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(11) | EP 1 314 484 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Spray booth |
| (57) The spray booth (1) can be notionally divided into a set of adjacent portions (Z1,
Z2...Zn) which can be ventilated independently of each other, and it is equipped with
means for detecting the position of the operator(s) (3) present inside the booth.
Thus, it is possible to ventilate only the portion (Zi) where the operator is present
and the immediately adjacent portions, instead of the whole booth volume, with a considerable
energy saving. The same principle can be generally applied to any closed room where
emission of harmful volatile substances takes place. |
[0001] The present invention concerns a spray booth. More particularly, the invention concerns a spray booth of the kind equipped with means for generating a forced airflow capable of avoiding inhalation of harmful volatile products by the operator.
[0003] Spray booths of the above kind are widely used for painting vehicle bodyworks, frames, aircraft parts and so on, but they can also be used for other processes, such as applying lutes and other materials involving volatile product exhalation.
[0004] It is known that particularly harmful volatile substances are used in all such processes. Although in industrial applications automatic robots are often used to operate inside the booth, resorting to one or more operators for the whole process or anyway for specific operations or final touches is not infrequent.
[0005] To avoid the risk that the operator(s) inhale(s) harmful substances, the present regulations require that a forced airflow is generated in the booth, with a suitable speed to quickly and constantly evacuate harmful substances.
[0006] Since the airflow is to be constantly maintained during the process and it must have a suitable speed (about 0.5 m/sec), it is necessary to provide suitably sized aspirators and/or fans that, of course, are strongly energy consuming.
[0007] Moreover, in many regions in the world and for several months in the year, the air introduced into the booth is to be heated or cooled to reach a comfortable temperature for the operator.
[0008] A further problem related with the use of spray booths of the described kind is the need to decontaminate the exhausted air before discharging it again into the outer environment.
[0009] Due to the considerable amount of air passing through the booth, decontaminating equipment capable of bearing so heavy a working load are therefore required. Indeed, it is to be remembered that conventional spray booths have a great volume (e.g. in aerospace industry booths with a surface area exceeding 100 m2 are used).
[0010] Therefore, it is an object of the present invention to provide a spray booth that ensures the optimum and efficient exhaust of harmful volatile materials so as to meet the existing regulations and that does not have the above drawbacks.
[0011] The above and other objects are achieved by the spray booth as claimed in the appended claims.
[0012] The invention is based on the assumption that it is not necessary to ventilate the whole of the booth at the above mentioned speed, but only those areas inside the booth where the operators are present. Indeed, harmful substance emission, being related with the working cycle, is concentrated only where the operators are present. Moreover, a quick and effective exhaust of said substances is required only where the operators are present.
[0013] The spray booth according to the invention is characterised by the use of a set of independent aeration systems, each capable of effectively ventilating a portion of reduced volume of the booth itself.
[0014] Moreover the invention entails the use of means capable of detecting at any instant the position(s) of the operator(s) present inside the spray booth. In such manner, it is possible to actuate only those ventilation systems corresponding to the sections where the operators are present.
[0015] Advantageously, thanks to the splitting of the booth volume, a considerable energy saving is achieved with an important reduction in the operating costs, without thereby substantially adding to the booth manufacturing costs.
[0016] Moreover, according to the invention, the operator can safely work, since the necessary airflow is ensured in the section he occupies in any working phase.
[0017] A preferred exemplary embodiment of the invention will now be better disclosed with reference to the accompanying drawings, in which:
- Fig. 1 is a diagrammatic side view of a spray booth according to the invention;
- Fig. 2 is a cross-sectional view along line II - II of the spray booth shown in Fig. 1;
- Fig. 3 is a diagrammatic side view of a spray booth according to a second preferred embodiment.
[0018] Referring to Fig. 1, there is shown a spray booth according to the invention, generally denoted by reference numeral 1 and comprising a base 1a, side walls 1b to 1e and a ceiling if. Such parts define a substantially free room for housing one or more articles to be processed.
[0019] The floor of spray booth 1 is divided into a set of platforms (P1, P2...Pn) that notionally divide said booth 1 into a set of adjacent regions Z1, Z2...Zn. Each region Z1, Z2...Zn is equipped with an independent ventilation system, comprising at least one blower and one aspirator, disclosed in more detail hereinafter.
