WO1988006724A1 - Apparatus for measuring the permeability of sheet material - Google Patents

Apparatus for measuring the permeability of sheet material Download PDF

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Publication number
WO1988006724A1
WO1988006724A1 PCT/GB1988/000172 GB8800172W WO8806724A1 WO 1988006724 A1 WO1988006724 A1 WO 1988006724A1 GB 8800172 W GB8800172 W GB 8800172W WO 8806724 A1 WO8806724 A1 WO 8806724A1
Authority
WO
WIPO (PCT)
Prior art keywords
chamber
pressure
voltage
sheet material
volume
Prior art date
Application number
PCT/GB1988/000172
Other languages
French (fr)
Inventor
Alan John Parsons
Robert Edward Hurley
Original Assignee
The British Millerain (1922) Co. Ltd.
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 The British Millerain (1922) Co. Ltd. filed Critical The British Millerain (1922) Co. Ltd.
Priority to GB8919119A priority Critical patent/GB2230096A/en
Publication of WO1988006724A1 publication Critical patent/WO1988006724A1/en

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
    • G01N15/082—Investigating permeability by forcing a fluid through a sample
    • G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change

Definitions

  • the present invention relates to apparatus for measuring the permeability of sheet material such as waterproofed or water- resistant fabric. ' •
  • the material When measuring the permeability of a sheet material to a liquid, the material is held with one face in contact with the liquid and the other face exposed to the atmosphere. The pressure of the liquid is increased at a controlled rate and the pressure at which a specified number of liquid droplets are observed to have broken through the material is a measure of the permeability of the material.
  • liquid pressure should be increased at the same controlled rate for each measurement of permeability.
  • apparatus for measuring the permeability of sheet material comprising: a chamber for containing liquid and having an opening for the sheet material to be held across; means for clamping the sheet material across said openings; means for varying the volume of the chamber; a transducer for measuring the pressure in the chamber and providing an electrical signal indicative of the measured pressure; means for converting said electrical signal to a voltage proportional to said pressure; means for generating a reference voltage which is art increasing function of time and is directly proportional to the desired, pressure in the chamber; a comparator for comparing the first-mentioned voltage with the reference voltage and, if the first mentioned voltage is less than the reference voltage, generating an electrical error signal; means for receiving the electrical error signal and, when such a signal is received, operating the second-mentioned means to decrease the volume of the chamber thereby to increase the pressure therein.
  • the reference voltage increases linearly as a function of time.
  • the means for adjusting the volume of the chamber is preferably a stepping motor which advances by one step each time an error signal is generated.
  • the chamber is variable in volume by means of a piston or plunger which may be advanced into or withdrawn from the chamber.
  • the piston or plunger may act upon a movable wall which bounds part of the chamber.
  • the movable wall may be constituted by a diaphragm.
  • the apparatus comprises a mechanical assembly 1 and an electronic control unit 2.
  • the mechanical assembly 1 comprises a vessel 3 defining a chamber 4 having an open top, a metal clamp 5, a piston 6 for varying the volume of the chamber, a stepping motor 7 for actuating the piston, and a pressure gauge 8 for measuring the pressure in the chamber.
  • the vessel 3 has a rim 9 which defines the open top of the chamber 4 and a flat base 10.
  • a rubber O-ring 11 is located in a groove in the rim 9.
  • a sheet of material 12, the permeability of which is to be measured can be clamped across the open top of the chamber 4 by ' means of the clamp 5, which has a circular lower portion which presses the material against the rim of the vessel, the O-ring forming a water-tight seal between the material and the vessel.
  • the clamp 5 is operated and urged against the rim 9 of the vessel 3 by means not shown.
  • the piston 6 is disposed in a first opening in the base 10 of the vessel 3.
  • the opening is water-tightly closed by a rolling diaphragm 13 which overlies and cnforrrB to the top and side of the piston 6.
  • the diaphragm 13 is held against the underside of the base 10 by a ring 14 which is secured to the base by fastening means (not shown).
  • the pressure gauge 8 comprises a strain gauge pressure transducer and is mounted in a second opening in the base 10 in such a manner as to water-tightly seal the opening and serves to measure the pressure in the chamber 4.
  • the stepping motor 7 operates, through reduction gearing, a drive shaft 15 on which is mounted for rotation therewith an internally threaded drive sleeve 16.
  • a screw-threaded drive rod 17 engages in the sleeve 16 and is held against rotation.
  • the upper end portion of the rod 17 carries the piston 6.
  • limit switches 18 and 19 which are tripped by the piston at its intended upper and lower limits of travel respectively.
  • the electronic control unit 2 comprises a crystal controlled clock 30, a ramp generator 31, a comparator 32, an indicator unit 33, a master logic control unit (MLCU) 34 and a stepping motor control 35.
  • MLCU master logic control unit
  • the comparator 32 comprises an operational amplifier and a level detector.
  • the crystal controlled clock 30 comprises a quartz crystal oscillator which generates accurate clock pulses.
  • the clock pulses are fed to the ramp generator 31, which includes a digital- to-analogue converter which converts the clock pulses to an accurate ramp voltage.
