Invention is credited to Charles J. McPhee.
United States Patent |
3,834,682 |
McPhee |
September 10, 1974 |
MIXING COLUMN FOR MEDICAL HUMIDIFIER AND METHOD OF HUMIDIFYING
INHALABLE GASES
Abstract
A multi-stage sieve plate humidifier column with a series of
plastic snap together modular mixing units that combine to form an
elongated vertical column with interconnected mixing chambers. The
column is confined inside a liquid supply bottle where it is
submerged in a liquid used to humidify an inhalable gas such as
oxygen or air. In a method of humidification, the gas is bubbled
into a lower portion of the submerged column, transferred through
the interconnecting chambers of the column where the bubbles are
broken up and mixed with liquid, and then the humidified gas
collected near a top of the column and conducted to a patient for
inhalation.
Inventors: |
McPhee; Charles J. (Sylmar,
CA) |
Assignee: |
American Hospital Supply
Corporation (Evanston, IL)
|
Family
ID: |
23005493 |
Appl.
No.: |
05/264,314 |
Filed: |
June 19, 1972 |
Current U.S.
Class: |
261/123;
128/200.13; 261/DIG.65 |
Current CPC
Class: |
B01F
13/002 (20130101); B01F 3/04007 (20130101); A61M
16/16 (20130101); A61M 2205/42 (20130101); Y10S
261/65 (20130101) |
Current International
Class: |
A61M
16/16 (20060101); A61M 16/10 (20060101); B01F
3/04 (20060101); B01F 13/00 (20060101); B01f
003/04 (); A61m 015/00 () |
Field of
Search: |
;128/186-188,194
;261/122-123,114R,DIG.65 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Miles; Tim R.
Assistant Examiner: Chiesa; Richard L.
Attorney, Agent or Firm: Barger; Larry N. Merrick; Robert
T.
Claims
I claim:
1. In an inhalation therapy system for administering a humidified
gas to a patient, an inhalation therapy humidifer comprising in
combination:
a disposable container including an outer wall for defining a
liquid-containing reservoir;
a liquid at least partially filling said container reservoir;
a tubular multi-stage mixing column for containing gas therein
fitting within container and spaced from said container wall and
having a lower portion submerged in and communicating with said
liquid, said column having means defining a plurality of
series-interconnected gas-liquid mixing chamber for progressively
humidifying the inhalation gas with the liquid as the gas ascends
through the series of interconnecting mixing chambers in said
column, said chambers being separated by a transverse partition
common to adjacent chambers having a plurality of holes connecting
adjacent chambers for breaking up inhalation gas into bubbles in
the column to increase the gas-liquid interface, the chamber having
tubular walls connected to and extending between said partitions
and defining an independent conduit opening into the lower portion
of said column, and communicating with said liquid in the column;
said humidifier having a humidified-gas outlet communicating with
the uppermost chamber for directing humidified gas to a patient
being treated.
2. The combination as set forth in claim 1 wherein the humidifier
is disposable and the mixing column is permanently connected to the
container so the mixing column cannot be used with more than one
container.
3. The combination as set forth in claim 1 wherein the mixing
chambers are vertically stacked units one upon another and form an
elongated vertical column, the lowermost portion of which column is
submerged in said liquid.
4. The combination as set forth in claim 3 wherein said conduit
includes means for connecting a pressurized dry gas supply source
with a lowermost chamber of the column.
5. The combination as set forth in claim 4 wherein the dry gas feed
tube is disposed within said vertical column.
6. An inhalation therapy humidifier comprising in combination: a
container; a liquid at least partially filling said container; a
multi-stage mixing column fitting within said container and having
a portion submerged in said liquid, said column having a plurality
of interconnected gas-liquid mixing chambers for humidifying the
gas with the liquid as the gas passes through the interconnecting
mixing chambers, each gas-liquid mixing chamber comprising a
transverse sieve plate floor and a vertical tubular wall member
connected to said sieve plate, each sieve plate and tubular wall
member forming a modular mixing unit connected in vertically
stacked relationship to similar units to form the multi-stage
mixing column of the humidifier.
7. The combination as set forth in claim 6 wherein the sieve plate
of each module has a dry gas feed tube protruding through the sieve
plate.
8. The combination as set forth in claim 6 wherein each modular
gas-liquid mixing chamber has snap fit connecting means for
attaching to a similar mixing unit.
