U.S. patent application number 13/995222 was filed with the patent office on 2013-10-17 for device for washing hands.
The applicant listed for this patent is Amit Chakrabortty, Amit Sah, Rudra Saurabh Shresth. Invention is credited to Amit Chakrabortty, Amit Sah, Rudra Saurabh Shresth.
Application Number | 20130269733 13/995222 |
Document ID | / |
Family ID | 45350764 |
Filed Date | 2013-10-17 |
United States Patent
Application |
20130269733 |
Kind Code |
A1 |
Chakrabortty; Amit ; et
al. |
October 17, 2013 |
DEVICE FOR WASHING HANDS
Abstract
The present invention is in the field devices for hand washing,
in particular the washing and drying of hands in public bathrooms.
Accordingly it is an object of the present invention to provide a
device for cleaning hands, especially a device for wetting hands,
depositing a cleansing and/or disinfecting composition and rinsing
consecutively, using a low amount of water. It has been found that
an air-water jet nozzle assembly comprising two nozzles wherein a
first nozzle is in fluid communication with a feed liquid source;
and a second nozzle connected to a source of compressed air may be
used to clean hands using low amounts of water in a short time.
Inventors: |
Chakrabortty; Amit;
(Bangalore, IN) ; Sah; Amit; (Bangalore, IN)
; Shresth; Rudra Saurabh; (Bangalore, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chakrabortty; Amit
Sah; Amit
Shresth; Rudra Saurabh |
Bangalore
Bangalore
Bangalore |
|
IN
IN
IN |
|
|
Family ID: |
45350764 |
Appl. No.: |
13/995222 |
Filed: |
December 14, 2011 |
PCT Filed: |
December 14, 2011 |
PCT NO: |
PCT/EP2011/072677 |
371 Date: |
July 1, 2013 |
Current U.S.
Class: |
134/26 ;
134/99.1 |
Current CPC
Class: |
A47K 1/00 20130101; A47K
7/04 20130101; A47K 10/48 20130101; A47K 2210/00 20130101 |
Class at
Publication: |
134/26 ;
134/99.1 |
International
Class: |
A47K 1/00 20060101
A47K001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 2010 |
IN |
3520/MUM/2010 |
Feb 22, 2011 |
EP |
11155304.6 |
Claims
1. A device for washing hands comprising a chamber comprising: i)
An opening for inserting at least one hand; ii) At least one of a
air-water jet nozzle assembly, characterized by comprising two
nozzles wherein a first nozzle (PW) is in fluid communication with
a feed liquid source; and a second nozzle (PA) connected to a
source of compressed air; wherein, the first nozzle is at an angle
(.alpha.) of between 1 and 60.degree. relative to the central axis;
and the second nozzle is at an angle (.phi.) of between 1 and
45.degree. relative to the central axis (NOR); and wherein the air
nozzle does not co-axially surround the water passage; and wherein
the mouth of the second nozzle (OPA) is positioned more forward in
the direction of the flow along the direction of the central axis
than the mouth of the first nozzle (OPW), wherein the offset
distance (OS) between the mouth of the first nozzle and the second
nozzle is between 0.5 and 5 mm in said direction.
2. A device according to claim 1, wherein: a) the mouth of the
first nozzle of the device has an opening of 0.2-3.5 mm.sup.2; b)
the mouth of the first nozzle of the device is less than 1 mm away
from the wall of the second nozzle.
3. A device according to claim 1, wherein the device is connected
to a separate unit comprising a compressor and a reservoir for
holding the liquid, the compressor being the source of the
compressed air and the reservoir holding the liquid being the
liquid source.
4. A process for cleansing a hand with an air-water jet nozzle
assembly comprising two nozzles wherein a first nozzle is in fluid
communication with a feed liquid source; and a second nozzle
connected to a source of compressed characterized in that the first
nozzle is at an angle (.alpha.) of between 1 and 60.degree.
relative to the central axis; and the second nozzle is at an angle
(.phi.) of between 1 and 45.degree. relative to the central axis
(NOR); and wherein the air nozzle does not co-axially surround the
water passage; and wherein the mouth of the second nozzle (OPA) is
positioned more forward in the direction of the flow along the
direction of the central axis than the mouth of the first nozzle
(OPW), wherein the offset distance (OS) between the mouth of the
first nozzle and the second nozzle is between 0.5 and 5 mm in said
direction; and comprising the steps of: a) Spraying a fine mist of
detergent composition onto the hand; b) Rinsing the hand by
spraying a fine mist of water onto it; c) Drying the hand by
blowing air onto the hand.
