The present invention relates to a method for local ventila¬ tion of printing machines or similar machines where poison¬ ous vapours or polluting gases appear or are produced, and wherein air is admitted at one side of the machine and wherein a removal of poisonous vapours and polluted air ta¬ kes place at the opposite side of the machine.

In local ventilation, for example at printing machines where poisonous vapours or polluting gases are produced or appear, exhaustion arrangements similar to vapour-hoods are most of¬ ten used, that is arrangements wherein an exhaust funnel connected to a ventilation system is mounted over the pol¬ luting machine.

As naturally the exhaust funnel must not get in the way of the machine operator, the exhaust funnel is placed at some distance over the machine which means that the exhaust sy¬ stem works effectively only if an extra large exhaust capa¬ city is put to work, that is an extra large exhausted amount of air per unit of time. Yet in practice it is often seen that the exhaust funnel is swung aside permanently to faci¬ litate access to the machine. Moreover such a compromise in¬ volves rather large general supplementary costs of heating and eventually cleaning the supplementary air which must be admitted to the site instead. Such an extraneous consumption of local ventilation will also lead to draught inconvenien¬ ces and generally affect the interior climate significantly. These circumstances in practice most often mean that for reasons of economy an insufficient exchange of air is put to work such that local ventilation becomes insufficient also.

It is a purpose of the invention to provide a method for lo¬ cal ventilation of the kind mentioned initially, and by means of which a significantly improved local ventilation may be attained in a simple and economical way.

The method according to the invention is distinctive in that the admission of air takes place in a directed and active way by means of one or more nozzles, and that the removal of poisonous vapours and polluting air takes place by means of one or more exhaust openings which are placed opposite the said supply nozzles - at a distance therefrom. Thus particu¬ larly as a result of the fact that the admission of air ta¬ kes place actively and in a directed way - a very signifi¬ cantly improved local ventilation is attained wherein it be- comes possible to remove poisonous vapours etc. very close to the source, the method according to the invention utili¬ zing an actively controlled curtain of air which is guided closely past the position or positions where poisonous va¬ pours etc. appear or are produced and which then is exhaus- ted at the opposite side of the machine together with the poisonous vapours etc. In fact because of the application of a removal of ^* the poisonous vapours etc. very closely to the source, a minimum of air can be applied which means a corre¬ sponding reduction of the costs of heating and eventually cleaning the replacement air. Still an additional and maybe a most significant advantage of the invention is the fact that-for the operator, operation access to the machine is not affected at all.

For use at a printing machine it can be expedient in connec- tion with the method according to the invention that the ad¬ mission of air is effected by means of a number of nozzles which at one side of the machine are placed in line prefe¬ rably along the front, back and top thereof, and which are adapted to direct air into, along and around the zone of the machine where poisonous vapours appear, and that the removal of polluting gases is effected by means of a number of ex¬ haust openings which are placed, preferably opposite the supply nozzles, at the opposite side of the machine and pre¬ ferably in line along the front, back and top thereof with a view to effective exhaustion of poisonous vapours etc. from the said zone.

The invention also relates to a system of apparatus for use in the method according to the invention, that is for local ventilation, particularly at a zone of a printing machine where poisonous vapours or gases are produced or appear, and comprising an air supply duct, adapted for placement at a side of the said zone, with a number of air supply nozzles, an air exhaust duct, adapted for placement at the opposite side of the zone, with a number or air exhaust openings, and ventilator means adapted for supplying, respectively exhaus- ting air, the system of apparatus being distinctive in that the air supply duct is adapted to extend along a side edge area of the zone, that the air supply duct comprises a large number of air supply nozzles which preferably are adapted for individual alignment of the direction of the air jet, that the air exhaust duct is adapted to extend along an op¬ posite side edge of the zone, and that the air exhaust duct comprises a large number of air exhaust openings which pre¬ ferably are placed opposite the air supply nozzles - at a distance therefrom.

