WO2020183069A1 - A humidity measuring device and method - Google Patents

A humidity measuring device and method Download PDF

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Publication number
WO2020183069A1
WO2020183069A1 PCT/FI2020/050160 FI2020050160W WO2020183069A1 WO 2020183069 A1 WO2020183069 A1 WO 2020183069A1 FI 2020050160 W FI2020050160 W FI 2020050160W WO 2020183069 A1 WO2020183069 A1 WO 2020183069A1
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WO
WIPO (PCT)
Prior art keywords
air
barrier part
humidity measuring
measuring device
humidity
Prior art date
Application number
PCT/FI2020/050160
Other languages
French (fr)
Inventor
Jaakko ALA-PAAVOLA
Marko Oikarinen
Original Assignee
Mato Engineering Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mato Engineering Oy filed Critical Mato Engineering Oy
Publication of WO2020183069A1 publication Critical patent/WO2020183069A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/56—Investigating or analyzing materials by the use of thermal means by investigating moisture content
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D11/00—Component parts of measuring arrangements not specially adapted for a specific variable
    • G01D11/24—Housings ; Casings for instruments
    • G01D11/245—Housings for sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/38—Concrete; Lime; Mortar; Gypsum; Bricks; Ceramics; Glass
    • G01N33/383—Concrete or cement
    • G—PHYSICS
    • G12—INSTRUMENT DETAILS
    • G12B—CONSTRUCTIONAL DETAILS OF INSTRUMENTS, OR COMPARABLE DETAILS OF OTHER APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G12B9/00—Housing or supporting of instruments or other apparatus
    • G12B9/02—Casings; Housings; Cabinets

Definitions

  • the present invention relates to a humidity measuring device and more particularly to a humidity measuring device comprising an air-filled chamber.
  • Resistive humidity sensors measure a change in electrical impedance of a hygroscopic medium. The results are inaccurate due to the properties of the electrodes and the contact to the material to be measured, and further due to a specific conductivity of a material, e.g. caused by salt or minerals. Optical absorption is applicable only to measurements of gases.
  • hyperspectral imaging is applicable only for measuring the moisture content of a surface of a material.
  • the borehole method is a common method used in humidity measurements in concrete.
  • a borehole is drilled to the concrete and a humidity probe is left in the borehole until the humidity in the hole has reached an equilibrium state with the surrounding concrete and the stabilized values can be read.
  • the further disadvantage of using the borehole method in concrete is the risk of damaging heating elements or tubing embedded in the concrete when drilling the boreholes.
  • a humidity measuring sensor comprising an air-filled space as a measurement space inside the sensor. This kind of sensors are used as immersed sensors inside a moist material, for instance.
  • the problem is a water vapour condensing in the air-filled space as the temperature decreases inside the air-filled chamber. The water condensed on the sensor destroys the measurement results. If the sensor is able to recover it will, however, take a long time.
  • An object of the present invention is to provide a humidity measuring device so as to alleviate the above problems.
  • the invention is based on the idea of a humidity measuring device comprising a humidity measuring sensor.
  • the humidity measuring device comprises a first surface forming an air-filled chamber and the air-filled chamber comprising the humidity measuring sensor inside the chamber.
  • the first surface comprising a first barrier part being permeable to air and water vapour, and the first barrier part forming a flow path between inside the air-filled chamber and outside the first surface.
  • the device comprises a second surface arranged to surround the first barrier part, the second surface comprising a second barrier part being permeable to air and water vapour, and the second barrier part forming a flow path between inside the second surface and outside the second surface.
  • the first barrier part and the second barrier part arranged successively to form a flow path between inside the air-filled chamber and outside the second surface.
  • the device comprises an air gap between the first barrier part and the second barrier part providing a capillary break.
  • the air gap between parallel layers of material provides a capillary break, i.e. stops capillary action.
  • the air gap may be created by means of a supporting part positioned between the first barrier part and the second barrier part creating a distance between the first barrier part and the second barrier part.
  • the supporting part comprises a hydrophobic material or a non-porous material.
  • the air gap reduces the risk of water vapour condensation inside the air-filled chamber as it stops the capillary action between the first barrier part and the second barrier part. As the water condensation on the sensor in the air-filled chamber is prevented the reliability of the humidity measuring device is increased.
  • the humidity measuring device may comprise an enclosure surrounding the first surface and the second surface, and the outer surface of the enclosure comprising an opening to form a flow path between outside the enclosure and inside the enclosure.
  • the enclosure may comprise watertight material.
  • the material can comprise a polymer-based watertight material.
  • the device may comprise a housing surrounding the enclosure, and the housing comprises a part permeable to air and water vapour, and the part is positioned to a location of the enclosure comprising the opening.
  • the second barrier part is preferably positioned to the vicinity of the outer surface of the enclosure to provide a direct contact between the part permeable to air and water vapour of the housing and the second barrier part.
  • the humidity surrounding the housing can enter the air-filled chamber to the humidity measuring sensor through the part of the housing permeable to air and water vapour via the second and first barrier parts.
  • the device may comprise a housing surrounding the first surface, and the housing comprises a part permeable to air and water vapour, and the housing is forming the second surface. Then the part of the housing which is permeable to air and water vapour forms the second barrier part.
  • the housing may be made of material which is permeable to air and water vapour. Then the whole housing is able to absorb or release humidity with the surroundings.
  • the housing material may comprise cement-based materials, e.g. concrete, mortar or polymer modified cement, for instance.
  • first barrier part and the second barrier part may be porous material and comprise a different average pore-size.
  • the flow of water vapour includes both gas and liquid phases of water, and hence, the pore radius affects the rate of transport.
  • the material of the first barrier part and the second barrier part comprises an average pore-size in the range of 1 to lOOnm. Further, the material of the first barrier part and the second barrier part may comprise an average pore-size in the range of 3 to 30nm, preferably 5 to 20 nm.
  • the relative humidity in the air-filled chamber remains on a lower level than in the air gap between the first and second barrier parts. This reduces the risk of water vapour condensation inside the air-filled chamber when the temperature in the chamber decreases.
  • the measurement data of the relative humidity in the air-filled chamber is then multiplied with a correction coefficient in order to obtain true measurement data.
  • first barrier part and the second barrier part may comprise same material.
  • the material of the first barrier part and the second barrier part may comprise cement paste, and the average pore-size is in the range of 1 to lOOnm. Pore sizes are classified as the following: micropores 1 to lOOnm, mesopores lOOnm to 10 pm, macropores 100 pm to 1 cm.
  • the air-filled chamber may comprise a temperature measuring sensor.
  • the enclosure or the housing is not thermally insulated, and the heat is conducted to the air-filled chamber. It is also possible to position the temperature measuring sensor inside the enclosure or inside the housing material.
  • the measuring device may comprise also a pressure sensor inside the chamber.
  • the pressure sensor can indicate a change in the prevailing conditions in the surroundings of the humidity measuring device. For instance, when the humidity measuring device is inserted in concrete before the pouring of the concrete the increase in the pressure indicates the moment when the humidity measuring device is immersed in the concrete.
  • the space between the enclosure and the air-filled chamber may filled.
