A nozzle 20 has a fluid flow passage 26 which defines a fluid flow path from an inlet 5 end of said passage towards an outlet end of said passage. A restrictor 29a is movable under the control of an actuation system 27 relative to the passage to vary the minimum cross-sectional area of the fluid flow path through the passage. The restrictor 29 is moved to project into the passage to provide a restricted opening in the passage or removed from the passage to allow an unrestricted flow through the 10 passage. The nozzle 20 is particularly suitable for use in a beverage preparation machine to generate microfoam in a beverage. When the restrictor 29 is retracted from the passage 29, the passage and the restrictor can be cleaned by flushing the nozzle. The restrictor 29 may be a pin-like member aligned with the passage and moveable parallel to the axis of the passage.

A mixing apparatus is described. The mixing apparatus has a first port for receiving milk, a second port for receiving steam, and a mixing chamber for mixing the milk, the steam, and air. A channel arrangement connects the first port and the second port, and defines an air intake channel which leads to a frothing section. The mixing apparatus is designed such that, in use, the frothing section fills sufficiently with steamed milk that has a direct path from the second port to the mixing chamber is interrupted by the steamed milk. This provides a noise reduction during use of the mixing apparatus. A flow reducing means, such as a barrier, may be used for this purpose.

A mixing apparatus is described. The mixing apparatus has a first port for receiving milk, a second port for receiving steam, and a mixing chamber for mixing the milk, the steam, and air. A channel arrangement connects the first port and the second port, and defines an air intake channel which leads to a frothing section. The mixing apparatus is designed such that, in use, the frothing section fills sufficiently with steamed milk that has a direct path from the second port to the mixing chamber is interrupted by the steamed milk. This provides a noise reduction during use of the mixing apparatus. A flow reducing means, such as a barrier, may be used for this purpose.

A bag for producing a foam-in-bag dunnage material comprises a closed edge portion and, in a non-sealed state of the bag, an open edge portion, the closed and open edge portions delimiting an inner bag volume. The invention proposes that a bag structure of the bag comprises a mixing chamber which is adapted to receive foam precursor substances, which is arranged within the inner bag volume, which is at least partially and initially delimited against the remainder of the inner bag volume, and which in the non-sealed state of the bag is connected to the open edge portion.

A bag for producing a foam-in-bag dunnage material comprises a closed edge portion and, in a non-sealed state of the bag, an open edge portion, the closed and open edge portions delimiting an inner bag volume. The invention proposes that a bag structure of the bag comprises a mixing chamber which is adapted to receive foam precursor substances, which is arranged within the inner bag volume, which is at least partially and initially delimited against the remainder of the inner bag volume, and which in the non-sealed state of the bag is connected to the open edge portion.

A foam production method includes mixing liquid nitrogen with a foaming material to produce foam. A gas is produced in situ from liquid nitrogen. As the ratio of the volume of the gas produced by gasification of liquid nitrogen to the volume of the liquid nitrogen is relatively high, when a large gas supply flow is needed to generate a large foam flow, a liquid nitrogen storage device of a small volume can be used instead of bulky air supply devices such as high-pressure gas cylinders, air compressors, air compressor sets and the like, reducing the volume of the air supply device. In addition, the liquid nitrogen used in foaming will release nitrogen gas after the foam blast, such that the nitrogen is also able to inhibit combustion on the surface of burning materials, accelerating the extinguishing of the fire.

A foam production method includes mixing liquid nitrogen with a foaming material to produce foam. A gas is produced in situ from liquid nitrogen. As the ratio of the volume of the gas produced by gasification of liquid nitrogen to the volume of the liquid nitrogen is relatively high, when a large gas supply flow is needed to generate a large foam flow, a liquid nitrogen storage device of a small volume can be used instead of bulky air supply devices such as high-pressure gas cylinders, air compressors, air compressor sets and the like, reducing the volume of the air supply device. In addition, the liquid nitrogen used in foaming will release nitrogen gas after the foam blast, such that the nitrogen is also able to inhibit combustion on the surface of burning materials, accelerating the extinguishing of the fire.

An insert assembly for a foam generating device includes a first insert and a second insert with a channel defined therethrough. Inserts may be formed by two shell halves that are coupleable to one another to define the channel. A plurality of ribs extends along an interior surface of the channel. Pad structures defined by porous media are provided in the channel and gripped by the plurality of ribs. The pads receive cleaning solution passing through the channel and cause foam to be generated by breaking-up the cleaning solution and agitating. The ribs may be arranged horizontally relative to a longitudinal axis of the insert assembly and retain the pads within the device. Inserts may be arranged in series along a longitudinal axis of the foam generating device with the pad structures arranged within the channel.

An insert assembly for a foam generating device includes a first insert and a second insert with a channel defined therethrough. Inserts may be formed by two shell halves that are coupleable to one another to define the channel. A plurality of ribs extends along an interior surface of the channel. Pad structures defined by porous media are provided in the channel and gripped by the plurality of ribs. The pads receive cleaning solution passing through the channel and cause foam to be generated by breaking-up the cleaning solution and agitating. The ribs may be arranged horizontally relative to a longitudinal axis of the insert assembly and retain the pads within the device. Inserts may be arranged in series along a longitudinal axis of the foam generating device with the pad structures arranged within the channel.

A turbine system includes a foam generating assembly having an in situ foam generating device at least partially positioned within the fluid passageway of the turbine engine, such that the in situ foam generating device is configured to generate foam within the fluid passageway of the turbine engine.