NZ626154B - A valve - Google Patents
A valveInfo
- Publication number
- NZ626154B NZ626154B NZ626154A NZ62615414A NZ626154B NZ 626154 B NZ626154 B NZ 626154B NZ 626154 A NZ626154 A NZ 626154A NZ 62615414 A NZ62615414 A NZ 62615414A NZ 626154 B NZ626154 B NZ 626154B
- Authority
- NZ
- New Zealand
- Prior art keywords
- valve
- flow path
- pool
- ground water
- water
- Prior art date
Links
- 239000003673 groundwater Substances 0.000 claims abstract description 61
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 55
- 238000007789 sealing Methods 0.000 claims abstract description 14
- 238000001914 filtration Methods 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims description 2
- 230000035945 sensitivity Effects 0.000 abstract description 6
- 230000002706 hydrostatic Effects 0.000 abstract description 4
- 210000001699 lower leg Anatomy 0.000 description 26
- 239000011152 fibreglass Substances 0.000 description 6
- 230000000875 corresponding Effects 0.000 description 5
- 239000004519 grease Substances 0.000 description 4
- 241001415961 Gaviidae Species 0.000 description 3
- 230000000295 complement Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 2
- 238000010079 rubber tapping Methods 0.000 description 2
- 229920002943 EPDM rubber Polymers 0.000 description 1
- 240000008528 Hevea brasiliensis Species 0.000 description 1
- 241000269346 Siren Species 0.000 description 1
- 230000003213 activating Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000001066 destructive Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229920001194 natural rubber Polymers 0.000 description 1
- 230000000630 rising Effects 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
- E04H4/00—Swimming or splash baths or pools
- E04H4/14—Parts, details or accessories not otherwise provided for
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K15/00—Check valves
- F16K15/02—Check valves with guided rigid valve members
- F16K15/021—Check valves with guided rigid valve members the valve member being a movable body around which the medium flows when the valve is open
- F16K15/023—Check valves with guided rigid valve members the valve member being a movable body around which the medium flows when the valve is open the valve member consisting only of a predominantly disc-shaped flat element
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
- F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/7722—Line condition change responsive valves
- Y10T137/7837—Direct response valves [i.e., check valve type]
Abstract
hydrostatic relief valve (10) for relieving ground water pressure on an in-ground swimming pool is disclosed. The valve includes a body (30) defining a flow path, an element (20) mounted to be moved in a direction from a position which blocks the flow path to retain the pool water to a position in which the flow path is open to allow ground water into the swimming pool, and a sealing arrangement defining an effective area over which ground water acts to drive the element in one direction and an effective area over which the pool water acts to drive the element in the opposite direction. The ratio between the effective area over which ground water acts and the effective area over which the pool water acts has a value of at least 0.9. This ratio is advantageous in providing a valve with high sensitivity to a pressure differential between the ground water and the pool water. which the flow path is open to allow ground water into the swimming pool, and a sealing arrangement defining an effective area over which ground water acts to drive the element in one direction and an effective area over which the pool water acts to drive the element in the opposite direction. The ratio between the effective area over which ground water acts and the effective area over which the pool water acts has a value of at least 0.9. This ratio is advantageous in providing a valve with high sensitivity to a pressure differential between the ground water and the pool water.
Description
A VALVE
FIELD
This invention relates to valves for relieving ground water pressure on swimming
pools.
“Swimming pool” and similar terms as used herein take in spa baths and like
structures for containing water in which a person may bathe.
BACKGROUND
A typical swimming pool is an upwardly-open cup-like structure for containing pool
water. The pressure of the contained water tends to downwardly and outwardly drive
the pool. On the other hand, in the case of in-ground pools, ground water pressure
acts on the pool tending to drive it inwardly and upwardly.
Rising ground water is problematic for in-ground pools. When the ground water
pressure exceeds the pool water pressure, the pool can bulge and/or crack and/or
float out of the ground in the manner of a boat. Bulging and/or cracking are the more
common failure modes in fibreglass pools whereas floating is the more common
failure mode in concrete pools.
Swimming pools now incorporate pressure relief valves with the intent of addressing
these problems. These valves are also known as hydrostatic relief valves.
