WO2019180198A1

WO2019180198A1 - Fume hood

Info

Publication number: WO2019180198A1
Application number: PCT/EP2019/057227
Authority: WO
Inventors: Jürgen Liebsch
Original assignee: Waldner Laboreinrichtungen Gmbh & Co. Kg
Priority date: 2018-03-23
Filing date: 2019-03-22
Publication date: 2019-09-26
Also published as: EP3768443A1; EP3768443B1; DE102018107016A1; ES2973009T3

Abstract

The present invention relates to a fume hood (1), comprising: a housing (10) which defines a working space (19), the housing (10) having a movably mounted front pane (14) on its front side; a work surface (20) which delimits the working space (19) on the bottom side; and an ionisation electrode (100) which is located in an inflow profile (102) located on the front edge of the work surface (20). The fume hood according to the invention also comprises an arm support (40) which is located in the region of the working opening (11) and at a distance from the inflow profile (102), wherein the arm support (40) extends along its longitudinal direction substantially over the entire width of the weighing fume hood (1) and has end faces, and wherein a side wall (15), which laterally defines the working space (19), a face of the armrest (40), and the inflow profile (102) are connected to a one-piece corner profile (50), wherein the side wall (15), a face of the armrest (40), and the inflow profile (102) are inserted into said corner profile (50).

Description

fume hood

The present invention relates to a fume hood.

Fume hoods are an integral part of laboratories. All laboratory work involving the handling of gases, vapors, suspended solids or liquids in hazardous amounts and concentrations must be carried out in laboratory fume cupboards to protect laboratory personnel. For this purpose a variety of fume hoods, such as. Standing hoods or table hoods, have been developed, the common feature of which is provided at the front of the fume hood sash, which can be moved in the vertical direction from a closed position to an open position. In the closed position, the sash closes the working space provided inside the fume cupboard to prevent leakage of the sometimes dangerous substances from the working space for the laboratory personnel.

However, the weighing process of pharmaceutically active or toxic substances must also be carried out by the laboratory staff in fume cupboards, so-called weigh-in weighings. Because the weighing process, in which such substances are handled "open" and using High-resolution scales (resolution of up to 0.001 mg) pose a significant risk, since particles invisible to the naked eye, the size of which is in the micrometer or nanometer range, are released airborne by such substances and can reach the laboratory personnel via the air. For this reason, weighing systems have a ventilated and ventilated working space accessible from the front for the laboratory worker via a working opening. In a sitting or standing position, the lab assistant introduces his forearms into the workspace, usually laying them on an armrest, handling the laboratory utensils and substances on the worktop. Such utensils include the high-resolution laboratory balances already mentioned above, but also containers in which the various substances to be portioned are located, and other tools such as a spatula to retrieve the substances from the container and place them in a weighing boat on the laboratory balance. After weighing the substances, these are optionally transferred to another container.

In laboratory fume hoods, the handling of powdery substances as a result of electrostatic effects may lead to adhesion of the powdery substances on the non-conductive surfaces of the fume hood as well as on the surfaces of the experimental equipment set up in the working space. This problem occurs especially with small particles whose diameter is in the micrometer or nanometer range.

The adhesion of these powdered particles can greatly affect the working process, for example, this can make weighing processes a highly accurate weighing of substances impossible. In addition, adherent particles increase the risk of carryover on the clothing of the laboratory fume lab personnel. It is therefore an object of the present invention to obviate, at least minimize, the disadvantages of the prior art and, moreover, to obtain advantages not attainable with conventional fume hoods. In particular, the object of the present invention is to further increase the safety of the laboratory staff when working with a fume hood and to further improve the accuracy of any weighing processes.

This object is achieved by the combination of features of independent claim 1. Optional or preferred features are given in the dependent claims.

