WO2013185891A1

WO2013185891A1 - Fume cupboard for high thermal loads

Info

Publication number: WO2013185891A1
Application number: PCT/EP2013/001646
Authority: WO
Inventors: Jürgen Liebsch
Original assignee: Waldner Laboreinrichtungen Gmbh & Co. Kg
Priority date: 2012-06-13
Filing date: 2013-06-05
Publication date: 2013-12-19
Also published as: DE102012105132A1

Abstract

Fume cupboard (1) for high thermal loads which comprises a housing having a working chamber (4) arranged therein, having a front slide (3) which can be displaced between a closed position and an open position and, at least in the open position, allows access to the working chamber (4), and having a channel (11) which can be connected fluidically to an exhaust-air system. The front slide (3), in the open position, is at least partially accommodated in the channel (11).

Description

Trigger for high thermal loads

The present invention relates to a vent designed in particular for high thermal loads, and safe with the experiment in a working space of the trigger even at high temperatures, i. without outbreak of hazardous or toxic gases or the like can be performed.

Conventional fume hoods generally comprise a housing, a working space arranged inside the housing, and a mostly vertically displaceable sash, which allows the user access to the working space. As a result, experiments or experiments with pollutant-containing, toxic or even explosive substances, e.g. Chemicals are carried out without endangering the health or physical disability of the user.

In conventional prints, a gap is provided by design between the vertically displaceable sash and the trigger housing. Through this air gap and through an always existing air gap between a lower edge of the sash and a worktop of the working space, air is sucked in from the area immediately surrounding the trigger. As a result, a substantially stable gas cylinder, whose axis of rotation extends along the width of the working space, forms in the working space.

For fume hoods that are at high thermal loads, for example at

Heating loads of 4 kW per meter of clear width of the fume cupboard, which are operated in the working area, create thermal conditions through the release of heat energy, which changes the flow behavior or flow pattern of the gases within the working space. For example, there are buoyancy effects in the area of the strongly heated sash, which favor an outburst of contaminated air and other existing gases from the working space. Even with an increase in the suction power of the exhaust system, with which the trigger is fluidly connected, and the provision of a lip or brush seal between sash and trigger housing can not be ensured that no harmful gases from the workspace get outside. This is because the highly heated gases rise faster due to a significantly increased buoyancy force and thus significantly changes the flow pattern in the working space. A reinforcement of the possibly existing sealing lips between sash and trigger housing is not possible in any measure, as this would require an increased effort for vertical displacement of the sash by itself, which in turn would violate safety-related aspects, as well as less powerful people in an emergency in the Must be able to close the sash quickly. For example, European Standard EN 14175-2 of 1 August 2003 stipulates that the force required to displace the sash must not exceed 30N and 50N for multi-part sashes.

From DE 10 2007 005 905 AI all the features of the preamble of claim 1 are known. Here, a trigger for high thermal loads is described in which to avoid the escape of pollutants through the air gap between the trigger housing and sash on the hood a draft designed as a C-profile channel is arranged, showing the open side in the direction of the sash. This channel is connected via extraction nozzles with an exhaust air system to suck the exiting through the air gap gases and thus to prevent the outbreak of these gases in the laboratory space.

US 6,089,970 A describes a .energetically optimized trigger, wherein the upper part of the sash is received in the open position in a channel. Through this channel, air is directed downward in a vertical direction along the inner and outer surfaces of the Sash blown out. At the same time air is blown upwards in the vertical direction in the area of the front edge of the worktop. The air thus exhausted forms an air curtain intended to prevent the escape of contaminated air from the working space.

It is an object of the invention to provide a trigger for high thermal loads, in which the risk of leakage of pollutant-containing gases from the working space at high thermal load of the working space is further reduced.

This object is achieved by a trigger for high thermal loads, comprising a housing having a working space disposed therein, a sash which is displaceable between a closed position and an open position and allows access to the working space, and a channel provided with a Exhaust air system is fluidly connected, includes. The trigger according to the invention is characterized in that the sash is at least partially received in its open position in the channel.

Characterized in that the sash is partially received in its open position in the channel, charged air, which rises along the high thermal load strongly heated sash upwards, out into the channel and then sucked out of this through the exhaust system. As a result, the escape of pollutant-containing gases from the working space at high thermal load is avoided, or at least significantly reduced, i. the retention capacity of the trigger is improved. This also affects the energy balance of the deduction, since compared to conventional deductions the suction power of the exhaust system at a constant Rückhalteyermögenbzw. constant outbreak safety is reduced

Preferably, the sash is received in the closed position in the channel or at least substantially flush with a lower end of the channel. According to a further preferred embodiment of the invention, the channel has a width which is greater than or equal to a width of the sash.

Further preferably, the channel comprises an inner wall facing the working space and an opposite outer wall, each of which extends in the vertical direction, and the sash is displaceable substantially centrally between the inner wall and the outer wall.

According to a further preferred embodiment of the invention overlaps in the closed position of the sash with the inner wall and / or the outer wall of the channel along a direction of displacement of the sash.

