U.S. patent number 3,815,748 [Application Number 05/292,316] was granted by the patent office on 1974-06-11 for universal basin for use in a sewer system.
This patent grant is currently assigned to Per Pontoppidan Sorensen. Invention is credited to Jorgen Mosbaek Johannessen.
United States Patent |
3,815,748 |
Johannessen |
June 11, 1974 |
UNIVERSAL BASIN FOR USE IN A SEWER SYSTEM
Abstract
A basin for use in a sewer system and having a draining device
designed as a cover consisting of a housing with a submerged inlet
opening and a centrally located outlet opening, the said housing
containing an outlet chamber with a circular or helical sidewall
along which an inlet tube opens tangentially into the outlet
chamber. When the water level in the basin raises, the water
flowing into the outlet chamber is caused to circulate in such a
manner that it works as a centrifugal brake retarding the water
flow.
Inventors: |
Johannessen; Jorgen Mosbaek
(Koge, DK) |
Assignee: |
Per Pontoppidan Sorensen
(Solrod Strand, DK)
|
Family
ID: |
8135962 |
Appl.
No.: |
05/292,316 |
Filed: |
September 26, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Sep 28, 1971 [DK] |
|
|
4705/71 |
|
Current U.S.
Class: |
210/163;
404/4 |
Current CPC
Class: |
E03F
5/14 (20130101); E03F 5/02 (20130101); E03F
5/105 (20130101); E03F 5/101 (20130101); E03F
5/16 (20130101); E03F 5/021 (20130101); Y02A
10/36 (20180101); Y02A 10/30 (20180101) |
Current International
Class: |
E03F
5/00 (20060101); E03F 5/16 (20060101); E03F
5/10 (20060101); E03F 5/14 (20060101); E03F
5/02 (20060101); B01d 021/26 () |
Field of
Search: |
;210/163,512 ;52/12
;404/4,5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hart; Charles N.
Assistant Examiner: Calvetti; F. F.
Attorney, Agent or Firm: Waters; Eric H.
Claims
What I claim is:
1. Universal basin for use in a sewer system, such as a manhole,
gully, sedimentation basin, equalizing basin, and oil and petrol
interceptor; comprising a container having an inlet gate, an inlet
pipe and a discharge opening; and a draining device mounted in said
discharge opening for draining off an approximately constant amount
of water through the discharge opening per unit of time, said
draining device comprising a cover having spaced end walls and an
annular well connecting said end walls defining a hollow housing, a
first one of said end walls facing toward said basin having a
submerged inlet opening formed therein, the other of said end walls
having a centrally located outlet opening communicating with an
outlet piping system, an outlet chamber being provided in said
housing having a curved side wall portion, an inlet tube extending
along said side wall portion and opening tangentially into said
outlet chamber; and fastening means being formed along the
periphery of said housing for securing said cover to the discharge
opening of said basin.
2. Universal basin as claimed in claim 1, said housing having an
inlet chamber, a partition separating said inlet chamber and said
outlet chamber, an inlet strainer interconnecting said chambers, a
bottom chamber forming a trap, and said inlet tube connecting said
bottom chamber and said outlet chamber, said inlet tube having a
discharge end forming the inlet opening to said outlet chamber.
3. Universal basin as claimed in claim 1, including a groove in the
bottom of said basin in parallel with the plane of the draining
device, a protective cover having submerged openings being mounted
in said groove so as to cover the draining device while
simultaneously forming a sedimentation- and clarification chamber
between said device and the protective cover.
4. Universal basin as claimed in claim 3, said groove including
hinge means for hinged connection of said protective cover to said
basin.
5. Universal basin as claimed in claim 1, comprising a conical
annular groove encompassing said discharge opening and tapering in
relative to the direction of installation of said draining device
in said openings, a sealing and locking ring engaged in a recess in
said groove retaining said draining device in said opening; and a
removal ring fastened to the lower end of said sealing and locking
ring facing said basin adapted to facilitate removal of the latter
from said groove.
6. Universal basin as claimed in claim 2, said end wall facing the
basin forming a protective cover, said inlet opening in said end
wall being at its bottom edge that is submerged at lowest water
level, a vertical venting tube at the basin side of said end wall,
having bottom end thereof open to the basin at a point proximate
the center of said end wall and the top end of said venting tube
opening into the upper end of said inlet chamber, a downwardly
directed outlet tube communicating with the centrally located
outlet opening in said other end wall, said outlet chamber having a
helical side wall and forming a centrifugal brake, said inlet
chamber, bottom chamber and inlet tube together forming a trap, and
said outlet tube and the inlet tube of the centrifugal brake
forming a syphon system in which the lower end of the inlet tube
projecting into the bottom chamber is located at a level above the
bottom end of the outlet tube.