Certain fibreglass pools incorporate a hydrostatic relief valve incorporating a vertically
oriented cylindrical tubular body having a diameter of about 50mm. The body includes
a lower externally-threaded portion by which the body is threadingly engaged with the
pool floor.
The cylindrical body is capped by a concentrically-mounted horizontal disc, mounted
to move vertically. The disc is constrained by a spring mounting which downwardly
drives the disc to compress an O-ring seal between the disc and the cylindrical body.
Thus a sealing arrangement is formed so as to block the vertical flow path through the
centre of the cylindrical body.
This sealing arrangement serves to prevent the pool water escaping from the pool via
the valve. When the ground water pressure sufficiently exceeds the pool water
pressure, the ground water acting on the disc upwardly drives the disc against its
spring mounting. The disc is lifted about 10mm from the cylindrical body to define a
cylindrical gap through which the ground water may flow radially outwards into the
pool.
Some concrete swimming pools incorporate a hydrostatic relief valve in the form of a
“grease plate”. A grease plate is an arrangement including a circular aperture formed
in the floor of the pool. This aperture has a diameter in the vicinity of 160mm and an
upwardly-diverging conical wall. A thin-walled dinner plate-like disc fits within the
aperture and has a conical rim complementary to the conical wall of the aperture. The
top of the disc is typically filled with concrete (and tile, etc) to match the finish of the
pool floor. The complementary conical surfaces are coated in grease so that they may
co-operate to form an effective seal.
Despite the use of such valves, pools continue to fail. The present inventors have
recognised that such failures may be attributed to existing relief valves:
1. allowing ground water pressure to build to destructive levels before the valve
opens; and/or
2. providing inadequate pressure relief even when opened.
Australian Standard AS/NZS 1839:1994 suggests that pressure relief valves should
“operate to relieve external water pressure so that the maximum pressure differential
across the valve cannot exceed 30mm of water”. The inventors’ own investigations
have shown that various existing valves do not even open at this pressure differential.
The inventors have also recognised that existing valves leak and so sometimes
require a diver to enter the pool to service the valve. Indeed diving is typically
required whenever a grease plate is actuated.
Accordingly the invention aims to provide an improved valve for relieving ground
water pressure on a swimming pool, or at least to provide an alternative valve in the
marketplace.
It is not admitted that any of the information in this patent specification is common
general knowledge, or that the person skilled in the art could be reasonably expected
to ascertain or understand it, regard it as relevant or combine it in any way at the
priority date.
SUMMARY
In a first aspect, there is provided a valve, for relieving ground water pressure on a
swimming pool for containing pool water, including
a body defining a flow path; and
an element mounted to be moved in a direction
from a position in which at least one feature of the element co-operates with at
least one feature of the body to form a sealing arrangement to block the flow
path to retain the pool water;
to a position in which the flow path is open to allow ground water into the
swimming pool;
the sealing arrangement defining
an effective area over which the ground water pressure acts to drive the element
in the direction; and
an effective area over which pool water pressure acts to drive the element
opposite the direction;
the co-operable features being configured such that a ratio
of the effective area over which the ground water pressure acts
to the effective area over which pool water pressure acts
has a value of at least 0.9.
The body is preferably mountable at a point of the pool. Alternatively it may be an
integral part of the pool. Preferably it is at a low point of the pool.
Preferably the co-operable features are configured such that the ratio has a value of
at least 0.95. Most preferably the co-operable features are configured such that the
ratio has a value of more than 0.97.
Optionally the co-operable features include
a resilient portion of one of the element and the body; and
a projection of the other of the element and the body;
the resilient portion and the projection each encircle the flow path; and
in transverse cross-section the projection defines a tip for pressing into the resilient
portion.
Preferably in transverse cross-section the projection is in substance V-shaped, at
least at the tip.
The resilient portion may be a ring carried in an annular groove, and is preferably a
resilient portion of the body.
The valve may include a constraint by which the element is constrained, relative to
the body, so as to automatically move, when pressure relief is no longer required,
from its position in which the flow path is open to its position in which the flow path is
blocked.
The valve is preferably configured to when open allow ground water into the pool via
the flow path at at least a rate over at least some of a range of ground water
pressures up to and including a pressure differential above the pool water pressure;
wherein
the rate is at least 150 L/min; and
the pressure differential is at most 150mm(water).