According to the invention, a fume hood comprises a housing which defines a working space, the housing having on its front side a movably mounted front screen, a worktop which bounds the working space on the bottom side, and an ionizing electrode arranged in an inflow profile arranged on the front edge of the worktop is. Furthermore, the fume hood comprises an armrest, which is arranged in the region of the working opening and spaced from the inflow, the armrest along its longitudinal direction extends substantially over the entire width of the weighing trigger and has end faces, and wherein in each case a side wall, the side of the working space determines each one end face of the armrest and the inflow are connected to a one-piece corner profile. The side wall, one end face of the armrest and the inflow profile are inserted into the corner profile.

According to a preferred embodiment of the invention, the fume hood is a weighing tray for weighing pharmaceutically active or toxic substances in a laboratory, the normal Use has an always open work opening below the windshield, and wherein the windshield is rotatably connected to an upper part of the housing, such that the windshield is pivotable from an open position to a closed position.

Preferably, the windshield is a movable in the vertical direction from an open position to a closed position sash, which closes the working space in the closed position.

According to a further preferred embodiment of the invention, the ionization electrode is detachably inserted into the inflow profile. Preferably, the ionization electrode can be mounted in the inflow profile without tools.

According to a preferred embodiment of the invention, the inflow extends over the width of the worktop.

Preferably, the ionization electrode is flush with the surface used in the inflow.

More preferably, the ionization electrode extends over at least 75% of the width of the inflow profile.

Preferably, the fume hood further comprises a support carrying the weight of the housing, the worktop and the armrest, wherein the corner profile is additionally connected to the carrier. More preferably, the carrier is inserted in the corner profile.

The invention will now be described purely by way of example with reference to a preferred embodiment with reference to the accompanying drawings. From the figures show:

Fig. 1 is a front perspective view of a conventional fume hood;

FIG. 2 shows a sectional view along the section line A-A shown in FIG. 1; FIG.

Fig. 3 is a perspective view of a corner profile of the trigger shown in Figure 1;

4 shows a cross section perpendicular to the x-direction through a corner profile according to an embodiment of the invention; and

Fig. 5 is a perspective view of an ionization module according to an embodiment of the invention.

For better understanding of the figures and their sectional views and the corresponding description of the figures, a Cartesian coordinate system has been drawn in some of the figures. Unless stated otherwise, the x direction refers to the width extension, the y direction to the depth extension and the z direction to the vertical extent of the fume hood. Although all of the aspects described here relate to a weighing fume hood, they can also be used in a fume hood which has on its front side a sash that can be moved vertically from a closed position to an open position, via which in the open position the work space within the fume cupboard. In the closed position, the sash prevents access to the working space.

In addition, all of the aspects described here are described in connection with a weighing trigger, which is operated in recirculation mode. These aspects can also be used with a weighing siphon that is operated in the exhaust air mode. The same applies to a fume hood of the type mentioned above.

Although in the following description of exhaust air is mentioned, so that is the air meant, which is removed from the working space of the weighing fume hood and then fed to an exhaust air filter system for cleaning purposes. Even with a weighing fume hood, which is operated in the exhaust air mode, that is, one which is connected to a building-side exhaust air system, air must be removed from the work space before it is discharged into the atmosphere on the building side. Thus, the only difference is that in the embodiment described here, the exhausted and filtered exhaust air is re-supplied to the laboratory space in which the weighing fume hood is installed, while in an exhaust-operated weighing fume exhaust air through a building-side installed exhaust duct into the atmosphere is blown out.

In addition, it should be noted that some of the aspects described here are also true for a closed insulator or Containment system can be used. An isolator or containment system is a trigger, on the front side of which two openings are provided, which are tightly sealed on the inside within the working space by means of two gloves mostly made of rubber. The laboratory assistant, so to speak, grabs his hands through the openings and immediately slips over his work gloves.

The weighing tray 1 illustrated in FIG. 1 preferably comprises essentially the following components: a housing 10, a work surface 20, a carrier 30, an arm rest 40, a filter system 60, a ventilator 70 and an outlet 90, which preferably has a hose 80 is connected to the fan 70.

The carrier 30, which is preferably designed as a table frame, comprises in the embodiment shown here four legs 31, whose bottom end is provided in each case with a leveling not described in detail. This leveling is advantageous if the floor on which the weighing tray 1 is placed has any unevenness, so that with the help of one or more leveling a shaking of the entire trigger 1 can be avoided.

