FR2770879A1 - Self=priming siphon, e.g. for watering plants or removing pools of water from terraces or swimming pool covers - Google Patents

Abstract

The siphon consists of an inverted U-shaped tube (9) filled with a hydrophilic material and having its descending branch (8) extended by a tube (12) of smaller diameter than the siphon. When the end of the rising branch (10) is immersed in a container (2) of liquid (3) the liquid fills the siphon as far as the upper surface (11) of the liquid. It then continues to rise by capillary action until it passes the top point (30) of the siphon and passes down the descending branch and continues to flow as long as the outlet end of the extension tube (12) lies below the level of the liquid surface. The siphon tube (9) can be made from a supple material so it can be bent to the shape of the liquid container, or it can be rigid or semi-rigid, and it can contain an additional perforated tube inside the hydrophilic material or outside the siphon tube for a faster flow. The extension tube can be between 1 and 6 mm and preferably 4 mm in diameter, and can be equipped with a valve to regulate the flow.

Description

The present invention relates to a self-priming siphon, and more particularly to a device combining capillarity and the siphon, in particular but not exclusively, a device for watering plants from a reserve of water.

Devices for operating on the principle of a water tower are known for watering plants (patents JP 011 24435 and US 1453 401). Water is taken from the base of the container which must therefore have connections provided for this purpose. The container specially designed for this use, therefore has the disadvantage of having a cost and a bulk.

Devices operating by capillarity are known, for example described in French patent 1,493,029 or in German patent 93 19107, but which give a very reduced flow rate.

There is currently no sprinkler device which combines the following advantages:
without energy input,
with a flow rate adjustable from 0 to several hundred liters per day,
starts and re-starts easily,
from any tank (the level of which is higher than
pour point),
with the possibility of seeing the water flowing (which is reassuring for
the user).

The present invention aims to provide all these advantages.

The self-priming siphon according to the invention shown in fig. 2 includes:
an inverted U-shaped tube (9) which contains a hydrophilic material (15).

The descending branch (8) of the U (9) is extended by a pipe (12) of smaller section than that of the tube (9).

When immersing the rising branch (10) of the U (9) in a liquid (3) as shown in fig. 2, the liquid enters the branch (10) expelling the air which escapes through the open end of the pipe (12).

The liquid arrives at level (11) where it balances with the level of the locus in the container.

Then, the liquid continues to rise by capillarity, in the hydrophilic material (15).

Once the high point (30) has been reached, the liquid continues to wet the hydrophilic material, descending into the branch (8) of the U.

When the liquid arrives at the inlet of the tube (12) if the latter has a section small enough for the surface tension of the liquid to obstruct its passage, it accumulates in the reservoir (16) thus formed.

When the height of the accumulated liquid is sufficient, so that its pressure is greater than the resistance force due to the surface tension, the liquid is forced to engage in the tube (12) and the diameter thereof being smaller , this results in a liquid column (20) of a greater height, therefore a greater depression.

This column of liquid entrained by its weight descends along the tube (12) and causes a suction which initiates the siphon.

By way of nonlimiting example, an exemplary embodiment shown in FIGS. 1 and 2 will be described below.

A rigid plastic tube (9) 50 cm long and 12 mm inside diameter is bent into a U shape.

 It is filled with a hydrophilic material (15).

It is put in the inverted position and its branch (10) is immersed in a container (2) filled with water.

The air escaping through the other end of the tube (9), the water rises in the branch (10), up to the level (11).

Then, by capillary action, the water continues to rise to cross the upper part (30) and descend into the branch (8).

When the hydrophilic material (15) is well wetted, the water begins to come out drop by drop through the end (19) of the branch (8) of the tube (9) (FIG. 1).

This device, similar to that described in patent FR 1493 029 is used for drip irrigation.

This device has the disadvantage of giving a very small flow rate (of the order of 1/4 liter per day), because it works only by capillary action and not in a siphon, hence the need to initiate it to exert a suction for example with the mouth or with a pear.

On the other hand, the device according to the invention can supply hundreds of liters per day, because it works as a self-priming siphon.

Indeed, the invention proposes (fig. 2) to extend the branch (8) of the tube (9) by a pipe (12) with an inner diameter smaller than the diameter of the tube (9), for example 4 mm.

The hose (12) is connected to the tube (9) by means of a plug (17) forming a sleeve, and possibly a tap (14) (FIG. 3) intended to regulate the flow rate.

The tubes used being transparent, we observe the phenomena that occur.

 1 ") When the branch (10) of the U is immersed in water, it quickly fills in its submerged part up to level (11).

 2 ") The water then rises by capillary action and completely wets the hydrophilic material (15) (one can moreover visualize the progress of the water by using a hydrophilic material which changes color when it is wet, or else by coloring the water).