9. The combination as set forth in claim 8 wherein the snap fit
means includes an annular rib adjacent one end of the mixing unit
and an annular groove adjacent an opposite end of the unit.
10. The combination as set forth in claim 6 wherein there is a
perforate cap member attached to the lowermost mixing chamber, said
cap member being submerged in said liquid and having openings
therethrough causing liquid to flow upwardly into said column.
11. In a humidifier column the improvement of a modular mixing unit
comprising a sieve plate; a tubular wall member connected to said
sieve plate; and a dry gas feed tube attached to said unit formed
by the tubular wall and sieve plate, said dry gas feed tube
extending from an upper end to a lower end of the mixing unit; said
unit having attachment means adjacent its upper end and adjacent
its lower end; whereby a plurality of said mixing units can be
vertically stacked and connected together at their attaching means
to provide a multi-stage mixing column for liquid and gas.
12. The combination as set forth in claim 11 wherein the tubular
wall extends below sad sieve plate.
13. The combination as set forth in claim 11 wherein the tubular
wall is cylindrical and has a central vertical longitudinal axis
and the dry gas feed tube is co-axial with and concentrically
disposed within the tubular wall, whereby modular mixing units can
be connected together without rotationally orienting one relative
to the other.
14. The combination as set forth in claim 11 wherein the sieve
plate has a series of holes therethrough each with a diameter of
0.070 to 0.120 inches.
15. The combination as set forth in claim 11 wherein the dry gas
feed tube has connecting means at one end for receiving a dry gas
tube of an adjacent modular mixing unit.
16. The combination as set forth in claim 15 wherein the dry gas
tube connecting means includes an enlarged receiving sleeve
connected with the sieve plate and this sleeve has an inwardly
tapered lip surface, an internal annular receiving surface inside
the sleeve having a diameter larger than the internal diameter of
the gas tube, and a shoulder surface laterally extending from the
annular receiving surface tothe dry gas tube's internal receiving
surface; whereby the dry gas tubes of a series of modular mixing
units fit together and provide an elongated dry gas feed line with
a generally constant internal diameter.
17. The combination as set forth in claim 11 wherein the modular
mixing unit has an upstanding annular flange above said sieve plate
for connecting to a tubular wall member of a modular mixing unit
immediately thereabove.
18. The combination as set forth in claim 17 wherein the modular
mixing unit has an upstanding annular flange has retention means
thereon for forming a snap fit with the tubular wall of the mixing
unit immediately thereabove.
19. The combination as set forth in claim 18 wherein the modular
mixing unit includes a retention means adjacent a lower portion of
its tubular wall for snap fitting with a retention means on an
upstanding annular skirt of a modular mixing unit immediately
therebelow.
20. The combination as set forth in claim 19 wherein the snap fit
means includes a mating rib and groove structure for holding
together adjacent modular mixing unit.
21. In an inhalation therapy system, a multi-stage mixing column
for a disposable medical gas humidifier including a bottle with an
outer wall forming a reservoir; a liquid at least partially filling
said bottle a tubular column vertically depending into said bottle,
spaced from said wall and having at least a lower portion thereof
submerged in and communicating with said liquid; a series of
vertically spaced, transverse perforated plates extending across
and disposed within said column and defining series-connected
chambers; a vertical dry gas tubular feed line of smaller cross
sectional passage area than the mixing column axially disposed
within said mixing column and extending through said perforated
plates, so as to feed isolated pressurized dry gas axially from a
top portion of the column through the various perforated plates to
a bottom chamber of the column; connector means for attaching said
dry gas feed line to a pressurized dry gas supply source; and
connecting means for attaching an upper portion of the mixing
column with a conduit for channeling humidified gas from a top of
the mixing column to a patient for inhalation therapy, said
perforated plates being constructed and arranged to retain liquid
thereabove and above the level of liquid in said bottle
reservoir.
22. The combination as set forth in claim 21 wherein the mixing
column includes a bottom cap having at least one opening
therethrough for passage of liquid into the column from within the
bottle and surrounding the lowermost chamber of the mixing
column.
23. The combination as set forth in claim 22 wherein the dry gas
feed line has a bottom exit port adjacent and above said bottom cap
so dry gas can be fed into an area within the bottom cap and mixed
with liquid and humidified as the gas ascends through the vertical
mixing column exteriorly of said tubular feed line.