For stability reasons, the legs 31 are connected to one another by transverse struts 32, which extend either along the width (X-direction) and / or along the depth (Y-direction). On the support 30 supports a worktop 20. This can be achieved by a 3-point storage or by a 4-point storage. Likewise, the housing 30 is located on the support 30. Thus, the support 30 carries the weight of the housing 10, the worktop 20 and the armrest 40. In the embodiment shown in Fig. 1 carries the carrier 30th preferably in addition the weight of the exhaust air or circulating air filter system 60 and the fan 70 and the tube 80th

The housing 10, which defines a working space 19, comprises on the rear side of the working space 19 a double-walled 16a, 16b designed rear wall 16. Within the double-walled rear wall 16 is a cavity 16c (FIG. 2), through which the exhaust air in the direction of the exhaust air filter system 60th to be led. The housing 10 has as a lateral boundary two side walls 15 and at the front and top, a top 12 and a hinged front glass 14. The side walls 15, which may also serve as a lateral cover of the rear wall 16, and the upper part 12 are fixed connected to the rear wall 16 (16 a or 16 b), while the front screen 14 is pivotally or rotatably connected by means of preferably a hinge 13 with the upper part 12.

In Fig. 1, the windscreen 14 is shown in the closed position. However, it can be pivoted from this closed position into an open position, whereby any utensils required in the weighing tray can be introduced into the working space 19 and placed on the worktop 20. Such utensils include, for example, high-resolution laboratory carts, containers in which substances to be weighed are contained, as well as other containers into which an already weighed substance is finally transferred. Furthermore, smaller items such as work gloves, spatulas, weighing boats, and the like are normally used in such weigh-ins.

Below the pivotable windshield 14, a work opening 11, which is always open during the intended use of the weighing trigger 1, is arranged. Through this work opening 11 receives the Laboratory workers Access to the workspace 19. Normally, the laboratory worker is in a sitting position in front of the weighing trolley 1, the seating position being set so that the work opening 11 is at the level of the laboratory worker's slightly angled forearms, thus ergonomically performing work in the work space 19 can. In this sitting position, he observes through the transparent windshield 14 to be executed by him workflows. In order to allow a good all-round view of the events in the working space 19, the side walls 15 and the upper part 12 are preferably transparent. Preferably, the front panel 14, the upper part 12 and the side walls 15 are made of acrylic glass.

In order to give the laboratory worker a reflection that is as free from reflection as possible on the working device and utensils located on the work surface 20, which in turn contributes to fatigue-free working with the weighing trigger 1, the front pane 14 is convexly curved, as can be seen in FIG. Preferably, the radius of curvature is constant, so that the contour of the front screen 14 corresponds to a circle segment. Preferably, the upper part 12 is also convexly curved. The radius of curvature of the front screen 14 preferably corresponds to the radius of curvature of the upper part 12.

In order to facilitate the opening of the windshield 14, the lower edge of the windshield 14 has a bead which is preferably round in cross section (Y direction). This bead is in closed windshield 14 on a relative to the side wall 15 enlarged and arranged at the front edge vertical column 17 of the same diameter, which has a convex recess at its upper end, in which the bead of the windshield 14 comes to rest. In other words, the convex curvature of the bead at the lower edge of the windshield 14th corresponds to the curvature of the concave recess at the upper end of the vertical column 17 of the side wall 15th

In the area of the work opening 11 is an armrest 40, which could also be referred to as inflow with combined Armauflagefunktion, provided on the laboratory staff can hang up his forearms during his work, so he can perform his work as fatiguously and with a steady hand. The armrest 40 extends almost over the entire width (x-direction) of the working space 19. On the armrest 40 and integrated in this there is a control and / or display panel 42 through which the laboratory staff can operate important functions of the weighing 1 and / or indicates the laboratory staff important operating states of the weighing deduction 1.

