FUME cupboard and FUME cupboard system

Abstract

The invention relates to a fume cupboard (1), which includes A working space (20) and its working opening (4), A vertically moving sash (10) to cover the working opening (4) at least partially, An exhaust fan (7) to create suction in the working space (20) and flow rate in the working opening (4), a sash (10) position indication system, which system ( 1 ) includes means for indicating the sate lifting height of the sash (10), the sate lifting height being determined according to the safety limit of the flow rate of a preselected criterion, which means comprise a first sensor (14) for determining the lifting height (h) of the sash and a second sensor (12) for determining the flow rate in the working opening (4) a control device (16) for determining the flow rate and a display means (8) for indicating the safety limit. The control device (16) includes calculation means (22) for determining the lifting height (h) of the sash (10) corresponding to the variable safety limit of the flow rate on the basis on the data from said first and second sensors (14, 12), and said display means (8) is adapted to continuously indicate visually to the user the distance of the safety limit of the safe lifting height of the sash in relation to the current position of the sash. The invention also relates to a fume cupboard system.

Description

[0001] FUME CUPBOARD AND FUME CUPBOARD SYSTEM

[0002] The invention relates to a fume cupboard, which includes - a working space and its working opening, - a vertically moving sash to cover the working opening at least partially, with the lower edge of the sash delimiting the upper edge of the working opening, an exhaust fan to create suction in the working space and flow rate in the working opening, and - a sash position indication system, which includes means for indicating the safe lifting height of the sash, the safe lifting height being determined according to the safety limit of the flow rate of a preselected criterion, which means comprise a first sensor for determining the lifting height of the sash and a second sensor for determining the flow rate in the working opening, a control device for determining the flow rate and a display means for indicating the safety limit .

[0003] In addition, the invention relates to a fume cupboard system.

[0004] Substances detrimental to user and the environment are handled in fume cupboards . Between the user and the object being studied, there is a sash, which is usually of glass . A working opening is formed between the lower edge of the sash of the fume cupboard and the bottom of the working space to allow the hands to enter into the fume cupboard .

[0005] The sash prevents splashes flying on top of the user and at the same time reduces the working opening, so that the airflow needed for protection is smaller . By lifting the sash, a working opening with an inward airflow is created.

[0006] The standard series of the standard SFS-EN 14175 for fume cupboards defines the set value for the airflow from under the sash to the inside . More specifically, it is defined that the flow rate from the opening should normally be at least

[0007] 0 .5 m / s in the working opening . When the flow is -20%, i . e . less than 0 .4 m / s, the user must be warned of a dangerous situation . These safety limits correspond at any given moment to the position of the lower edge of the sash, i . e . the size of the working opening, which is determined by its height .

[0008] The safety limits correspond to successive thresholds of the sash lifting height . The user can thus anticipate the effect of lifting the sash . This is important if, due to the load situation, the dangerous range is unexpectedly close, so that with a small lift you are already in the "red" range .

[0009] A prior art art publication US 5215497 A is known, which, like traffic lights, shows the user with the current situation of whether the flow rate in the working opening is in a safe, harmful or dangerous range at the current lifting height of the sash . However, the user cannot in any way predict how much the lifting height can be changed while still remaining in a safe range .

[0010] The purpose of the invention is to provide a fume cupboard and a fume cupboard system that provide the user with a better visual indication of the working conditions than before . The characteristic features of this invention are set out in the accompanied claim 1 for the fume cupboard and in the accompanied claim 15 for the fume cupboard system.

[0011] The purpose of the fume cupboard according to the invention is achieved by a fume cupboard, which includes a working space and its working opening, a vertically moving sash to cover the working opening at least partially, with the bottom edge of the sash delimiting the upper edge of the working opening, an exhaust fan to create suction in the working space and flow rate to the working opening, and a sash position indication system. The indication system includes means for indicating the safe lifting height of the sash, the safe lifting height being determined according to the safety limit of the flow rate of a preselected criterion, which means comprise a first sensor for determining the lifting height of the sash and a second sensor for determining the flow rate in the working opening, a control device for determining the flow rate and a display means for indicating the safety limit . The control device includes calculation means for determining the lifting height of the sash corresponding to the variable safety limit of the flow rate on the basis on the data from the first and second sensors .

[0012] The display means is adapted to continuously indicate visually to the user the distance of the safety limit of the safe lifting height of the sash in relation to the current position of the sash .

[0013] With the help of the invention, the lifting height of the sash corresponding to the safety limit is determined proactively, whereby the effect of the change in the lifting height is indicated to the user . In other words, the distance between the safety limit and the current position is continuously visually displayed to the user for anticipation .

