WO1996024057A1 - A method of and apparatus for detecting decay in wood - Google Patents
A method of and apparatus for detecting decay in wood Download PDFInfo
- Publication number
- WO1996024057A1 WO1996024057A1 PCT/GB1996/000204 GB9600204W WO9624057A1 WO 1996024057 A1 WO1996024057 A1 WO 1996024057A1 GB 9600204 W GB9600204 W GB 9600204W WO 9624057 A1 WO9624057 A1 WO 9624057A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- wood
- hole
- gas
- gas sample
- decay
- Prior art date
- Legal status (The legal status 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 status listed.)
- Ceased
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Classifications
-
- 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
- G01N33/46—Wood
-
- 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
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/483—Physical analysis of biological material
- G01N33/497—Physical analysis of biological material of gaseous biological material, e.g. breath
- G01N33/4977—Metabolic gas from microbes, cell cultures or plant tissues
Definitions
- the present invention relates to apparatus for and a method of detecting decay in wood by analysing gas within the wood to detect one or more gases produced by aerobic metabolism by fungi in the wood.
- Overhead lines for electricity (132kV and below) and telephones are usually supported on wooden poles.
- Alternatives are concrete poles and steel lattice towers but these are generally more expensive.
- Plastic poles have also been developed for lightweight telephone signal carrying systems.
- the present invention provides a method of detecting decay in wood comprising the steps of boring a hole in the wood subject to decay, drawing a gas sample from the hole, and analysing the gas sample to determine the concentration of at least one gas produced by aerobic metabolism by fungi in the wood.
- the present invention also provides apparatus for detecting decay in wood comprising boring means for boring a hole in the wood subject to decay, and gas sampling means for drawing a gas sample from the hole for analysis to determine the concentration of at least one gas produced by aerobic metabolism by fungi in the wood.
- the present invention recognises that wood rot or decay is caused by living organisms - fungi.
- the main species responsible are basidomycetes and in particular lentinus lapideus. These organisms in the course of their metabolism secrete an extensive range of chemicals, e.g. acid/bases, alcohols, enzymes, hydrogen peroxide; all of which are present to a greater or lesser extent in the gas or vapour phase.
- Some of the molecular species are simple compounds like carbon dioxide and ammonia - typical products of aerobic metabolism. Others are complex molecules. The ensemble -of these gives rise to a typical odour. Any of these compounds in principle can be detected with a suitable gas sensor by boring a small hole in the wood and directly drawing the gas sample across a sensor.
- a gas sample can be trapped by adsorption onto a small quantity, e.g. a few grams at most, of an adsorber material such as granular activated carbon, and later analysed after thermal desorption by simple or even relatively sophisticated methods of analysis.
- an adsorber material such as granular activated carbon
- the concentration of the metabolite gas or gases in the gas sample will vary with ambient temperature since the metabolic activity of the fungi will depend on the ambient temperature. Thus, in the analysis of the gas sample in order to determine the extent of the decay in the wood it will be necessary to correct the measured concentration to take into account the ambient temperature. This can take the form of a temperature dependent correction factor.
- the gas which is produced by the fungi which can easily be measured is carbon dioxide.
- Sensors are commercially available to measure or detect carbon dioxide to parts per million (ppm) levels at reasonable cost. The same is true for most low molecular weight sample molecules, i.e. C . , CO, NH_.
- Such sensors are based on infrared absorption or electrochemical effects. Such sensors work at ambient temperatures, and the instruments can be made both portable and robust.
- the present invention is particularly applicable to the detection of decay or rot in poles which are part buried in the ground and provide structural support for a member, e.g. electricity or telephone overhead lines, the present invention is applicable to the detection of decay in wood generally.
- the method of the present invention can provide a measure of the residual lifetime of the pole since this is inversely proportional to the concentration of the or each of the gases generated by anaerobic metabolism, e.g. carbon dioxide. Also, the concentration of the or each gas determined in accordance with the method of the present invention can be used to provide an indication of active decay since this is directly proportional to the ambient temperature corrected concentration of the metabolite gas or gases.
- a typical pole rot detection system will consist of three separate and distinct items.
- a small battery powered portable drill capable of creating a small diameter hole, e.g. ⁇ 5mm to a depth of several centimetres is required. This will be operated at or near ground level by the linesman since all significant rot begins at ground level and extends thereafter downwards and/or upwards.
