The invention relates to an apparatus for adjusting air pressure of a room.
The invention further relates to a method for adjusting air pressure of a room.
As is well known, low-pressure devices are used on building and renovation sites to prevent dust from spreading to the surroundings of the work site.
According to regulations, low-pressure devices must be equipped with air filters. Generally, filtration of at least HEPA H13 grade is used. Low pressure is formed by blowing the filtered air out of the work site.
Microfiltration-generated low pressure on work sites has long been used especially on work sites where asbestos-containing structures are demolished. However, the use of microfiltration has also spread to work sites, in which stone dust, including concrete dust, is created, because all stone dust may cause a health risk. Studies show that quartz particles, for instance, correspond to asbestos in health hazards.
Regulations concerning dust control are tightened all the time. In the renovation of public sites, in particular, the current practice is already to observe the P1 classification, according to which low pressure should be used in the work space and the air in the work space should be filtered 6 to 10 times an hour. The targeted low pressure is 8 to 10 Pa below the air pressure of the surroundings.
The output capacity of a low-pressure air purification device handling the filtration and generating the low pressure shall naturally be calculated on the basis of the cubic volume of the space being purified. For instance, if the air volume of the site being renovated is 13 000 m3, the purification capacity needs to be at least 6 x 13 000 = 78 000 m3/h.
A low-pressure device lowers the air pressure in the space to substantially lower than the targeted low pressure, the pressure difference may be 50 to 60 Pa, for example, in comparison to the surroundings. This may cause problems. Firstly, a big pressure difference makes air control in the space and the opening of access doors and the like difficult. Secondly, removing a large amount of air from a space may cause a very high heat loss, especially in winter. After all, warm air is removed, the replacement air of which needs to be heated. Document
The apparatus and method for adjusting the air pressure of a room according to the invention are characterised by what is disclosed in the characterising parts of the independent claims 1 and 9. Other embodiments of the invention are characterised by what is disclosed in the other claims.
In the following, features of some embodiments of the invention are listed in a random order:
The idea of an embodiment is that a control means comprises a control plate that is fastened turnably to an air distribution casing in such a manner that it can be turned in front of a second air vent. This provides the advantage that the control plate is simple to implement and provides an extensive adjustment range.
The idea of an embodiment is that the control means is arranged to be adjusted manually and that an element reducing its motion sensitivity is arranged to it. This provides the advantage that manual adjustment can be done at low cost, and the element reducing motion sensitivity facilitates the adjustment of the apparatus.
The idea of an embodiment is that the control means is connected to be controlled by a control unit and that the control unit is connected to a pressure difference sensor detecting pressure difference in the room and its surroundings. This provides the advantage that adjustment does not require the presence of personnel and that the pressure difference can be kept as desired all the time.
The idea of an embodiment is that a second air vent is arranged to return air to the room and that the second air vent comprises a heater for heating the flowing air. This provides the advantage that the room can be heated by means of the returned air.
The idea of an embodiment is that the heater comprises an electric resistor. This provides the advantage that the electric resistor provides a simple and safe means of heating air.
The idea of an embodiment is that the apparatus comprises an air filter unit that is arranged in front of an air receive duct as seen in the flow direction, and a fan that is arranged to generate air flow through the apparatus. This provides the advantage that it is possible to take care of the adjustment of the air pressure level in the room and the filtration with the same apparatus.
The idea of an embodiment is that the air filter unit and fan are arranged in a low-pressure air purification device and that the apparatus comprises fastening means for fastening the air receive duct detachably and in a substantially air-tight manner to the low-pressure air purification device. This provides the advantage that the apparatus can be transported in smaller units and that, if necessary, the low-pressure air purification device can be used without the apparatus.
The idea of an embodiment is that the second air vent is equipped with a pipe output fitting that is attachable to the air duct for conveying air away from the air distribution casing. This provides the advantage that the second air vent is easily attached to the ventilation ducts of the room, for instance.
Some embodiments of the solution are explained in more detail in the accompanying drawings, in which
For the sake of clarity, the figures show some embodiments of the solution in a simplified manner. Like reference numerals identify like elements in the figures.