7. Universal basin as claimed in claim 6, comprising an air
stabilizer in said outlet chamber forming said centrifugal brake,
said air stabilizer being in the shape of a projection directed
radially inwardly from the helical side wall.
8. Universal basin as claimed in claim 6, comprising an inlet
strainer located between said inlet chamber and said bottom
chamber.
9. Universal basin as claimed in claim 1, comprising an emergency
overflow including a substantially vertical pipe in said basin, the
upper end of said pipe opening proximate the top of the basin, and
a combined basket and ball float supported on the upper end of, and
said pipe, the lower end of the pipe opening on the side of the
draining device remote from the basin.
10. Universal basin as claimed in claim 1, said housing being an
undivided double conical housing, a plurality of submerged inlet
openings being provided in the bottom part of one housing end wall,
an internal inlet tube extending tangentially to the housing
communicating with said inlet openings, and an outlet tube directed
downwardly from the discharge opening being centrally located in
the other end wall of said housing.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a universal basin for use in a sewer
system such as manhole, gully, sedimentation basin, equalizing
basin and oil and petrol interceptor. The said basin is designed as
a container cast in one piece or constructed of a number of rings
and a bottom part cast in one or more pieces with an inlet and an
outlet and means for draining off an approximately constant amount
of water through the outlet per time unit. The basin further
comprises a top plate or cone on which different types of grates
and covers or combinations thereof can be mounted.
2. Description of Prior Art
It has been proposed to use such universal basins as equalizing
basins in sewer systems in which sanitary and storm sewage normally
flow in one common pipe, thus avoiding a pipe system specifically
dimensioned for rain water peak loads, as the rain water during
heavy rainfalls will be dammed up in the equalizing basins, and be
discharged from these as a substantially constant flow distributed
over a longer period. However, it may also be desirable to use
similar basins in other types of sewer systems, such as in pipe
systems leading rain water into actual storm sewers, and on the
whole into sewer systems at locations where manholes, gullies and
catch basins are usually located, so that these are replaced by the
universal basin. It is a problem in such basins to avoid clogging
of the devices for draining off the water from the basin, since
these devices must have a relatively small outlet dimension so as
to produce a retarding effect on the outflow as the water rises in
the basin, and they should preferably not be any obstruction to
inspection and/or cleaning of the pipe system from the basin in
case of emergency.
SUMMARY OF THE INVENTION
It is the object of the invention to devise a universal basin of
the aforesaid kind, which can replace or combine separate basins
hitherto used in sewer systems, so as to make substantial savings
on the piping system possible, and at the same time to achieve a
number of sewerage advantages. More specifically it is an object of
the invention to devise a self-cleaning draining device of a simple
design which is capable of effectively braking the outflow of water
from the basin, when the water level in the basin rises.
Furthermore it is the object of the invention to provide a basin
with a drainage device so adapted and located in an outlet opening
of the basin that it may readily be opened for inspection and/or
cleaning.
The basin according to the invention is characteristic thereby that
the draining device is designed as a cover, consisting of a housing
with end walls, of which the wall facing the basin has a submerged
inlet opening, and that the wall facing the piping system is
provided with a centrally located outlet opening, the said housing
containing an outlet chamber, with a circular or helical side wall,
along which an inlet tube opens tangentially into the outlet
chamber, fastening means being furthermore formed along the
periphery of the housing for securing the cover to the outlet
opening of the basin.
The combined cover and draining device is of a robust and reliable
design, without moving parts, and water flowing into the outlet
chamber when the water level in the basin rises, is caused to
circulate in the chamber in such a manner that it works as a
centrifugal brake on the water flow. The draining device ensures
for the surface water (rain water) the necessary time of
retardation in the universal basin for effectively removing
impurities by straining, sedimentation and seperation
simultaneously providing the necessary minimum velocity of flow
through the outlet to keep this self cleaning.
