METHOD AND APPARATUS FOR CLEANING THE INTERIOR SURFACES OF BUILDINGS

APPAREIL SERVANT AU NETTOYAGE DES SURFACES INTERIEURES DES BATIMENTS ET METHODE CONNEXE

English Abstract

ABSTRACT OF THE DISCLOSURE
A method and apparatus for cleaning the interior surfaces of
buildings, especially the ceilings of office buildings, involves
producing a fine mist of cleaning liquid which is sprayed onto
said surfaces. This fine mist is produced by pumping a cleaning
liquid from a container by means of a pump which leads to a
delivery tube and which produces a pressure of at least 300 psi,
the liquid being atomized by a nozzle having a breadth less than
0.020 inches. The amount of liquid passing through the pump is
more than 5 times the amount passing through the nozzle, and the
remainder of this liquid is returned by a bypass line to the
container.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A process for cleaning the interior surfaces of
buildings including office ceilings, wherein a fine mist
of cleaning liquid droplets is sprayed onto said
surfaces, said fine mist being produced by pumping said
liquid form, a container by means of a pump which leads to
a delivery tube and which produces a pressure of at least
300 psi, and atomizing said liquid by means of a spray
gun having a nozzle with an oval-shaped orifice having a
breadth less than 0.020 inches and which produces a fan-
type spray, said fan-type spray being capable of being
directed by the spray gun upwardly onto ceiling surfaces,
the relationship of pressure to nozzle size being such
that the amount of liquid which passes through the nozzle
is less than 0.20 gall/minute, wherein the amount of
liquid passing through the pump is more than 5 times the
amount passing through the nozzle with the remainder of
the liquid being continuously returned via a bypass line
to said container, the amount of liquid being sprayed and
the fineness of the droplets being produced being such
that very little dripping occurs.
2. A process according to claim 1, wherein said
pressure is at least 750 psi.
3. A process according to claim 1 or claim 2,
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wherein the quantity of liquid being pumped is more than
10 times the amount which passes through said nozzle, the
amount passing through the nozzle being less than 0.10
gall/minute.
4. Apparatus for cleaning the interior surfaces of
buildings, including ceilings, comprising:-
a high pressure pump capable of pumping liquid
from a container at atmospheric pressure to an
outlet at a pressure of at least 300 psi, and
means for driving said pump;
a spray gun suitable for manual handling and
upwardly directed spraying and having a spray
nozzle with a breadth of less than 0.02 inches;
a delivery tube connecting said pump outlet to
said spray gun to allow liquid pumped from the
container to pass through the nozzle;
a bypass tube allowing liquid to pass from the
pump outlet back to the container;
a valve controlling a flow of liquid from the
pump outlet to the bypass tube; and
said valve and bypass tube being arranged, in
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relation to the capacity of the pump and the
orifice size, so that at least 80% of the liquid
pumped by the pump is returned to the container
via the bypass tube.
5. Apparatus according to claim 4, wherein said pump
is capable of producing an outlet pressure of at least
750 p.s.i.
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Description

~3~6665
SPECIFICATION
The present invention provides a method and apparatus for
cleaning the interior surfaces of buildings, and especially
ceilings of office buildings.
One known method for cleaning the ceiling of a building is
to spray a cleanin~ solution, usually including detergent and
water, onto the ceiling by means of a pump and spray gun.
Usually, the pressure used is around 40 psi to 60 psi, which
produces relatively large droplets on the ceiling which gives
10 rise to problems of dripping. The relatively small amounts of
liquid which need to be applied to a ceiling, being of the order
of 1 gallon per hour, have dictated the use of rather small pumps
of the kind which do not produce high pressures.
I have discovered that much more effective cleaning of
ceilings and such interior surfaces can be achieved with very
little dripping, by using a fine mist of small droplets. Such
droplets can be produced by using high pressures, for example at
least 300 psi and preferably over 750 psi, in association with
20 nozzles having a small orifice of less than 0.02 inches in
breadth. The use of high pressures requires pumps which pump
much more than 1 gallon per hour, but in accordance with a
further feature of the invention a large part of the liquid which
is pumped passes through a bypass valve and a bypass line back to
~5 the liquid container. Generally, the amount of liquid which is
pumped is more than 5 times the amount passing through the spray
gun nozzle, the remainder being returned to the container via the
bypass line.