  • the ramp voltage is an analogue represent ⁇ ation of a desired rate of pressure increase required in the chamber 4 and serves as a reference voltage or signal.
  • the frequency of the clock pulses may be varied to correspond to the desired rate of pressure ⁇ e.g. 10 or 60 mBar/min) increase in the chamber A,
  • the ramp voltage is supplied from the ramp generator 31 to the comparator 32.
  • the indicator unit comprises an amplifier 36, an analogue-to- digital converter 37, an indicator display 38 and an indicator trip limit 39.
  • the amplifier 36 receives an electrical voltage representative of the pressure in the chamber 4 from the pressure gauge 8 and amplifies the voltage.
  • the amplified voltage is supplied to the comparator 32 and to the analogue-to-digital converter 37.
  • the analogue-to-digital converter 37 converts the amplified voltage to a digital value which is supplied to the indicator display 38.
  • the pressure in the chamber 4 is indicated on indicator display 38.
  • the indicator trip limit 39 is connected to the indicator display 38 and to the MLCU 34.
  • the operational amplifier of the comparator 32 is operated under open loop gain conditions.
  • the inherent instability of the amplifier is increased, by feedback, such that in the region of balance it oscillates at a frequency determined by the feedback loop.
  • the output of the operational amplifier near balance thus consists of a d.c. component and a.c. component. This output is fed to the level detector which produces pulses (constituting error signals), the duration of which increase in proportion to the difference in the input voltages supplied to the comparator 32 from the amplifier 36 and the ramp generator 31.
  • the pulses are passed to the MLCU 34.
  • the MLCU 34 may signal the stepping motor control 35 to operate the stepping motor 7 to cause its shaft 15 to rotate continuously in a sense to lower the piston 6.
  • the piston 6 can be lowered until the lower limit switch 19 is tripped. Tripping of the switch 19 causes the MLCU 34 to signal the stepping motor control 35 to cause the shaft 15 of the stepping motor 7 to stop rotating.
  • Such operation of the stepping motor to lower the piston 6 until the switch 19 is tripped is referred to herein as resetting of the apparatus.
  • the MLCU 34 may also signal the stepping motor control 35 to operate the stepping motor 7 to cause its shaft 15 to rotate by individual steps in a sense to raise the piston 6 until the limit switch 18 is tripped. Tripping of the switch 18 causes the MLCU 34 to operate to reset the apparatus, i.e. as described above to signal the stepping motor control 35 to cause the shaft 15 of the stepping motor 7 to rotate continuously in a sense to lower the piston until the switch 19 is tripped.
  • the MLCU may also operate to signal the stepping motor control 35 not to operate the stepping motor 7 so that the piston 6 remains stationary.
  • the "Reset” button is pressed. This causes the MLCU 34 to act to reset the apparatus. Tripping of the limit switch 19 at completion of resetting is indicated on the indicator display.
  • the chamber 4 When the apparatus has been reset the chamber 4 is filled with water and a sheet of material 12, the permeability of which is to be measured, is placed across the open top of the chamber 4 and clamped to the rim 9 of the vessel 3 by the clamp 5.
  • the "Start" button is then pressed. This causes the ramp generator 31 to begin generating the ramp voltage.
  • the pressure gauge 8 transmits a voltage signal indicative of the pressure in the chamber 4 to the indicator unit 33.
  • the signal is amplified by the amplifier 36, passed to the comparator 32 and to the converter 37.
  • the converter 37 converts the signal to digital form.
  • the comparator 32 produces an error signal which is passed to the MLCU 34.
  • the MLCU 34 then, through the stepping motor control 35, causes the shaft 15 of the stepping motor 7 to rotate by one step in a sense such as to decrease the volume of the chamber 4 and thereby increase the pressure therein. By this procedure the pressure in the chamber 4, at any time during the measurement procedure, is maintained at or close to the desired pressure.
  • the pressure, as indicated on the indicator display 38, at which a predetermined number of droplets of water have passed through the sheet material 12 and are visible on its upper surface is a measure of the permeability of the material.
  • the "Hold” button may be pressed. This causes the MLCU 34 to act to disconnect the clock 30 from the ramp generator 31 so that, while the "Hold” button remains pressed the ramp voltage remains constant and accordingly the pressure in the chamber 4 remains constant.
  • the indicator trip limit 35 causes the MLCU 34 to operate to reset the apparatus thereby preventing the pressure in the chamber exceeding the specified maximum value.
  • the MLCU 34 operates to reset the apparatus, that is to cause the piston 6 to be lowered until the lower limit switch 19 is tripped when the reset button is pressed as described above, when the pressure detected by the pressure gauge 8 reaches the specified maximum level (e.g. 510 mBar), and when, as described above, the upper limit switch 18 is tripped.
  • the MLCU 34 also operates to reset the apparatus when the electrical power supply to the apparatus is switched on.
  • the MLCU 34 is constructed such that while resetting is being carried out, that is lowering of the piston 6, operation of either of the "Start" and "Hold” buttons has no effect.
  • the apparatus does not comprise a negative feedback loop. Such a loop is unnecessary because the ' design of the electronic control unit 2 and in particular because of the nature of the comparator 32.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
  • Examining Or Testing Airtightness (AREA)