  • the filling may comprise a water resistant moulded polymer material, resin, an epoxy resin or polyurethane. This filling protects the electronic sensors inside the air-filled chamber.
  • the device may comprise a third surface comprising a third barrier part, the third barrier part comprising calcium sulfate dihydrate, the third surface arranged between the first barrier part and the humidity measuring sensor, and an air gap between the first barrier part and the third barrier part.
  • the third barrier part is arranged between the first barrier part and the humidity measuring sensor such that the air and water vapour is moving to and from the humidity measuring sensor through the third barrier part.
  • the third barrier part protects the humidity measuring sensor and possible other sensors against the accumulation of dirt.
  • the third barrier part provides also protection against acidity and alkalinity. If the humidity measuring device is immersed in a material the third barrier prevents from the material solving components from entering the air-filled chamber.
  • the third barrier part acts as a filter but comprises a high water vapour permeability and a small water vapour flow resistance.
  • the measuring device comprises a memory for storing measurement data, and a processor, a transmitting system comprising a transmitter, a power source and an antenna for transmitting the measurement data wirelessly to a receiving device, and at least one of the following: the memory, the processor and the transmitting system, is positioned: on the outer surface of the second surface, or within the space between the enclosure and the air-filled chamber, or on the outer surface of the enclosure.
  • the measurement data may be transmitted via Internet of Things to cloud computing.
  • Internet of Thing can be connected by using The Long Range Wide Area Network, as an example.
  • the Long Range Wide Area Network, LoRaWAN, specification is a Low Power, Wide Area networking protocol designed to wirelessly connect battery operated things to the internet in regional, national or global networks.
  • LoRaWAN long battery life.
  • the humidity measuring device may be programmed to go into deep sleep mode when not transmitting messages, which maximizes battery life. Further, the LoRa signal itself requires a small power to generate and transmit. Further, cellular based technologies like NB-IOT and Cat-M can also be used for transmitting the measurement data.
  • the enclosure or enclosure walls are provided air and water vapour impermeable.
  • the enclosure walls prevent air and water vapour from flowing into the closed air-filled chamber space.
  • the enclosure ⁇ walls comprise a flow channel between the closed the closed air-filled chamber space inside the closed air-filled chamber and the outside of the closed air filled chamber.
  • the flow channel comprises a first barrier element arranged define the closed air-filled chamber space together with the chamber walls.
  • the first barrier element is air and water vapour permeable. The first barrier element blocks or closes the flow channel such that air and water vapour flow into and out of the closed air-filled chamber space occurs through the first barrier element.
  • the flow channel comprises a second barrier element arranged to the flow channel outside closed air-filled chamber space and at distance from the first barrier element such that a closed air gap is provided between the first and second barrier elements.
  • the second barrier element is air and water vapour permeable for providing flow path for air and water vapour flow into the closed air-filled chamber space and out of closed air-filled chamber space through flow channel and the first and second barrier elements and via the closed air gap.
  • the closed air gap is provided to the flow channel between the first and second barrier elements.
  • first barrier element or the second barrier element or the first and second barrier elements are made of porous material for providing air and water vapour permeability.
  • the porous material provides air and water vapour flow through flow channel and the first and second barrier elements and via the closed air gap.
  • the porous material of the first and second barrier elements comprises one of the following: mineral-based material, or concrete, or cement-based material, or calcium sulfate dihydrate -based material.
  • the material of the first and second barrier elements may be same or different.
  • the material of the inner chamber wall and the outer chamber wall maybe same or different.
  • the measurement device comprises a housing surrounding the closed air-filled chamber.
  • the housing being air and water vapour permeable.
  • the housing encloses the closed air-filed chamber and allows air and water vapour flow into the closed air-filled chamber space via the flow channel.
  • the measurement device comprises a housing surrounding the closed air-filled chamber.
  • the housing comprising a housing barrier element.
  • the housing barrier element is air and water vapour permeable and arranged to provide flow path for air and water vapour between the closed air- filled chamber and outside of the housing.
  • the housing encloses the closed air-filed chamber and housing barrier element allows air and water vapour flow into the closed air-filled chamber space via the flow channel.
  • the air and water vapour permeable housing or the air or water vapour permeable housing barrier element is arranged to form the first barrier element or the second barrier element.
  • the separate second barrier element may be omitted.
  • the first closed first air gap is provided between the first barrier element and the housing or the housing barrier element.
  • the measurement device comprises a housing surrounding the closed air-filled chamber.
  • the housing comprising one or more openings arranged to provide flow path for air and water vapour between the closed air-filled chamber and outside of the housing.
  • the invention is based on the idea of a method for measuring humidity, where the method comprises the humidity measuring device.
  • the method comprises: inserting the humidity measuring device in connection with the material to be measured, allowing the humidity from the material to be measured to flow through the second barrier part and through the first barrier part to the humidity measuring sensor inside the air-filled chamber, and measuring the humidity with the humidity measuring sensor.
  • the method may comprise: the device comprises a housing surrounding the first surface, and the housing comprises a part permeable to air and water vapour, and the housing forming the second surface , and inserting the humidity measuring device in concrete during or after the concrete is poured but prior to the concrete being fully cured, and allowing the concrete to cure and thereby the humidity measuring device forming an integral part of cured concrete.
  • the device may preferably be embedded into a freshly poured concrete.
  • the humidity measuring device provides information about the humidity profile under the surface.
  • the humidity measuring device can be positioned below the surface thus the surface above is free from protruding parts.
  • the depth of the measurement is not restricted to a depth close to the upper surface level of the material to be measured.
  • the humidity measuring device can be positioned inside the structure or material to be measured, e.g. a fresh poured concrete, and be permanently immersed in the material or left inside the structure to be measured, e.g. remain inside a solid material as the concrete cures/dries.
  • Figures la)-d) show a cross-sectional view of a humidity measuring device
  • Figure 2 shows a cross-sectional view of a humidity measuring device
  • Figures 3a)-c) show a cross-sectional view of a humidity measuring device
  • Figure 4 shows a cross-sectional view of a humidity measuring device
  • Figure 5 shows a cross-sectional view of a humidity measuring device inserted in a material.
  • Figures la)-d) show a humidity measuring device 1 comprising a humidity measuring sensor 2 in an air-filled chamber 4.
  • a first surface 24 is forming an air-filled chamber 4.
  • the humidity measuring sensor 2 is positioned inside the chamber 4.
  • the first surface 24 comprises a first barrier part 9 which is permeable to air and water vapour.
  • the first barrier part 9 forms a flow path between inside the air-filled chamber 4 and outside the first surface 24.
  • a second surface 25 is arranged to surround the first barrier part 9.
  • the second surface 25 comprises a second barrier part 8 which is permeable to air and water vapour.
  • the second barrier part 8 forms a flow path between inside the second surface 25 and outside the second surface 25.
  • the first barrier part 9 and the second barrier part 8 are arranged successively to form a flow path for air and water vapour between inside the air-filled chamber 4 and outside the second surface 25.
  • An air gap 10 is arranged between the first barrier part 9 and the second barrier part 8, and the air gap 10 provides a capillary break.
  • the humidity measuring device 1 comprises an enclosure
  • the air-filled chamber 4 is formed by a first surface 24, i.e. the air-filled chamber is inside the first surface 24.