In Fig. 1 hardly recognizable, an air passage between the underside of the armrest 40 and the worktop 20 is provided. Due to this air access, room air or ambient air can flow into the working space 19 due to the negative pressure prevailing in the working space 19. In addition, caused by the incoming air in the area of the front edge of the worktop 20, that also located in the vicinity of the surface of the worktop 20 moves air and transported back towards the rear wall 16 in which slot-shaped openings (not shown) becomes. Thus, so to speak, bottom air jets are produced along the worktop 20, which help to remove heavy gases or aerosols in the area of the worktop 20. By virtue of this additional supply air, the later-described fan 70 must apply less suction power to ensure the same retention capacity. In order to allow the supply air to flow as low as possible into the working space 19 through the gap between the armrest 40 and the worktop 20, the front edge of the worktop 20 is flow-optimized and convex. But also the armrest 40 is designed on its bottom side facing the work surface 20 and at its upper side facing the working opening 11 to optimize flow. As can be seen in FIG. 2, the cross-sectional profile of the armrest 40 corresponds to an airfoil profile. As a result, not only the ambient air through the air passage below the armrest 40, but also the ambient air through the work opening 11 as far as possible without turbulence and as laminar flow into the working space 19 during operation of the weighing trigger 1.

1 also shows a disposal system integrated in the working plate 20, which is indicated in FIG. 1 and FIG. 2 merely by means of a cylindrical connecting piece 21. For this purpose, a flush to the working space 19 with the work surface 20 and downwardly in the direction of the support 30 outstanding connection piece 21 is integrated into the worktop 20. By thus resulting, preferably closable with a removable lid opening when working in the weighing deduction waste materials, such as packaging material or work gloves, ergonomically favorable and safe from movement can be safely disposed of by utilizing gravity from top to bottom. Since such waste usually come into contact with the manipulated in the working space 19 toxic substances, they must be disposed of contamination within the working space 19 and may not be removed from the working space 19 through the working opening 11 or even through the raised windshield 14 and with the other in the laboratory accumulating waste to be disposed of. The downstairs outstanding connection piece 21 is provided on its outer contour with a plurality of annular grooves which serve for the attachment of waste bags (not visible in the figures) made of plastic by means of O-rings. The garbage bags can be designed as individual bags with closed bottom or as a continuous liner. During the change process, the garbage bags are sealed twice with a crimping tool or another tool, so that the waste materials, which can sometimes also contain vapors and aerosols, can neither escape from the removed garbage bag nor from the discharge interior 19.

As shown in FIG. 1, corner profiles 50 each connect a side wall 15 and an end of the armrest 40 to the carrier 30 and one of the legs 31, respectively.

Similarly, the lower edge of the side wall 15, which is preferably made of acrylic glass as the upper part 12 and the front panel 14, in a profile 18, which is preferably made of metal, edged. This profile 18 is in the mounted state on the underlying cross member 32.

It can also be seen in FIG. 1 that the work surface 20 has an edge-side elevation or bead. This bead, which is provided here without reference numerals, preferably runs around the entire circumference of the worktop and prevents the accidental spillage of toxic or chemical reactions triggering liquids or powders that can not pass over the edge of the worktop 20, but rather on the worktop 20 remain.

The worktop 20 is preferably constructed monolithically and preferably made of a technical ceramic. The weight of Worktop 20 is preferably (including, depending on size) in a range of 40 kg to 60 kg. To seal the working space 19, an elastic joint seal between the work surface 20 and the rear wall 16 and between the work surface 20 and the side walls 15 is provided both edge on both side edges and on the back.

The ambient air entering the working space 19 both through the passage of air between the armrest 40 and the work surface 20 and through the work opening 11 is introduced into the cavity by means of the fan 70 through slots (not shown) provided in the wall element 16b 16c of the rear wall 16 sucked. As can be seen in Fig. 2, the thus extracted air passes through an opening 16d in a preferably tubular connecting flange and then in the filter 62. After the exhaust air has been cleaned by the filter 62, it flows through an opening 69 in the Exhaust air filter housing 65 down in the direction of fan 70, through the hose 80 and exits through the outlet 90 in the laboratory space (Fig. 1) ·

All components of the exhaust air filter system 60, the fan 70, the hose 80 and the outlet 90 are preferably arranged below the worktop 20. All of these components of the weighing trigger 1 can preferably be fastened to the carrier 30 or to a downwardly extending extension of the rear wall 16 (FIG. 1).