Abstract

Apparatus (1, 2) for measuring the permeability of sheet material, comprises: a chamber (4) for containing liquid and having an opening for the sheet material to be held across; means (5) for clamping the sheet material across said openings; means (6) for varying the volume of the chamber; a transducer (8) for measuring the pressure in the chamber and providing an electrical signal indicative of the measured pressure; means (36) for converting said electrical signal to a voltage proportional to said pressure; means (31) for generating a reference voltage which is an increasing function of time and is directly proportional to the desired pressure in the chamber; a comparator (32) for comparing the first-mentioned voltage with the reference voltage and, if the first mentioned voltage is less than the reference voltage, generating an electrical error signal; means (34) for receiving the electrical error signal and, when such a signal is received, operating the second-mentioned means to decrease the volume of the chamber thereby to increase the pressure therein.

Description

Apparatus for measuring the permeability of sheet material
The present invention relates to apparatus for measuring the permeability of sheet material such as waterproofed or water- resistant fabric. ' •
When measuring the permeability of a sheet material to a liquid, the material is held with one face in contact with the liquid and the other face exposed to the atmosphere. The pressure of the liquid is increased at a controlled rate and the pressure at which a specified number of liquid droplets are observed to have broken through the material is a measure of the permeability of the material.
It is important to understand that to obtain reproducible results and to compare the permeability of one sheet material with another, the liquid pressure should be increased at the same controlled rate for each measurement of permeability.
It is an object of the present invention to provide apparatus for measuring the permeability of sheet material and, in which, the pressure of the liquid applied to the material is automatically controlled, without hunting, to within close tolerances.
In accordance with the present invention, there is provided apparatus for measuring the permeability of sheet material, comprising: a chamber for containing liquid and having an opening for the sheet material to be held across; means for clamping the sheet material across said openings; means for varying the volume of the chamber; a transducer for measuring the pressure in the chamber and providing an electrical signal indicative of the measured pressure; means for converting said electrical signal to a voltage proportional to said pressure; means for generating a reference voltage which is art increasing function of time and is directly proportional to the desired, pressure in the chamber; a comparator for comparing the first-mentioned voltage with the reference voltage and, if the first mentioned voltage is less than the reference voltage, generating an electrical error signal; means for receiving the electrical error signal and, when such a signal is received, operating the second-mentioned means to decrease the volume of the chamber thereby to increase the pressure therein.
Preferably the reference voltage increases linearly as a function of time.
The means for adjusting the volume of the chamber is preferably a stepping motor which advances by one step each time an error signal is generated.
Preferably the chamber is variable in volume by means of a piston or plunger which may be advanced into or withdrawn from the chamber.
The piston or plunger may act upon a movable wall which bounds part of the chamber. The movable wall may be constituted by a diaphragm.
The accompanying drawing shows by way of example an apparatus embodying the invention.
Referring to the drawing the apparatus comprises a mechanical assembly 1 and an electronic control unit 2.
The mechanical assembly 1 comprises a vessel 3 defining a chamber 4 having an open top, a metal clamp 5, a piston 6 for varying the volume of the chamber, a stepping motor 7 for actuating the piston, and a pressure gauge 8 for measuring the pressure in the chamber.