The apparatus 1 is arranged in the room 2 that is separated in a substantially air-tight manner from its surroundings with an air-tight boundary 3. The apparatus 1 is shown by a dot-and-dash line in the figure.
In this specification, a room refers to an entity of one or more rooms or corresponding spaces, which is isolated from its surroundings in a substantially dust- and air-tight manner so that it is possible to form a pressure difference to its surroundings.
The boundary 3 can be made up of parts of a building, such as walls, windows, floor, ceiling, and/or material, such as plastic film, tape, temporary non-bearing wall structures, added for sealing purposes.
The apparatus 1 comprises an air receive duct 4 arranged to receive air from the room 2. The receive duct 4 is at its simplest an opening in the device, but may naturally also comprise a suitably dimensioned pipe portion or the like.
In the embodiment shown in
Air flows from the air receive duct 4 to an air distribution casing 5. In addition to the air receive duct 4, also a first air vent 6 and a second air vent 7 are connected to the air distribution casing 5.
The air vents 6, 7 are arranged to convey air flowing from the receive duct 4 to the air distribution casing 5 out of the apparatus 1.
The first air vent 6 is arranged to convey air outside the room 2, such as to an adjacent room or out of the building. The second air vent 7 conveys air to the room 2, in other words, back to the space, from which it was removed.
Both the receive duct 4 and the air vent 6, 7 may be a simple opening, or it may comprise a suitably dimensioned pipe portion or the like.
A control means 8 is arranged in the air distribution casing 5 to adjust the flow resistance of the second air vent 7 in relation to the first air vent 6.
In the embodiment shown in
According to an idea, the control means 8 can be arranged elsewhere than in the air distribution casing 5, in either or both air vents 6, 7, for example.
The control means 8 now comprises a control plate or damper 9 that is fastened to the air distribution casing 5 to be turnable in relation to the second air vent 7. Instead of the control plate 9, a guillotine, register, rotatable valve disc or some other known air flow control means can also be used.
The second air vent 7 can be completely closed with the control plate 9, or the air flowing through it can be restricted so as to obtain the desired ratio of air flowing out of the apparatus through the different air vents 6, 7.
In an embodiment of the apparatus and method, the position of the control plate 9 is adjusted manually. In such a case, an element 10 that reduces the motion sensitivity of the control plate, such as a gas spring or friction mechanism, is connected to the control plate. This prevents an uncontrolled movement of the control plate 9 when the control plate 9 is adjusted in a strong air flow. When the correct position of the control plate 9 has been found, it is locked into this position with a suitable locking member.
In the embodiment shown in
The control unit 11 may comprise a programmable logic and/or processor, for instance, that executes a computer program code downloaded into the control unit. A pressure difference sensor 12 detecting a pressure difference between the room 2 and its surroundings is connected to the control unit 11.
The control unit 11 adjusts the position of the control plate 9 in such a manner that said pressure difference remains as desired. According to an idea, the pressure in the room 2 is approximately 8 to 10 Pa below the air pressure of the surroundings, but it should be noted that the pressure difference could also be other than this.
If the pressure difference exceeds a certain pre-set limit value, the control unit 11 turns the control plate 9 clockwise in the figure, which increases the ratio of air volume flow returning to the room 2 in relation to the air flow volume removed from the room 2.
If the pressure difference becomes smaller than a certain pre-set limit value, the control unit 11 turns the control plate 9 counterclockwise in the figure, which decreases the ratio of air volume flow returning to the room 2 in relation to the airflow volume removed from the room 2. Thus, the apparatus 1 is controlled automatically.
According to a third embodiment, the position of the control plate 9 is changed by an actuator, such as an electric motor, that is operated by a person responsible for the adjustment of the apparatus.
Thus, the control of the apparatus 1 can be manual or at least to some extent automatic. In a fully automatic solution, the use of the air flow controllers can be controlled on the basis of information obtained from various measuring arrangements. Said measuring arrangements can be based on measuring pressure difference, air pressure, air flow or the like. The operation of air flow control motors of the apparatus 1 is controlled by means of the measuring arrangements. According to an idea, the above-mentioned measuring arrangements are measurement sensors that are fixedly attached to the apparatus and measure pressure differences or the like through a flow pipe and thus control the air flow. The measuring and control apparatuses may also be measurement sensors or systems based on a radio signal, gsm signal or some other digital data transmission, which control the operation of the air flow control plates of the device.