Referring again to FIG. 1, a light source is provided for illuminating the work surface 20 and more preferably the entire working space 19, which is preferably arranged in the hinge 13. The light source illuminates the relevant for all workflows part of the working space 19 and completely the worktop 20. The hinge 13 has a three-piece, preferably cylindrical body, which more preferably has a constant diameter over the entire length (x-direction) of the hinge 13. As can be seen in FIG. 1, the hinge 13 is cantilevered and rotatably couples the windshield 14 to the upper part 12. The upper part 12 and the windshield 14 are connected to the hinge 13 via adjustable non-positive clamping connections. Because the clamping force is adjustable, the mounting of the weighing tray 1 is significantly facilitated.

Integrated in the hinge 13 is at least one light source which preferably comprises at least one LED strip, which preferably extends over at least 75% of the width or length (x direction) of the hinge 13. Preferably, two LED bands are provided, the color temperature mixed and, depending on the requirement, a different Kelvin number (color temperature) may have. Preferably, one of the LED bands has a color temperature of 3000 K, while the other LED band has a color temperature of 6000 K. By mixing the colors of the two LED strips, different color temperatures can be produced in the working space 19 in this manner, for example warm white (3000 K), neutral white (4500 K) or daylight white (6000 K).

Such defined color temperatures are required, for example, in the color detection of drug substances. Usually, the color of the drug substance to be weighed is compared with a calibrated color chart at a defined light temperature to determine the color of the drug substance. The light source or preferably at least one LED strip is encapsulated in a light-transmitting protective cover, which is preferably made of plastic. On the one hand, a chemical protection against aggressive substances that are handled in the working space 19 is achieved. But also a cleaning and decontamination of the working space 19 is facilitated, since the risk of a short circuit of the standing under electrical light source is avoided.

Not shown in the figures is a preferred rotary brake contained in the hinge. Preferably, and depending on the weight of the windscreen 14, a plurality of rotational brakes may be provided. By such a rotation brake causes an open windscreen 14 independently and brakes can move back to the closed position and not just fall down, which can lead to any damage or injury to the operator.

Also not shown in the figures is an angle limiter, which limits the opening angle of the front screen 14 upwards and thus determines the maximum open position of the front screen 14. This angle limiter is similar to a stop and is preferably adjusted so that the maximum open position of the windshield 14 is the one in which the windshield 14 can remain in an unstable equilibrium. Alternatively and further preferably, a detent (not shown) may be provided, which locks the front screen 14 in the maximum open position.

The worktop rests on a resilient element and has no direct contact with any component of the carrier 30, the rear wall 16 and the armrest 32. Thus, the worktop 20 is completely shock and vibration decoupled, so that any contact of the laboratory staff with a component of the weighing deduction, for example with the armrest 40 and the front screen 14, have no effect on any weighing results. Also, vibrations that may be caused by the fan 70 and continue through the exhaust air filter system 60 and the rear wall 16 are thus not transferred to the work surface 20. Likewise, the worktop 20 is decoupled from any building vibrations. Namely, should the laboratory in which the weighing tray 1 is installed, be located in a higher floor in which building vibrations occur more pronounced, by selecting a resilient element with a lower damping constant, for example, a gas spring, the worktop 20 completely of such building vibrations be shock and vibration decoupled. Of course, a gas spring can also be adjusted so that it absorbs other types of vibrations sufficiently.

In Fig. 3 is a perspective view of a node profile or corner profile 50 is shown, by means of which the armrest 40, one of the side walls 15 and the carrier 30, preferably here the pillar 31, are interconnected. The directions given below refer to a corner profile in the area of the front left corner area of the weighing unit 1.