The vessel 3 has a rim 9 which defines the open top of the chamber 4 and a flat base 10. A rubber O-ring 11 is located in a groove in the rim 9. A sheet of material 12, the permeability of which is to be measured can be clamped across the open top of the chamber 4 by' means of the clamp 5, which has a circular lower portion which presses the material against the rim of the vessel, the O-ring forming a water-tight seal between the material and the vessel.
The clamp 5 is operated and urged against the rim 9 of the vessel 3 by means not shown.
The piston 6 is disposed in a first opening in the base 10 of the vessel 3. The opening is water-tightly closed by a rolling diaphragm 13 which overlies and cnforrrB to the top and side of the piston 6. The diaphragm 13 is held against the underside of the base 10 by a ring 14 which is secured to the base by fastening means (not shown).
The pressure gauge 8 comprises a strain gauge pressure transducer and is mounted in a second opening in the base 10 in such a manner as to water-tightly seal the opening and serves to measure the pressure in the chamber 4.
The stepping motor 7 operates, through reduction gearing, a drive shaft 15 on which is mounted for rotation therewith an internally threaded drive sleeve 16. A screw-threaded drive rod 17 engages in the sleeve 16 and is held against rotation.
The upper end portion of the rod 17 carries the piston 6. When the drive shaft 15 and the sleeve 16 rotate, the rod 17 and hence the piston 6 are caused to move upwardly or downwardly, depending on the sense of rotation of the shaft, thereby respectively decreasing or increasing the volume of the chamber 4.
Below the water chamber 4 are mounted limit switches 18 and 19 which are tripped by the piston at its intended upper and lower limits of travel respectively.
The electronic control unit 2 comprises a crystal controlled clock 30, a ramp generator 31, a comparator 32, an indicator unit 33, a master logic control unit (MLCU) 34 and a stepping motor control 35.
The comparator 32 comprises an operational amplifier and a level detector.
The crystal controlled clock 30 comprises a quartz crystal oscillator which generates accurate clock pulses. The clock pulses are fed to the ramp generator 31, which includes a digital- to-analogue converter which converts the clock pulses to an accurate ramp voltage. The ramp voltage is an analogue represent¬ ation of a desired rate of pressure increase required in the chamber 4 and serves as a reference voltage or signal. The frequency of the clock pulses may be varied to correspond to the desired rate of pressure {e.g. 10 or 60 mBar/min) increase in the chamber A,
The ramp voltage is supplied from the ramp generator 31 to the comparator 32.
The indicator unit comprises an amplifier 36, an analogue-to- digital converter 37, an indicator display 38 and an indicator trip limit 39.
The amplifier 36 receives an electrical voltage representative of the pressure in the chamber 4 from the pressure gauge 8 and amplifies the voltage. The amplified voltage is supplied to the comparator 32 and to the analogue-to-digital converter 37. The analogue-to-digital converter 37 converts the amplified voltage to a digital value which is supplied to the indicator display 38.
The pressure in the chamber 4 is indicated on indicator display 38.
The indicator trip limit 39 is connected to the indicator display 38 and to the MLCU 34.
The operational amplifier of the comparator 32 is operated under open loop gain conditions. The inherent instability of the amplifier is increased, by feedback, such that in the region of balance it oscillates at a frequency determined by the feedback loop. The output of the operational amplifier near balance thus consists of a d.c. component and a.c. component. This output is fed to the level detector which produces pulses (constituting error signals), the duration of which increase in proportion to the difference in the input voltages supplied to the comparator 32 from the amplifier 36 and the ramp generator 31.
The pulses are passed to the MLCU 34.
The MLCU 34 may signal the stepping motor control 35 to operate the stepping motor 7 to cause its shaft 15 to rotate continuously in a sense to lower the piston 6. The piston 6 can be lowered until the lower limit switch 19 is tripped. Tripping of the switch 19 causes the MLCU 34 to signal the stepping motor control 35 to cause the shaft 15 of the stepping motor 7 to stop rotating. Such operation of the stepping motor to lower the piston 6 until the switch 19 is tripped is referred to herein as resetting of the apparatus.