[0014] It is useful for the user to know if the safety limit of a harmful situation is very close to the current position, so that he / she can lift the sash with care . In the fume cupboard according to the invention, the safety limit is continuously determined, so that it can change according to the movement of the sash and the user can always be sure that the lifting height is within a safe range .

[0015] Continuous here means that the user is provided with a continuous visual indication of how much the sash can be opened while still remaining within the safe operating range . Preferably, the lifting height of the sash refers to the position of the lower edge of the sash in relation to the lower edge of the working space, which determines the size of the working opening . In other words , the lifting height of the sash is the same as the position of the upper edge of the working opening .

[0016] Preferably, the calculation means are additionally adapted to determine a second variable safety limit, which the display means is also adapted to indicate to the user . In this way, several different ranges can be created with the help of safety limits, namely a safe range, a harmful range and a dangerous range, all of which are visually indicated to the user .

[0017] The preselected criterion is preferably the standard SFS-EN

[0018] 14175 and between the safe lifting height of the sash the flow rate in the working opening is at least 0 .5 m / s and between the dangerous lifting height less than 0 . 4 m / s .

[0019] Preferably, between the flow rates of the safety limit and the second safety limit, there is a gap of the harmful lifting height of the sash, which the display means is adapted to indicate to the user . With the help of the presentation of the harmful lifting height gap, it is possible for the user to temporarily utilize a lifting height that is lower than the dangerous lifting height, but enables a momentary use of a larger working opening .

[0020] Preferably, the display means is a controllable colored LED strip . The LED strip is a convenient way to implement a display means and allows the colors to be easily reproduced, making it easier to visualize the matter for the user . Preferably, the display means is adapted to show the lifting height of the sash from its lowest position to the safety limit in one color and from the safety limit to the highest position of the sash in another color . The colors make it easier for the user to visualize the safe lifting height range and the distance of the current lifting height to the safety limit .

[0021] The LED strip can include 10 to 300 , preferably 30 to 150 , most preferably 40 to 100 individually controlled single

[0022] LEDs . With such a number of single LEDs, a sufficiently high resolution is obtained, so that the safety limit can be indicated with a sufficient resolution of at least 2 cm. A single LED is preferably able to reproduce all the desired colors, for example green, yellow and red.

[0023] The colored LED strip may be adapted to display a green (G) , yellow (Y) and red (R) indication at and at least near the lower edge of the sash in the vertical direction . This way of presentation, similar to traffic lights, is very descriptive and easy to understand by the user .

[0024] Preferably, the length of the LED strip is 80 120% of the sash opening, i . e . the difference between the maximum lifting height and the minimum lifting height . This allows the user to detect the safety limit and the different operating ranges throughout the entire operating range of the sash .

[0025] Preferably, the fume cupboard includes an exhaust airflow controller, such as a damper, and its position means, which transmits position information to the control device .

[0026] Furthermore, the control device can then be an adaptive one in that it creates a database of position and flow parameters to predict the threshold value, the database being stored and updated in the memory register of the control device . Preferably, the first sensor for determining the lifting height of the sash comprises a potentiometer adapted to give a response value dependent on the lifting height .

[0027] Preferably, the second sensor for determining the flow rate in the working opening comprises a flow meter installed inside the fume cupboard or in the exhaust air duct .

[0028] The control device can roughly calculate the safe lifting height and the next threshold height of the sash based solely on the flow rate and the height position of the sash, if the duct suction is constant . Often the suction varies because the fan operates several fume cupboards, whereby the damper allows for the adjustment and its position sensor data is used in the calculation .

[0029] Preferably, the control device includes a learning system for determining the position of the sash corresponding to the position of the proactive safety limit by recording the position of the damper, flow rate and lifting height under different load conditions and storing them in a memory register, from which the control device is adapted to determine the indication to be displayed for the positions of the sash corresponding to the safety limit .

[0030] Alternatively, the control device includes a calculation system to determine the position of the sash corresponding to the proactive safety limit calculated from the values of the damper position, flow measurement and lifting height .

[0031] Determination of the lifting height of the sash corresponding to the safety limit or limits can be performed at a frequency of 0 . 1 100 Hz , preferably at a frequency of 0 .5 10 Hz . This allows the safety limit to be displayed almost in real time, even during the movement of the sash .

[0032] Preferably, the calculation instruments are software calculation instruments and the control device includes a calculation unit, memory for software calculation instruments and data transmission means for transferring data from the sensors to the calculation instruments . The calculation unit, memory and data transmission means may be enclosed in separate electronics housing, for example on top of a fume cupboard.