Also disclosed is a valve, for relieving ground water pressure on a swimming pool for
containing pool water, including
a body defining a flow path;
an element mounted to be moved in a direction
from a position in which the element blocks the flow path to retain the pool
water;
to a position in which the flow path is open to allow ground water into the
swimming pool; and
a constraint by which the element is constrained, relative to the body, so as to
automatically move, when pressure relief is no longer required, from its position in
which the flow path is open to its position in which the flow path is blocked;
wherein the valve is configured to when open allow ground water into the pool via the
flow path at at least a rate over at least some of a range of ground water pressures up
to and including a pressure differential above the pool water pressure;
the rate is at least 150 L/min; and
the pressure differential is at most 150mm(water).
The rate is preferably 300 L/min, or more preferably 450 L/min.
The pressure differential is preferably 75mm, or more preferably 30mm.
The valve is preferably configured such that:
when the element is in its position in which the flow path is open, the element and the
body together define a gap through which the ground water flows into the pool;
the gap has a cross-sectional area; and
the cross-sectional area, of the gap, at its smallest point is at least 3000mm , or more
preferably at least 8000mm .
Preferably the flow path has a cross-sectional area; and
the cross-sectional area, of the flow path, at its smallest point is at least 5,000mm , or
more preferably at least about 10,000mm .
Optionally the flow path is spanned by a filter for filtering debris from the incoming
ground water. Preferably the filter spans a portion of the flow path having a cross-
sectional area of at least about 10,000mm .
The constraint may include a threaded piece rotatable relative to the element.
Also disclosed is a valve, for relieving ground water pressure on a swimming pool for
containing pool water, including
a body defining a flow path;
an element mounted to be moved in a direction
from a position in which the element blocks the flow path to retain the pool
water,
to a position in which the flow path is open to allow ground water into the
swimming pool; and
a constraint by which the element is constrained, relative to the body, so as to
automatically move, when pressure relief is no longer required, from its position in
which the flow path is open to its position in which the flow path is blocked;
wherein the constraint includes a threaded piece rotatable relative to the element.
The threaded piece is preferably threadingly engaged with the element, and most
preferably defines a stop that limits movement of the element to define the position in
which the element blocks the flow path. The threaded piece may be rotatable to drive
the element away from the position in which the element blocks the flow path.
The valve preferably includes a jacking arrangement for driving the element away
from the position in which the element blocks the flow path.
Also disclosed is a valve, for relieving ground water pressure on a swimming pool for
containing pool water, including
a body defining a flow path;
an element mounted to be moved in a direction
from a position in which the element blocks the flow path to retain the pool
water,
to a position in which the flow path is open to allow ground water into the
swimming pool; and
a jacking arrangement for driving the element away from the position in which the
element blocks the flow path.
The jacking arrangement preferably includes a threaded piece rotatable relative to the
element to so drive the element, which piece is preferably threadingly engaged with
the element and most preferably defines a stop that abuts the body when so driving
the element.
The valve may include a mechanism for informing a pool attendant that the element is
and/or has been in its position in which the flow path is open, which mechanism may
incorporate a sensor for sensing the position of the element.
Preferably the valve includes a sensor for producing an output, the output being
interpretable external to the pool and indicative of the element being, and/or having
been, in its position in which the flow path is open.
Also disclosed is a valve openable to relieve ground water pressure on a swimming
pool and including a mechanism for informing a pool attendant that the valve is and/or
has been open.
Also disclosed is a valve openable to relieve ground water pressure on a swimming
pool and including a sensor for producing an output, the output being interpretable
external to the pool and indicative of the valve being, and/or having been, open.
Another aspect of the invention provides a swimming pool including a valve.
BRIEF DESCRIPTION OF DRAWINGS
An embodiment of the apparatus will now be described by way of example only with
reference to the accompanying drawings in which:
• Figure 1 is a perspective view of an exemplary valve;
• Figure 2 is a cut away view of the valve of Figure 1;
• Figure 3 is a cut away exploded view of the valve of Figure 1;
• Figure 4 is a perspective view of a body insert of the valve of Figure 1;
• Figure 5a is a top view of the body insert of Figure 4;
• Figure 5b is a vertical cross-section view of the body insert of Figure 4;
• Figure 6 is a vertical cross-section view of the disc of the valve of Figure 1;
• Figure 7 is a vertical cross-section view of a collar of the valve of Figure 1; and
• Figure 8 is a vertical cross-section view of a shank of the valve of Figure 1.