 3) Drops (19) fall from the hydrophilic material and gather at the inlet (16) of the tube (12).

 4) When several drops have fallen, the water begins to descend into the tube (12) in the form of a column of water (20) which descends causing suction.

 5) The water which descends into the tube (12) causes air bubbles.

 6) This air is replaced by water, the level of which can be seen rising in the branch (10) of the tube (9).

 7) When the level of this water reaches the upper level (30), it pours into the branch (8) and feeds the pipe (12) much more abundantly than a simple wick.

 8) It can be seen that the flow rate in the tube (12) becomes high, and depends on the height of fall, because the device then operates as a siphon.

 9) When the system is stabilized in operating mode, it no longer evacuates air bubbles. It can be seen that in the descending branch (8) there remains air, which does not present any drawback, because in this branch, the water flows, and the suction part of the siphon does not start until the tube (12 ).

The diameter of the pipe (12) is preferably less than or equal to 6 mm.

Diameters of the order of 2, 3 or 4 mm work very well.

A diameter of 5 or 6 mm is less favorable for the formation of a water column in the pipe (12).

Indeed, the water tends to run off, which has no effect on the priming of the siphon.

This defect can be partly corrected by the choice of the material constituting the tube (12). For example with a slightly frosted internal wall, favoring the attachment of water, thus being able to prevent its runoff.

For a diameter of the pipe (12) of less than 2 mm, the flow of water is more difficult, and the volume of aspirated air being smaller, the priming of the siphon is longer, more random, or even impossible for a diameter less than 1 mm.

Another important characteristic of the invention is that, when the hydrophilic material (15) is wetted (either that the siphon has already been used, or that it has been wetted voluntarily by soaking the device in water, the priming of the siphon is much faster.

Indeed, when the branch (10) is immersed in the liquid, the latter penetrates there and rises to the level (11), expelling the air which was contained therein. This air, escaping through the branch (8) and the pipe (12) carries in it a few drops of water which form columns which accelerate the priming of the siphon. In addition, the time which would have been necessary to wet the hydrophilic material is eliminated since this is already wet.

Under these conditions, the siphon can be primed even under unfavorable conditions.

For example when the level (11) of the liquid is too low compared to the level (30) for priming by capillarity, the siphon can still be primed by immersing the branch (10) partially in water.

In the event of defusing the siphon due to lack of water, this feature allows rapid re-priming as soon as the water level rises sufficiently. This even after several weeks of dryness, because the water contained inside the tube has very little possibility of evaporating.

Variants
The diameter of the tube (9) must be greater than that of the tube (12), because it must contain the hydrophilic material, and moreover contain sufficient vacuum to allow the water to pass when the siphon is primed.

With a too large diameter, the volume of air to be evacuated is large, which increases the priming time.

Too small a diameter reduces the flow.

A good dimension is 10 mm, because it allows the hydrophilic material to be introduced, without tightening too much to let spaces pass.

Indeed, it is advantageous that the hydrophilic material has a diameter slightly smaller than the inside diameter to leave a vacuum promoting a good flow of water when the siphon is in operation.

With a tube (9) with an internal diameter of 10 mm, we carried out the following 2 tests: - With the hydrophilic material of 10 mm in diameter, which therefore completely filled the tube, a pipe (12) of 4 mm in diameter and a difference 80 cm high, the flow is 1.5 liters per hour or 36 liters / day.

- All other things being equal, the 10 mm hydrophilic material is replaced by one 8 mm in diameter, there is then a flow rate of 9 liters per hour, ie 216 liters / day.

Through the transparent tube (9) we see the water circulating in the free space between the tube (9) and the hydrophilic material.

Since it is advantageous, when the siphon is defused, to keep as much water as possible inside the pipes, in order to speed up the re-priming, the tube (9) is closed at its ends by plugs (17) comprising only a hole with a diameter equal to that of the tube (12) (Figure 3).

The self-priming siphon object of the invention is used in many cases where there is a need to bring a liquid contained in a container to one or more other distribution points.

The siphon according to the invention is intended for watering plants, for example from a constant level tank, flush type - the flow rate being adjusted by means of the tap (14) from zero to several hundred liters per day, depending on the amount of plants to water.

Claims (1)

 CLAIM Self-priming siphon characterized by the fact that it consists of an inverted U-shaped tube inside which is hydrophilic material, the U-tube being extended at its downward part by a pipe of appreciably diameter smaller, so that the liquid, by capillary action crosses the high point of the U-shaped tube, then descends to the tube of smaller diameter to form a column which, driven by its weight causes a suction initiating the siphon.