[0033] The purpose of the fume cupboard system according to the invention is achieved by a fume cupboard system, which includes at least two fume cupboards according to one of the above embodiments of the invention and a common exhaust fan for the fume cupboards adapted to form suction in the fume cupboards .

[0034] The invention is described in detail below by referring to the accompanying drawings illustrating some embodiments of the invention, wherein

[0035] Figure 1 shows one fume cupboard from the front,

[0036] Figure 2 shows as a schematic diagram the positions of the sash of one of the fume cupboards according to the invention

[0037] Figures 3a - 3d show the flow rate in the opening in different loading conditions

[0038] Figures 4a - 4d show the adjustment potential of the sash in different loading conditions,

[0039] Figure 5 shows the system according to the invention . Figure 1 shows one fume cupboard 1 to which the invention can be applied. The fume cupboard 1 includes a working space 20 and has a working opening 4 at its front, which can be closed and opened by means of a sash 10 . The sash 10 can be stopped at any point between the extremes of its vertical movement .

[0040] On top of the fume cupboard 10 there are exhaust air ducts 6, through which harmful substances are discharged from the breathing air . The duct includes flow control means, in this case a damper 11 , to control the outlet flow . The exhaust air ducts 6 are routed to an exhaust fan 7 , in front of which in the direction of flow there is a damper 11 and as a second sensor 12 a flow sensor 24 with its transmitter . The exhaust fan 7 is often common to several fume cupboards (not shown) , so the exhaust fan cannot be used to control the flow of a single fume cupboard.

[0041] The damper can also be called a control flap .

[0042] The first sensor 14 connected to the sash 10 is a position sensor, which can be, for example, a potentiometer, giving a resistance value proportional to the height .

[0043] The inputs of the control device 16 are the flow sensor 24 ,

[0044] (transmitter F) , the damper 11 , its position sensor transmitter Y1 and the first sensor 14 of the sash, i . e . the position sensor (transmitter Y2 ) . The control device 16 can be a conventional microcontroller with a loaded control program . On the display means 8 , here the LED strip, there is a control unit 18 , which is controlled by the control device

[0045] 16 according to the program. Figure 1 also shows the multidimensional memory register 16. 1 , in which the connection between the flow rate and the height of the opening, and when using the damper 11 , its positions, are stored through a learning process . From this memory register, the control device determines directly or by interpolation the indicative positions to be displayed to the user .

[0046] In the embodiment of Figure 1 , the first sensor 14 for determining the lifting height of the sash comprises a potentiometer adapted to provide a response value dependent on the lifting height .

[0047] The second sensor 12 for determining the flow rate in the working opening 4 comprises a flow meter installed in the exhaust air duct 6 and its transmitter F, which transmits a message to the control device 16.

[0048] The display means 8 is a controllable colored LED strip . In

[0049] Figure 1 , the colored LED strip is adapted to show a green

[0050] (G) , yellow (Y) and red (R) bar as an indication at and at least in the vicinity of the lower edge 26 of the sash in its height direction . Preferably, the indication is layered color bars, with green, yellow and red superimposed, from which the current situation is read at the upper edge 4 . 1 of the working opening 4 (i . e . at the lower edge 26 of the sash 10 ) .

[0051] In Figure 1 , the upper edge 4 . 1 points to the upper end of the green bar, and is therefore in the green, i . e . safe range . The system has also proactively calculated the height of the bottom edge of the red bar . This is the next threshold, i . e . the color light indication has also been calculated near the bottom edge of the sash .

[0052] Different colors preferably indicate the following :

[0053] Green = predictable flow is 0 . 5 m / s and lifting height of the sash is no more than 30 cm . This indicates a safe, ecological and recommended range of use . Eco-friendliness is achieved especially by limiting the lifting height .

[0054] Yellow = predictable flow is over 0 .4 m / s . This still indicates a generally safe range of use, but the safety level is slightly reduced. At the same time, the use is no longer so ecological, as typically the sash opening is already quite large, resulting in high airflow and significant energy consumption in the form of heated indoor air being removed .

[0055] • Red = predictable flow is less than 0 .4 m / s . In this case, it is not safe to use the fume cupboard. The system also gives an audiovisual alarm.

[0056] Naturally, the flow rates and lifting height limit values presented above are only one example of an embodiment of a fume cupboard according to the invention and the flow rate and lifting height limits may vary according to the dimensions of the fume cupboard.