The MLCU 34 may also signal the stepping motor control 35 to operate the stepping motor 7 to cause its shaft 15 to rotate by individual steps in a sense to raise the piston 6 until the limit switch 18 is tripped. Tripping of the switch 18 causes the MLCU 34 to operate to reset the apparatus, i.e. as described above to signal the stepping motor control 35 to cause the shaft 15 of the stepping motor 7 to rotate continuously in a sense to lower the piston until the switch 19 is tripped.
The MLCU may also operate to signal the stepping motor control 35 not to operate the stepping motor 7 so that the piston 6 remains stationary.
In use of the apparatus, firstly, if the apparatus is not already reset, the "Reset" button is pressed. This causes the MLCU 34 to act to reset the apparatus. Tripping of the limit switch 19 at completion of resetting is indicated on the indicator display.
When the apparatus has been reset the chamber 4 is filled with water and a sheet of material 12, the permeability of which is to be measured, is placed across the open top of the chamber 4 and clamped to the rim 9 of the vessel 3 by the clamp 5.
The "Start" button is then pressed. This causes the ramp generator 31 to begin generating the ramp voltage. The pressure gauge 8 transmits a voltage signal indicative of the pressure in the chamber 4 to the indicator unit 33. The signal is amplified by the amplifier 36, passed to the comparator 32 and to the converter 37. The converter 37 converts the signal to digital form.
As described above, if the voltage passed to the comparator 32 from the amplifier 36 is less than the ramp voltage, the comparator 32 produces an error signal which is passed to the MLCU 34. The MLCU 34 then, through the stepping motor control 35, causes the shaft 15 of the stepping motor 7 to rotate by one step in a sense such as to decrease the volume of the chamber 4 and thereby increase the pressure therein. By this procedure the pressure in the chamber 4, at any time during the measurement procedure, is maintained at or close to the desired pressure.
The pressure, as indicated on the indicator display 38, at which a predetermined number of droplets of water have passed through the sheet material 12 and are visible on its upper surface is a measure of the permeability of the material.
If desired, the "Hold" button may be pressed. This causes the MLCU 34 to act to disconnect the clock 30 from the ramp generator 31 so that, while the "Hold" button remains pressed the ramp voltage remains constant and accordingly the pressure in the chamber 4 remains constant.
If and when the piston 6 reaches its intended upper limit- of travel it trips the upper limit switch 18 which then passes a signal to the MLCU 34. The MLCU 34 then, through the stepping motor control
35, causes the stepping motor 7 to operate to reset the apparatus.
If the pressure in the chamber 4, as sensed by the pressure gauge 8, reaches a specified maximum value, e.g. 510 mBar, then the indicator trip limit 35 causes the MLCU 34 to operate to reset the apparatus thereby preventing the pressure in the chamber exceeding the specified maximum value.
It will be understood that the MLCU 34 operates to reset the apparatus, that is to cause the piston 6 to be lowered until the lower limit switch 19 is tripped when the reset button is pressed as described above, when the pressure detected by the pressure gauge 8 reaches the specified maximum level (e.g. 510 mBar), and when, as described above, the upper limit switch 18 is tripped. The MLCU 34 also operates to reset the apparatus when the electrical power supply to the apparatus is switched on. The MLCU 34 is constructed such that while resetting is being carried out, that is lowering of the piston 6, operation of either of the "Start" and "Hold" buttons has no effect.
It will be appreciated that the apparatus does not comprise a negative feedback loop. Such a loop is unnecessary because the ' design of the electronic control unit 2 and in particular because of the nature of the comparator 32.