Preferably, a lower end of the inner wall is aligned with a lower end of the outer wall in the horizontal direction.

Further preferably, a suspension of the sash extends at least partially in the channel.

Still more preferably, the channel comprises side walls formed by side walls of the housing.

According to a further preferred embodiment of the invention, the trigger further comprises a arranged on a rear side of the working space and extending in the vertical direction collecting channel, which is fluidly connected to the channel via a horizontal portion of the channel.

Preferably, the channel is at least partially formed of a gas-impermeable material.

Hereinafter, with reference to the accompanying drawings, an embodiment of. Invention described in more detail.

1 shows a schematic cross-sectional view of a trigger according to an embodiment. Fig. 1 shows a schematic cross-sectional view of a trigger 1 according to an embodiment of the invention, which is optimized for thermal loads. This deduction meets all the criteria set out in the European Standard EN 14175-7: 2012 of May 2012.

The trigger 1 comprises a housing with a bottom or a

Table 2, two side walls (not shown), a rear wall 15, a ceiling plate 16 and a vertically displaceable sash 3. This set inside the trigger 1 a working space 4, the displacement of the sash 3 from a closed position, in the the sash or its lower edge 9 is located near the table top 2, is made accessible to a user in an open position shown in the figure. The open position may be any position of the sash different from the closed position. In other words, the sash is slidable from the closed position to a plurality of open positions, including a maximum open position which determines the maximum working height of the trigger. At the front of the trigger and to a large extent above the closed sash there is a channel 1, whose structure and function will be described in more detail below.

The sash 3 is like conventional sash wire racks or timing belt and arranged at the upper end of the housing pulleys connected to counterweights, whereby the sash 3 is maintained at a displacement in the vertical direction (z-direction) regardless of its position in equilibrium. In the channel 11 is preferably not shown in the figure suspension of the Frontschiebejrs 3rd

Between the working space 4 and the rear wall 15 of the trigger 1 or the ceiling plate 16 of the trigger 1, there is a baffle wall or baffle 5 a, 5 b which has two parts and which has openings 6 a, 6 b, 6 c and 6d. The spaces located between the baffle 5 a, 5 b and the rear wall 15 or the ceiling plate 16 of the working space 4 are sucked off via a collecting channel 7, in which a negative pressure prevails, so that the gases present or produced in the working space can be sucked out of this , The negative pressure in the collecting channel 7 is generated via a building-side installed exhaust system or a pump that is installed in the area of the trigger. The free end of the collecting channel 7 is in this case via a

Hose or a suitable exhaust duct (not shown) connected to the exhaust system or the pump installed on the building side. For example, in a mobile trigger the pump may also be provided directly in the collecting channel 7, wherein the collection channel 7, one end of a hose is attached, the other end is placed, for example, through a window of the building to direct the pollutant-containing gases to the outside.

At the front edge 8 of the table top 2, at the front edge of the side posts (not shown) of the trigger and at a lower end of the sash 3 flow-shaped inflow profiles are provided, which are in particular airfoil-shaped profile parts with forward or downward directed incident surface can act. The inflow profiles may be formed as hollow profiles from which support beams formed from compressed air in the form of floor and wall beams (not free jets) are output into the working space 4. In this regard, reference is also made to the European patent EP 1 444 057 B1 of the Applicant, the disclosure content of which is incorporated herein by reference in its entirety.

In addition to other safety-related aspects, the European standard EN 14175-7: 2012, which came into force in May 2012, which replaced the German standard DIN 12924-2, stipulates a detailed type examination, such as the break-out safety of a trigger at high temperatures. mixing loads must be checked. Accordingly, two heating plates must be in a precisely defined position in the drawing room. The robustness and the retention capacity must each be tested without thermal load and with a thermal load of 4 kW per meter of clear width of the trigger. The temperature in the working space can reach 300 ° C or more.

In the figure, for the sake of simplicity, only one heating device 10 is shown, which is required by the type examination described in the European standard EN 14175-7: 2012.

When the heater 10 is turned on, as shown in the

Figure 11 shown arrows, the cold air flowing from the outside into the working space 4, which initially moves almost along the y-direction shown in the figure, on the one hand by the contact with the surface of the heater 10 and on the other by that of the Heating device 10 and from the equally heated surfaces of the working space 4 (this also applies to the working space 4 facing surface 19 of the partially open sash 3) radiated heat heated, causing the heated gas mixture as shown by the arrows 12 in the working space 4 rises obliquely upward and hits the baffle plate 5a. As a result of the obliquely arranged baffle plate 5b is formed in the upper region of the working space 4, a gas roller 17 whose axis of rotation is substantially in a direction which is perpendicular to the y- and z-direction, however, portions of the gas mixture, as by the Arrow 18 indicated, flow down.

If, in turn, heat is given off to the gas mixture in the working space 4 in the region of the sash 3 via its surface 19 facing the working space 3, buoyancy effects occur, as a result of which the gas mixture in the working space 4 on the sash 3 rises upward in positive z-direction (arrows 20). , Since the surface of the sash 3 facing away from the working space 4 is also strongly heated, the air impinging on this surface from the outside also increases, as indicated by the arrows 21, upwards.