DESCRIPTION OF EMBODIMENTS
The figures illustrate a valve 10 including a moveable element in the form of disc
member 20 capping a tubular body 30. A shank 40 co-operates with each of the disc
and the body 30 to constrain the movement of the disc 20 relative to the body 30.
As best shown in Figure 3, the body 30 includes a body insert 31 carried within a
collar 32. The insert 31 carries a seal member 33 and is capped at its lower end by a
filter member 34. A circular array of eight screws 35 fastens insert 31 to the collar 32.
The insert 31 is an integrally molded body including an upright cylindrical tubular
portion 31a having an internal diameter A (Figure 5b) of about 153mm corresponding
to a cross-sectional area of about 18,400m . The insert 31 is about 93mm high
(dimension B).
The upper end of the insert 31 is spanned by a trio of equi-spaced radial spokes 31b
carrying a cylindrical tubular hub 31c concentric to the portion 31a. In the illustrated
insert 31, each spoke 31b has a uniform rectangular transverse cross-section along
its length, although it is also contemplated that the lower surface of each spoke will
extend downwardly away from the central hub 31c at an oblique angle, so that each
spoke 31b is triangular in elevation to better transmit vertical loads from the central
hub 31c to the outer walls 31a. Increasing the thickness of the spoke in the direction
of flow (vertical as drawn) increases the strength of the spoke, substantially without
impeding flow as would be the case if the spoke were made wider.
The hub 31c has an internal diameter of about 15mm, an external diameter of about
30mm and is about 26mm high. The hub 31c sits about 1mm shy of the top of the
insert 31.
An outwardly extending radial flange 31d encircles the upper end of the insert 31. The
flange 31d is about 17mm thick and has an external diameter of about 201mm. Eight
vertical counter sunk through-holes 31e open through the flange 31d to co-operate
with the screws 35. The holes 31e are equi-spaced on a pitch circle having a
diameter of about 185mm and being concentric to the portion 31a.
The top of the insert 31 carries an upwardly-open circular channel 31f. The channel
31f runs concentric to the body 31a and has a rectangular transverse cross-section
about 10mm wide by about 8mm deep. A centre line of the groove has a diameter of
about 162mm.
To accommodate the groove 31f, the top about 21mm of the cylindrical interior of the
insert 31 is stepped down to a diameter of about 145mm. The spokes 31b are about
11mm wide and sit within this 21mm section whereby the cross-sectional area of the
interior of the insert 31 is at this point about 14,000mm .
The interior of the insert 31 is a flow path through which ground water flows upwardly
to provide pressure relief.
The disc 20 is another integral body. It includes an internally-threaded through-bore
21 located concentrically to its circular outer periphery.
An annular ring 22 projects downwardly from the disc 20. The ring 22 runs
concentrically to the outer periphery of the disc and has a V-shaped cross-section.
The cross-section of the projection 22 is about 8mm wide by about 8mm high. The tip
of the cross-section, i.e. the vertex of the V shape, sits at a diameter of about 162mm
in this example.
The upper surface of the disc 20 is domed and meets the disc’s outer periphery 23 at
a shallow angle. Testing has shown that the installed valve 10 does not cause any
noticeable problems for suction cleaners, robot cleaners or manual vacuums.
Likewise, testing has shown that suction cleaners, robot cleaners and manual
vacuums do not cause any problem for the valve.
The collar 32 has an internal diameter of about 202mm from which a radial flange 32a
inwardly projects to a diameter of about 166mm. The flange 32a carries a circular
array of through-bores complementary to the array of through-bores 31e. In this
example, the through-bores are threaded through-bores. The threads of the bores are
preferably formed by the insertion of screw thread coils, such as those sold under the
trade mark Heli-Coil®.
In other variants of the collar 32, the bores of the flange 32a are replaced by upwardly
open blind bores to co-operate with self-tapping screws instead of bolts.