  • the first surface 24 comprises the walls 12b of the air-filled chamber 4 and the first barrier part 9.
  • a humidity measuring sensor 2 is positioned inside the air-filled chamber 4.
  • the air-filled chamber 4 is in connecting with the surroundings of the enclosure 3 through a connecting portion 5.
  • the connecting portion 5 extends to an outer surface of the enclosure 6 and the outer surface of the enclosure 6 comprises an opening 7 for the connecting portion 5.
  • the connecting portion 5 forms a flow path for air and water vapour between inside the air-filled chamber 4 and outside of the enclosure 3.
  • the connecting portion 5 comprises a cross-sectional area which is the cross-sectional area of the flow channel for air and water vapour.
  • the first surface 24 comprises a first barrier part 9.
  • the device comprises a second surface 25 which comprises the walls 12a of the connecting portion 5 extending between the first barrier part 9 and the second barrier part 8 and the second barrier part 8.
  • the first 9 and the second barrier parts 8 are inserted to the connecting portion 5.
  • the first barrier 9 and the second barrier 8 parts are arranged successively, the first barrier part 9 after the second barrier part 8 in the flow direction from the outside of the enclosure 3 to inside of the air-filled chamber 4.
  • the first barrier 9 and the second barrier parts 8 form a flow path for air and water vapour between inside the air-filled chamber 4 and outside the second surface 25.
  • the first barrier 9 and the second barrier parts 8 are permeable to air and water vapour and they both cover the cross-sectional area of the connecting portion 5 preventing a bypass flow of the air and water vapour inside the connecting portion 5.
  • An air gap 10 is arranged between the first 9 and second barrier 8 parts providing a capillary break.
  • the air gap 10 may be created by means of supporting part 11, which is positioned between the first barrier part 9 and the second barrier part 8 to create a distance between the first barrier part 9 and the second barrier part 8.
  • Examples of supporting parts 11 are a nut or a hollow sleeve.
  • the first barrier part 9 and the second barrier part 8 can also be fastened to the wall 12a of the connecting portion 5 at a distance apart from each other.
  • the enclosure 3 and the walls 12b of the air-filled chamber 4 inside the enclosure 3 preferably comprise watertight material.
  • the enclosure walls 3 are provided air and water vapour impermeable such that air and water vapour may not flow through the enclosure walls 3.
  • the enclosure walls 3 comprise a flow channel between the closed the closed air-filled chamber space 4 inside the closed air-filled chamber and the outside of the closed air filled chamber, as shown in figure la.
  • the flow channel is provided with the first barrier element 9 arranged to the flow channel.
  • the first barrier element 9 blocks or closes the flow channel.
  • the first barrier element 9 is arranged to define the closed air-filled chamber space 4 together with the enclosure walls 3.
  • the flow channel further comprises the second barrier element 8 arranged to the flow channel outside closed air-filled chamber space 4 and at distance from the first barrier element 9 such that a closed air gap 10 is provided between the first and second barrier elements 9, 8.
  • the second barrier element 8 blocks or closes the flow channel.
  • the air gap 10 is formed between the first and second barrier elements 9, 8 in the flow channel.
  • the air gap 10 provides a capillary break to the flow channel between the first and second barrier elements 9, 8. Thus, flow of liquid water to the closed air-filled chamber space 4.
  • the first and second barrier elements 9, 8 are air and water vapour permeable for providing flow path for air and water vapour flow into the closed air-filled chamber space 4 and out of closed air-filled chamber space 4 through flow channel and the first and second barrier elements 9, 8 and via the closed first air gap 10.
  • the humidity measuring device 1 comprises a hemispherical shape.
  • the base of the hemisphere comprises a watertight material which is preferably hydrophobic providing a capillary break.
  • the outer hemispherical portion is formed of the second barrier part 8 of the second surface 25.
  • the inner hemispherical shaped portion is formed of the first barrier part 9 of the first surface 24.
  • the first surface 24 which is formed of a part of the base and the first barrier part 9 is forming the air-filled chamber 4.
  • the air gap 10 providing the capillary break is arranged between the first 9 and the second barrier parts 8.
  • the first 9 and the second barrier parts 8 are supported to the base of the hemisphere.
  • the humidity measuring device 1 comprises a cuboid or a cube shape.
  • the first 24 and the second surface 25 comprise a cuboid or cube shape and are formed of the first barrier part 9 and the second barrier part 8.
  • the cuboid or cube shaped second surface 25 contains the inner cuboid or cube shaped first surface 24.
  • the humidity measuring device 1 comprises a spherical shape.
  • the first 24 and the second surface 25 comprise a spherical shape and are formed of the first barrier part 9 and the second barrier part 8.
  • the spherical shaped second surface 25 contains the inner spherical shaped first surface 24.
  • the first barrier part 9 and the second barrier part 8 may comprise same material or different material.
  • the first barrier part 9 and the second barrier part 8 are porous material.
  • the materials of the first barrier part 8 and the second barrier part 9 can comprise a different average pore-size.
  • the material of the first barrier 9 and the second barrier 8 can comprise cement paste, and the average pore-size is in the range of 1 to lOOnm.
  • Figure 2 shows a humidity measuring device of Figure la) comprising a third surface 26 comprising a third barrier part 13.
  • the third barrier 13 is inside the first surface 24.
  • the third barrier part 13 is inserted in the connecting portion 5 and arranged between the first barrier part 9 and the humidity measuring sensor 2.
  • Between the first barrier part 9 and the third barrier part 13 is an air gap 10b, i.e. the third barrier part 13 is arranged a distance apart from the first barrier part 9.
  • the third barrier part 13 covers the cross-sectional area of the connecting portion 5 guiding air and water vapour to flow through the third barrier part 13.
  • the third barrier part 13 material comprises calcium sulfate dihydrate.
  • the third surface 26 and the third barrier part 13 is shown in connection of the device 1 shown in Figure la).
  • the arrangement of the third surface 26 and the third barrier part 13 can be applied also to the devices 1 shown in Figures lb)-ld).
  • the shape of the third surface 26 and the third barrier part 13 preferably correspond the shape on the first surface 24 and first barrier part 9.
  • the third barrier part 13 may be a hemispherical shaped portion positioned within the first barrier part 9 of the first surface 24 at a distance apart from the first barrier part 9 and supported to the base.
  • the space 14 between the enclosure 3 and the air-filled chamber 4 can be filled with a water resistant material.
  • FIGs 3a) -c) show a humidity measuring device 1 comprising a housing 15 surrounding the enclosure 3.
  • the hatching is omitted for the sake of clarity.
  • the housing 15 comprises a part made of material permeable to air and water vapour 16 as shown in Figure 3a).
  • the part permeable to air and water vapour 16 is positioned to a location of the enclosure 3 comprising the opening 7 for the connecting portion 5.
  • the major part of the surrounding housing 15 may be made of material permeable to air and water vapour as shown in Figure 3b).
  • the part permeable to air and water vapour 16 of the surrounding housing 15 is a substantially integral piece wherein the water vapour and air can distribute and covers the surface of the enclosure 3 comprising the opening 7 and extends to cover part of the surfaces of the enclosure 3 surrounding the connecting portion 5.