[0057] When the sash is down, there is a green bar at the bottom edge of the side of the sash, i . e . a range extending from the bottom to the lowered height of the sash at the current parameters . Above it there is a yellow range . The red range is indicated if it is calculable . Otherwise, the red indicator only appears when the sash is raised, in which case the preset limit values , for example 0 .5 and 0 .4 m / s, can be converted into a height that is indicated in colors .

[0058] Figure 2 shows the situation where the sash is up so that the upper edge 4 . 1 of the working opening 4 hits the red bar .

[0059] This indicates a dangerous situation, wherein toxic gases or vapors can enter the room. The sash 10 must be lowered so that to bring the upper edge 4 . 1 of the working opening 4 at least into the yellow range . During lowering the sash 10 , the calculation means 22 of the control device 16 continuously calculate the heights of the bars R, Y, G, and the heights of the bars are likely to change slightly when the sash reaches its target height, because the phenomena are not linear and the control device calculates indicative data on the heights of the other bars . As shown in Figures 3a 3d, the flow rate in the working opening 4 depends mainly on the positions of the bottom edge

[0060] 26 of the sash 10 and the damper, but the variation in suction, i . e . the effect of other fume cupboards, must be taken into account .

[0061] By opening the damper only brings the situation under control up to the limit when the damper is fully open, in which case the working height must be limited earlier . In the situation displayed in Figure 3c, the duct suction has decreased below the critical safety limit and the safe flow rate is undershot, even though the damper is fully open .

[0062] A working opening of 30 cm is generally considered to be the ecological limit , so in case 3a the green area ends at this height of 30 cm . In case 3c, the fume cupboard is far too open and the flow rate is in the dangerous range . In the case of Figure 3d, the damper would provide additional flow to compensate for raising the sash to 30 cm.

[0063] The system proves to be particularly useful when the dangerous range is close, i . e . a small lift will reduce the flow rate to the dangerous range . This kind of situation can happen especially when the load situation is high due to other fume cupboards, wherein the suction capacity is not enough to compensate for the larger flow opening due to the lifting . The control device 16 includes a learning system for registering and storing the position of the damper 11, the flow measurement and the lifting height thresholds in order to anticipate the indications of the display means 8.

[0064] The following table shows the parameters of figures 4a - 4b:

[0065] In Figure 4c, the yellow upper limit C y can be calculated as follows . Now the lifting height is on the border between green and yellow. In Figure 4c, the damper is in the 70% position, i.e. 30% of the capacity remains.

[0066] Yellow (Y) upper limit h.y:

[0067] Vg = Vy

[0068] 0.5m / s*w*h . g=0.4m / s*w*h . y

[0069] -> h . y=0.5 / 0.4*h . g=5 / 4 *h.g = 17.9cm

[0070] However, this could be compensated by an additional 30% reserve . The damper can be opened further to achieve a flow rate of 0.5 m / s in the working opening.

[0071] Green (G) upper limit h.g:

[0072] 10cm / 70% = h.g / 100%

[0073] -> h.g=10cm* (100 / 70) =14.3cm In Figure 4d, 40% of the capacity is in use, i .e . 60% remains .

[0074] The upper limit of the yellow Dyin figure 4d is calculated as follows:

[0075] Yellow (Y) upper limit h.y:

[0076] Vg = Vy

[0077] 0.5m / s*w*h . g=0.4m / s*w*h . y

[0078] -> h . y=0.5 / 0.4*h . g=5 / 4 *h.g = 31.3cm

[0079] In Figure 4d, the damper is in the 40% position, i .e. 60% of the capacity remains.

[0080] Green (G) upper limit h.g.:

[0081] 10cm / 40% = h.g / 100%

[0082] -> h.g=10cm* (100 / 40) = 25 cm

[0083] However, this could be compensated by an additional 30% reserve . The damper can be opened further to achieve a flow rate of 0.5 m / s in the working opening.

[0084] In the case of Figures 4a and 4b, the flow cannot be increased by the damper when it is already fully open (100%) .

[0085] In contrast, in the cases shown in Figures 4c and 4d, opening the damper allows an additional flow of 30% or 60% and the sash can be lifted safely.

[0086] Figure 5 shows a schematic diagram of the fume cupboard system according to the invention. The fume cupboard system includes at least two, preferably 3 5, fume cupboards 1 according to any one of the embodiments of the invention above, having a common exhaust fan 7. By using a single common exhaust fan 7 in connection with several fume cupboards 1 according to the invention, the user can easily anticipate how much the sash can be lifted while still maintaining the flow rate in the working opening at a sufficient level for safe working by continuously indicating the safety limit to the user . When using a common exhaust fan, anticipating without a display means would be challenging, as the safe lifting height of the sash of an individual fume cupboard can vary depending on the load situation of the exhaust fan .