24. The combination as set forth in claim 21 wherein the column is
spaced from the container wall along its submerged portion so the
liquid in the reservoir and column muffles the mixing of gas and
liquid in the column.
25. A modular unit for constructing a multi-stage mixing column for
liquid and gas comprising: a one piece integrally molded
thermoplastic unit including a tubular housing wall and a
transverse porous sieve plate extending across the housing wall; an
internal dry gas tube formed with the sieve plate and housing wall;
said housing wall and dry gas tube each including coupling means at
their opposite ends for joining the unit to a similar one piece
modular unit to form an elongated multi-compartment mixing
column.
26. The combination as set forth in claim 25 wherein the tubular
housing wall includes a rib and groove construction for snap
fitting two or more modular units together.
27. The combination as set forth in claim 25 wherein the tubular
housing wall has an upstanding annular flange adjacent its upper
end which flange has an annular beveled wedge surface thereon.
28. The combination as set forth in claim 25 wherein the tubular
housing wall includes a depending annular flange adjacent its lower
end with a beveled wedge surface thereon.
29. The combination as set forth in claim 25 wherein the dry gas
tube is integrally formed with the sieve plate and centrally
located thereon so as to have a common longitudinal axis with the
tubular housing wall.
30. The combination as set forth in claim 25 wherein the gas tube
includes a coupling member at an upper end, and said coupling
member includes an enlarged receiver sleeve with an inwardly
tapered upper lip surface, a transverse shoulder surface below said
lip surface and an inner wall surface between the lip surface and
shoulder surface; and said dry gas tube has a lower coupling
portion that includes a tapered end surface adapted to engage the
tapered lip surface of a dry gas tube receiving sleeve of an
adjacent similar modular unit, whereby the modular units can be
coupled to form a continuous dry gas feed line extending through a
plurality of modular mixing units.
31. A method of humidifying a medical gas for direct administration
to a patient during inhalation therapy comprising the steps of:
forcing pressurized dry medical gas confined axially and downwardly
into a lower reservoir portion of a container at least partially
filled with a humidifying liquid;
restricting the gas axially and directing it progressively upwardly
through a series of vertically stacked interconnecting chambers
with a portion of the chambers being submerged in said liquid and
portion of the chambers extending above the liquid reservoir;
progressively increasing the humidity of the gas in each successive
vertical chamber forcing the gas through a series of vertically
spaced perforated plates while contained in said chambers and
maintaining a body of liquid above the perforated plates above the
liquid level in the container reservior and progressively forming
gas bubbles at each of the perforated plates and passing it through
the plates with an increasing gas-liquid interface before it
ascends through the liquid above the plates and at a substantially
reduced noise level;
collecting the gas most highly humidified adjacent the top of the
container; and
conducting the humidified gas into a feed line adapted to be
connected to a patient for breathing.
32. The method as set forth in claim 31 including progressively
directing the gas through at least three humidifying chambers as it
proceeds from a lower portion of the container to an upper portion
of the container.
Description
BACKGROUND
In recent years inhalation therapy has been used very extensively
for treatment of emphysema and other lung and respiratory diseases,
as well as postoperative treatment and cardiac patient care. One
form of inhalation therapy involves mixing a breathable gas such as
air or oxygen with a liquid. This humidified gas is supplied to a
mask, nasal cannula, or tent where it is breathed by the patient
and absorbed by his lungs. A conventional medical humidifier system
includes a dry gas source such as a portable oxygen tank or central
oxygen supply system of a hospital, coupled with a container of
humidifying liquid. Humidification in the past has been
accomplished by atomizing the liquid into the gas or simply
bubbling the gas into the liquid from an end of a submerged tube.
Sometimes the end of the tube would have a porous gas diffusing
covering.
There have been several problems in the past with these gas-liquid
mixing humidifiers. One of the problems was the limit of absorbed
liquid carried by the gas to the patient for breathing. Often a
physician desired to have very high relative humidity of the
humidified gases inhaled. This is so that the nasal and other
membranes would not dry out. The previous humidifiers produced
humidified gas roughly in the range of 60 to 75 percent relative
humidity. A physician sometimes desires relative humidities at 80
percent or more.
In previous humidifiers there was also a problem of an unpleasant
gurgling or churning noise as the gas was bubbled into the liquid.