In an appropriate embodiment of the draining device according to
the invention, the outlet chamber is separated from an inlet
chamber by a partition, and the chambers are in connection with
each other through an inlet strainer (grate) and a bottom chamber
which forms a trap, and which is in connection with the outlet
chamber through a delivery tube the discharge end of which forms
the inlet opening to the outlet chamber.
Straining and sedimentation is necessary to avoid clogging up of
the small outlet and accumulation of sand and smaller particles in
the piping system. To prevent pollution and damage to the
biological filters in sewage treatment plants, it is important that
any occurring oil and petrol are separated off in the universal
basin. To protect the draining device against floating and
precipitable substances it is appropriate according to the
invention that the bottom of the universal basin is provided with a
groove or a hinge parallel to the plane of the draining device, in
which a protective cover with submerged openings is mounted so that
it can be opened and so as to cover the draining device,
simultaneously forming a sedimentation- and clarification chamber
in front of the draining device. The protective cover, which, for
example, may be provided with a vertical partition located on its
underside to prevent rotation of the liquid beneath the cover, may
easily be swung aside when access to the sewer pipe is desired. The
draining device itself may easily be removed when, as is the case
in one embodiment of the invention, it is mounted in a groove by
means of a sealing and locking ring, which at its lower end on the
side facing the basin has a bow attached by means of a strap. By
means of a tool or, for example, a boat-hook, the said bow may
easily be grasped and the sealing ring pulled off, by which the
draining device may be removed.
If desired the draining device according to the invention may be
mounted on spacers cast in the basin in such manner that, when the
sealing ring is torn off, a ring-shaped opening is formed along the
periphery of the draining device, whereupon the outlet area is
immediately substantially increased.
More particularly, the universal basin may be provided with an
emergency overflow which will function during very heavy rain falls
and thereby reduce the quantity of water dammed up and the duration
of damming up. This overflow may consist of a vertical pipe with a
combined basket and ball float attached to the top end of the
pipe.
A preferred embodiment of the draining device according to the
invention is characteristic thereby that such wall of the draining
device housing as is facing the basin forms a protective cover with
an inlet opening at its bottom edge that is submerged at lowest
water level and with a vertical venting tube, the lower end of
which opens into the upper part of the basin at a point close to
the center of the end wall, whereas its upper end opens at the top
of the inlet chamber. Further the end wall facing the piping system
is provided with a central outlet opening, communicating with a
downwardly directed outlet tube where the outlet chamber forms a
centrifugal brake with a circular or helical side wall and is in
connection with the inlet chamber through a bottom chamber and an
inlet tube, which together form a trap. Furthermore the outlet tube
forms together with the inlet tube to the centrifugal brake a
syphon system, in which the lower end of the inlet tube that
projects into the bottom chamber is located at a level above the
lower end of the outlet tube.
In view of the risk of clogging up and the outflowing water
quantity, the draining device is provided with an outlet opening of
maximum size and the protective cover on the inlet side forms at
lowest occouring water level a sufficiently submerged inlet, so
that a certain amount of oil or petrol can be separated off in the
universal basin above the inlet. The bottom chamber, which is
filled with water before its installation, functions as a trap at
low water level in the basin. When the water in the basin at rising
water level is blocking the bottom opening of the air venting tube,
air will be trapped and pressurized in the upper part of the inlet
chamber. This pressure acts on the water level in the bottom
chamber and forces the water up through the inlet tube until the
water level in the bottom chamber has reached a level below the
bottom edge of the inlet tube, whereupon the air will suddenly
penetrate below the water column in the inlet tube and into the
centrifugal brake formed by the outlet chamber. The pressure drop
in the inlet chamber causes a heavy water flow from the basin into
this chamber and further into the bottom chamber and the outlet
chamber where the water quickly rises to above the outlet opening
so that air is trapped and pressurized in the upper part of the
outlet chamber. The outlet tube now functions as the outlet of a
syphon. By a further rise of the water level in the basin the water
level in the centrifugal brake rises above the inlet tube, and at
last the water rotates along the periphery of the centrifugal brake
and the trapped air is hurled out as small bubbles through the
outlet opening while the centrifugal braking effect on the rotating
water will commence to operate. To avoid premature braking effect
an inwardly directed projection may according to the invention be
provided on the side wall of the centrifugal brake, behind which
the air may at the beginning be partly sheltered until the
rotational velocity of the water is sufficient to hurl out the
remaining air, whereby the full braking effect is established.