The corner profile 50 has a base portion 51, from which extends in the z direction, a projection 53 down, the dimension is again chosen so that it can be fitted into the designed as a hollow profile leg 31. In addition, the corner profile 50 has a slot-shaped recess 54 running in the z-direction, the depth (y-direction) of which is chosen so that it is suitable for the positive reception and stable mounting of the side wall 15 sufficient. In the x-direction extends from the upper end portion of the corner profile 50, a pin-shaped projection 55 whose dimension and cross-section is chosen so that it can be fitted into the supporting surface-shaped and formed as a hollow profile armrest 40. The flow-optimized airfoil profile of the armrest 40 can be clearly seen in FIG.

As has already been described above, the working opening 11 facing surface of the armrest 40 is optimized for flow and convex. In Fig. 3 it can be seen that the upward (z-direction) directed surface 52 of the corner profile 50 has a corresponding flow-optimized and convex contour. This ensures a flush flush connection between the surface 52 of the corner profile 50 and the surface of the armrest 40. Thus, the supply air in the region of the corner profile 50 can flow through the working opening 11 into the working space 19 with little turbulence.

As can be seen in Fig. 1, such Eckprofile 50 are both in the front left and in the front right corner of the

Weighing deduction 1 provided.

Such corner profiles 50 not only simplify the assembly of the weighing tray 1, but they also offer advantages in terms of the required regular cleaning and decontamination of

Weighing unit 1, as there are no steps, hard-to-reach areas or even open recesses that are difficult to clean. In addition, corner profiles 50 designed in this way ensure a low-turbulence inflow of the room air into the working space 19 in the region of the corner profiles 50. Likewise in FIG. 3, an operating and / or display panel 42 is shown, which is completely integrated in the armrest 40. The control and / or display panel 42 is flush mounted and liquid-protected in the armrest 40. Any electrical lines which supply power to the operating and / or display panel 42 or any data lines may run completely within the armrest 40. They are therefore neither visible from the outside, nor complicate the cleaning of the weighing deduction.

The display and / or control panel 42 may preferably have only display elements on which various operating functions of the weighing tray 1 are displayed. But it can also be a combined field of control and display elements 42, via which also various functions of the weighing deduction can be operated. An audible or visual warning signal can also be output via the field 42.

Preferably, the display and control panel 42 includes five illuminated capacitive touch panels and an acoustic warning sounder. All operating states of the weighing deduction can be displayed and switched ergonomically favorable in this way. The laboratory worker, who usually sits in front of the weighing trigger 1, can thus preferably operate all the functions of the weighing trigger via the field 42 and can also be displayed there without having to greatly change his seating position or even have to get up.

Since the display and / or control panel 42 comprises capacitive touch panels, an inadvertent contact of one of the touch panels with a forearm, which is usually covered by a very poorly electrically conductive garment and normally rests on the armrest 40, does not cause activation of the touch panel and thus none Changing an operating state of the weighing trigger 1. Preferably, the touch panels include, for example, "weighing on / off", "light on / off", color temperature 3000K / 4500K / 6000 K "," alarm ",

"Filter change", "Ionization on / off".

FIG. 4 shows a cross section perpendicular to the x-direction through the corner profile 50, the armrest 40, an inflow profile 102, an ionization electrode 100 and the worktop 20. For better understanding, the armrest 40 is shown hatched over the entire surface, although this is preferably formed hollow.

In Fig. 4 can be clearly seen that at the front edge of the worktop 20, an inflow 102 is arranged, which is like the armrest 40 flow-optimized in the manner of a support surface formed. The inflow profile 102 is completely decoupled from the worktop 20. In the width direction (x direction), the inflow profile 102 has a recess 104, which is preferably rectangular in cross section, into which an ionization electrode 100 is preferably detachably inserted. In this case, the surface of the ionization electrode 100 is formed flush with the surface of the inflow profile 102 that is optimized for flow. Preferably, the ionization electrode 100 is positively inserted into the inflow 102 and can therefore be removed without tools from this again.