Optionally, the flange 32a carries more than one array of bores so that there is at
least one spare array of bores to be used if and when the first array of bores is worn
out. For example, when self-tapping screws are used, they may not find adequate
purchase if returned to the original holes after the insert 31 has been removed, e.g. to
service the valve. By way of example, the flange 32a might carry 16 equi-spaced
bores making up two arrays of eight equi-spaced bores, the arrays being angularly
offset from each other by half a pitch.
The shank 40 is another integrally formed piece. It includes an upright body 41. The
body is cylindrical, having an external diameter of about 15mm, excepting that four
1mm deep machined flats (not shown) run along its vertical length and are equi-
spaced about its periphery. The upper end of the shank 40 terminates in an
externally-threaded portion 42 above an outwardly-projecting radial flange 43. An
outwardly opening annular groove 49 separates the portion 42 from the flange 43.
A tool-engaging feature 44 is provided. In this example, the tool-engaging feature 44
is an Allen key receiving socket mounted concentrically within the top end of the
shank 40. A lower end of the shank 40 terminates in an externally-threaded portion
45. The shank 40 is mostly hollow. A blind-bore 46 runs from the collar 43 and
downwardly opens from the shank 40. This hollowing out reduces the weight of the
shank 40.
The member 34 is an upwardly-open cup-like member including a planar floor 34a
encircled by a short cylindrical wall 34b projecting upwards from the floor 34a.
The member 34 is configured to be fitted to the lower end of the insert 31. In
particular the wall 34b is dimensioned to snugly fit over a portion at the lower end of
the portion 31a which is stepped down to a reduced cylindrical diameter. As such the
cylindrical interior of the member 34 has a larger cross-sectional area than the interior
of the portion 31a.
The interior of the member 34 forms part of the flow path through which ground water
flows upwardly through the body 30 and the floor 34a is a filter for filtering debris from
that flow of water. In this example, the floor 34a is a web of material carrying a pattern
of closely spaced circular apertures. Of course other forms of filters are possible,
such as meshes and sponges, etc.
In the assembled valve 10, portion 42 of shank 40 threadingly engages bore 21, and
the body 41 skewers the hub 31c. An O-ring (not shown) carried within the groove 49
sealingly engages a chamfered lower end of the bore 21. A washer 47 is fitted over
the end 45 and a nut 48 in turn threadingly engaged with the end 45 whereby the hub
31c (and as a consequence the body insert 31) is captured on the shaft 41 of the
shank 40.
The washer 47 is dimensioned to abut a downwardly-facing annular step at the lower
end of the portion 41. The nut 48 is tightened on the portion 45 to clamp the washer
47 against that step, such that the washer 47 is fixed relative to the shank 40. The
flats (or “flutes”) of the portion 41 are one form of surface formation serving to
significantly reduce the potential for build up that could, if left unchecked, jam the
valve.
In operation, the disc 20 carries the shank 40 as it moves vertically, such that the
collar 43 and the washer 47 alternately abut the hub 31c so as to constitute stops
limiting the vertical movement of the disc 20 relative to the body 30. In particular,
downward forces on the disc 20 are centrally transmitted rather than borne by the
disc’s thin periphery 23. The shank 40, washer 47 and nut 48 thus together constitute
a constraint for constraining the movement of the disc 20.
In this example, the body 30 has a resilient portion in the form of a sealing ring 33
carried within the groove 31f. The ring 31 is dimensioned to fit snugly within this
groove.
The V-profiled ring 22 sits in register above the sealing ring 33. The ring 22 of the disc
and the ring 33 of the body 30 co-operate to form a sealing arrangement encircling
the cylindrical flow path of the body 30 such that the disc 20 blocks that flow path.
When the valve 10 is closed as in Figures 1 and 2, the annular vertex of the ring 22
presses about 3mm into the seal 33 and the seal 33 conforms to the vertex to define
an annular contact patch between the rings 22, 33 which is about 1mm wide
corresponding to an internal diameter of about 161mm and an external diameter of
about 163mm.
Both ground water and pool water are effectively sealed out of this contact patch.
These inner and outer diameters respectively correspond to the effective areas over
which the ground water and the pool water act to vertically drive the disc 20 in
opposite directions. In this example, the effective area over which the ground water
acts to upwardly drive the disc 20 is about 20,400mm corresponding to ¼ x π x 161 .
The effective area over which the pool water acts to downwardly drive the disc 20 is
about 20,900mm corresponding to ¼ x π x 163 . Thus the ratio of these areas is over
0.97.
