Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FLUID TRANSFER SYSTEMS AND VALVES THEREFOR
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Field of the Invention
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This invention is directed to fluid transfer systems
such as are used in combination with a liquid storage vessel
to draw liquid therein and to dischar~e liquid therefrom, and to
valves for use in such sys~ems in combination with an air pump
and a prime mover for the pump.
Review of the Prior Art
The handling of contaminated and/or corrosive liquids,
e.g. containing abrasives or sludges therein, presents consider- -
able problems, particularly in view of the hazard to any pumping
mechanism used for the transfer of the liquids into and out of
a vessel used for its storage and/or transfer. In order to avoid
the need for passage of such liquids through the pump it is usual
to employ a reversible air pump arranged to control the pressu~e
condition within the container into which the contaminated liqu,id
is drawn under suction, or from which it is expelled by contai~er
- pressurization.
Such pumps are of high capacity and high pressure and
consequently are relatively expensive; owing to the nature of
the liquids or semi-liquids requiring to be pumped, and the
quality of the operators frequently used for sUch work, it i8
extremely difficult to substantially entirely preclude the carry-
over of small quantities of liquids to the pump of the system,
and even small quantities ~ill be sufficient to damage the expen-
sive pump.
,1 , The present invention'provides a fluid transfer system
~i and a valve therefor wherein the passage of liquid or air-borne
contaminants to the pump i8 substantially precluded.
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Definition of the Invention
In accordance with this invention there is provided
a fluid transfer system for transferring liquid from a source
thereof to the interior of a liquid-receiving tank by the
withdrawal of air from the said interior and for transferring
liquid from the tank interior to the exterior thereof by the
supply of air to the said interior comprising: an air transfer
pump unit for the said withdrawal of and supply of air; and air
transfer passage connecting the interior of the tank to the air
transfer pump unit; a first float responsive means positioned
at least partly in the tank interior and actuated in response
to the presence of a predetermined level of liquid in the tank
interior to close the air transfer passage and thereby preclude
the passage of liquid into the air transfer passage; and a
secondary float valve means connected in the air transfer passage
between the said air pump unit and the said first float responsive
means and actuated in response to receipt of liquid from the air
transfer passage between the first float responseive means and
; itself to close the air transfer passage and thereby further
preclude the possibility of passage of liquid from the tank
interior to the air transfer pump unit.
; The float responsive means may include a float posi-
tioned to be engaged by liquid in the tank, and switch means
are connected therewith for actuation on floatation of the
float in the liquid to terminate withdrawal of air from the
said tank interior. The system may be employed in combination
`` with an engine connected in driving relation with the air transfer
, pump unit for operation thereof, wherein said switch means
comprises a disabling switch operable upon the presence of the
said predetermined level of liquid in the tank interior to
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stop operation of the engine and thereby prevent ~peration of
the pump unit. Preferably the system is used in combination
with a truck wherein the said tank is a liquid transfer tank
- mounted on the truc~ and having said engine as the propulsive
means therefore, said float responsive means being mounted at
the top of the tank.
A system and valve means in accordance with the
present invention is of particular utility for a truck-mounted
tank and pump system, in that a suction hose may be connected
from the truck tank to a source of contaminated liquid to be
pumped into the tank. The truck engine power take-off powers
the pump which is arranged by an associated controllable valve
system to evacuate the interior of the tank connected via the
above-mentioned primary and a secondary float valves. When the
tank is sufficiently filled with the liquid to trip the primary
float valve the truck engine is shut-down, in the manner dis-
closed, by disconnecting the ignition. Thus the truck may be
left unattended during the tank filling operation without posing
any danger of damage to the comparatively expensive air pump.
` 20 Description of the Drawings
A preferred embodiment will now be described, by way
of example, with reference to the accompanying diagrammatic
drawings, wherein:
FIGURE 1 iS a side view of a tank truck incorporating
a fluid transfer system in accordance with the present invention,
FIGURE 2 is a diametrical sectional elevation of a
primary float-responsive valve means in accordance with this
invention, and
FIGURE 3 is a front elevation of a secondary float-
responsivs valvs with thg front cover rsmovsd.