5. A process according to claim 4, wherein said process is preceded
by the step of spraying a fine mist of water onto the hand for
wetting.
6. A process according to claim 4, wherein the air is heated to
30.degree.-70.degree. C.,
7. A process according to claim 4, wherein the ratio of air to
water from the nozzle assembly is between 90:10 and 99.9:0.1.
Description
FIELD OF THE INVENTION
[0001] The present invention is in the field devices for hand
washing, in particular the washing and drying of hands in public
bathrooms.
BACKGROUND OF THE INVENTION
[0002] Washing hands is commonly perceived as hygienic and proven
to be an effective way to prevent spreading of several
diseases.
[0003] Surveys show that people do not always wash their hands in
public bathrooms (also known as restrooms). Without wishing to be
bound by a theory it is commonly perceived that public bathroom
themselves are not hygienic and users prefer not to touch anything
inside a public bathroom and wish to leave them at their earliest
opportunity.
[0004] Over the years many things have been tried to make hand
washing in public bathrooms more attractive.
[0005] For decades, electric dryers haven been used for drying
hands after washing, to avoid dirty towels and paper towel
dispensers that can run out of stock.
[0006] Soap dispensers have replaced soap bars and automatic taps
have solved the problem of touching a dirty tap knob after washing
to turn the water off.
[0007] U.S. Pat. No. 3,918,987 A (Kooper, Rudolph J.) discloses a
hand and forearm cleaning device plurality of nozzles that eject
streams of fluids inwardly at predetermined rates and pressure in
order to perform washing procedure. Though the device discloses an
integrated solution for hand wash, it, however, do not address the
issue of saving water and using minimal amount for the
operation.
[0008] All of these solutions are still highly cumbersome and time
and space consuming. Furthermore, although these developments have
improved the common handwashing practice, an integrated solution
for washing, disinfecting and drying hands that consumes less water
remains to be desired.
[0009] Accordingly it is an object of the present invention to
provide a device.
[0010] It is a further object to provide a device for wetting
hands, depositing a cleansing and/or disinfecting composition and
rinsing consecutively.
[0011] It is yet another object to provide a device that also dries
the hands after washing.
[0012] It is yet another object to use low amounts of water during
washing.
[0013] Surprisingly it has been found that an air-water jet nozzle
assembly comprising two nozzles wherein a first nozzle is in fluid
communication with a feed liquid source; and a second nozzle
connected to a source of compressed air may be used to clean hands
using low amounts of water in a short time.
SUMMARY OF THE INVENTION
[0014] Accordingly, the present invention provides a device for
washing hands comprising a chamber comprising an opening for
inserting at least one hand, at least one of an air-water jet
nozzle assembly comprising two nozzles wherein a first nozzle is in
fluid communication with a feed liquid source; and a second nozzle
connected to a source of compressed air.
[0015] In another aspect the invention provides a process for
cleansing a hand with an air-water jet nozzle assembly comprising
two nozzles wherein a first nozzle is in fluid communication with a
feed liquid source; and a second nozzle connected to a source of
compressed air; and comprising the steps of: spraying a fine mist
of detergent composition onto the hand; rinsing the hand by
spraying a fine mist of water onto it; and drying the hand by
blowing air onto the hand.
[0016] These and other aspects, features and advantages will become
apparent to those of ordinary skill in the art from a reading of
the following detailed description and the appended claims. For the
avoidance of doubt, any feature of one aspect of the present
invention may be utilised in any other aspect of the invention. The
word "comprising" is intended to mean "including" but not
necessarily "consisting of" or "composed of." In other words, the
listed steps or options need not be exhaustive. It is noted that
the examples given in the description below are intended to clarify
the invention and are not intended to limit the invention to those
examples per se. Similarly, all percentages are weight/weight
percentages unless otherwise indicated. Except in the operating and
comparative examples, or where otherwise explicitly indicated, all
numbers in this description indicating amounts of material or
conditions of reaction, physical properties of materials and/or use
are to be understood as modified by the word "about". Numerical
ranges expressed in the format "from x to y" are understood to
include x and y. When for a specific feature multiple preferred
ranges are described in the format "from x to y", it is understood
that all ranges combining the different endpoints are also
contemplated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 shows a schematic drawing of the air-water jet
nozzles
[0018] FIG. 2 shows drawings of the air-water jet nozzles.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The present invention provides a device for hand washing.