  • Figure 3c shows a housing 15 where the whole surrounding housing is made of material permeable to air and water vapour.
  • the material permeable to air and water vapour in the housing 15 comprises concrete, polymer modified cement or cement paste, for instance.
  • the humidity in the part of the housing 16 which is made of porous material, in this case of material permeable to air and water vapour, reaches the humidity of the environment over a time period.
  • Figure 4 shows a humidity measuring device 1 comprising also other sensors inside the air-filled chamber 4 in addition to the humidity measuring sensor 2.
  • the air-filled chamber 4 comprises a temperature measuring sensor 17 and a pressure sensor 18.
  • the measuring device 1 comprises also a memory 19 for storing measurement data, and a transmitting system 20 comprising a transmitter, a power source and an antenna for transmitting the measurement data wirelessly to a receiving device 21, and a processor 23 for processing the data. They are located to the space 14 between the enclosure 3 and the air-filled chamber 4.
  • FIG 5 shows a cross-sectional view of a humidity measuring device 1 inserted in a wet material 22.
  • the humidity measuring device 1 is embedded into a poured concrete, for instance.
  • the device 1 comprises a housing 15 permeable to air and water vapour surrounding the enclosure 3.
  • the housing 15 receives humidity from the surrounding wet material 22.
  • the housing 15 can comprise a part 16 or the major part of the housing or the whole housing can be made of material permeable to air and water vapour as described in Figures 3a)-c).
  • the housing 15 is surrounding the first surface 24 forming the air-filled chamber 4.
  • the housing 15 comprises at least a part which is permeable to air and water vapour 16 and that part 16 is arranged at a distance of the air gap 10 from the first barrier part 9.
  • the water vapour is transferred through the part permeable to air and water vapour 16 to the air gap 10 providing a capillary break.
  • the relative humidity reaches close to 100% in the air gap 10 during a period of time at the beginning. From the air gap 10 the water vapour is transferred through the first barrier part 9 to the air-filled chamber 4.
  • the device 1 can also comprise a third barrier part 13 as described in Figure 2.
  • the air-filled chamber 4 comprises inside a humidity measuring sensor 2, a temperature measuring sensor 17 and a pressure sensor 18.
  • the relative humidity in the air-filled chamber 4 remains on a lower level than in the air gap 10 between the part permeable to air and water vapour 16 and the first barrier part 9. This reduces the risk of water vapour condensation inside the air-filled chamber 4 when the temperature in the chamber 4 decreases as the curing/drying proceeds. For instance, as the relative humidity reaches close to 100% in the air gap 10 in the beginning the relative humidity reaches 70..90% in the air-filled chamber 4. The measurement data of the relative humidity in the air-filled chamber 4 is then multiplied with a correction coefficient in order to obtain true data.
  • the humidity measuring device 1 also comprises within a memory 19 for storing measurement data, a processor 23 and a data transmitting system 20 comprising a transmitter, a power source and an antenna for transmitting the measurement data wirelessly to a receiving device 21.
  • the receiving device 21 is located externally.
  • the wet material 22 e.g. concrete, cures/dries during a period of time the inserted the humidity measuring device 1 forms an integral part of cured/dried material.
  • the humidity measuring device 1 measures the humidity and the temperature inside the curing and cured material, e.g. concrete.
  • the measurement data of a concrete can be applied to determining the strength of the concrete and timing an installation of flooring or surface coatings, for instance.
  • Part list 1 a humidity measuring device; 2 a humidity measuring sensor; 3 an enclosure; 4 a chamber; 5 a connecting portion; 6 an outer surface of an enclosure; 7 an opening; 8 a second barrier part; 9 a first barrier part; 10, 10b an air gap; 11 a supporting part; 12a-b a wall; 13 a third barrier part; 14 a space; 15 a housing; 16 a part permeable to air and water vapour; 17 a temperature measuring sensor; 18 a pressure sensor; 19 a memory; 20 a data transmitting system; 21 a receiving device; 22 material, 23 a processor, 24 a first surface, 25 a second surface, 26 a third surface.

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Abstract

The invention relates to a humidity measuring device comprising a humidity measuring sensor (2) comprising a first surface (24) forming an air-filled chamber (4), the air-filled chamber (4) comprising the humidity measuring sensor (2) inside the chamber (4), the first surface (24) comprising a first barrier part (9) being permeable to air and water vapour. A second surface (25) arranged to surround the first barrier part (9), the second surface (25) comprising a second barrier part (8) being permeable to air and water vapour. The first barrier part (9) and the second barrier part (8) arranged successively to form a flow path between inside the air-filled chamber (4) and outside the second surface (25), an air gap (10) between the first barrier part (9) and the second barrier part (8) providing a capillary break.

Description

A HUMIDITY MEASURING DEVICE AND METHOD
FIELD OF THE INVENTION
The present invention relates to a humidity measuring device and more particularly to a humidity measuring device comprising an air-filled chamber.
BACKGROUND OF THE INVENTION
In the prior art humidity of gases is measured with a hygrometer utilizing a capacitive sensor. The sensor is placed in a direct contact with the flowing gas. The measurement is based on a change in the measured capacitance.
In the prior art humidity of solids is measured with the following known methods: by taking a sample and weighing the sample for determining humidity, using of resistive humidity sensors, applying optical absorption, using hyperspectral imaging and X-ray fluorescence.
Resistive humidity sensors measure a change in electrical impedance of a hygroscopic medium. The results are inaccurate due to the properties of the electrodes and the contact to the material to be measured, and further due to a specific conductivity of a material, e.g. caused by salt or minerals. Optical absorption is applicable only to measurements of gases.
Other methods listed above are mostly suitable for laboratory uses because of the cost of the measuring device and the large size of the measurement device. Additionally, hyperspectral imaging is applicable only for measuring the moisture content of a surface of a material.
Known methods for determining humidity in solid materials are taking a sample and weighing the sample for determining humidity and a borehole method, where a borehole is drilled to the solid material. The disadvantages of the methods are destruction of the solid material, slowness of the process and several stages of operation necessary. Additionally, the destructed solid material has to repaired afterwards.
The borehole method is a common method used in humidity measurements in concrete. A borehole is drilled to the concrete and a humidity probe is left in the borehole until the humidity in the hole has reached an equilibrium state with the surrounding concrete and the stabilized values can be read. The further disadvantage of using the borehole method in concrete is the risk of damaging heating elements or tubing embedded in the concrete when drilling the boreholes. In the prior art it is known a humidity measuring sensor comprising an air-filled space as a measurement space inside the sensor. This kind of sensors are used as immersed sensors inside a moist material, for instance. The problem is a water vapour condensing in the air-filled space as the temperature decreases inside the air-filled chamber. The water condensed on the sensor destroys the measurement results. If the sensor is able to recover it will, however, take a long time.
BRIEF DESCRIPTION OF THE INVENTION
An object of the present invention is to provide a humidity measuring device so as to alleviate the above problems.
The objects of the invention are achieved by a humidity measuring device and a method for measuring humidity which are characterized by what is stated in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims.