In Fig. 4 it can also be seen that the armrest 40 is disposed above the inflow 102. The clear distance between the armrest 40 and the inflow 102 allows the supply of room air in the working space 19 due to the prevailing in the working space 19 negative pressure. The ionization electrode 100 preferably has electrodes arranged equidistantly over its length, to which preferably an alternating voltage is applied, for example +6 kV and -6 kV. As a result of the alternating voltage, the room air flowing into the working space 19 is alternately electrically charged and negatively charged, and thus neutralized on average. The application of an alternating voltage has proved to be particularly advantageous in that the charging of the adhering to surfaces of powdery particles is unknown, ie it is unknown whether the particles are positively or negatively charged. A DC voltage could thus not discharge similarly charged particles. The incoming air, which passes through the standing under AC ionization electrode 100 is thus charge neutralized in the time average and can discharge particles of both polarities.

The inflow profile 102, which may preferably also be formed in one piece with the work surface 20, is introduced into the respectively assigned corner profile 50, like the arm support 40, preferably inserted. The corner profile 50 is preferably preferably inserted into the nearby table leg 31. Only the corner profile 50 connects the armrest 40 and the inflow 102.

5, an ionization module is shown in a perspective view. The modular construction of corner profile 50, arm support 40, inflow profile 102, and ionization electrode 100 has tremendous advantages in that if, for some reason, an ionization electrode 100 were not necessary for specific trials, the entire module would be removed and replaced by that shown in FIG Module can be replaced. In other words, not all fume hoods must be permanently equipped with an ionizing electrode 100, because the ionization module can be easily and without tools removed and replaced by a conventional module. This increases the range of application of the weighing tray described here, and at the same time the costs for the laboratory operator are reduced because of the exchangeable modules, since not every weighing unit necessarily has to be equipped with an ionizing electrode.

The features of the fume hood described above can be combined as desired. Even if a combination of individual features may be technically devious, however, the skilled person will recognize which features can be technically combined with each other.

Claims

claims:

1. fume hood (1), comprising a housing (10) having a

Working space (19) defines, wherein the housing (10) has on its front side a movably mounted front screen (14), a work surface (20) which limits the working space (19) on the bottom side, and an ionization electrode (100) in an on arranged the front edge of the worktop (20)

Inflow profile (102) is arranged, and further comprising an armrest (40) which is arranged in the region of the working opening (11) and from the inflow profile (102), wherein the armrest (40) along its longitudinal direction in

Substantially extends over the entire width of the weighing trigger (1) and has end faces, and wherein in each case one

Side wall (15) which defines the working space (19) laterally, each one end face of the armrest (40) and the inflow (102) are connected to a one-piece corner profile (50), and wherein the side wall (15), one end face of the

Armrest (40) and the inflow (102) in the corner profile (50) are inserted.

2. fume hood (1) according to claim 1, wherein the fume hood a

Weighing trigger (1) for weighing pharmaceutically effective or

toxic substances in a laboratory that is at

intended use an always open

Work opening (11) below the windshield (14), and wherein the windscreen (14) is rotatably connected to an upper part (12) of the housing (10), such that the windscreen (14) from an open position to a closed position is pivotable.

3. fume hood (1) according to claim 1, wherein the windshield (14) is a movable in the vertical direction from an open position to a closed position sash, which closes the working space (19) in the closed position.

4. fume hood (1) according to one of vohergehenden claims, wherein the ionizing electrode (100) is releasably inserted into the inflow (102).

5. fume hood (1) according to one of vohergehenden claims, wherein the ionizing electrode (100) in the inflow (102) is mounted without tools.

6. fume hood (1) according to one of vohergehenden claims, wherein the inflow (102) extends over the width of the work surface (20).

7. fume hood (1) according to one of vohergehenden claims, wherein the ionization electrode (100) flush in the surface

Inflow profile (102) is inserted.

8. fume hood (1) according to one of vo voicing claims, wherein the ionizing electrode extends over at least 75% of the width of the inflow (102).

9. fume hood (1) according to one of the preceding claims, further comprising a support (30) carrying the weight of the housing (10), the worktop (20) and the armrest (40), wherein the corner profile (50) in addition is connected to the carrier (30).

10. fume hood (1) according to claim 9, wherein the carrier (30) in the corner profile (50) is inserted.