The device according to the invention may further be suitable for
drying hands. The device is particularly suitable for use in public
bathrooms, such as airport bathrooms, gas station bathrooms, office
bathrooms, hospital bathrooms, etc. In home application of the
device is also envisaged.
[0020] The device according to the invention comprises a chamber
comprising an opening for inserting at least one hand, and an
air-water jet nozzle assembly comprising two nozzles wherein a
first nozzle is in fluid communication with a feed liquid source;
and a second nozzle connected to a source of compressed air.
[0021] Chamber
[0022] The chamber comprises an opening for inserting a hand for
washing with the device. The chamber may optionally comprise more
than one opening for inserting two or more hands simultaneously, or
a larger opening for the same purpose.
[0023] The opening may be at any end of the chamber. The most
suitable sides for an opening is either at the top, for vertical
insertion of the hands, or at one of the sides for horizontal
insertion, or anywhere in between. An opening for the insertion of
hands at the bottom, is not excluded from the scope of this
application, but is typically not preferred by the intended
user.
[0024] The chamber further comprises an air-water jet nozzle
assembly comprising two nozzles, one for air and one for a liquid.
Preferably the chamber may comprise more than one air-water jet
assembly, even more preferably the device contains an array of
air-water jet nozzles that simultaneously cover the whole surface
of the hand, at least one side at the time, but preferably on both
sides.
[0025] Air-Water Jet Assembly
[0026] The air-water jet assembly comprises two nozzles wherein a
first nozzle is in fluid communication with a feed liquid source;
and a second nozzle connected to a source of compressed air. The
air-water jet device is incorporated into a hand washing
device.
[0027] The liquid source may be any water source, either provided
to the air-water jet device straight from the water mains, through
a pump, through a pressured container holding the water or by any
other means, or even by gravity (i.e. by placing the water
reservoir above the height of use of the air-water jet.
[0028] The feed liquid may be any liquid. For regular skin
cleansing an aqueous composition is typically preferred. The nozzle
for the liquid is called water nozzle herein below, but it is
understood that the water nozzle may pass water or any other
liquid, including aqueous liquids and other skin treatment
composition optionally comprising benefit agents.
[0029] Similarly, the air source may be any air source, either
provided through a compressor, separate from, or built into the
hand washing device, or through a compressed air line, such as
often available in hospitals.
[0030] It is preferred that the air may be heated. It is preferred
that the air temperature is at least 30.degree. C., more preferably
at least 35.degree. C., still more preferably at least 40.degree.
C., but typically less than 70.degree. C., more preferably less
than 65.degree. C., or even less than 60.degree. C.
[0031] Both, the first nozzle, (water nozzle) and the second nozzle
(air nozzle) are positioned relative to an imaginary central axis
(NOR). The first nozzle is positioned at an angle (a) of between 1
and 60.degree., preferably between 10.degree. and 30.degree.
relative to the central axis; and the second nozzle is at an angle
(.phi.) of between 1 and 45.degree., preferably between 15.degree.
and 30.degree. relative to the central axis.
[0032] The mouth of the second nozzle is positioned more forward in
the direction of the flow along the direction of the central axis
than the mouth of the first nozzle, wherein the offset (OS)
distance between the mouth of the first nozzle and the second
nozzle is between 0.5 and 5 mm in said direction, preferably 1-3
mm.
[0033] The best results are obtained when the first nozzle has an
opening of between 0.05 and 10 mm.sup.2, preferably even at least
0.2 mm.sup.2, and not more than 7 mm.sup.2, more preferably not
more than 5 mm.sup.2 or even less than and 3 mm.sup.2. Similarly,
the opening of the second nozzle is preferably between 0.2 and 3
mm.sup.2.
[0034] For nozzles with a circular opening, the diameter of the
first nozzle is preferably between 0.25 and 3.5 mm, preferably at
least 0.5 mm, but preferably not more than 3 mm, more preferably
not more than 2.5 mm, or even less than 3 mm; while the diameter of
the second nozzle is preferably between 0.5 and 2 mm.
[0035] The scope of the present invention further includes
configurations comprising two or more water nozzles directed at a
single air nozzle. Although this adds to the complexity of the
device, which is generally not preferred, it provides the
additional benefit of point of action mixing or reacting different
or incompatible ingredients. Additionally different nozzle
geometries are contemplated, including but not limited to circular,
square, rectangular and oval openings, for either one or both
nozzles. For larger surfaces, a slit type (oval or rectangular) air
nozzle and a similarly dimensioned water nozzle, or multiple water
nozzles are preferred, more preferably the ratio between the
longest side-to-side distance and the shortest side-to-side
distance of the oval or rectangular slit, is between 2:1 and 20:1,
still more preferably between 2:1 and 10:1. Cross or star shaped
air nozzles with one or more water nozzles being positioned between
the extending parts (i.e. in the indentations) are also
contemplated in this context.
