Field of the invention

The invention relates to a device for producing a mixture according to the preamble of claim 1. The invention also relates to a method for producing a mixture according to the preamble of claim 5. in the context of the invention, 'medium' is understood to mean 'liquid or gaseous substance'. In particular, this involves mixing water and a foam concentrate to form a mixture with a desired degree of mixing.

Background of the invention

Many embodiments of devices and methods are known for mixing two or more media into a mixture with a desired degree of mixing, for example mixing a liquid (water) with a foaming agent (foam concentrate) and/or a gas (air) when producing of an (extinguishing) foam. The mixing takes place in a mixing pipe and/or a mixing chamber, whereby use is often made of additional mixing means in the form of fixed or moving parts that provide extra shear forces and turbulence in a flow of the media to be mixed, for instance DE3034622A1 , GB2130910A , US20G3045588A1, US8919745BI, andlJS201712G092A1. The media to be mixed can herein be supplied via lines provided with one or more check valves to a mixing chamber, which may or may not be provided with additional mixing means, for instance CN 108635702 A.

The invention now provides a device for producing a mixture, which device is simpler in construction, more compact and more robust than known devices and in addition has other advantages. The invention also provides a method for producing a mixture by means of such a device, with which method a desired degree of mixing can be achieved efficiently and effectively. Summary of the invention

The invention provides a device according to claim 1. The invention also provides a method according to claim 5. By ‘upstream of and ‘downstream of is meant within the scope of the invention ‘in the direction of passage of the check valve before’ respectively ‘in the direction of passage of the check valve after’. Thus, the shear forces and turbulence generated by the check val ve are used to achieve the desired degree of mixing of the first medium and the second meaium. A mixing pipe and/or a mixing chamber, and possibly additional mixing means in the form of fixed or moving parts, can thus be omitted. The mixing takes place in a limited space which allows for a more compact device.

The invention is further elucidated below on the basis of exemplary embodiments.

Brief description of the drawings

In the drawings: figure 1 shows a first exemplary embodiment of a device according to the invention; figure 2 shows a second exemplar)' embodiment of a device according to the invention; and figure 3 shows a line with a check valve according to the prior art arranged therein.

Further explanation and implementation examples

The device (1) according to the invention shown in figure 1 comprises a first supply line (5) for supplying a first medium (3), here water, a number, here four, second supply lines (6) for supplying a second medium (4), here a foam concentrate, and a discharge line (7) for discharging a produced mixture (2) of the two media (3,4). The device (1) also comprises a check valve (8) comprising a housing (9) and, here two, parts (10) movable relative to the housing (9) for passing a medium flow in a passing direction, here the water (3) supplied through the first supply line (5) and subsequently mixed with the supplied foam concentrate (4), wherein the movable parts (10) are in a first position (solid lines), and for blocking a medium flow in a blocking direction wherein the movable parts (10) are in a second position (dashed lines). According to the invention, the housing (9) is provided on a first side and upstream of the movable parts (10) with a first inlet (11) for letting in into the housing (9) the water (3) supplied by the first supply line (5), provided on a second side and downstream of the movable parts (10) with an outlet (12) for letting out the mixture produced (2) from the housing (9) to the discharge line (7), and provided in the vicinity of the movable parts (10) and upstream of the outlet (12) with, here four, second inlets (13) arranged in the housing (9) for letting in, distributed, into the housing (9) the foam concentrate (4) supplied through the second supply lines (6),

The housing (9) is here provided with a first flange (14) on the first side and a second flange (15) on the second side, The first supply line (5) is here provided with a third flange (16) and the discharge line (7) with a fourth flange (17), wherein the first flange (14) and the third flange (16) are mutually connected in a medium-tight manner, and the second flange (15) and the fourth flange (17) are mutually connected in a medium-tight manner. The whole of the check valve (8) with flanges (14,15) is thus interchangeable with an existing check valve (8') with flanges (14', 15') as shown in figure 3. A line with a built-in check valve (S') according to the prior art, can thus be easily converted to a device (1 ,1 ' ) according to the invention.

Producing the mixture (2) of water (3) and the foam concentrate (4) comprises supplying the water (3) through the first supply line (5), supplying the foam concentrate (4) through the second supply lines (6), and discharging the produced mixture (2) through the discharge line (7). According to the invention, the production also comprises letting in, at the first side of the housing (9) and upstream of the movable parts (10), through the first inlet (11) into the housing (9) the water (3) supplied through the first supply line (5), letting out the mixture (2) from the housing (9) to the discharge line (7) on a second side of the housing (9) and downstream of the movable parts (10) through the outlet (12), and letting the foam concentrate (4) supplied by the supply lines (6) into the housing (9) in the vicinity of the movable parts (10) and upstream of the outlet (12) through the second inlets (13), distributed, which achieves an even better mixing of the water (3) and the foam concentrate (4). The shear forces and turbulence generated by the check valve (8) are thus used to achieve a desired degree of mixing.

The device (1') according to the invention shown in figure 2 is largely the same as the device (1) shown in figure 1. Here, the first flange (14) and the second flange (15) together with a jacket (18) provided for this purpose now form a chamber (19) which is connected to the second inlets (13). The chamber (19) is herein provided with a third ineet (20) for letting in into the chamber (19) the foam concentrate (4) now supplied through only one second supply line (6). Thus, the foam concentrate (4) can be let in into the chamber (19) through the third inlet (20) and let in from the chamber (19) through the second inlets (13) in the vicinity of the movable parts (10) into the housing (9), distributed, which achieves an even better mixing of the water (3) and tire foam concentrate (4).

According to the invention, the surface of the two movable parts (10) can be provided with, for example rib-shaped or conical, projections (not shown) for generating even more shear forces and turbulence, resulting in even better mixing of the water (3) and the foam concentrate (4).

Preferably, the two movable parts (10) are urged from the first position (solid lines) to the second position (dashed lines) by means of urging means (not shown) provided for this purpose. According to the invention, the geometry of the check valve (8) and the degree of urging by the urging means can be tuned to such a relation between the pressure drop across the check valve and the position of the two movable parts (10), and thus the flow resistance of the check valve (8) and the flow rate and flow velocity differences in the medium flow, that a desired amount of turbulence and shear forces in the medium occurs in the check valve (8), both at lower and higher pressure drops and flow rates, and thereby a desired degree of mixing of the water (3) and the foam concentrate (4) is achieved.