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Description of the Preferxed Embodiment
Referring to Figure 1 a truck 10 has a bulk liquid
tank 12 mounted thereon. A power take-off shaft 14 from the
truck engine (not shown) is connected in driving relation
with an air compressing or evacuating pump unit 16 of known type
operable in known manner, e.g. by change-over valves in its piping,
in air compressing or air evacuating mode with regard to an
external connection hose 18, through which the interior of the
tank may be respectively selectively pressurized or evacuated under
the control of an operator. The structure of such pump units is
sufficiently well known to those skilled in the art as not to
require any more detailed explanation or illustration. A primary
float responsive valve means 20 in accordance with the invention
is mounted at the top of the tank 12 in the wall 22 thereof,
and is connected by a hose 24 with a secondary float valve 26,
to which the hose 18 also connects.
'~ Referring now especially to Figure 2, the interior of
the valve 20 is divided by a barrier 28 into a lower or secondary
chamber 30 bounded by perforated walls 32, which constitute
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a particle filter. This chamber 30 and the tank interior con-
stitute a so-called second zone of the system. A gas transfer
passage formed by a tube 36 mounted in the barrier 28 and having
a chamfered seat portion 38 cDnnects the secondary chamber 30
to a primary chamber 40 which is partially bounded by an air
filter cartridge 42 of cylindrical form, a ring 44 serving to
locate the cartridge radially. This chamber 40 constitutes
~- part of the so-called first zone of the system. A cylindrical
wall 50 of the valve is welded into an aperture in the tank
wall 22 and has clamp brackets 52 fixed thereto for the attach-
ment of bolts 54 which serve to secure a cover 56 on the valve.
A resilient gasket 58 is interposed between the cover 56 and
the upper edge of the filter cartridge 42, the cover completing
the chamber 40.
A float 60 is mounted by means of coaxially aligned,
diametrically-opposed stems 62 and 64 for vertical movement -
in upper and lower guides 66, The upper stem 62 engages the
operating member 68 of a switch 70 mounted on the inside of
the cover 56, from which a connection 72 extends to the igni-
tion system 74 of the vehicle (illustrated diagrammatically in
Figure 1).
, The secondary float valve26 includes an internal
' barrier 28, a passage tube 36 and a valvefloat 60, but does
not include a switch 70 and does not necessarily include
particle filter 32 and/or air filter 42. A sight glass 76 pér-
mits visual detection of the presence of liquid within the
valve 26, and a removeable drain plug 78 facilitates drainage
of liquid from out of the valve.
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In operation, the inlet of a fillex hose 80 is sub-
merged beneath the surface of a liquid to be transferred to
` the interior of the tank 12, and the valve 82 is opened; upon
engagement of the engine power take off 14 to drive the pum~
16 in an air evacuating mode air pressure within the tank 12
is reduced and liquid flows through the hose 80 to fill the
` tank. When the liquid level raises the float 60 sufficiently
to actuate the cut-off switch 7b the circuit represented by
connection 72 is opened and the ignition of the truck engine
is switched off. Closure of the valve 82 completes the opera-
tion. In order to empty the tank 12 when desired the output
of pump 16 is reversed to positively pressurize the tank 12
and discharge the liquid contents of the tank when the valve
92 is opened.
`~ 15 A further function provided by the primary valve 20
is the cooperation of the spherical float member 60 with the
. chamfered seat 38 to provide a positive barrier to the flow of
; liquid from the second zone into the first zone, and also to
preclude upward splashing of the liquid into contaminating
relation with the air filter cartridge 42 during movement of
the truck. In the event that some liquid should nevertheless
escape past the valve 20 it i~ further prevented by the secon-
dary valve 26 from reaching the pump.
It will be understood that the portion of the vehicle
engine ignition circuit controlled by the switch 70 will
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tion of the truck engine in a truck driving mode may be
effected after completion of a tank filling operation, despite
the above-mentioned dlsabling of the engine ignition circuit by
~, 30 the actuation of the switch 68. The specific electrical
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circuit required for such operation will be apparent to those
skilled in the art and further description and illustration
thereof is not believed necessary. The present invention
thus provides a simple, low cost and robust control system
and valve therefor which may be readily operated, serviced
and maintained.
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