The invention is based on the idea of a humidity measuring device comprising a humidity measuring sensor. The humidity measuring device comprises a first surface forming an air-filled chamber and the air-filled chamber comprising the humidity measuring sensor inside the chamber. The first surface comprising a first barrier part being permeable to air and water vapour, and the first barrier part forming a flow path between inside the air-filled chamber and outside the first surface. The device comprises a second surface arranged to surround the first barrier part, the second surface comprising a second barrier part being permeable to air and water vapour, and the second barrier part forming a flow path between inside the second surface and outside the second surface. The first barrier part and the second barrier part arranged successively to form a flow path between inside the air-filled chamber and outside the second surface. The device comprises an air gap between the first barrier part and the second barrier part providing a capillary break.
The air gap between parallel layers of material provides a capillary break, i.e. stops capillary action. The air gap may be created by means of a supporting part positioned between the first barrier part and the second barrier part creating a distance between the first barrier part and the second barrier part. The supporting part comprises a hydrophobic material or a non-porous material.
The air gap reduces the risk of water vapour condensation inside the air-filled chamber as it stops the capillary action between the first barrier part and the second barrier part. As the water condensation on the sensor in the air-filled chamber is prevented the reliability of the humidity measuring device is increased.
In an embodiment the humidity measuring device may comprise an enclosure surrounding the first surface and the second surface, and the outer surface of the enclosure comprising an opening to form a flow path between outside the enclosure and inside the enclosure. The enclosure may comprise watertight material. The material can comprise a polymer-based watertight material.
In an embodiment the device may comprise a housing surrounding the enclosure, and the housing comprises a part permeable to air and water vapour, and the part is positioned to a location of the enclosure comprising the opening. The second barrier part is preferably positioned to the vicinity of the outer surface of the enclosure to provide a direct contact between the part permeable to air and water vapour of the housing and the second barrier part. The humidity surrounding the housing can enter the air-filled chamber to the humidity measuring sensor through the part of the housing permeable to air and water vapour via the second and first barrier parts.
In an embodiment the device may comprise a housing surrounding the first surface, and the housing comprises a part permeable to air and water vapour, and the housing is forming the second surface. Then the part of the housing which is permeable to air and water vapour forms the second barrier part.
In an embodiment the housing may be made of material which is permeable to air and water vapour. Then the whole housing is able to absorb or release humidity with the surroundings. The housing material may comprise cement-based materials, e.g. concrete, mortar or polymer modified cement, for instance.
In an embodiment the first barrier part and the second barrier part may be porous material and comprise a different average pore-size. The flow of water vapour includes both gas and liquid phases of water, and hence, the pore radius affects the rate of transport.
In an embodiment the material of the first barrier part and the second barrier part comprises an average pore-size in the range of 1 to lOOnm. Further, the material of the first barrier part and the second barrier part may comprise an average pore-size in the range of 3 to 30nm, preferably 5 to 20 nm.
The relative humidity in the air-filled chamber remains on a lower level than in the air gap between the first and second barrier parts. This reduces the risk of water vapour condensation inside the air-filled chamber when the temperature in the chamber decreases. The measurement data of the relative humidity in the air-filled chamber is then multiplied with a correction coefficient in order to obtain true measurement data.
In an embodiment the first barrier part and the second barrier part may comprise same material.
In an embodiment the material of the first barrier part and the second barrier part may comprise cement paste, and the average pore-size is in the range of 1 to lOOnm. Pore sizes are classified as the following: micropores 1 to lOOnm, mesopores lOOnm to 10 pm, macropores 100 pm to 1 cm.
In an embodiment the air-filled chamber may comprise a temperature measuring sensor. The enclosure or the housing is not thermally insulated, and the heat is conducted to the air-filled chamber. It is also possible to position the temperature measuring sensor inside the enclosure or inside the housing material.
In an embodiment the measuring device may comprise also a pressure sensor inside the chamber. The pressure sensor can indicate a change in the prevailing conditions in the surroundings of the humidity measuring device. For instance, when the humidity measuring device is inserted in concrete before the pouring of the concrete the increase in the pressure indicates the moment when the humidity measuring device is immersed in the concrete.
In an embodiment the space between the enclosure and the air-filled chamber may filled. The filling may comprise a water resistant moulded polymer material, resin, an epoxy resin or polyurethane. This filling protects the electronic sensors inside the air-filled chamber.
In an embodiment the device may comprise a third surface comprising a third barrier part, the third barrier part comprising calcium sulfate dihydrate, the third surface arranged between the first barrier part and the humidity measuring sensor, and an air gap between the first barrier part and the third barrier part. The third barrier part is arranged between the first barrier part and the humidity measuring sensor such that the air and water vapour is moving to and from the humidity measuring sensor through the third barrier part. The third barrier part protects the humidity measuring sensor and possible other sensors against the accumulation of dirt.
Further, the third barrier part provides also protection against acidity and alkalinity. If the humidity measuring device is immersed in a material the third barrier prevents from the material solving components from entering the air-filled chamber. The third barrier part acts as a filter but comprises a high water vapour permeability and a small water vapour flow resistance.
In an embodiment the measuring device comprises a memory for storing measurement data, and a processor, a transmitting system comprising a transmitter, a power source and an antenna for transmitting the measurement data wirelessly to a receiving device, and at least one of the following: the memory, the processor and the transmitting system, is positioned: on the outer surface of the second surface, or within the space between the enclosure and the air-filled chamber, or on the outer surface of the enclosure. For instance, the measurement data may be transmitted via Internet of Things to cloud computing. Internet of Thing can be connected by using The Long Range Wide Area Network, as an example. The Long Range Wide Area Network, LoRaWAN, specification is a Low Power, Wide Area networking protocol designed to wirelessly connect battery operated things to the internet in regional, national or global networks. The benefit of LoRaWAN is long battery life. The humidity measuring device may be programmed to go into deep sleep mode when not transmitting messages, which maximizes battery life. Further, the LoRa signal itself requires a small power to generate and transmit. Further, cellular based technologies like NB-IOT and Cat-M can also be used for transmitting the measurement data.
As the measurement data is transmitted wirelessly there is no need to bring a measurement data retrieving device close to the humidity measuring device.
In one embodiment, the enclosure or enclosure walls are provided air and water vapour impermeable. Thus, the enclosure walls prevent air and water vapour from flowing into the closed air-filled chamber space.
In one embodiment, the enclosure §walls comprise a flow channel between the closed the closed air-filled chamber space inside the closed air-filled chamber and the outside of the closed air filled chamber. The flow channel comprises a first barrier element arranged define the closed air-filled chamber space together with the chamber walls. The first barrier element is air and water vapour permeable. The first barrier element blocks or closes the flow channel such that air and water vapour flow into and out of the closed air-filled chamber space occurs through the first barrier element.
The flow channel comprises a second barrier element arranged to the flow channel outside closed air-filled chamber space and at distance from the first barrier element such that a closed air gap is provided between the first and second barrier elements. The second barrier element is air and water vapour permeable for providing flow path for air and water vapour flow into the closed air-filled chamber space and out of closed air-filled chamber space through flow channel and the first and second barrier elements and via the closed air gap.
The closed air gap is provided to the flow channel between the first and second barrier elements.