Claims

CLAIMS1. A fume cupboard (1) , which includes a working space (20) and its working opening (4) , a vertically moving sash (10) to cover the working opening (4) at least partially, with a lower edge (26) of the sash (10) delimiting an upper edge (4.1) of the working opening, an exhaust fan (7) to create suction in the working space (20) and flow rate in the working opening (4) , a sash (10) position indication system, which system(1) includes means for indicating the safe lifting height of the sash (10) , the safe lifting height being determined according to a safety limit of the flow rate of a preselected criterion, which means comprise a first sensor (14) for determining the lifting height (h) of the sash and a second sensor (12) for determining the flow rate in the working opening (4) , a control device (16) for determining the flow rate and a display means (8) for indicating the safety limit, characterized in that the control device (16) includes calculation means (22) for determining the lifting height (h) of the sash (10) corresponding to the variable safety limit of the flow rate on the basis on data from the first and second sensors (14, 12) , and the display means (8) is adapted to continuously indicate visually to a user a distance of the safety limit of the safe lifting height of the sash in relation to a current position of the sash.

2. The fume cupboard (1) according to Claim 1, characterized in that the calculation means (22) are additionally adapted to determine a second variable safety limit, which the display means (8) is also adapted to indicate to the user.

3. The fume cupboard (1) according to Claim 1 or 2, characterized in that the preselected criterion is standardSFS-EN 14175 and between the safe lifting height (h) of the sash (10) the flow rate in the working opening (4) is at least 0.5 m / s and between the dangerous lifting height (h) less than 0.4 m / s.

4. The fume cupboard (1) according to Claim 3, characterized in that between the flow rates of the safety limit and the second safety limit there is a gap of a harmful lifting height (h) of the sash (10) , which the display means(8) is adapted to indicate to the user.

5. The fume cupboard (1) according to any of Claims 1 -4, characterized in that the display means (8) is a controllable colored LED strip.

6. The fume cupboard (1) according to Claim 5, characterized in that the display means (8) is adapted to display the lifting height (h) of the sash (10) from its lowest position to the safety limit in one color and from the safety limit to a highest position of the sash (10) in another color.

7. The fume cupboard (1) according to Claim 5 or 6, characterized in that the LED strip includes 10 to 300, preferably 30 to 150, most preferably 40 to 100 individually controlled single LEDs.

8. The fume cupboard (1) according to any of Claims 5 -7, characterized in that the colored LED strip is adapted to display a green (G) , yellow (Y) and red (R) indication at and at least near the lower edge (26) of the sash in the vertical direction .

9. The fume cupboard (1) according to any of Claims 1 -8, characterized in that the first sensor (14) for determining the lifting height (h) of the sash (10) comprises a potentiometer adapted to give a response value dependent on the lifting height (h) .

10. The fume cupboard (1) according to any of Claims 19, characterized in that the second sensor (12) for determining the flow rate in the working opening (4) comprises a flow sensor (24) installed inside the fume cupboard (1) or in the exhaust air duct (6) .

11. The fume cupboard (1) according to any of Claims 1 -10, characterized in that the display means (8) is placed next to the sash (10) .

12. The fume cupboard (1) according to any of Claims 1 -11, characterized in that it includes a flow controller, such as a damper (11) , positioned in the exhaust air duct (6) , and its position sensor connected to a control device (16) .

13. The fume cupboard (1) according to Claim 12, characterized in that the control device (16) includes a learning system for determining the lifting height (h) of the sash (10) corresponding to the variable safety limit by recording the position of the damper (11) , flow rate and lifting height (h) under different load conditions and storing them in a memory register (16.1) , from which the control device (16) is adapted to determine the indication to be displayed for the lifting height (h) of the sash (10) corresponding to the safety limit.

14. The fume cupboard (1) according to any of Claims 1 -13, characterized in that the control device (16) includes a calculation system to determine the lifting height (h) of thesash (10) corresponding to the safety limit by calculating it from the values of the damper (11) position, flow measurement and lifting height (h) .

15. A fume cupboard system, which includes at least two fume cupboards (1) and a common exhaust fan (7) for the fume cupboards (1) adapted to form suction to the fume cupboards(1) , characterized in that the fume cupboards (1) are fume cupboards (1) according to any of Claims 1 - 14.

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