Between the inlet chamber and the bottom chamber may be inserted a
strainer at such a distance from the wall of the draining device,
that larger typical longitudinal solids are not able to turn and
pass through the strainer.
According to the invention the universal basin can be provided with
an emergency overflow which, when the basin is almost filled,
constitutes a bypass bypassing the draining device.
A simple embodiment of the draining device may be used in cases
where the outlet opening has to be of a size sufficient to
eliminate any major risk of clogging. The said draining device
consists of an undivided double conical housing with a number of
submerged inlets provided in the bottom part of one wall of the
housing and opening into an internal inlet tube extending
tangentially to the housing, and with an external outlet tube
directed downwardly from the outlet which is centrally provided in
the other wall of the housing.
BRIEF DESCRIPTION OF THE DRAWING
In the following the invention will be described in more detail in
connection with some embodiments and with reference to the drawing
in which
FIGS. 1 and 2 show vertical and horizontal sections of a universal
basin with a draining device,
FIG. 3 shows a vertical section of a gully and supplementing
basin,
FIG. 4 shows a vertical section of a gully for street and space
drainage,
FIG. 5 shows a vertical section of a gully for roof drainage,
FIGS. 6-9 show on different scales a vertical section and plan the
draining device shown in FIGS. 1 and 2,
FIG. 10 shows the outlet flow characteristic of the draining device
according to the invention,
FIGS. 11 and 12 show in front elevation and vertical section a
draining device of simple embodiment, and
FIG. 13 shows a draining device mounted in a larger cover.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The universal basin 1 shown in vertical and horizontal section in
FIGS. 1 and 2 replaces a gully and/or a manhole, and is provided at
places, where these are normally located. In the side of the basin
the desired forms of pipe lead-ins and connections (2) may be
provided, as shown in principle by the dotted lines. The pipe
lead-in or connection (2) is through a cleaning and inspection
opening (3) in connection with the inside of the universal basin.
In the cleaning opening a groove (4) of reverse conical shape in
relation to the direction of mounting may be cast or formed (for
details see FIG. 6), in which the draining device (5) can be
mounted by means of a sealing and locking ring (6). To protect the
draining device against floating and precipitable solids, a groove
(7) in the bottom of the universal basin is provided with a
protective cover (8) that can be opened. The said cover has at
either end an inlet opening (9), which is submerged at lowest water
level, and a handle (10). The protective cover divides the bottom
of the universal basin into a sedimentation chamber (11) and a
clarification chamber (12).
If desired the basin may be provided with an emergency overflow in
the form of a pipe (30) which at its upper end carries a combined
basket and ball float (28) and at its lower end opens at the
outside of the draining device (5).
FIG. 3 is a vertical section of a gully and supplementing basin
used as a supplement to the volume of the universal basin in case
the latter together with the outlet is insufficient to drain the
desired area. The outlet leads to the universal basin.
FIGS. 4 and 5 show in vertical section a gully for street and space
drainage and a gully for roof drainage respectively. The outlets
from these also lead to a universal basin.
The draining device (5) according to FIG. 6 is in the embodiment
shown constructed as a double conical housing consisting af two
bowls (13 and 14) facing each other and joined by means of a flange
joint. The bowl (14) forms in combination with an internal bowl
(16) an outlet chamber, which constitutes a centrifugal brake
provided with an outlet opening (15) which together with the
centrifugal brake (16), an air stabilizer (17), an outlet tube (18)
and the pressure head occurring in the universal basin at any time
determines the flow velocity through the outlet as the basin is
filled and drained. The centrifugal brake (16) is in addition to
the air stabilizer (17) provided with an inlet tube (19) which
together with the outlet tube (18) constitutes a syphon. The lower
end of the inlet tube (19) opens into a bottom chamber (20) forming
a trap with same. FIG. 8 shows the bottom chamber (20) as viewed
from line VIII--VIII in FIG. 6. The top of the bottom chamber wall,
is designed as an inlet strainer (21) which is located at such a
distance from the wall of the centrifugal brake that larger
typically longitudinal solids are unable to turn and pass through
the inlet strainer whose inlet openings have a slightly smaller
cross-section than the inlet tube (19), the outlet opening (15) and
the outlet tube (18). The bowl (13) which forms an inlet chamber is
at its upper end provided with a venting opening (22), a venting
tube (23) and two submerged inlet openings (24).