In one embodiment, first barrier element or the second barrier element or the first and second barrier elements are made of porous material for providing air and water vapour permeability. Thus, the porous material provides air and water vapour flow through flow channel and the first and second barrier elements and via the closed air gap.
In some embodiments, the porous material of the first and second barrier elements comprises one of the following: mineral-based material, or concrete, or cement-based material, or calcium sulfate dihydrate -based material.
The material of the first and second barrier elements may be same or different. Similarly, the material of the inner chamber wall and the outer chamber wall maybe same or different.
In one embodiment, the measurement device comprises a housing surrounding the closed air-filled chamber. The housing being air and water vapour permeable. The housing encloses the closed air-filed chamber and allows air and water vapour flow into the closed air-filled chamber space via the flow channel.
In one embodiment, the measurement device comprises a housing surrounding the closed air-filled chamber. The housing comprising a housing barrier element. The housing barrier element is air and water vapour permeable and arranged to provide flow path for air and water vapour between the closed air- filled chamber and outside of the housing.
The housing encloses the closed air-filed chamber and housing barrier element allows air and water vapour flow into the closed air-filled chamber space via the flow channel.
In one embodiment, the air and water vapour permeable housing or the air or water vapour permeable housing barrier element is arranged to form the first barrier element or the second barrier element. Thus, the separate second barrier element may be omitted. The first closed first air gap is provided between the first barrier element and the housing or the housing barrier element.
In one embodiment, the measurement device comprises a housing surrounding the closed air-filled chamber. The housing comprising one or more openings arranged to provide flow path for air and water vapour between the closed air-filled chamber and outside of the housing.
The invention is based on the idea of a method for measuring humidity, where the method comprises the humidity measuring device. The method comprises: inserting the humidity measuring device in connection with the material to be measured, allowing the humidity from the material to be measured to flow through the second barrier part and through the first barrier part to the humidity measuring sensor inside the air-filled chamber, and measuring the humidity with the humidity measuring sensor.
In an embodiment the method may comprise: the device comprises a housing surrounding the first surface, and the housing comprises a part permeable to air and water vapour, and the housing forming the second surface , and inserting the humidity measuring device in concrete during or after the concrete is poured but prior to the concrete being fully cured, and allowing the concrete to cure and thereby the humidity measuring device forming an integral part of cured concrete. The device may preferably be embedded into a freshly poured concrete.
An advantage of the invention is that the humidity measuring device provides information about the humidity profile under the surface. The humidity measuring device can be positioned below the surface thus the surface above is free from protruding parts. The depth of the measurement is not restricted to a depth close to the upper surface level of the material to be measured. For instance, the humidity measuring device can be positioned inside the structure or material to be measured, e.g. a fresh poured concrete, and be permanently immersed in the material or left inside the structure to be measured, e.g. remain inside a solid material as the concrete cures/dries.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in detail by means of specific embodiments with reference to the enclosed drawings, in which
Figures la)-d) show a cross-sectional view of a humidity measuring device;
Figure 2 shows a cross-sectional view of a humidity measuring device;
Figures 3a)-c) show a cross-sectional view of a humidity measuring device;
Figure 4 shows a cross-sectional view of a humidity measuring device; and
Figure 5 shows a cross-sectional view of a humidity measuring device inserted in a material.
DETAILED DESCRIPTION OF THE INVENTION
Figures la)-d) show a humidity measuring device 1 comprising a humidity measuring sensor 2 in an air-filled chamber 4. A first surface 24 is forming an air-filled chamber 4. The humidity measuring sensor 2 is positioned inside the chamber 4. The first surface 24 comprises a first barrier part 9 which is permeable to air and water vapour. The first barrier part 9 forms a flow path between inside the air-filled chamber 4 and outside the first surface 24. A second surface 25 is arranged to surround the first barrier part 9. The second surface 25 comprises a second barrier part 8 which is permeable to air and water vapour. The second barrier part 8 forms a flow path between inside the second surface 25 and outside the second surface 25. The first barrier part 9 and the second barrier part 8 are arranged successively to form a flow path for air and water vapour between inside the air-filled chamber 4 and outside the second surface 25. An air gap 10 is arranged between the first barrier part 9 and the second barrier part 8, and the air gap 10 provides a capillary break.
In Figure la), the humidity measuring device 1 comprises an enclosure
3 comprising an air-filled chamber 4 inside the enclosure 3. The air-filled chamber
4 is formed by a first surface 24, i.e. the air-filled chamber is inside the first surface 24. The first surface 24 comprises the walls 12b of the air-filled chamber 4 and the first barrier part 9. A humidity measuring sensor 2 is positioned inside the air-filled chamber 4. The air-filled chamber 4 is in connecting with the surroundings of the enclosure 3 through a connecting portion 5. The connecting portion 5 extends to an outer surface of the enclosure 6 and the outer surface of the enclosure 6 comprises an opening 7 for the connecting portion 5.
The connecting portion 5 forms a flow path for air and water vapour between inside the air-filled chamber 4 and outside of the enclosure 3. The connecting portion 5 comprises a cross-sectional area which is the cross-sectional area of the flow channel for air and water vapour.
The first surface 24 comprises a first barrier part 9. The device comprises a second surface 25 which comprises the walls 12a of the connecting portion 5 extending between the first barrier part 9 and the second barrier part 8 and the second barrier part 8. The first 9 and the second barrier parts 8 are inserted to the connecting portion 5. The first barrier 9 and the second barrier 8 parts are arranged successively, the first barrier part 9 after the second barrier part 8 in the flow direction from the outside of the enclosure 3 to inside of the air-filled chamber 4. The first barrier 9 and the second barrier parts 8 form a flow path for air and water vapour between inside the air-filled chamber 4 and outside the second surface 25. The first barrier 9 and the second barrier parts 8 are permeable to air and water vapour and they both cover the cross-sectional area of the connecting portion 5 preventing a bypass flow of the air and water vapour inside the connecting portion 5.
An air gap 10 is arranged between the first 9 and second barrier 8 parts providing a capillary break. The air gap 10 may be created by means of supporting part 11, which is positioned between the first barrier part 9 and the second barrier part 8 to create a distance between the first barrier part 9 and the second barrier part 8. Examples of supporting parts 11 are a nut or a hollow sleeve. The first barrier part 9 and the second barrier part 8 can also be fastened to the wall 12a of the connecting portion 5 at a distance apart from each other.
The enclosure 3 and the walls 12b of the air-filled chamber 4 inside the enclosure 3 preferably comprise watertight material.
Accordingly, in the embodiment of figure la the enclosure walls 3 are provided air and water vapour impermeable such that air and water vapour may not flow through the enclosure walls 3.
The enclosure walls 3 comprise a flow channel between the closed the closed air-filled chamber space 4 inside the closed air-filled chamber and the outside of the closed air filled chamber, as shown in figure la. The flow channel is provided with the first barrier element 9 arranged to the flow channel. The first barrier element 9 blocks or closes the flow channel. The first barrier element 9 is arranged to define the closed air-filled chamber space 4 together with the enclosure walls 3.