[0036] Without wishing to be bound by a theory, it is thought that
the present invention derives its performance from the positioning
of the nozzles relative to the imaginary axis and the offset of the
water nozzle (first nozzle) relative to the air nozzle (second
nozzle). Because of this positioning, the feed liquid coming from
the water nozzle forms a film around the air nozzle, and because of
this, it gives a finer spray at a lower liquid-to-air ratio (i.e.
using less liquid). The air flow from the air nozzle is thought to
create a local under-pressure that ensures that the liquid is
driven in the direction of the air nozzle along the air nozzle tip,
regardless of in which direction the nozzle is pointed.
Furthermore, the liquid flow is not affected by the air pressure
due to the separation of the air and water nozzle openings, which
is a common problem with internal mix nozzle designs.
[0037] It is preferred that the distance of the hands from the
nozzles is at least 1 cm and at most 15 cm The distance is
preferably at least 2 cm, more preferably at least 3 cm, or even at
least 4 cm. The distance is preferably not more than 12 cm, more
preferably not more than 10 cm, or even not more than 8 cm.
[0038] It is preferred that the liquid:air ratio is between 10:90
and 1:9999, more preferably less than 5:95, still more preferably
less than 4:96, even more preferably less than 3:97, less than 2:98
or even less than 1:99, while the ratio is preferably higher than
3:9997, more preferably higher than 5:9995.
[0039] It is further preferred that there is only a short distance
between the opening of the water nozzle and the side of the air
nozzle, this distance is preferably less than 2 mm, more preferably
less than 1 mm, or even less than 0.5 mm. It is most preferred that
the opening of the water nozzle is touching the air nozzle.
[0040] It is preferred that the air nozzle does not co-axially
surround the water passage. It is also preferred that the water
nozzle does not co-axially surround the air nozzle.
[0041] The air pressure of the air source is preferably in the
range of 1 to 5 bar. The air preferably has a velocity of greater
than 80 m/s at the exit of the nozzle (the nozzle opening),
preferably greater than 120 m/s, more preferably greater than 180
m/s, and most preferably greater than 250 m/s. Although the
invention would work up to very high air velocities, it is
preferred for constructional reasons and convenience for the user,
that the air velocity is less than the speed of sound (i.e. less
than 334 m/s). Depending on the nozzle diameter, the airflow rate
is preferably between 3 and 50 l/min, preferably more than 5 l/min
or even more than 10 l/min. The air flow rate is preferably less
than 40 l/min, more preferably less than 30 l/min or even less than
25 l/min.
[0042] The liquid flow rate is typically between 2 and 100 ml/min,
preferably more than 5 ml/min or even more than 10 ml/min, while
the liquid flow rate is preferably less than 80 ml/min, more
preferably less than 50 ml/min, or even less than 40 ml/min.
[0043] Configuration
[0044] The air and/or liquid sources may be incorporated into the
device, or be fitted in a separate unit. In the latter case, a
separate unit comprising a compressor, a compressed air cartridge
or cylinder, or another source of air and/or a liquid reservoir,
optionally connected to the water mains, is provided. The unit is
connected to a hand held device by means of a tubing as air line
and/or water line.
[0045] A device that is fully integrated with the air, water and
drain plumbing is preferred for public bathrooms, while in home,
the water may be added and the drain may be emptied manually.
[0046] Nozzle Array
[0047] The device comprises at least one nozzle assembly,
comprising an air nozzle and a water nozzle.
[0048] It is preferred that the device comprises several nozzles
per hand, preferably between 1 and 25 per hand. However, for the
purpose of easy positioning and operation between 1 and 12 nozzles
per hand is found to give the best results. The nozzles may be
configured such that they spray one side of the hand only, or both
sides simultaneously. The nozzle assemblies may be configured as a
row along a linear profile, or in a curved manner, e.g. a curve
following the shape of an average hand. Typically a row of nozzles
comprises between 1 and 6 nozzle assemblies, preferably between 2
and 4 assemblies. It is also contemplated in the context of the
present invention to have more than one row of nozzle assemblies
per side of the hand.