Over prolonged periods of time such as several days or a week that
a patient received inhalation therapy this noise sometimes became
very annoying.
SUMMARY OF THE INVENTION
I have overcome the problems of the previous medical humidifiers
for inhalation therapy by providing a multi-stage stacked sieve
plate column submerged in the liquid supply bottle. This column
includes a series of vertically spaced sieve plates that divide the
column into a series of separate chambers. In a method of
humidifying gas, the dry gas is bubbled into a lower portion of the
submerged column and mixes with liquid in each chamber as the gas
is transferred upwardly from one chamber to the next. At a top of
the submerged column the humidified gas is collected at very high
relative humidities of approximately 82 percent and then conducted
to a patient for breathing.
The submerged mixing column with its series of stacked sieve plates
repeatedly break up the gas bubbles into small bubbles to provide
large gas-liquid innerface surface area for molecular transfer
during the humidifying process. This submerged mixing column has a
unique construction in that it is formed of a series of modular
snap together thermoplastic units. The column formed in this way is
sufficiently inexpensive so as to be confined in and become a
permanent part of a liquid supply bottle. Once the contents of the
bottle have been consumed to a desired level, the entire bottle,
multi-stage mixing column, etc., are discarded. This reduces the
risk of cross-contamination between patients.
The submerged stacked humidifier column with its multiple sieve
plates also acts as a muffler to quiet the humidifying process.
Instead of a loud gurgling noise, there is an almost imperceptible
muffled sound coming from the submerged humidifier column. This
muffling effect is believed to be caused by the continual breaking
and rebreaking of the bubbles into small bubbles. Therefore no
large bubbles break out of the liquid surface to cause a noisy
churning or gurgling noise. The muffled sound is generally confined
to the column with little noise transmitted beyond the
container
THE DRAWINGS
FIG. 1 is a front elevational view partially in section showing the
submerged modular humidifier column in the liquid supply
bottle;
FIG. 2 is an enlarged sectional view of the lower three mixing
chambers of the submerged humidifier column;
FIG. 3 is a further enlarged sectional view of an individual
snap-together modular unit of the humidifier column;
FIG. 4 is an enlarged sectional view of a bottom cap that snaps to
the humidifier column;
FIG. 5 is a cross sectional view taken along line 5--5 of FIG. 3;
and
FIG. 6 is a sectional view taken along line 6--6 of FIG. 4.
DETAILED DESCRIPTION
Referring to these drawings, FIG. 1 shows the medical humidifier
system connected for administering humidified gas to a patient. The
system includes a dry gas source 1 shown schematically in the form
of a threaded nipple from an oxygen tank or oxygen wall supply line
of a hospital. Connected to this dry gas source is a dual passage
adapter 2 which is explained in more detail in my co-pending
application entitled "Port System for Medical Humidifier Container"
filed June 9, 1972, Ser. No. 264,315. This adapter 2 is permanently
connected at the time of use to a cap 3 of a liquid supply bottle 4
and this cap is in turn permanently connected to bottle 4. Thus,
adapter 2 can reliably support the bottle 4 from its cap 3 when the
bottle is suspended from dry gas source 1 as shown in FIG. 1.
Inside bottle 4 is a liquid 5 and a submerged humidifier column 6.
It is to this submerged humidifier column that the present
invention pertains. As shown in FIG. 1 the column is divided into a
series of separate compartments numbered from 7 through 12. A
compartment at a top of the humidifier column indicated at 13 is
connected to a special defoamer housing 14. This defoamer housing
14 separates out humidified gases ready for transfer to a patient
and recycles large water drops and foam to the liquid 5. This
defoamer chamber is explained in more detail in my co-pending
application entitled "Defoaming Device for Medical Humidifier"
filed June 19, 1972, Ser. No. 264,350, and now U.S. Pat. No.
3,793,810.
In operation, the FIG. 1 humidifier arrangement has a dry gas
source 1 that feeds into a dry gas tube 15. This dry gas tube 15
has an outlet 16 adjacent a bottom of the liquid filled container.
Throughout this specification the term "dry gas" is used to
distinguish oxygen air, etc., before it becomes humidified in the
mixing column. As seen in FIG. 1, this dry gas tube 15 extends
through a center axial portion of the stacked vertical column.