- a sampling device is also provided which draws gas samples, mixed inevitably with ambient air from the hole in the pole across a sensor or a cartridge of adsorber material such as granular activated carbon or a similar material.
- the linesman either carries the sensor itself in a portable battery powered form or a number of adsorbing cartridges of only a few grams in weight, and a device to draw a known quantity of gas into the sensor or over the adsorber.
- the device to draw a known quantity of gas into the sensor or over the adsorber can be hand-operated, e.g. a syringe or it can be battery operated such as a dosing pump operated on a timed basis with a known reproducible volume flow rate which is temperature adjusted if necessary for density.
- the gas to be detected is carbon dioxide
- the portable sensor can be a portable carbon dioxide detector.
- the analysis of the gas sample can be carried out at a remote location.
- the adsorbed gas e.g. carbon dioxide can be desorbed thermally into an appropriate detector at a later time and in another e.g. central location where the signals generated by the detector can be recorded and linked by a computerised data handling system to generate data on the pole in question and indicate the level of decay activity.
- the ambient temperature or temperature of the wood if likely to be different from the ambient temperature, is measured using a temperature sensor. This temperature can then be used to determine the correction factor used in the analysis.
- the extent and level of activity can be measured and recorded as being directly proportional to the level of carbon dioxide (and other gaseous metabolic products) detected and/or recorded. Rot damage which is inactive will not show significant levels of metabolic product gases. Small volumes of active rot will show lower levels of carbon dioxide (and other gaseous metabolic products) than large areas. Therefore gaseous products of rot organism metabolism will indicate the "product" of "extent” and "activity” of decay. Therefore a good indicator of the residual lifetime of the pole can be given by
- sampling points in the pole should be selected near to the suspect area, but at a distance, say 10-20cms from any large holes, splits or cavities.
- the holes should be drilled horizontally or inclined upwards.
- a fungus poison e.g. or boron compound should then be inserted into the hole and the hole should then be plugged afterwards with wooden or plastic dowels to avoid generating an area in the pole which may be prone to decay.
- Gas sampling tubes used for drawing a gas sample from the hole can comprise flexible plastic tubes which should be changed between each pole and flushed with ambient air between each individual sampling point on an individual pole.
- Poles which have a great deal of active decay present can show concentrations of carbon dioxide of up to 1.5%.
- the presence of a lesser degree of decay can be expected to give rise to levels of carbon dioxide above ambient in the 0-2,000 ppm range. Suitable detectors are available for this range or ranges.
- rot detection equipment consisting of three separate and distinct items, i.e. a small battery powered portable drill, a sampling device, and either a sensor or an adsorbant material, it is possible to combine these components in one hand-held battery powered device for ease of use by a linesman.
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- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Food Science & Technology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Biomedical Technology (AREA)
- General Physics & Mathematics (AREA)
- Medicinal Chemistry (AREA)
- Pathology (AREA)
- Molecular Biology (AREA)
- Wood Science & Technology (AREA)
- Biophysics (AREA)
- Hematology (AREA)
- Urology & Nephrology (AREA)
- Sampling And Sample Adjustment (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
There is described a method of detecting decay in wood comprising the steps of boring a hole in the wood subject to decay and drawing a gas sample from the hole. The gas sample is analysed to determine the concentration of at least one gas produced by aerobic metabolism by fungi in the wood. There is also described an apparatus for detecting decay in wood comprising boring means for boring a hole in the wood subject to decay and gas sampling means for drawing a gas sample from the hole for analysis to determine the concentration of at least one gas produced by an aerobic metabolism by fungi in the wood.
Description
A METHOD OF AND APPARATUS FOR DETECTING DECAY IN WOOD
The present invention relates to apparatus for and a method of detecting decay in wood by analysing gas within the wood to detect one or more gases produced by aerobic metabolism by fungi in the wood.
Overhead lines for electricity (132kV and below) and telephones are usually supported on wooden poles. Alternatives are concrete poles and steel lattice towers but these are generally more expensive. Plastic poles have also been developed for lightweight telephone signal carrying systems.