It should be noted that the above alternatives for turning the control plate 9 can also be applied to control means 8 of other type.
The apparatus 1 can be equipped with a heating device 13 to heat the air flowing in the second air vent 7. In the embodiment shown in
The apparatus 1 is connected to a low-pressure air purification device 17 that comprises an air filter unit 15, through which air removed from the room 2 flow into the apparatus 1. The air filter unit 15 may comprise one or more filter elements arranged in series. In an embodiment, the air filter unit 15 comprises a filter element of HEPA H13-grade or higher.
The low-pressure air purification device 17 also comprises a fan 16 that produces an air flow required in the operation of the apparatus 1 and low-pressure purification device 17. The fan 16 is typically an electric fan. The capacity of the fan 16 is dimensioned to achieve the necessary air flow. According to an idea, the capacity is enough to filter the room 2 air 6 to 10 times an hour. The replacement air of the room 2 can be taken from outside the building or inside the building, but outside the room 2. The present invention brings about an especially big cost saving during the heating period, because the amount of cold replacement air from outdoors can be reduced. In addition, this provides the advantage that any temporary building heaters in the room 2 operate with the higher operating efficiency, the higher the temperature of the replacement air coming to them is.
The apparatus 1 comprises fastening means 18, with which the air receive duct 4 can be detachably and substantially air-tightly fastened to the vent of the low-pressure purification device 17. Thanks to the fastening means 18, the apparatus 1 and low-pressure purification device 17 can be moved and transported separately and only connected to each other in the room 2. To move the apparatus, it can be equipped with wheels 20. If necessary, the low-pressure air purification device 17 can also be used without the apparatus 1.
The second air vent 7 of the apparatus 1 is equipped with a pipe output fitting 19 that is dimensioned for connection to any generally used ventilation pipe. This way, the air in the air vent 7 can be conveyed away from the apparatus 1. According to an idea, the second air vent 7 is connected to a normal ventilation duct 21 of the room 2, which is isolated from the ventilation machine of the room by plugging, for instance. This way, the heat of the return air and the pressure equalization gain can be evenly distributed in the room 2, which is advantageous in large and multiform rooms, in particular. Another advantage may be derived from the fact that the ventilation ducts of the room 2 can be kept under overpressure all the time, in which case any dust caused by an operation in the room 2 will not enter the ventilation ducts.
The principle of the apparatus 1 and method does not differ per se from what is shown in
Heat recovery 22, with which thermal energy is recovered from the air removed from the room 2, can be arranged in the first air vent 5. This thermal energy can be utilized in heating the air flowing in the second air vent 7, for instance. It should be noted that heat recovery 22 can also be arranged in the apparatus shown in
In some cases, features disclosed in this application may be used as such, regardless of other features. On the other hand, when necessary, features disclosed in this application may be combined in order to provide different combinations.
In summary, the apparatus of the invention is characterised in that it comprises an air receive duct that is arranged to receive air from the room, an air distribution casing connected to the receive duct, first and second air vents connected to the air distribution casing and arranged to convey air coming from the receive duct out of the apparatus, and a control means arranged to adjust the flow resistance of the second air vent in relation to that of the first air vent.
Further, it can be noted that the method of the invention is characterised by connecting the air receive duct to receive air from the room, conveying air from the receive duct to the air distribution casing, conveying a first part of the air from the air distribution casing to the first air vent and through it out of the room, and conveying a second part of the air from the air distribution casing to the second air vent and through it back to the room, and adjusting the flow resistance of the second air vent in relation to that of the first air vent.
The drawings and the related description are only intended to illustrate the idea of the invention. It is apparent to a person skilled in the art that the invention is not restricted to the embodiments described above, in which the invention is described by means of some examples, but many modifications and different embodiments of the invention are possible within the scope of the inventive idea defined in the following claims.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.