Liquid from the bottle enters through a series of passages in a
bottom cap portion 17 to at least partially fill the chambers 7
through 12. The number of chambers filled depends on the level of
liquid 5 in bottle 4. To insure that a sufficient portion of the
humidifier column is always submerged for proper humidification an
indented portion 55 indicates that the bottle should be replaced
when the liquid in the bottle has been consumed down to this
level.
During the humidification process, the dry gas is bubbled up
through a series of transverse sieve plates in the submerged
column, illustrated as 18, 19, 20 and 21. Each of these sieve
plates has a series of holes for breaking up the large bubbles and
muffling the mixing noise. The details of the modular sieve plate
units will be explained in more detail with reference to subsequent
drawings.
The submerged multi-chambered humidifier column explained above is
better shown in the more enlarged view of FIG. 2. Here, as briefly
explained before, the dry gas from a dry gas source 1 is fed
through a dry gas column 15. As the dry gas exits through bottom
end 16 of dry gas tube, the bubbles move upwardly through the
liquid 5 in the lowermost chamber 7. This causes the molecular
liquid to diffuse across the liquid-gas interface of the bubble
wall. The dry gas thus takes on a higher humidity as expressed in
FIG. 2 as H.sub.1. The humidified gas then proceeds upwardly in the
column through a porous sieve plate 18. Sieve plate 18 has a series
of holes that break up the large air bubbles that tend to form in
an air pocket portion 22 of chamber 7. Breaking up the bubbles in
this way creates a very large number of small bubbles that have a
greater surface area of the liquid-gas interface. This causes
improved mixing and the gas picks up a higher humidity in chamber 8
as illustrated by H.sub.2. This process is repeated as the gas
proceeds upwardly through the several stacked vertical chambers
separated by sieve plates.
An advantage of breaking up the bubbles with a series of sieve
plates rather than with a porous covering over a single outlet of a
submerged tube is that the sieve plate bubbles have a very short
half life and cause considerably less foaming in a liquid
containing a bacteriastat, such as a paraben.
At an upper area of the bottle, the humidified gas is collected and
passes through a passage 25 where it is thereafter conducted
through a tube 26 leading to a patient. The patient can thus
breathe the humidified gas with a very high relative humidity
during inhalation therapy. The previous medical humidifiers used
essentially a one stage humidifying process by using the entire
bottle contents as a mixing chamber. One process bubbled dry as
into the liquid bottle. Another process used an atomizer inside the
bottle. These previous humidifiers would gt the relative humidity
to be approximately 60 to 75 percent when it was administered to a
patient. The applicant's improved humidifier system can deliver
humidified gas at relative humidities of approximately 82 percent.
By more closely approximating the relative humidity of the
respiratory tract, the patient suffers less drying of the mucous
membrane.
The improved modular mixing column with the sieve plates shown in
FIG. 2 also provide a very important advantage over previous one
stage humidifiers. The atomizing type humidifiers create an
annoying wheezing sound. The single chamber bubble type humidifiers
cause an annoying gurgling or churning sound as the bubbles were
free to migrate unbroken from the bottom of the container to a top
liquid surface. Such unrestricted bubbles tended to cling together
and burst into large bubbles as they moved upwardly to cause a
splashing and churning at a top surface of the liquid 5 when they
broke through the liquid surface. Over long periods of time this
caused a very annoying sound to the patient and the attending
physicians and nurses.
With my improved multi-stage humidifier column, these bubbles are
rebroken into small bubbles at each transfer across the sieve
plates. After the bottle had been filled with liquid, but before
the dry gas tube has been turned on, the level in the bottle, and
the level within the column are the same. All chambers below the
liquid level are completely filled with liquid, and all chambers
above the liquid level are empty.
When the dry gas tube is supplied with pressurized dry gas as
illustrated in FIGS. 1 and 2, this increases the pressure in the
chambers and forces some of the liquid out of each chamber. This
displaced liquid takes the course of least resistance, and the
increased pressure exerted from the bottom of the column causes the
displaced liquid to move to a chamber above. Although the liquid in
the humidifier is not at a boiling temperature as in a coffee
percolator, it visually appears to act somewhat like a coffee
percolator in moving liquid up the column above the liquid level in
the bottle. Additionally, turbulence of the gas above the liquid
level in each chamber is believed to cause some entrainment of the
liquid with the gas as the gas move to a higher chamber. Also,
contributing to this upward movement of liquid is the small size of
ports in the sieves. The sieves have openings of approximately
0.093 inch diameter, and these small openings allow only slow
downward draining of the liquid subject to pressure therebeneath;
the bubbles, of course, pass through liquid accumulated in the
stacked chambers.