The inventors have recognised that this ratio is important, that a higher ratio is
desirable, and that the ratio can be improved by enlarging the valve and/or reducing
the width of the contact patch.
This critical ratio corresponds to the “sensitivity” of the valve – the ratio of the pool
water pressure to ground water pressure at which the pressure forces on the disc 20
are in balance, such that any relative increase in ground water pressure will cause the
valve to open.
The force exerted on the disc 20 for each of the pool water and the ground water can
be calculated using the following formula by substituting the appropriate area and
height of the supported water column.
F=Aρgh
where:
A is the effective area in m
ρ is 1000 kg-m
g is 9.81 m-sec
h is the depth of the (pool or ground) water in m.
By applying this formula to the present valve when installed in the floor of a typical 1.5
m deep swimming pool, it can be calculated that the pool water exerts a downward
force on the disc 20 of about 310N (equivalent to about 31kg). It can also be
calculated that when the ground water rises to a height of 1.53m above the valve (i.e.
30mm above the pool water) that the ground water exerts an upward force of about
310N, such that the pressure forces are in balance and any further increase in the
ground water pressure will cause the valve to open to provide pressure relief.
Strictly speaking, the ground water pressure must rise sufficiently to also overcome
the weight of the disc 20 and the shank 40. These weights are small relative to the
above pressure forces and can be safely neglected for present purposes.
The above theory has been proven by practical study. Test results have shown that
the valve 10 reliably opens when the ground water rises to about 30mm above the
pool water. In addition to the improved sensitivity, this sealing arrangement has been
found to produce a more effective seal which is less affected by dirt and debris than
various existing seals.
It is contemplated that the disc 20 be spring mounted (e.g. a helical compression
spring may circle the shaft 41 and act between the hub 31c and the washer 47) to
reduce leakage of the pool water when the ground water pressure is low, although
experimentation suggests that this is not necessary.
The present inventors have recognised that some pool failures occur due to ill-
informed pool attendants observing that the pool water level has risen (or perhaps
even that the pool is overflowing) during or shortly after heavy rainfall, and in
response thereto activating the pool pump to drive water out of the pool via the back
wash line. A typical pool pump in its low, medium and high speed settings will deliver
about 150, 300 and 450 litres per minute respectively in this mode of operation.
Experimentation has shown that various existing pressure relief valves simply cannot
cope with these flow rates.
The valve 10 is configured to achieve these flow rates and more. Indeed testing has
shown that the valve 10 can provide effective pressure relief at up to 900 L/min. That
said, smaller valves are contemplated for use in smaller pools in which the pump will
typically be smaller and/or operated at less than its maximum output.
The design features to achieve these flow rates include the filter 34a spanning a large
cross-section to minimise the fluid velocity and associated restriction to flow
therethrough. Preferably the filter 34a has an open area not less than 50% of its total
surface area. When the valve 10 is open, the disc 20 sits above the body 30 leaving a
cylindrical gap between the vertex of the rib 22 and the ring 33 through which ground
water flows radially outwards. The shank 40 and the hub 31c are co-operably
dimensioned to allow for about 20mm of vertical travel such that this cylindrical
surface is about 17mm high corresponding to a cross-sectional area of about
8,600mm (given by π x 162 x 17).
Sensitivity ratios of 0.9, 0.95 and 0.97 respectively correspond to activation (valve-
open) pressures of 150mm, 75mm and 45mm in a typical 1.5m deep pool. 150mm is
considered the maximum that a fibreglass pool could reasonably be expected to
withstand whereas 75mm is considered to be a more practical figure. Valves having
sensitivity ratios over 0.97 have been tested to relieve pressure at a pressure
differential of about 30mm, which pressure differential corresponds to the Australian
Standard with which all Australian pools should comply.
Preferred forms of the valve 10 incorporate a mechanism for informing a pool
attendant that the valve is opened. In one simple implementation this might be a light,
or a portion of the valve having a colour contrasting to other portions of the valve and
the pool floor, arranged to be concealed in the valve-closed position then revealed
when the valve is opened. Other forms of the valve may include a sensor, such as an
electrical sensor, for producing an output that may be interpreted by equipment
external to the pool. Optionally this external equipment might produce an alarm (e.g.
a siren and/or a warning light) and/or automatically intervene to stop or at least slow
the emptying of the pool. By way of example, the external equipment might intervene
by closing the back wash line and/or deactivating the pump. Various implementations
of the sensor and the external equipment are possible. In particular both wired and
wireless variants are contemplated.