Claims

1. Apparatus for measuring the permeability of sheet material, comprising: a chamber for containing liquid and having an opening for the sheet material to be held across; means for clamping the sheet material across said openings; means for varying the volume of the chamber; a transducer for measuring the pressure in the chamber and providing an electrical signal indicative of the measured pressure; means for converting said electrical signal to a voltage proportional to said pressure; means for generating a reference voltage which is an increasing function of time and is directly proportional to the desired pressure in the chamber; a comparator for comparing the first-mentioned voltage with the reference voltage and, if the first mentioned voltage is less than the reference voltage, generating an electrical error signal; means for receiving the electrical error signal and, when such a signal is received, operating the second-mentioned means to decrease the volume of the chamber thereby to increase the pressure therein.
2. Apparatus according to claim 1, wherein the reference'voltage increases linearly as a function of time.
3. Apparatus according to any preceding claim, wherein the means for adjusting the volume of the chamber is preferably a stepping motor which advances by one step each time an error signal is generated.
4. Apparatus according to any preceding claim, wherein the chamber is variable in volume by means of a piston or plunger which may be advanced into or withdrawn from the chamber.
5. Apparatus according to claim 4, wherein the piston or plunger acts upon a movable wall which bounds part of the chamber.
6. Apparatus according to claim 5, wherein the movable wall is constituted by a diaphragm.
PCT/GB1988/000172 1987-03-05 1988-03-07 Apparatus for measuring the permeability of sheet material WO1988006724A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8919119A GB2230096A (en) 1987-03-05 1988-03-07 Apparatus for measuring the permeability of sheet material

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8705204 1987-03-05
GB878705204A GB8705204D0 (en) 1987-03-05 1987-03-05 Measuring permeability of sheet material

Publications (1)

Publication Number Publication Date
WO1988006724A1 true WO1988006724A1 (en) 1988-09-07

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Application Number Title Priority Date Filing Date
PCT/GB1988/000172 WO1988006724A1 (en) 1987-03-05 1988-03-07 Apparatus for measuring the permeability of sheet material

Country Status (3)

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AU (1) AU1391188A (en)
GB (3) GB8705204D0 (en)
WO (1) WO1988006724A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2233769A (en) * 1989-06-30 1991-01-16 Bibby Ltd Noel Vapour transmission test apparatus
CN102183444A (en) * 2011-01-27 2011-09-14 中国商用飞机有限责任公司 Device and method for testing gas permeability in inner direction of paving layer surface
CN103398934A (en) * 2013-08-07 2013-11-20 胡红钱 Fabric water-permeability resistance hydrostatic pressure tester as well as control system and testing method thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3073149A (en) * 1959-12-30 1963-01-15 Charles E Mongan Method and apparatus for evaluating impedance characteristics of porous materials
DE1773256A1 (en) * 1968-04-20 1972-01-13 Brecht Walter Prof Dr Ing Device for the continuous determination of the water permeability of sieves and felts, especially of wet felts in paper and cardboard production
EP0118967A1 (en) * 1983-02-02 1984-09-19 Halliburton Company Apparatus for controlling pressure in a chamber
US4480463A (en) * 1981-03-23 1984-11-06 B.A.T. Cigaretten-Fabriken Gmbh Process for determining the resistance to draw and the gas _permeability of a test piece and a device for carrying out such a process
US4531404A (en) * 1983-12-29 1985-07-30 Mobil Oil Corporation Flow cell assembly

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3073149A (en) * 1959-12-30 1963-01-15 Charles E Mongan Method and apparatus for evaluating impedance characteristics of porous materials
DE1773256A1 (en) * 1968-04-20 1972-01-13 Brecht Walter Prof Dr Ing Device for the continuous determination of the water permeability of sieves and felts, especially of wet felts in paper and cardboard production
US4480463A (en) * 1981-03-23 1984-11-06 B.A.T. Cigaretten-Fabriken Gmbh Process for determining the resistance to draw and the gas _permeability of a test piece and a device for carrying out such a process
EP0118967A1 (en) * 1983-02-02 1984-09-19 Halliburton Company Apparatus for controlling pressure in a chamber
US4531404A (en) * 1983-12-29 1985-07-30 Mobil Oil Corporation Flow cell assembly

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2233769A (en) * 1989-06-30 1991-01-16 Bibby Ltd Noel Vapour transmission test apparatus
GB2233769B (en) * 1989-06-30 1992-10-28 Bibby Ltd Noel Vapour transmission testing apparatus
CN102183444A (en) * 2011-01-27 2011-09-14 中国商用飞机有限责任公司 Device and method for testing gas permeability in inner direction of paving layer surface
CN103398934A (en) * 2013-08-07 2013-11-20 胡红钱 Fabric water-permeability resistance hydrostatic pressure tester as well as control system and testing method thereof

Also Published As

Publication number Publication date
GB8705204D0 (en) 1987-04-08
GB8919119D0 (en) 1989-11-08
GB2230096A (en) 1990-10-10
GB8805341D0 (en) 1988-04-07
AU1391188A (en) 1988-09-26

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