[0049] The device of the present invention may further incorporate
other cleaning features such as bristles, scrubbers and/or
massaging elements, but from a hygiene perspective this is not
preferred.
[0050] An array with air-water jet nozzles may be mounted on a
movable rig, such that the mist spray may be moved over a larger
area instead of using more nozzles.
[0051] The device may further comprise an air compressor as air
source. The compressor may be built into chamber of the device, or
provided as a separate device that is connected to the air-water
jet by means of a tube. The compressor preferably provides at least
1 bar pressure and not more than 5 bar, preferably less than 4 bar.
Thus, very low power compressors, typically in the range of 0.05 to
1 HP, can be used to achieve the above specifications. Due to a
pressure drop in the tubing and the device, the pressure at the air
nozzle will preferably be in the range of 1 to 4 bar, more
preferably 2 to 3 bar. A device with a means to set the pressure is
also contemplated; in this case the user is, for instance, able to
choose between skin surface cleansing, or deep pore cleansing.
[0052] The liquid source may be the water mains, i.e. directly
connected to the faucet, or be in the form of a separate reservoir.
The pressure on the liquid source for use with the cleaning device
may be relatively low, preferably at least 0.05 bar, more
preferably at least 0.1 bar, but preferably not more than 3 bar,
more preferably less than 2.5 bar, still more preferably less than
2 bar.
[0053] When a separate reservoir is used as liquid source, said
reservoir may be filled with water only, a cleaning composition, a
composition comprising benefit agents.
[0054] The liquid reservoir may be placed above the level of use of
the cleaning device, such as to provide pressure, or may be
pressured separately. When pressured separately, it is especially
preferred that the reservoir is pressurised with compressed air
from the compressed air source.
[0055] Drying
[0056] The device according to the invention may further provide
the possibility to dry the hands after cleaning/treating.
[0057] This may be done by blowing only air, preferably heated air,
through the air nozzles; and stop the water flow to the water
nozzles. Alternatively a separate array of nozzles for the drying
into the same washing and drying chamber is also contemplated.
[0058] It is preferred that the air velocity is at least 10 m/s,
more preferably at least 20 m/s, still more preferably at least 30
m/s, while the air velocity is typically less than 200 m/s, more
preferably less than 150 m/s, or even less than 100 m/s.
[0059] It is preferred that the airflow is at least 10 L/s,
preferably at least 20 L/s, still more preferably at least 30 L/s,
or even at least 50 L/s, while the flow is typically less than 1000
L/s, or more preferably less than 800 L/s, still more preferably
less than 500 Us, still more preferably less than 300 L/s, or even
less than 100 L/s.
[0060] It is preferred that the temperature of the air for drying
in s at least 30.degree. C. more preferably at least 40.degree. C.,
or even more than 50.degree., but typically less than 100.degree.
C., more preferably less than 90.degree. C., still more preferably
less than 80.degree., or even less than 70.degree. C.
[0061] The air may be blown from any direction, but preferably from
the top to the bottom.
[0062] Treatment Compositions
[0063] Different kinds of treatment compositions are envisaged
within the scope of this invention.
[0064] The device according to the invention may apply to the skin
various skin care and cleansing products, including but not limited
to hand soap, hand hygiene and fragrance compositions.
[0065] It is preferred that the contact time of the product with
the skin before rinsing is at least 5 seconds, more preferably at
least 10 seconds, still more preferably at least 15 seconds, or
even at least 20 seconds.
[0066] It is preferred that the hand cleaning method according to
the invention, is capable of cleaning a hand in less than 1 minute,
preferably less than 45 seconds, or even less than 30 seconds.
[0067] The pH of the compositions is preferably neutral or mildly
acidic, more preferably between pH 2 and 9, still more preferably
at least pH 3, while more preferably less than pH 8, still more
preferably less than pH 7, or even less than pH 6.
[0068] Hand Cleansing
[0069] Hand cleansing compositions and/or sanitisation products
typically comprise surfactants, preferably anionic surfactants,
such as SLS and SLES, soluble soaps and/or non-ionic surfactants
such as alcohol ethoxylates. The concentration of the surfactants
is typically 0.2-5 g/L, preferably 1-3 g/L.
[0070] Hand Sanitisation
[0071] The device is also suitable for spraying a hand sanitisation
agent onto the hand. The sanitisation agent may be incorporated in
the cleansing composition, or may be applied instead of washing, or
after washing. Common sanitisation agents include lower alcohols
and quaternary ammonium biocides, as commonly understood by the
skilled person.