For use for example at a printing machine the system of ap¬ paratus according to the invention may with particular ad¬ vantage be employed in such a way that the air supply duct, at the side of the machine as first mentioned, is adapted to extend along edge areas of the front, back and top thereof, that the air supply nozzles are formed and placed in such a way that the air supplied by the individual nozzles can be led into, along and around the said zone, and that the air exhaust duct and openings at the opposite side of the machi¬ ne are adapted to extend along edge areas of the front, back and top thereof with a view to effective exhaustion of poisonous vapours etc from the said zone.

And preferably the air supply ducts are provided with a num¬ ber of mounting holes for air supply nozzles formed as pre¬ fabricated nozzle members preferably of plastics material, the said nozzle members are adapted for individual alignment at the final step of fabrication or at assembly, namely by

angular adjustment or rotation of the nozzle channel itself which opens up into a spherical nozzle head, and the mentio¬ ned nozzle member is adapted to be removably attached in the said mounting holes.

In special situations it may moreover be advantageous that the air supply duct, at a side facing the machine, comprises an air guiding plate, and that the nozzle channels of the air supply nozzles are turned angularly toward the air guid¬ ing plate, that is to say that the air guiding plate can constitute an additional guiding surface for the air curtain mentioned earlier.

Moreover it can be expedient that nozzle members as mentio¬ ned with no nozzle channel may form a blind plug for moun¬ ting in the said mounting holes, for example opposite of protruding machine parts.

In the following the invention will be more closely explain¬ ed with reference to the drawing, wherein:-

Fig . 1 is a perspective view of a printing machine with an embodiment of a system of apparatus according to the inven- tion.

Fig. 2 illustrates the principle of ventilation according to the invention.

Fig. 3 shows an alternative ventilation system according to the invention, and

Fig. 4 is a side view - part in section - of a detail at a system of apparatus according to the invention.

The printing machine 2 as shown in Fig. 1 comprises to ma¬ chine consoles 4 and 6 of which the machine console 4 at the left represents the front of the printing machine, that is the side from which the printing unit θ is operated. The

printing unit 8 as shown comprises an inking unit and a num¬ ber of printing cylinders which in operation constitute wet surfaces consisting amongst others of organic solvents, that is a source of poisonous vapours etc.

An arrow 10 shows the feed direction of the printing shop machine. At the inner side of the machine console 4, along outer front, back and top edges thereof, an air supply duct 12 adapted for the machine console 4 is mounted, with a lar¬ ge number of air supply nozzles 14 (Fig. 4) which then are mounted at the side of the air supply duct 12 which faces the printing unit 8. At the top the air supply duct 12 is provided with a fan 16 which collects air from the room, cf. the arrow 18, and which via the air supply nozzles 14 sees to the admission of air inward along the affected surfaces of the printing unit 8, the nozzle channels 20 (Fig. 4) of the individual air supply nozzles being individually aligned with regard to both the actual angle of the nozzle channel 20 and to the actual angular pitch that the nozzles 14 are mounted with in the air supply duct 12. Correspondingly, at the inner side of the machine console 6, along front, back and top edges thereof, an air exhaust duct 22 adapted for the machine console 6 is mounted, with a large number of air exhaust openings which are not shown, but which in principle are placed opposite of the air supply nozzles 14 - only at ^• the opposite side of the printing unit 8. At the top the air exhaust duct 22 is provided with an exhauster stub 24 inten¬ ded for connection to an exhaust system which can be common for a number of printing units 8 or a number of printingshop machines .

In the method, respectively the system of apparatus accor¬ ding to the invention it is the aim to attain the highest air velocity (entrain ent speed) in the immediate vicinity of the surfaces of the printing unit, and this is attained most optimally by means of the aligned nozzles 14 which are mounted at the operator side of the printing machine, that is by guiding an air current or an air curtain inward

against and along the surfaces of the printing unit 8. The air current or air curtain thus will entrain poisonous va¬ pours etc. along the surfaces of the printing unit and to¬ wards the opposite side of the machine for active exhausti- on.