It is normal practice to test wooden poles for decay (a) before climbing them and (b) on a routine basis. The main method currently used is to strike the pole with a hammer and listen to the resultant sound. Generally speaking, this method will reveal serious problems with decay (rot) , although this depends on the skill of the linesman. In cases where decay is not very obvious and dramatic, the method lacks accuracy. Further, it has no predictive power and cannot distinguish active from inactive rot.
It is therefore an object of the present invention to provide apparatus for and a method of detecting decay in wood which is more accurate and cost effective.
The present invention provides a method of detecting decay in wood comprising the steps of boring a hole in the wood subject to decay, drawing a gas sample from the hole, and analysing the gas sample to determine the concentration
of at least one gas produced by aerobic metabolism by fungi in the wood.
The present invention also provides apparatus for detecting decay in wood comprising boring means for boring a hole in the wood subject to decay, and gas sampling means for drawing a gas sample from the hole for analysis to determine the concentration of at least one gas produced by aerobic metabolism by fungi in the wood.
The present invention recognises that wood rot or decay is caused by living organisms - fungi. The main species responsible are basidomycetes and in particular lentinus lapideus. These organisms in the course of their metabolism secrete an extensive range of chemicals, e.g. acid/bases, alcohols, enzymes, hydrogen peroxide; all of which are present to a greater or lesser extent in the gas or vapour phase. Some of the molecular species are simple compounds like carbon dioxide and ammonia - typical products of aerobic metabolism. Others are complex molecules. The ensemble -of these gives rise to a typical odour. Any of these compounds in principle can be detected with a suitable gas sensor by boring a small hole in the wood and directly drawing the gas sample across a sensor. Alternatively, a gas sample can be trapped by adsorption onto a small quantity, e.g. a few grams at most, of an adsorber material such as granular activated carbon, and later analysed after thermal desorption by simple or even relatively sophisticated methods of analysis.
The concentration of the metabolite gas or gases in the gas sample will vary with ambient temperature since the metabolic activity of the fungi will depend on the ambient temperature. Thus, in the analysis of the gas sample in order to determine the extent of the decay in the wood it will be necessary to correct the measured concentration to take into account the ambient temperature. This can take
the form of a temperature dependent correction factor.
Conveniently, the gas which is produced by the fungi which can easily be measured is carbon dioxide. Sensors are commercially available to measure or detect carbon dioxide to parts per million (ppm) levels at reasonable cost. The same is true for most low molecular weight sample molecules, i.e. C . , CO, NH_. Such sensors are based on infrared absorption or electrochemical effects. Such sensors work at ambient temperatures, and the instruments can be made both portable and robust.
Although the present invention is particularly applicable to the detection of decay or rot in poles which are part buried in the ground and provide structural support for a member, e.g. electricity or telephone overhead lines, the present invention is applicable to the detection of decay in wood generally.
For wooden poles, the method of the present invention can provide a measure of the residual lifetime of the pole since this is inversely proportional to the concentration of the or each of the gases generated by anaerobic metabolism, e.g. carbon dioxide. Also, the concentration of the or each gas determined in accordance with the method of the present invention can be used to provide an indication of active decay since this is directly proportional to the ambient temperature corrected concentration of the metabolite gas or gases.
A typical pole rot detection system will consist of three separate and distinct items. A small battery powered portable drill capable of creating a small diameter hole, e.g. < 5mm to a depth of several centimetres is required. This will be operated at or near ground level by the linesman since all significant rot begins at ground level and extends thereafter downwards and/or upwards. A sampling device is also provided which draws gas samples,
mixed inevitably with ambient air from the hole in the pole across a sensor or a cartridge of adsorber material such as granular activated carbon or a similar material. The linesman either carries the sensor itself in a portable battery powered form or a number of adsorbing cartridges of only a few grams in weight, and a device to draw a known quantity of gas into the sensor or over the adsorber. The device to draw a known quantity of gas into the sensor or over the adsorber can be hand-operated, e.g. a syringe or it can be battery operated such as a dosing pump operated on a timed basis with a known reproducible volume flow rate which is temperature adjusted if necessary for density. Where the gas to be detected is carbon dioxide the portable sensor can be a portable carbon dioxide detector.
Where an adsorber material such as granular activated carbon is used to sample the gas, the analysis of the gas sample can be carried out at a remote location. The adsorbed gas, e.g. carbon dioxide can be desorbed thermally into an appropriate detector at a later time and in another e.g. central location where the signals generated by the detector can be recorded and linked by a computerised data handling system to generate data on the pole in question and indicate the level of decay activity.