The flow channel further comprises the second barrier element 8 arranged to the flow channel outside closed air-filled chamber space 4 and at distance from the first barrier element 9 such that a closed air gap 10 is provided between the first and second barrier elements 9, 8. The second barrier element 8 blocks or closes the flow channel.
The air gap 10 is formed between the first and second barrier elements 9, 8 in the flow channel.
The air gap 10 provides a capillary break to the flow channel between the first and second barrier elements 9, 8. Thus, flow of liquid water to the closed air-filled chamber space 4.
The first and second barrier elements 9, 8 are air and water vapour permeable for providing flow path for air and water vapour flow into the closed air-filled chamber space 4 and out of closed air-filled chamber space 4 through flow channel and the first and second barrier elements 9, 8 and via the closed first air gap 10.
In Figure lb) the humidity measuring device 1 comprises a hemispherical shape. The base of the hemisphere comprises a watertight material which is preferably hydrophobic providing a capillary break.
The outer hemispherical portion is formed of the second barrier part 8 of the second surface 25. The inner hemispherical shaped portion is formed of the first barrier part 9 of the first surface 24. The first surface 24 which is formed of a part of the base and the first barrier part 9 is forming the air-filled chamber 4. The air gap 10 providing the capillary break is arranged between the first 9 and the second barrier parts 8. The first 9 and the second barrier parts 8 are supported to the base of the hemisphere.
In Figure lc) the humidity measuring device 1 comprises a cuboid or a cube shape. The first 24 and the second surface 25 comprise a cuboid or cube shape and are formed of the first barrier part 9 and the second barrier part 8. The cuboid or cube shaped second surface 25 contains the inner cuboid or cube shaped first surface 24.
In Figure Id) the humidity measuring device 1 comprises a spherical shape. The first 24 and the second surface 25 comprise a spherical shape and are formed of the first barrier part 9 and the second barrier part 8. The spherical shaped second surface 25 contains the inner spherical shaped first surface 24.
In Figures lc) and Id) the air gap 10 between the first barrier part 8 and the second barrier part 9 is created by means of supporting part 11. The first barrier part 8 and the second barrier part 9 are attached to the supporting part 11 to create a distance between the first barrier part 8 and the second barrier part 9.
The first barrier part 9 and the second barrier part 8 may comprise same material or different material.
The first barrier part 9 and the second barrier part 8 are porous material. The materials of the first barrier part 8 and the second barrier part 9 can comprise a different average pore-size.
For instance, the material of the first barrier 9 and the second barrier 8 can comprise cement paste, and the average pore-size is in the range of 1 to lOOnm.
Figure 2 shows a humidity measuring device of Figure la) comprising a third surface 26 comprising a third barrier part 13. The third barrier 13 is inside the first surface 24. The third barrier part 13 is inserted in the connecting portion 5 and arranged between the first barrier part 9 and the humidity measuring sensor 2. Between the first barrier part 9 and the third barrier part 13 is an air gap 10b, i.e. the third barrier part 13 is arranged a distance apart from the first barrier part 9. The third barrier part 13 covers the cross-sectional area of the connecting portion 5 guiding air and water vapour to flow through the third barrier part 13. The third barrier part 13 material comprises calcium sulfate dihydrate.
In Figure 2 the third surface 26 and the third barrier part 13 is shown in connection of the device 1 shown in Figure la). The arrangement of the third surface 26 and the third barrier part 13 can be applied also to the devices 1 shown in Figures lb)-ld). The shape of the third surface 26 and the third barrier part 13 preferably correspond the shape on the first surface 24 and first barrier part 9. For instance, in Figure lb) the third barrier part 13 may be a hemispherical shaped portion positioned within the first barrier part 9 of the first surface 24 at a distance apart from the first barrier part 9 and supported to the base.
The space 14 between the enclosure 3 and the air-filled chamber 4 can be filled with a water resistant material.
Figures 3a) -c) show a humidity measuring device 1 comprising a housing 15 surrounding the enclosure 3. The hatching is omitted for the sake of clarity. The housing 15 comprises a part made of material permeable to air and water vapour 16 as shown in Figure 3a). The part permeable to air and water vapour 16 is positioned to a location of the enclosure 3 comprising the opening 7 for the connecting portion 5.
The major part of the surrounding housing 15 may be made of material permeable to air and water vapour as shown in Figure 3b). The part permeable to air and water vapour 16 of the surrounding housing 15 is a substantially integral piece wherein the water vapour and air can distribute and covers the surface of the enclosure 3 comprising the opening 7 and extends to cover part of the surfaces of the enclosure 3 surrounding the connecting portion 5.
Figure 3c) shows a housing 15 where the whole surrounding housing is made of material permeable to air and water vapour.
The material permeable to air and water vapour in the housing 15 comprises concrete, polymer modified cement or cement paste, for instance. The humidity in the part of the housing 16 which is made of porous material, in this case of material permeable to air and water vapour, reaches the humidity of the environment over a time period.
Figure 4 shows a humidity measuring device 1 comprising also other sensors inside the air-filled chamber 4 in addition to the humidity measuring sensor 2. The air-filled chamber 4 comprises a temperature measuring sensor 17 and a pressure sensor 18. The measuring device 1 comprises also a memory 19 for storing measurement data, and a transmitting system 20 comprising a transmitter, a power source and an antenna for transmitting the measurement data wirelessly to a receiving device 21, and a processor 23 for processing the data. They are located to the space 14 between the enclosure 3 and the air-filled chamber 4.
Figure 5 shows a cross-sectional view of a humidity measuring device 1 inserted in a wet material 22. The humidity measuring device 1 is embedded into a poured concrete, for instance. The device 1 comprises a housing 15 permeable to air and water vapour surrounding the enclosure 3. The housing 15 receives humidity from the surrounding wet material 22. The housing 15 can comprise a part 16 or the major part of the housing or the whole housing can be made of material permeable to air and water vapour as described in Figures 3a)-c).
The housing 15 is surrounding the first surface 24 forming the air-filled chamber 4. The housing 15 comprises at least a part which is permeable to air and water vapour 16 and that part 16 is arranged at a distance of the air gap 10 from the first barrier part 9. The water vapour is transferred through the part permeable to air and water vapour 16 to the air gap 10 providing a capillary break. The relative humidity reaches close to 100% in the air gap 10 during a period of time at the beginning. From the air gap 10 the water vapour is transferred through the first barrier part 9 to the air-filled chamber 4. The device 1 can also comprise a third barrier part 13 as described in Figure 2. The air-filled chamber 4 comprises inside a humidity measuring sensor 2, a temperature measuring sensor 17 and a pressure sensor 18.
The relative humidity in the air-filled chamber 4 remains on a lower level than in the air gap 10 between the part permeable to air and water vapour 16 and the first barrier part 9. This reduces the risk of water vapour condensation inside the air-filled chamber 4 when the temperature in the chamber 4 decreases as the curing/drying proceeds. For instance, as the relative humidity reaches close to 100% in the air gap 10 in the beginning the relative humidity reaches 70..90% in the air-filled chamber 4. The measurement data of the relative humidity in the air-filled chamber 4 is then multiplied with a correction coefficient in order to obtain true data.