[0020] As it will be better disclosed hereinbelow, platforms P1, P2...Pn are connected to pressure sensitive detectors. In this manner, thanks to the pressure exerted by the weight of operator 3 onto the various platforms, it is always possible to locate operator 3 himself within spray booth 1 and to suitably actuate the ventilation system.
[0021] Referring to Fig. 1, when operator 3 is on platform Pi, the ventilation system is actuated only for region Zi and for adjacent region Zj, i. e. for the regions where removal of harmful volatile substances by means of the airflow is actually necessary. The ventilation systems associated with the other regions keep inactive, thereby allowing a considerable energy saving.
[0023] Each region Zi of spray booth 1 may be subdivided into a central portion Ci, which is used for spray operations, an upper portion Mi, called "plenum", and a lower portion Fi, devoted to the system filtering the air used for ventilation.
[0024] Ducts 5 located at both sides of central portion Ci are connected to blowers, not shown in the drawing. Said blowers send an airflow at a temperature and a speed suitable for meeting the present regulations through plenum Mi and into central portion Ci, so as to reach the operator and the surrounding environment.
[0025] The airflow, now contaminated by the volatile substances present in central portion Ci, arrives at lower portion Fi of booth 1 through platforms Pi.
[0026] In the preferred embodiment shown in Fig. 2, lower portion Fi is devoted to a wet filtering system 13. The contaminated airflow is made to pass through water supplied by taps 15 and is collected at the bottom of filtering system 13. In this way, most of the harmful substances carried by the airflow are deposited into water, where they can more easily be confined.
[0027] The partly decontaminated air is then sucked into ducts 19 thanks to the action of aspirators, not shown in the drawing, provided in the same ducts 19.
[0028] The aspirators force the airflow along a fixed path. Air is then sent to suitable decontaminating equipment (comprising e.g. a set of carbon filters) before being exhausted into the external environment.
[0029] It is self evident that the blowers and the aspirators are so sized that they ensure effective ventilation of the volume of the only central portion Ci of region Zi.
[0030] Fig. 2 diagrammatically shows also the operation of platforms Pi, on which the selective ventilation of spray booth 1 is based.
[0031] Platforms Pi consist of movable grids, linked to a stationary floor 8 through a set of resilient joints 11. Thanks to the deformation of joints 11 because of the weight of operator 3, it is possible to detect on which platform Pi operator 3 is and, consequently, to actuate or to stop the ventilation system of region Zi.
[0032] Fig. 3 diagrammatically shows a second preferred embodiment of the invention. Said embodiment differs from the previous one in respect of the means used for selectively ventilating the region of booth 1 where operator 3 is.
[0033] Instead of using independent blowers and aspirators for each booth region Z1, Z2...Zn, here a single blower is used, sending the forced airflow into upper portion M (the so-called plenum) of booth 1.
[0034] Plenum M is separated from the underlying room by a set of partitions or shutters S1u, S2u... Snu in register with the underlying platforms P1, P2...Pn. Similarly, second partitions or shutters S1d, S2d ... Snd are present beneath platforms P1, P2...Pn.
[0035] If, referring to Fig. 3, operator 3 is on platform Pi, only upper shutters Siu and Sju and the corresponding lower shutters Sid and Sjd are opened, whereas all remaining shutters remain closed, Thus, the airflow will concern only regions Zi and Zj where operator 3 is present.
[0036] Clearly, the system of platforms connected to pressure detectors arranged to detect the operator's position is typical of the illustrated embodiment. The spray booth of the invention can use any means for detecting the operator's position inside it. For instance, use can be made of photocells or portable transmitters worn by the operators and associated with a receiver connected to the ventilation system.
[0037] Similarly, the use of a plurality of blowers and aspirators is typical of the illustrated embodiment. Similar results could be achieved for instance by using a single, centralised ventilation system for the whole booth, jointly with a set of valves or partitions arranged to direct the airflow to the desired sections only,
[0038] In the disclosed embodiments, ventilation systems creating a downward vertical airflow have been used. Clearly however the spray booth of the invention can suitably use ventilation systems creating an upward vertical airflow or a laterally directed airflow,
[0039] By way of non limiting example, an estimation is given of the energy saving attainable by using the ventilation system according to the invention in a spray booth 15 m long, 7 m wide and 5 m high. Said booth has a volume of 525 m3 and its base has a surface area of 105 m2.