In order to allow for ambient temperature fluctuations, the ambient temperature or temperature of the wood, if likely to be different from the ambient temperature, is measured using a temperature sensor. This temperature can then be used to determine the correction factor used in the analysis.
The extent and level of activity can be measured and recorded as being directly proportional to the level of carbon dioxide (and other gaseous metabolic products) detected and/or recorded. Rot damage which is inactive will not show significant levels of metabolic product
gases. Small volumes of active rot will show lower levels of carbon dioxide (and other gaseous metabolic products) than large areas. Therefore gaseous products of rot organism metabolism will indicate the "product" of "extent" and "activity" of decay. Therefore a good indicator of the residual lifetime of the pole can be given by
1
- kl(extent) (activity) = k2[C02] r T where k1 is a constant and k2 is a constant which is a function of the T temperature of the wood.
In order to ensure accurate sampling of metabolic gases, sampling points in the pole should be selected near to the suspect area, but at a distance, say 10-20cms from any large holes, splits or cavities. The holes should be drilled horizontally or inclined upwards. In order to arrest the spread of decay a fungus poison e.g. or boron compound should then be inserted into the hole and the hole should then be plugged afterwards with wooden or plastic dowels to avoid generating an area in the pole which may be prone to decay.
In order to avoid contaminating different sampling bores, care should be taken to clean and sterilise the drill bits used with ethanol or a similar solution. If possible a fresh drill bit should be used for each pole inspection.
Gas sampling tubes used for drawing a gas sample from the hole can comprise flexible plastic tubes which should be changed between each pole and flushed with ambient air between each individual sampling point on an individual pole.
Poles which have a great deal of active decay present can show concentrations of carbon dioxide of up to
1.5%. The presence of a lesser degree of decay can be expected to give rise to levels of carbon dioxide above ambient in the 0-2,000 ppm range. Suitable detectors are available for this range or ranges.
Although the rot detection equipment has been described consisting of three separate and distinct items, i.e. a small battery powered portable drill, a sampling device, and either a sensor or an adsorbant material, it is possible to combine these components in one hand-held battery powered device for ease of use by a linesman.
Claims
1. A method of detecting decay in wood comprising the steps of boring a hole in the wood subject to decay, drawing a gas sample from the hole, and analysing the gas sample to determine the concentration of at least one gas produced by aerobic metabolism by fungi in the wood.
2. A method as claimed in Claim 1 wherein a said gas comprises carbon dioxide.
3. A method as claimed in Claim 1 or Claim 2 wherein said step of analysing comprises the step of analysing the gas composition of said gas sample.
4. A method as claimed in any preceding claim wherein said step of analysing the gas sample is performed directly as the gas sample is drawn from the hole.
5. A method as claimed in any one of Claims 1 to 3 including the step of drawing the gas sample over an adsorber material whereby the gas sample is adsorbed, transporting the adsorber material to a remote location for analysis, and heating the adsorber material to desorb the gas sample for analysis at the remote location.
6. A method as claimed in Claim 5 wherein said adsorber material is granular activated charcoal.
7. A method as claimed in any preceding claim wherein the level of decay is proportional to the concentration of said at least one gas.
8. A method as claimed in any preceding claim including the step of measuring the ambient temperature or the temperature of the wood to determine a temperature correction factor to be used in the analysis of the gas sample.
9. A method as claimed in any preceding claim wherein the wood comprises a pole part buried in the ground and providing structural support for a member, the step of boring comprising the step of drilling a small hole in the pole at or near ground level.
10. A method as claimed in Claim 9 wherein said hole is several centimetres deep and less than about 5mm wide.
11. A method as claimed in Claim 9 or Claim 10 wherei said hole is drilled horizontally or inclined upwards int the pole.
12. A method as claimed in any one of Claims 9 to 1 including the step of cleaning drill bits used for drillin said hole before drilling.
13. A method as claimed in any one of Claims 9 to 1 including the step of inserting a fungus poison into th hole after the gas sample has been drawn from the hole.
14. A method as claimed in any one of Claims 9 to 1 including the step of plugging the hole after the ga sample has been drawn from the hole.