The humidity measuring device 1 also comprises within a memory 19 for storing measurement data, a processor 23 and a data transmitting system 20 comprising a transmitter, a power source and an antenna for transmitting the measurement data wirelessly to a receiving device 21. The receiving device 21 is located externally. As the wet material 22, e.g. concrete, cures/dries during a period of time the inserted the humidity measuring device 1 forms an integral part of cured/dried material.
The humidity measuring device 1 measures the humidity and the temperature inside the curing and cured material, e.g. concrete. The measurement data of a concrete can be applied to determining the strength of the concrete and timing an installation of flooring or surface coatings, for instance.
The invention has been described above with reference to the examples shown in the figures. However, the invention is in no way restricted to the above examples but may vary within the scope of the claims.
Part list: 1 a humidity measuring device; 2 a humidity measuring sensor; 3 an enclosure; 4 a chamber; 5 a connecting portion; 6 an outer surface of an enclosure; 7 an opening; 8 a second barrier part; 9 a first barrier part; 10, 10b an air gap; 11 a supporting part; 12a-b a wall; 13 a third barrier part; 14 a space; 15 a housing; 16 a part permeable to air and water vapour; 17 a temperature measuring sensor; 18 a pressure sensor; 19 a memory; 20 a data transmitting system; 21 a receiving device; 22 material, 23 a processor, 24 a first surface, 25 a second surface, 26 a third surface.

Claims

1. A humidity measuring device comprising a humidity measuring sensor (2), characterized in that the humidity measuring device (1) comprises:
- a first surface (24) forming an air-filled chamber (4),
- the air-filled chamber (4) comprising the humidity measuring sensor (2) inside the chamber (4),
- the first surface (24) comprising a first barrier part (9) being permeable to air and water vapour, and the first barrier part (9) forming a flow path between inside the air-filled chamber (4) and outside the first surface (24),
- a second surface (25) arranged to surround the first barrier part (9),
- the second surface (25) comprising a second barrier part (8) being permeable to air and water vapour, and the second barrier part (8) forming a flow path between inside the second surface (25) and outside the second surface (25),
- the first barrier part (9) and the second barrier part (8) arranged successively to form a flow path between inside the air-filled chamber (4) and outside the second surface (25),
- an air gap (10) between the first barrier part (9) and the second barrier part (8) providing a capillary break.
2. A humidity measuring device according to claim 1, characterized in that the humidity measuring device (1) comprises:
- an enclosure (3) surrounding the first surface (24) and the second surface (25),
- the enclosure (3) comprises watertight material, and
- the outer surface of the enclosure (6) comprising an opening (7) to form a flow path between outside the enclosure (6) and inside the enclosure (6).
3. A humidity measuring device according to claim 2, characterized in that the device (1) comprises a housing (15) surrounding the enclosure (3), and the housing (15) comprises a part permeable to air and water vapour (16), and the part (16) is positioned to a location of the enclosure (3) comprising the opening (7).
4. A humidity measuring device according to claim 2, characterized in that the device (1) comprises a housing (15) surrounding the first surface (24), and the housing (15) comprises a part permeable to air and water vapour (16), and the housing (15) is forming the second surface (25).
5. A humidity measuring device according to any of claims 3-4, characterized in that the housing (15) is permeable to air and water vapour.
6. A humidity measuring device according to any of claims 3-5, characterized in that the housing (15) comprises concrete.
7. A humidity measuring device according to any of claims 3-5, characterized in that the housing (15) comprises cement-based material.
8. A humidity measuring device according to any of claims 1- 7, characterized in that the material of the first barrier part (9) and the second barrier part (8) comprises an average pore-size in the range of 1 to lOOnm.
9. A humidity measuring device according to any of claims 1- 7, characterized in that the material of the first barrier part (9) and the second barrier part (8) comprises an average pore-size in the range of 3 to 30nm, preferably 5 to 20 nm.
10. A humidity measuring device according to any of claims 1-9, characterized in that the first barrier part (9) and the second barrier part (8) comprise same material.
11. A humidity measuring device according to any of claims 1- 10, characterized in that the air-filled chamber (4) comprises a temperature measuring sensor (17) and/or pressure sensor (18).
12. A humidity measuring device according to any of claims 1- 11, characterized in that the device (1) comprises a memory (19) for storing measurement data, a processor (23) and a transmitting system (20) comprising a transmitter, a power source and an antenna for transmitting the measurement data wirelessly to a receiving device (21), and at least one of the following: the memory (19), the processor (23) and the transmitting system (20), is positioned:
- on the outer surface of the second surface (25), or - within the space (14) between the enclosure (3) and the air-filled chamber (4), or
- on the outer surface of the enclosure (3).
13. A humidity measuring device according to any of claims 1- 12, characterized in that the device (1) comprises:
- a third surface (26) comprising a third barrier part (13),
- the third barrier part (13) comprising calcium sulfate dihydrate,
- the third surface (26) arranged between the first barrier part (9) and the humidity measuring sensor (2), and
- an air gap (10b) between the first barrier part (9) and the third barrier part (13).
14. A method for measuring humidity, the method comprising a humidity measuring device (1) according to any of claims 1-13, characterized in that the method comprises:
- inserting the humidity measuring device (1) in connection with a material (22) to be measured,
- allowing the humidity from the material (22) to be measured to flow through the second barrier part (8) and through the first barrier part (9) to the humidity measuring sensor (2) inside the air-filled chamber (4),
- measuring the humidity with the humidity measuring sensor (2).
15. A method for measuring humidity according to claim 14, characterized in that the method comprises:
- the humidity measuring device (1) comprises a housing (15) surrounding the first surface (24),
- the housing (15) comprises a part permeable to air and water vapour
(16),
- the housing (15) forming the second surface (25),
- inserting the humidity measuring device (1) in concrete during or after the concrete is poured but prior to the concrete being fully cured, and
- allowing the concrete to cure and thereby the humidity measuring device (1) forming an integral part of cured concrete.
PCT/FI2020/050160 2019-03-12 2020-03-12 A humidity measuring device and method WO2020183069A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002023158A1 (en) * 2000-09-18 2002-03-21 Vaisala Oyj Device for measuring the diffusion of a gaseous substance on a surface of a material
US20170212094A1 (en) * 2016-01-26 2017-07-27 Quipip, Llc Systems, apparatus and methods for obtaining measurements concerning the strength and performance of concrete mixtures
US20170364039A1 (en) * 2015-01-27 2017-12-21 Tdk Corporation Sensor
US20180011076A1 (en) * 2016-07-11 2018-01-11 Quipip, Llc Sensor device, and systems and methods for obtaining measurements of selected characteristics of a concrete mixture

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002023158A1 (en) * 2000-09-18 2002-03-21 Vaisala Oyj Device for measuring the diffusion of a gaseous substance on a surface of a material
US20170364039A1 (en) * 2015-01-27 2017-12-21 Tdk Corporation Sensor
US20170212094A1 (en) * 2016-01-26 2017-07-27 Quipip, Llc Systems, apparatus and methods for obtaining measurements concerning the strength and performance of concrete mixtures
US20180011076A1 (en) * 2016-07-11 2018-01-11 Quipip, Llc Sensor device, and systems and methods for obtaining measurements of selected characteristics of a concrete mixture

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