In the embodiment disclosed the draining device (5) is secured in
an integrally cast reverse conical groove (4) by a sealing and
locking ring (6). The said conical groove is at the side facing the
pipe system provided with combined anchors and spacers (25), which
when the sealing and locking ring (6) is removed ensure an outlet
slit along the periphery of the draining device housing. The
sealing and locking ring (6) has at its lower end a removing ring
(27) provided with a strap (26). When this ring is pulled upwards
the sealing and locking ring (6) and thereupon the draining device
(5) may be removed.
The universal basin and the draining device, in which the bottom
chamber (20) is filled with water prior to its installation
operates as follows: When the rain water is flowing into the
universal basin (1) it has normally, after passing a downpipe or a
grate passed a strainer, in which the larger impurities are caught.
The water then flows into the sedimentation chamber (11) in which
entrained sand and smaller impurities settle before the water flows
through the submerged inlet openings (9) into the clarification
chamber (12). In the clarification chamber (12) the remaining
suspension of particles in the water are precipitated before they
reach the inlet strainer (21) owing to the very quiet and slow
water flow below the protective cover (8). The slow water flow
below the protective cover, ensures together with the submerged
inlet openings (24) and the small outlet that oil and petrol washed
down by the rain water, have time to be separated from the water
before the water reaches the piping system.
When the water in the universal basin owing to the inflow into it,
has reached a level at which the lower opening of the venting tube
(23) is blocked, the air trapped between the two bowls (13 and 14)
will be pressurized. This pressure spreads to the water surface in
the bottom chamber (20) so as to force the water in same through
the inlet tube (19). When the water in the universal basin has
risen to a certain level the water surface in the bottom chamber
has sunk to a level slightly below the lower edge of the inlet tube
(19) and forms a concave. Now a state of balance is reached, in
which an additional slight decline of the water level in the bottom
chamber causes the air to penetrate below the water column in the
inlet tube (19), blowing it into the centrifugal brake in a split
second, thereby opening a narrow passage between the water surface
in the bottom chamber and the lower edge of the inlet tube (19).
Owing to the pressure a large amount of the trapped air quickly
disappears through this passage. The subsequent pressure drop
between the bowls causes a sudden rise of the water level in front
of the inlet strainer (21), and the flow through the outlet starts,
because the bottom chamber is quickly filled, whereupon the
centrifugal brake is filled to a level where the water closes the
outlet opening (15). The air thereby trapped in the upper part of
the centrifugal brake, will now be pressurized and thereby prevent
any further rise of the water level in the centrifugal brake for
the time being. The flow through the outlet opening (15) thereupon
fills the outlet tube (18) so that this starts to function as the
outlet tube of a syphon. The outflow from the universal basin has
now obtained the minimum velocity which is conditioned by the head
between the lower edge of the venting tube (23) and the lower edge
of the outlet tube (18) and the intermediate pressure losses. If
the water continues to rise in the universal basin the inlet
velocity through the inlet tube (19) will increase, causing the
water level in the centrifugal brake to rise in the side at which
the inlet is located, by which the water surface will adopt a
position inclining towards the outlet opening. Conversely the water
level at the other side of the chamber will fall slightly, so that
a small portion of the trapped air may escape through the outlet
opening. By continued increase in pressure the inlet velocity
increases so that the water is caused to rotate along the periphery
of the centrifugal brake, and the trapped air is hurled out as
small bubbles, while the water starts rotating in front of the
outlet opening and the centrifugal braking effect begins to
operate. To avoid a premature braking effect a projection (17) is
provided in the upper part of the centrifugal brake (16). This
projection (17) serves as an air stabilizer as the air may be
partly sheltered behind it until the pressure and consequently the
rotational velocity of the water, increases so much that the
remaining air is at last hurled out, thereby establishing full
braking effect.
When later the water level in the universal basin (1) has dropped
to a level below the bottom edge of the venting tube (23), the air
will enter the said tube, and the water level in front of the inlet
strainer will drop to the same level as the water level in the
basin. Owing to the syphon action in the outlet tube (18) water is
then sucked from the bottom chamber (20) until the water level in
this has dropped sufficiently to allow air to be sucked in through
the inlet tube (19) whereupon the outlet chamber which forms a
centrifugal brake will be filled with air, until the water level in
the said chamber has dropped to the outlet opening (15). The air
thereupon will be sucked into the outlet tube (18) and interrupt
the syphon action. The surplus water quantity in the centrifugal
brake (16) which is located above the bottom edge of the top part
of the inlet tube (18), subsequently flows back through this tube
and down into the bottom chamber, so that a trap is established,
and the draining device is ready for the next time water flows into
the universal basin.