It is also contemplated that the valve and/or the external equipment might include
facility for data storage to prevent the pool being emptied when the valve has recently
been opened. By way of example, the sensor might continue producing the output for
a period of time after the valve has closed.
The illustrated valve 10 is intended for installation in a fibreglass swimming pool. The
collar 32 is configured to be permanently fixed to the fibreglass body of the pool
during manufacture of the fibreglass body. The other components can be installed
later such that they are replaceable/serviceable items. Indeed it is contemplated that
these other items be sold together as a kit. For the avoidance of doubt, this kit fits the
description of “a valve” as the wording is used herein.
To assemble these other components, firstly insert 31, member 34, shank 40, washer
47 and nut 48 are together assembled. This assembly step might occur at the factory.
This sub-assembly is then dropped into the installed collar 32 and rotated to move the
holes 31e into registration with the hole of the flange 32a. Screws 35 are then
inserted and with a suitable tool, in this case an Allen key, rotated to rigidly mount the
sub-assembly to the collar. The screws 35 threadingly engage the holes of the flange
32a. Desirably the top inner edge of the flange 32a has a stepped profile (not shown)
to accommodate an O-ring (not shown), which O-ring is axially compressed to
sealingly engage the insert 31 when the screws 35 are tightened.
Next the disc 20 is sat atop the shank 40 and an Allen key inserted through the bore
21 to engage the socket 44. By rotating the Allen key, and in turn the shank 40,
relative to the disc 40, the threading engagement of the disc 20 with the end portion
42 of the shank 40 is completed.
These assembly steps may easily be reversed, e.g. to replace a degraded seal 33 or
clear a blocked filter 34a.
The shank 40a and the disc 20 together, including the threading engagement of those
components and the tool-engaging feature 44, constitute a jacking arrangement for
driving the disc 20 away from its closed, sealing, position. By rotating the shank 40,
the disc 20 is driven upwards relative to shank 40, and the abutment of the flange 43
with the hub 31c prevents the shank 40 moving downwards.
This jacking arrangement aids in disassembly of the valve. Typically such
disassembly would be performed by a diver in a water-filled pool. Unless this happens
to be when the ground water pressure is high (i.e. when the valve is open or close to
opening), then a significant pressure differential downwardly drives the disc 20,
effectively clamping the valve closed. The jacking arrangement serves to drive the
disc against this pressure differential.
Once the seal is broken, the pressure differential disappears and the disc 20 can be
rotated about the shank 20 to be removed. By working quickly, a skilled diver can
replace the sealing ring 33 while only an acceptable volume of water is lost from the
pool. The lost water serves to backwash the filter 34a and so remove debris
therefrom.
Of course other forms of jacking arrangement are possible.
The seal 33 is preferably formed of silicon sponge. This material is found to produce a
better seal (i.e. a seal with less leaking) than natural rubber and to have a more
durable shape less inclined to swell, shrink or otherwise disfigure than EPDM sponge.
The shank 40 acts as a constraint or guide to control the motion of the disc 20, such
that the disc 20 remains in place to automatically return to its valve-closed position
without intervention by a pool attendant. The valve 10 re-seals automatically when the
ground water drops to about 30mm below the pool water.
Claims (30)
1. A valve, for relieving ground water pressure on a swimming pool for containing pool water, including a body defining a flow path; and 5 an element mounted to be moved in a direction from a position in which at least one feature of the element co-operates with at least one feature of the body to form a sealing arrangement to block the flow path to retain the pool water; to a position in which the flow path is open to allow ground water into the 10 swimming pool; the sealing arrangement defining an effective area over which the ground water pressure acts to drive the element in the direction; and an effective area over which pool water pressure acts to drive the element 15 opposite the direction; the co-operable features being configured such that a ratio of the effective area over which the ground water pressure acts to the effective area over which pool water pressure acts has a value of at least 0.9.
2. The valve of claim 1 wherein the co-operable features are configured such that the ratio has a value of at least 0.95.