In order to prevent that on the sash 3 in the working space 4 rising upward gas mixture (contaminated air) can escape from the working space 4, an upwardly closed channel 11 (receiving shaft) is provided. This channel 11 is preferably formed by portions of the housing side walls (not shown), an outer wall 12 and an inner wall 13. The channel inner wall 13 and the channel outer wall 12 extend in the vertical direction from an upper side of the housing in the direction of the table top 2 of the working space. The channel 11, whose width is preferably greater than or equal to the width of the sash 3, is fluidly connected to one or more conduits 14 as shown in the figure. These lines 14 may be part of the channel 11 or be formed as pipes or elastic hoses. The line 14 is in turn fluidly connected to the collecting channel 7, so that the gas mixture rising on the outside and inside of the sash 3 can be sucked out via the collecting channel 7.

The channel 11 is formed such that the sash 3 is at least partially received therein when the sash 3 is raised from its closed position, i. in positive z-direction, is moved to its open position.

In order to prevent the gas mixture ascending in the channel 11 from escaping out of the working space 4, in particular the outer wall 12 and the portions of the housing side walls which form the side surfaces of the channel 11 are made of hermetically sealing, gas-impermeable materials. The inner wall 13 is also preferably made of hermetic sealing, gas-impermeable material. However, gas-permeable materials can be used for this purpose, since the escape of gas from the working space 4 is prevented by the outer wall 12.

The lower ends of the outer wall 12 and the inner wall 13 are preferably arranged at the same z-height, as shown in the figure. Preferably, in the closed position of the sash 3, the lower ends of the outer wall 12 and the inner wall 13 overlap in the z-direction with the upper edge of the sash 3. Preferably, only the lower end of the outer wall 12 or the lower end of the inner wall 13 with overlap the upper edge of the sash 3 in the closed position. However, such an overlap is not absolutely necessary, because it is already sufficient that the distance between the upper edge of the sash 3 and the lower end of the outer wall 12 and / or the inner wall 13 is so small that no polluted air from the working space 4 after can escape outside. This distance may vary depending on the flow rate of the (loaded) air in this area. If an overlap is provided, this preferably occurs over the entire width of the channel 11.

The materials used for Draft 1 are selected to meet the chemical resistance and thermal resistance requirements of European Standard EN 14175-7: 2012 of May 2012. Furthermore, the trigger 1, for example, in the collecting channel 7 not shown temperature and gas flow sensors, which are connected to temperature and gas flow monitoring systems that emit a visual and audible alarm when falling below a required gas flow or exceeding a maximum allowable temperature. The principle of extracting hot air rising in the region of the sash over a channel in which the sash is at least partially received in its open position is applicable to any type of trigger intended to be operated at high thermal loads. So this principle is applicable to table tops, stand-offs, mobile prints and the like ..

Claims

claims

A high thermal load hood (1) comprising:

a housing having a working space (4) disposed therein, a sash (3) slidable between a closed position and an open position and allowing access to the working space (4) at least in the open position, and

a channel (11) fluidly connectable to an exhaust air system, characterized in that

the sash (3) is at least partially received in the channel (11) in the open position.

Second trigger (1) for high thermal loads according to claim 1, characterized in that the sash (3) is received in the closed position in the channel (11) or at least substantially flush with a lower end of the channel (11) ,

Third extractor (1) for high thermal loads according to claim 1 or 2, characterized in that the channel (11) has a width which is greater than or equal to a width of the sash (3).

4. extractor (1) for high thermal loads according to one of the preceding claims, characterized in that the channel (11) one ne the working space (4) facing the inner wall (13) and an opposite outer wall (12), each of which extend in the vertical direction, and that the sash (3) is substantially centrally between the inner wall (13) and the outer wall (12) displaceable.

5. extractor (1) for high thermal loads according to claim 4, characterized in that in the closed position the sash (3) with the inner wall (13) and / or the outer wall (12) of the channel (11) along a displacement direction ( z) of the sash (3)

5 overlaps.

6. Heater (1) for high thermal loads according to claim 4 or 5, characterized in that a lower end of the inner wall (13) with a lower end of the outer wall (12) in the horizontal direction curse i o tet.

7. extractor (1) for high thermal loads according to one of the preceding claims, characterized in that a suspension of the sash (3) extends at least partially in the channel (11).

15

A high thermal discharge hood (1) according to any one of the preceding claims, characterized in that the channel (11) comprises side walls formed by side walls of the housing.

9. High-temperature extraction hood (1) according to one of the preceding claims, further comprising a collection channel (7) arranged at a rear side of the working space (4) and extending in the vertical direction, which is in fluid communication with the channel (11) via a horizontal Section (14) of the channel (11) is connected.

25

10. fume hood (1) for high thermal loads according to one of the preceding claims, characterized in that the channel (11) is at least partially formed of a gas-impermeable material.