[0072] Operation
[0073] While using the device, the air-water jet may be used
continuously, or discontinuously. One way of operation that is
considered is to use the air-water jet during part of the
operation. In another embodiment, the air-water jet is used in the
first part of the cleaning process for cleaning and run with only
the liquid flow or the liquid flow and low air flow to deposit a
benefit agent to the hand, such as a hand cream or lotion.
[0074] In another embodiment the air-water jet is operated in a
pulsed mode i.e. the air flow is controlled in an on-off fashion
over time. In yet another embodiment the handheld device is fitted
with a push button to switch the air-water jet on or off while
cleansing and treatment skin (also including hair, scalp and other
keratinous surfaces are defined herein above).
[0075] In any of the discontinuous operations, it is preferred to
open and shut the air and/or liquid lines with a suitable solenoid
valve.
[0076] A valve system may also be used to open the liquid and/or
air lines when the device is in operation, while shutting the
liquid and/or air lines when the device is not in use.
[0077] The invention will now be illustrated with reference to the
following non-limiting figures and examples. The embodiments and
examples are by way of illustration only and do not limit the scope
of invention in any manner.
[0078] Accordingly, the invention provides a process for cleansing
a hand with an air-water jet nozzle assembly comprising two nozzles
wherein a first nozzle is in fluid communication with a feed liquid
source; and a second nozzle connected to a source of compressed
air; and comprising the steps of spraying a fine mist of detergent
composition onto the hand, rinsing the hand by spraying a fine mist
of water onto it, drying the hand by blowing air onto the hand.
[0079] Preferably, the process is preceded by the step of spraying
a fine mist of water onto the hand for wetting.
[0080] The most preferred temperature of the air for reasons of
skin comfort is 30.degree.-70.degree. C.
[0081] The ratio of air to water from the nozzle assembly is
typically between 90:10 and 99.9:0.1
DETAILED DESCRIPTION OF THE DRAWINGS
[0082] FIG. 1 shows a configuration wherein, the nozzle (N) has the
outlet port for liquid (OPW) positioned away from the substrate
relative to the outlet port for air (OPA), offset by a distance
(OS). The angle of incidence of the outlet port for liquid with
respect to the substrate (FS) is defined by the angle. The angle of
incidence of the outlet port for air with respect to the substrate
(FS) is defined by the angle. The dashed line NOR represents an
imaginary line which is normal to the surface of the substrate. As
is apparent, in this embodiment of the nozzle the angle is greater
than the angle. The air exits from the nozzle through outlet port
for air (OPA) and the liquid exits through the outlet port for
liquid (OPW).
[0083] FIG. 2 shows a configuration with 1 air nozzle and 1 water
nozzle.
EXAMPLES
[0084] The invention will now be demonstrated by means of the
following non-limiting examples.
Example 1
Hand Cleansing
[0085] In this example the cleansing of hands by means of the
device according to the present invention is compared to regular
hand cleansing with the same cleaning formulation.
[0086] Pre-Treatment
[0087] Prior to the test, the hands of the example and the
comparative example were decontaminated with 70% alcohol to remove
the normal flora from the hands, and were allowed to dry and were
washed with sterile distilled water to remove traces of
alcohol.
[0088] Then 100 microlitres containing of 10.sup.7 cells of non
pathogenic strain of E.coli (in the 100 microlitre) was applied
onto each hand and the volunteers were asked to spread the culture
across the palms and fingers.
[0089] One hand (example 1) was washed with 10 ml of 3 g/L of an
ethoxylated alcohol non-ionic surfactant
(C.sub.<12>EO.sub.<7>, non-ionic surfactant) for 15
seconds and the other hand (Comparative example A) was washed with
the same amount of the same surfactant using the air-water jet
device according to the invention for 15 seconds.
[0090] The air-water jet in the example comprised two nozzle
assemblies; and the air pressure for the air-water jet device was 4
bar with a liquid flow rate of 20 ml/min per nozzle assembly.
[0091] The handwashing according to the invention was carried out
in an air-tight chamber for safety purposes.
[0092] The remaining bacteria on the hands were measure in a
conventional method.
[0093] Results
[0094] The washing results in terms of residual colonies (expressed
as CFU/hand) are given in the table below.
[0095] Results
TABLE-US-00001 Example 1 Comp A Applied log CFU/hand 7 7 Residual
log CFU/hand 4.2 3.6
[0096] It becomes clear from table above that the washing process
with the air-water jet device removes about 0.6 log more of the
E.coli than the conventional washing method.
* * * * *