By removing the pollution of air immediately at the surfaces of the printing unit, that is where the concentration of poisonous vapours etc. is largest, two main advantages are primarily achieved; the poisonous vapours etc. do not escape into the area immediately around the machine where the ope¬ rator is often present and has his breathing zone, and the polluted air does not escape into the premises to contribute to the general pollution of the air on the premises. The ad¬ vantage first mentioned may not be achieved by means of a traditional exhaustion, for example a "vapour hood" over the machine, as the poisonous vapours etc. which do not escape to the sides or downward will pass through the breathing zo¬ ne of the operator in an ascending direction. In practicing the invention one can moreover work with a generally smaller amount of air exhausted than when using traditional systems which in turn leads to lower costs of installation, lower consumption of electricity for driving fans and lower con¬ sumption of energy for heating replacement air.

In fig. 2 the principle of the ventilating method according to the invention is shown. At the left the air supply duct 12 with the air supply nozzle 14 is found again - and at the right the air exhaust duct 22 and the exhaust connection 24. The solid-line arrow 26 illustrates the poisonous va¬ pours etc., that is the pollution, and the lateral arrows 28 illustrate how the entrained surrounding air virtually en¬ capsulates and entrains the pollution 26 towards the exhaust duct 22, the air current or air curtain as a whole being shown at 30.

In connection with the invention, the system shown in Fig. 1 with a separate fan 16 connected directly to the air supply

duct 12 and with a common exhaustion at the secondary side is preferably used; but as shown in Fig. 3 it may be possib¬ le to use a principle wherein a common fan or blower 32, a branch pipe 34 and a pressure regulator or choke valve 36 is used, a relatively small portion of exhausted air being di¬ verted beyond the fan 32 and is reused as air to supply via the branch pipe 34, the necessary pressure for blowing-in via the branch pipe 34 being attained by choking at the pressure regulator 36.

Polluted air present between the air supply duct 12 and the exhaust duct 22 is entrained and led away via the latter, an air velocity sufficient to guide polluted air to the exhaust duct 22 being attained by means of blown-in air from the nozzles of the air supply duct. The polluted air is drawn through the fan 32 and, for the sake of the greater part, discharged via the pressure regulation 36. With a suitable arrangement of the air supply duct 12 and corresponding nozzles, an air pressure of the order of magnitude of 200 Pa will be sufficient for effective ventilation. Thus the sy- stem is suitable for use in connection with common fans of low-pressure, mediumpressure and high-pressure types (va¬ cuum), and only minimal amounts of recycled air will be able to escape into the surroundings.

Likewise, in the system of apparatus shown in Fig. 1, a blow-in pressure of the order of magnitude of 200 Pa is used, and preferably nozzles of the kind shown in Fig. 4 are used which are manufactured from plastics material by injec¬ tion moulding, the nozzle member 38 itself being prefabrica¬ ted, though, before the nozzle channel 22 is shaped. As in- dicated the nozzle channel 22 can be formed in the nozzle member 38 with an angular inclination between the inclined axes 40 shown. And when mounted in side openings 42 of the air supply duct 12 the nozzle members may additionally be given a suitable angular pitch. Without a nozzle channel 22 the nozzle members 38 serve as blind plugs for use in plug-

ging side openings 42, for example in front of protruding parts of a printing machine.

The plastics nozzles 14 are very easily mounted in the cir¬ cular side openings 42 of the air supply duct 12, and dis- mounting the nozzles 14 is also effected easily - but the nozzles 14 will most often be destroyed thereby; it will be of no importance, however, if a few nozzles are destroyed, as precisely the nozzles can be manufactured as a very cheap volume product,.

Additionally it should be mentioned that also the individual nozzle channels 22 of the nozzles 14 can be individually ad¬ justed regarding the actual diameter of the nozzle channel 22. It may for example be expedient to adjust the diameter of the nozzle channel at neighboring nozzles to plugged nozzle positions - in froint of protruding machine parts; but also in situations where an extra high concentration of poisonous vapours occurs locally in a printing machine it will be appropriate to intensify the airflow additionally by adjustment of the diameter of the nozzle channel. As a whole practicing the invention involves working with an individual adaptation of the nozzles 14 as to both direction and capa¬ city .