[0040] It is assumed that a forced airflow at a speed of 0.5 m/s is to be sent, after heating air by 10°C to bring it to a comfortable temperature for the operator.
[0041] If a prior art spray both is used, since the whole booth is to be reached by the same airflow, an air flow rate of 189,000 m3 per hour is required and 567,000 Kcal per hour have to be used for heating said air.
[0042] If the spray booth of the invention is used, let us assume that the booth length is divided into sections 2 m long and that only the two sections adjacent to the operator are ventilated. In this case, the volume to be ventilated decreases from 525 m3 to 140 m3. Under these assumptions, an airflow rate of 50,400 m3 per hour and 151,200 Kcal per hour to heat said air are sufficient.
[0043] The spray booth of the invention affords an energy saving of 415,800 Kcal per hour. If a period of 100 workdays is considered, during which the booth is used 24 hours a day, said energy saving corresponds to about 199,584 Kg fuel.
[0044] Advantageously moreover a considerable saving in the installation and operation costs of the air decontaminating system will be achieved, since the amount of air to be decontaminated when leaving the booth is substantially reduced.
[0045] By way of example only, an approximate calculation of the cost savings attainable with the booth of the previous example is given, assuming that the booth has to operate 220 days per year, 24 hours a day.
[0046] When using a prior art booth, the volume of air to be exhausted will be 189,000 m3. The actual cost for setting up a decontaminating system meeting the existing regulations for the above air amount is about 2 to 2.5 Millions Euros.
1. A spray booth (1) comprising a base (1a), side walls (1b to 1e) and a ceiling (1f),
defining inside them a substantially free room for housing one or more articles to
be processed, said booth (1) being equipped with means for generating inside said
room a forced airflow capable of quickly changing air contained therein, characterised in that the booth is equipped with means for detecting the position of the operator (3) inside
the booth and is divided into adjacent regions or portions (Z1, Z2...Zn), each equipped
with corresponding means for generating said forced airflow, said generating means
being actuated and stopped so as to confine said flow in the region substantially
occupied by the operator (3).
2. A spray booth (1) according to claim 1, characterised in that it comprises a floor beneath which at least one filtering station (13) is provided
for filtering the contaminated airflow.
3. A spray booth (1) according to claim 2, characterised in that the filtering station (13) comprises a wet filtering system and a plurality of carbon
filters.
4. A spray booth (1) according to claim 1, characterised in that the means for detecting the exact position of the operator (3) comprise a set of
platforms (P1, P2...Pn) connected with detectors responsive to the pressure exerted
by the weight of the operator (3).
5. A spray booth (1) according to claim 1, characterised in that the means for detecting the exact position of the operator (3) comprise a portable
transmitter worn by the operator (3) and a receiver tuned to the frequency of said
transmitter and connected to a system controlling the ventilation of the booth (1).
6. A spray booth (1) according to claim 1, characterised in that the means for detecting the exact position of the operator (3) comprise a set of
photocells located on the booth walls (1b to 1e) so as to form a grid defining the
portions (Z1, Z2...Zn) of the booth (1).
7. A spray booth (1) according to claim 1, characterised in that the means for generating the airflow in the portions (Z1, Z2...Zn) of the booth (1)
comprise at least one blower and at least one aspirator for each said portion (Zi)
of the booth (1), and in that said blower and said aspirator are controllable independently of the blowers and
aspirators of the adjacent portions.
8. A spray booth (1) according to claim 1, characterised in that the means for generating the airflow in the portions (Z1, Z2...Zn) of the booth (1)
comprise: a blower in communication with the upper booth portion or plenum (M); a
set of independent upper shutters (Slu, S2u... Snu) in said plenum, which shutters
can be opened and closed to define a fixed path for the airflow coming from the blower,
wherein said path is arranged to lead from the blower to anyone of the portions (Zi)
of the booth (1); a set of lower shutters (S1d, S2d ... Snd) in the floor of the booth,
said lower shutters being in register with said upper shutters; and an aspirator in
communication with a lower booth portion located beneath said floor, and in communication
with the internal room of the booth through said lower shutters.