3. The valve of claim 1 wherein the co-operable features are configured such that the ratio has a value of more than 0.97. 5
4. The valve of any one of claims 1 to 3 wherein the co-operable features include a resilient portion of one of the element and the body; and a projection of the other of the element and the body; the resilient portion and the projection each encircle the flow path; and 10 in transverse cross-section the projection defines a tip for pressing into the resilient portion.
5. The valve of claim 4 wherein in transverse cross-section the projection is in substance V-shaped at least at the tip.
6. The valve of claim 4 or 5 wherein the resilient portion is a ring carried in an 15 annular groove.
7. The valve of claim 4, 5 or 6 wherein the resilient portion is a resilient portion of the body.
8. The valve of any one of claims 1 to 7 including a constraint by which the element is constrained, relative to the body, so as to automatically move, when pressure relief 20 is no longer required, from its position in which the flow path is open to its position in which the flow path is blocked.
9. The valve of any one of claims 1 to 8 wherein the valve is configured to when open allow ground water into the pool via the flow path at at least a rate over at least some of a range of ground water pressures up to and including a pressure differential above the pool water pressure; 5 the rate is at least 150 L/min; and the pressure differential is at most 150mm(water).
10. The valve of claim 9 wherein the rate is 300 L/min.
11. The valve of claim 9 wherein the rate is 450 L/min.
12. The valve of claim 9, 10 or 11 wherein the pressure differential is 75mm(water). 10
13. The valve of claim 9, 10 or 11 wherein the pressure differential is 30mm(water).
14. The valve of any one of claims 1 to 13 configured such that when the element is in its position in which the flow path is open, the element and the body together define a gap through which the ground water flows into the pool; the gap has a cross-sectional area; and 15 the cross-sectional area, of the gap, at its smallest point is at least 3000mm .
15. The valve of claim 14 wherein the cross-sectional area, of the gap, at its smallest point is at least 8000mm .
16. The valve of anyone of claims 1 to 15 wherein the flow path has a cross-sectional area; and the cross-sectional area, of the flow path, at its smallest point is at least 5,000mm .
17. The valve of claim 16 wherein the cross-sectional area, of the flow path, at its smallest point is at least about 10,000mm .
18. The valve of any one of claims 1 to 17 wherein the flow path is spanned by a 5 filter for filtering debris from the incoming ground water.
19. The valve of claim 18 wherein the filter spans a portion of the flow path having a cross-sectional area of at least about 10,000mm .
20. The valve of claim 8 wherein the constraint includes a threaded piece rotatable relative to the element to assemble and disassemble the valve. 10
21. The valve of claim 20 wherein the threaded piece is threadingly engaged with the element.
22. The valve of claim 20 or 21 wherein the threaded piece defines a stop that limits movement of the element to define the position in which the element blocks the flow path. 15
23. The valve of any one of claims 20 to 22 wherein the threaded piece is rotatable to drive the element away from the position in which the element blocks the flow path.
24. The valve of any one of claims 1 to 22 including a jacking arrangement for driving the element away from the position in which the element blocks the flow path.
25. The valve of claim 24 wherein the jacking arrangement includes a threaded 20 piece rotatable relative to the element to so drive the element.
26. The valve of claim 25 wherein the threaded piece is threadingly engaged with the element.
27. The valve of claim 25 or 26 wherein the threaded piece defines a stop that abuts the body when so driving the element. 5
28. The valve of any one of claims 1 to 27 including a mechanism for informing a pool attendant that the element is, and/or has been, in its position in which the flow path is open.
29. The valve of any one of claims 1 to 28 including a sensor for producing an output, the output being interpretable external to the pool and indicative of the 10 element being, and/or having been, in its position in which the flow path is open.
30. A swimming pool including the valve of any one of claims 1 to 29.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NZ627191A NZ627191A (en) | 2013-08-22 | 2014-06-12 | A valve |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2013903185 | 2013-08-22 | ||
AU2013903185A AU2013903185A0 (en) | 2013-08-22 | A valve | |
AU2014902023 | 2014-05-28 | ||
AU2014902023A AU2014902023A0 (en) | 2014-05-28 | A valve |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ626154A NZ626154A (en) | 2014-07-25 |
NZ626154B true NZ626154B (en) | 2014-10-29 |
Family
ID=
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