15. A method as claimed in any one of Claims 9 to 1 wherein residual lifetime of the pole is determined a being inversely proportional to the concentration of sai at least one gas.
16. Apparatus for detecting decay in wood comprising boring means for boring a hole in the wood subject to decay, and gas sampling means for drawing a gas sample from the hole for analysis to determine the concentration of at least one gas produced by aerobic metabolism by fungi in the wood.
17. Apparatus as claimed in Claim 16 including analysing means for determining the concentration of said at least one gas produced by aerobic metabolism by fungi in the wood.
18. Apparatus as claimed in Claim 16 or Claim 17 wherein said boring means comprises a drill.
19. Apparatus as claimed in any one of Claims 16 to 18 wherein said gas sampling means includes an adsorber material over which the -gas sample is drawn, and heating means for heating said adsorber material at a remote location to thermally desorb the gas sample for analysis at said remote location.
20. Apparatus as claimed in Claim 19 wherein said adsorber material comprises granular activated carbon.
21. Apparatus as claimed in any one of Claims 16 to 20 including a fungus poison for insertion into the hole after the gas sample has been drawn therefrom.
22. Apparatus as claimed in any one of Claims 16 to 21 including a plug to plug the hole after the gas sample has been drawn therefrom.
23. Apparatus as claimed in any one of Claims 16 to 22 including a temperature sensor to measure the temperature of the wood or the ambient temperature, and temperature correction means to correct for the measured temperature during the analysis of the gas sample.
24. A method of detecting decay in wood substantially as hereinbefore described.
25. Apparatus for detecting decay in wood substantially as hereinbefore described.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9501739.8 | 1995-01-30 | ||
| GB9501739A GB2297381A (en) | 1995-01-30 | 1995-01-30 | Detecting decay in wood |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1996024057A1 true WO1996024057A1 (en) | 1996-08-08 |
Family
ID=10768779
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/GB1996/000204 Ceased WO1996024057A1 (en) | 1995-01-30 | 1996-01-30 | A method of and apparatus for detecting decay in wood |
Country Status (2)
| Country | Link |
|---|---|
| GB (1) | GB2297381A (en) |
| WO (1) | WO1996024057A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19743119C1 (en) * | 1997-09-30 | 1998-11-12 | Deutsche Telekom Ag | Wood power line mast testing method |
| GB2401174B (en) | 2003-04-30 | 2007-02-21 | Ecolab Sevices Ltd | Method and apparatus for detection of trace volatiles |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4314027A (en) * | 1980-07-21 | 1982-02-02 | Iowa State University Research Foundation, Inc. | Method of detecting mold toxin infected grains |
| DE3509704A1 (en) * | 1985-03-18 | 1986-09-18 | Kamm, Willibald F.G., Dipl.-Ing., 4970 Bad Oeynhausen | Method and device for determining the internal state of trees or of wooden component parts |
| GB2256054A (en) * | 1991-05-20 | 1992-11-25 | Forintek Canada Corp | Testing wood samples for decay |
| US5263359A (en) * | 1992-12-09 | 1993-11-23 | International Flavors & Fragrances Inc. | Method and apparatus for simultaneously analyzing aroma emitted from the interior and exterior of living tree and optionally from living fruit |
-
1995
- 1995-01-30 GB GB9501739A patent/GB2297381A/en not_active Withdrawn
-
1996
- 1996-01-30 WO PCT/GB1996/000204 patent/WO1996024057A1/en not_active Ceased
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4314027A (en) * | 1980-07-21 | 1982-02-02 | Iowa State University Research Foundation, Inc. | Method of detecting mold toxin infected grains |
| DE3509704A1 (en) * | 1985-03-18 | 1986-09-18 | Kamm, Willibald F.G., Dipl.-Ing., 4970 Bad Oeynhausen | Method and device for determining the internal state of trees or of wooden component parts |
| GB2256054A (en) * | 1991-05-20 | 1992-11-25 | Forintek Canada Corp | Testing wood samples for decay |
| US5263359A (en) * | 1992-12-09 | 1993-11-23 | International Flavors & Fragrances Inc. | Method and apparatus for simultaneously analyzing aroma emitted from the interior and exterior of living tree and optionally from living fruit |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2297381A (en) | 1996-07-31 |
| GB9501739D0 (en) | 1995-03-22 |
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