FIG. 10 shows the outlet flow characteristic for the draining
device according to the invention, the outflowing water quantity in
litres per second being indicated as a function of the pressure
head in water column metres. The quantity of outflowing water at a
certain pressure head is indicated at point a, and the quantity
will increase to point b at increasing pressure head, whereupon the
centrifugal braking effect is established as the water in front of
the outlet opening starts to rotate. By a continued increase in
pressure head the rotational velocity of the water will increase
and thereby cause an increased braking effect, so that the quantity
outflowing per second in spite of increasing pressure head remains
substantially constant until point c is reached. When point c is
reached, all air in the centrifugal brake (16) will be displaced,
and full braking effect is established. By a continued increase in
pressure head the outflow increases in normal manner parabolically
to point d. When the pressure head again drops, the outflow
decreases according to the same parabola to point e, whereupon the
syphon action in the draining device is interrupted by the intake
of air, and a minor backflow of water to the bottom chamber (20)
forms a trap which provides the counterpressure and the pressure
equalization that reactivates the syphon action, so that the
minimum velocity necessary for the self-cleaning is obtained.
If the flow of water to the universal basin (1) is no more than
corresponds to the pressure head at point f, the outflow quantity
drops with the braking effect obtained to point g, whereupon air
intake and backflow as described above are repeated.
FIGS. 11 and 12 show a more simple embodiment of a draining device
which may replace that shown in FIGS. 6-9 in cases where the outlet
and consequently the outlet opening have to be of such size that it
involves no appreciable risk of clogging under available
conditions. The said draining device is installed and dismantled in
the same way as that shown in FIGS. 6-9. However, there is no trap
to be filled with water before installation.
In the embodiment disclosed in FIGS. 11 and 12 the draining device
shown is constructed as a double conical housing, consisting of two
bowls (13' and 14') facing each other and joined by means of a
flange joint, and with their total volume functioning as a
centrifugal brake. The bowl (13') is at its bottom provided with a
number of inlet openings (24') and an inlet tube (19'). The bowl
(14') is provided with an outlet opening (15') and an outlet tube
(18') which together with the bowl (13') at top is provided with a
projection (17').
The draining device shown in FIGS. 11 and 12 and installed in a
universal basin operates as follows: When the water level in the
universal basin rises owing to inflowing water, the water flows
through the inlet openings (24') into the inlet tube (19') which
directs the water into the draining device along its internal
periphery. When the water has reached the outlet opening (15') it
flows into the pipe system through the outlet tube (18') which is
filled by and by and will function as the outlet of a syphon.
Accordingly, the trapped air above the outlet opening will be
subjected to pressure and thereby prevent further rising of the
water level between the bowls (13' and 14'). By continued rising of
water level in the universal basin the inflow velocity through the
inlet tube (19') increases so that the water is hurled along the
internal periphery, causing the trapped air to escape as small
bubbles, while the water starts rotating in front of the outlet
opening (15') and the centrifugal braking effect begins to operate.
To prevent premature braking effect a projection (17') is provided
in the upper part of the centrifugal brake (16'). This projection
(17') functions as an air stabilizer as the air may be partly
sheltered behind the edge until the pressure and consequently the
rotational velocity of the water increase to a point at which the
remaining air is hurled out, establishing full braking effect. When
later the water level in the universal basin (1') has again dropped
to a level equal to the bottom end of the outlet tube (18'), the
syphon action in this is interrupted causing a backflow through the
inlet tube (19'), by which any impurities at the inlet openings are
washed back and precipitated.
The outlet flow characteristic is equal to that shown in FIG. 10,
except starting at zero.
It will be appreciated that the draining device may be installed in
many ways differing from that shown in FIG. 6. For instance it may,
as shown in FIG. 13, be mounted in a groove (4) surrounding an
opening in a larger cover (31) covering a large inspection opening
in the basin.
With the use of universal basins according to the design disclosed,
a tight and closed sewer piping system is provided, which for
instance, in addition to water draining may be used to carry off
smoke or fumes, for instance, through the pipe (2) in FIG. 2,
connected to flues from boilers such as central heating boilers in
residential buildings.
* * * * *