After pressure in the dry gas tube has been turned off,
substantially all of the liquid in the column will settle to the
approximate level as the liquid in the bottle, with all chambers
below the liquid level being substantially entirely filled with
liquid, and all chambers above the liquid level will substantially
empty. This function of the mixing column provides a mixing column
with an effective liquid length for mixing that is not limited by
its submerged length or the depth of liquid in the bottle. This
causes a very definite muffling action of the mixing within the
chambers. Also the chambers are confined in a tubular mixing column
located in the center portion of the bottle. The surrounding liquid
5 also acts as a sound deadening barrier between the mixing column
and an outer wall of the bottle 4.
Having discussed the complete multi-chambered column and how it
works above, the individual modular units of the column will now be
discussed. An individual modular unit 30 is shown in further
enlarged sectional view of FIG. 3. This unit 30 is shown in FIGS. 1
and 2 as defining the chamber 7. This modular unit 30 includes a
tubular outer wall 31 that has an upstanding flange 32 at its upper
end and a downwardly extending flange 33 at its lower end. These
respective flanges include a groove 34 on an outer surface of
flange 32 and an annular rib 35 on an inner surface of lower flange
33. These two flanges also have respective tapered lead-in surfaces
36 and 37. These flange structures are formed so that a series of
identical modular units such as 30 can be snapped together into a
vertical stacked column as shown in FIG. 2. The top flange 32 of
one modular unit mates a lower flange of a modular unit directly
above.
Each modular unit includes a sieve plate 18 which is integral with
tubular wall 31 and extends transversely across the chamber 7 of
the modular unit. The sieve plate includes a series of holes
illustrated as 39 and 40 and the arrangement of these holes which
break up the large bubbles of gas is shown in more detail in FIG.
5.
Integral with the sieve plate and concentrically disposed on a
common longitudinal axis with a cylindrical outer wall 31 is a dry
gas tube segment 41. This dry gas tube segment includes an integral
sleeve portion 42 adjacent its upper end. This sleeve portion 42
has a receiving surface 43 that extends between a tapered lead-in
surface 44 and a stop shoulder 45. A lower end of the dry gas tube
segment includes an external tapered lead-in surface 46. Thus when
a series of modular units 30 are snapped together to form the
vertical stacked humidifier column, the dry gas tube segments will
interfit to create the elongated dry gas column or tube 15 with a
generally constant internal diameter that extends from a top
portion of the medical liquid bottle to a bottom portion 16. The
dry gas tube segment 41 is on a common longitudinal axis with outer
tube wall 31. Thus, when the modular units are snapped together
there need be no angular rotational orientation of the parts to get
them to fit together.
At a bottom of the multi-chambered mixing column is a bottom cap
50. This bottom cap has an upstanding flange 51 of similar
construction to upstanding flange 32. A transverse bottom wall 52
of the bottom cap includes a series of holes 53 and 54. This bottom
cap 50 snaps into the bottom end of the lowermost modular mixing
unit to form the bottom mixing chamber. Liquid 5 from the bottle
enters the multi-stage mixing humidifier column through holes such
as 53 ad 54.
FIG. 5 shows the arrangement of the holes in sieve plate 18. Here,
a typical arrangement in the sieve plate includes two rings of
holes with each hole being from 0.070 to 0.120 inch diameter. I
have found holes in this range 0.093 inch diameter for example, are
very effective in breaking up the large air bubbles while still
providing sufficient opening for gas and liquid transfer across the
sieve plates. The hole arrangement in the bottom cap is shown in
FIG. 6. Four holes such as 53 and 54 in bottom wall 52 are
sufficient to supply the column with liquid. These holes are from
0.070 inch to 0.120 inch diameter.
The modular mixing units and bottom cap 50, I have found, snap
together very effectively and form a sturdy vertical column when
injection molded of a thermoplastic material such as polypropylene.
The injection molded modular unit of the humidifier column permit
it to be made sufficiently inexpensive so it can be discarded after
a single use.
In the above description of my invention, I have used specific
embodiments to describe my invention. However, it is understood by
those skilled in the art that modifications can be made to these
embodiments without department from the spirit and scope of the
invention.
* * * * *