13~65
Further in accordance with the invention, apparatus for
cleaning the interior surfaces of buildings, comprises:-
a high pressure pump capable of pumping liquid from a
container at atmospheric pressure to an outlet at a
pressure of at least 300 psi, with means for driving
said pump;
a spray gun suitable for manual handling and having a
spray nozzle orifice with a breadth of less than 0.02
inches;
a delivery tube connecting said pump outlet -to said
spray gun to allow liquid pumped from the container to
pass through the nozzle;
a bypass tube allowing liquid to pass from said pump
outlet back to said container; and
a valve controlling flow of liquid from said pump
outlet to said bypass tube;
said valve and bypass tube being arranged, according to
the capacity of the pump and the orifice size, so that
?5 at least 80~ of the liquid pumped by the pump is
returned to the container via the bypass line.
The invention will now be described with reference to the
30 accompanying drawing, which shows diagramatically a preferred
apparatus in accordance with the present invention.
.
The apparatus comprises, essentially, a container 1 for the
cleaning liquid, a liquid pumping unit 2, and a spray gun 3.
: -2-

~3~66~
Container 1 has a capacity of about 1 gallon of cleaning
liquid and provides for about 1 hour of operation. Cleaning
liquids used are various formulations of water with detergents,
caustic soda, and/or bleaching agents. A preferred solution
which gives good results is a mixture of 1 part detergent
liquid and one part bleach liquid to 24 parts water. The
bleach liquid is a 12% solution of sodium hypochlorite in water
(e.g. 12gm/lOOcc). The preferred detergent liquid is a
solution in water containing less than 1% each of nonionic
detergent and a phosphate, and less than 2~ of 2-butoxy
ethanol.
A suction tube 10 leads from the container 1 to pump P of
the pumping unit 2, this being belt driven by electric motor M.
Pump P is a high pressure reciprocating pump of the general
type shown in U.S. Patents Nos. 3,80~,508 which issued May 7,
1974 to ~aruyama Mfg. Co. Ltd. and 3,930,756 which issued
January 6, 1976 to Cat Pumps Corporation of Mlnneapolis,
Minnesota, U.S.A. The preferred model is one designated Number
282,110 produced by Ca-t Pumps Corporation, and having a
capacity of about 1 gallon per minute.
The outlet 11 from pump P goes to a pressure regulating
valve 12, preferably a model 6548LAY Hoche valve made by Hoche
Controls of New Jersey, U.S.A. This arranged to allow flow of
liquid into a delivery tube 14 leading to the spray gun 3, but
when the pressure at the spray gun is higher than a certain
setting, say 500 psi and in any event higher than 300 psi, a
bypass port in the valve opens and allows liquid to flow
through the bypass line 16 back to the container 1. The valve
thus serves to maintain a pressure of about 500 psi in the
delivery tube 14, since the capacity of the pump P is much
higher than the throughput of the spray gun. A pressure gauge
may be provided to check this pressure. The spray gun 3 has a
trigger 17 which controls flow of the liquid to a nozzle 18.
--3--

13~
This nozzle has a small oval orifice which is interchangeable
according to the particular requirements of the cleaning
procedure. The orifices controls flow of the liquid to a
nozzle 18; as shown in the drawing the spray gun 3 can be used
to direct the spray upwardly onto a ceiling. Nozzle 18 has a
small oval orifice which is interchangeable according to the
particular requirements of the cleaning procedure. The
orifices used produce a fan-type spray of 50 or 65 included
angle, and the orifice.s are sized so that their breadth (i.e.
the minor cross-sectional dimension of the oval shaped opening)
is always less than 0.020 inches. For example, orifices with a
breadth of 0.011, 0.013, 0.015, and 0.018 may be used. The
largest of these orifices has a throughput of 0.18 gallons per
minute when supplied at 500 psi pressure. Since the pump is
delivering 1 gallon per minute, over 80% of the liquid which is
pumped is continuously recycled -through the valve 12 and the
bypass line 16 back to the container. In other words, the
amount of liquid being pumped is more than 5 times the amount
which passes through the spray gun nozzle. For smaller
orifices, the amount being pumped may be more than 10 times the
amount passing through the nozzle. By this means, it is
possible to use a high pressure pump even for delivering only a
small amount of liquid to the spray gun.
Pressures of over 1,000 psi and up to 3,000 psi may be
used. The fine atomization which is achleved produces good
cleaning with very little dripping. The fine droplets serve to
dissolve grease and to neutralize static electricity which
tends to hold dirt onto ceilings, the dirt drops in
substantially dry form and can be removed by vacuum cleaners.

Representative Drawing