Patent Grant
11105060
The present disclosure is directed at a pole shield for installation around a pole structure, such as highway luminaire supports and utility poles for telephone, cable and electricity.
Pole structures are used for a variety of purposes, such as, but not limited to, highway luminaire supports and utility poles for telephone, cable and electricity. These pole structures are typically made from materials such as wood, steel or concrete.
Generally with wooden pole structures, the wood is treated to protect the pole structure from insect damage, pest attacks (such as woodpeckers and ants) and any rotting effects from moisture, which can be expensive and time-consuming. Such treatments may also make the pole structure more susceptible to fire, as they generally involve some form of petrochemical, which is impregnated into the wood of the pole structure. Other types of pole structures, such as steel and concrete pole structures may be susceptible to environmental damage, such as fire. Older pole structures made of any material may require extra structural support. Further, with some electrical steel poles, electrical insulating material may need to be provided at the point where the steel pole exists the ground in order to protect people touching the pole structure in the event of a ground fault. If these types of pole structures are damaged and are no longer functional, this can cause a service interruption to consumers, such as to those consumers travelling on highways and those who rely on these pole structures for providing telephone, cable and electricity services. It can be expensive and time consuming to replace such pole structures.
High intensity wild fires are fast-moving flame fronts that can damage or destroy utility structures, even when the exposure time is relatively short. Wood utility poles are particularly susceptible to wild fire damage from both large and small fires but other types of pole structures may also suffer damage after exposure to wild fires. While the number of wild fire events over the last 30 years seems to be relatively constant, the size of the fires appears to be increasing with time. Wild fires have devastating effects in many countries, such as the United States, Canada and Australia.
According to a first aspect, there is provided a pole shield comprising a sheet of composite material forming a hollow structure having an open first end and an opposed open second end for circumferentially extending around a pole structure. The sheet of composite material comprises from about 50% to about 80% by weight of a reinforcement impregnated with about 20% to about 50% of a polyurethane resin composition comprising a combination of a polyol component and a polyisocyanate component.
According to another aspect, there is provided a pole shield comprising one or more than one sheet of composite material forming a hollow structure having an open first end and an opposed open second end for circumferentially fitting around a pole structure, the one or more than one sheet of composite material comprising from about 50% to about 80% by weight of a reinforcement impregnated with about 20% to about 50% of a polyurethane resin composition comprising a combination of a polyol component and a polyisocyanate component, wherein the pole shield has fire resistant properties.
The reinforcement may be glass. The polyol component may comprise a plurality of OH groups that are reactive towards the polyisocyanate component and the polyisocyanate component may comprise a plurality of NCO groups that are reactive towards the polyol component. The OH:NCO mixing ratio, by volume, of the polyurethane resin composition may be from about 1.0:5.0 to about 5.0:1.0. The polyol component may comprise a polyether polyol, a polyester polyol, or a mixture thereof. The polyisocyanate component may comprise an aromatic isocyanate, an aliphatic isocyanate, or a mixture thereof.
The sheet or sheets of composite material may be from about 0.2 mm to about 20.0 mm thick. The sheet or sheets of composite material may comprise a plurality of layers. The sheet or sheets of composite material may comprise between 2 and 12 layers. The sheet or sheets of composite material may include an opening extending from the first end to the second end and the sheet or sheets of composite material may be movable between a receiving position where the opening is expanded to receive the pole structure and a closed position where the opening is reduced and the sheet or sheets of composite material circumferentially extends around the pole structure. The sheet or sheets of composite material may be biased in the closed position. In the closed position a portion of the sheet or sheets of composite material may overlay another portion of the sheet or sheets of composite material.
The hollow structure may be a cylindrical tube and the cross-sectional areas of the open first end and the open second end are substantially the same. The hollow structure may be a tapered tube and the cross-sectional area of the open first end may be less than a cross-sectional area of the open second end.
According to another aspect, there is provided a pole shield structure comprising two or more pole shields according to the first aspect stacked one on top of the other with the open first end of a first of the pole shields connecting to the open second end of a second of the pole shields to increase the height of the pole shield extending around the pole structure.
The open first end of the first pole shield may overlap with the open second end of the second pole shield. The open first end of the first pole shield may be received within the open second end of the second pole shield. The open second end of the second pole shield may be received within the open first end of the first pole shield. The open first end of the first pole shield may be connected to the open second end of the second pole shield by a fastener.
The first pole shield may have a greater internal dimension than an external dimension of the second pole shield such that at least a portion of the second pole shield nests within the first pole shield when the pole shield structure is unassembled.
According to another aspect, there is provided a kit for constructing a pole shield structure comprising two or more pole shields according to the first aspect.
A first of the pole shields may have a greater internal dimension than an external dimension of a second of the pole shields, such that at least a portion of the second pole shield nests within the first pole shield.
This summary does not necessarily describe the entire scope of all aspects. Other aspects, features and advantages will be apparent to those of ordinary skill in the art upon review of the following description of specific embodiments.
These and other features will become apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to in any way limit the scope to the particular embodiment or embodiments shown, wherein:
Directional terms such as “top,” “bottom” and “vertical” are used in the following description for the purpose of providing relative reference only, and are not intended to suggest any limitations on how any article is to be positioned during use, or to be mounted in an assembly or relative to an environment.
The present disclosure relates to a pole shield for installation around a pole structure, such as highway luminaire supports and utility poles for telephone, cable and electricity. In particular the present disclosure relates to a pole shield for installation around a utility pole. The pole shield is designed to protect the pole structure from damage, such as insect damage, pest attack, the rotting effects from moisture, UV damage and to provide structural support and fire resistance.
Referring now to
In an embodiment of the pole shield 10 shown in
Referring now to
In an embodiment of a pole shield 200 shown in
In alternative embodiments, the pole shield may comprise two or more sheets of composite material that are joined together to form a hollow, tubular or other shaped pole shield, that may or may not be tapered. The two or more sheets of composite material that make up the pole shield can be positioned in place around an existing installed pole structure, such as a utility pole and joined together to form the pole shield surrounding the pole structure.
The sheet or sheets of composite material comprise reinforcement impregnated with a polyurethane resin. The polyurethane resin holds the reinforcement to form the desired shape while the reinforcement generally improves the overall mechanical properties of the polyurethane resin. The composite material comprises about 20-50% by weight of the polyurethane resin, or any amount therebetween, for example, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48%, or any amount therebetween, by weight of the polyurethane resin, and comprises about 50-80% by weight of the reinforcement, or any amount therebetween, for example, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78%, or any amount therebetween, by weight of the reinforcement.
By the term “reinforcement,” it is meant a material that acts to further strengthen the polyurethane resin of the composite material, such as, for example, but not limited to, fibers, particles, flakes, fillers, or mixtures thereof. The reinforcement generally improves the overall mechanical properties of the polyurethane resin. Reinforcement typically comprises glass, carbon, or aramid; however, there are a variety of other reinforcement materials that can be used, as would be known to one of skill in the art. These include, but are not limited to, synthetic and natural fibers or fibrous materials, for example, but not limited to polyester, polyethylene, quartz, boron, basalt, ceramics and natural reinforcement, such as fibrous plant materials, for example, jute and sisal.
The polyurethane resin composition comprises a polyol component and a polyisocyanate component. The polyurethane resin composition may be a thermosetting resin composition which is a liquid reaction mixture used to impregnate the reinforcement and is then set or cured to provide a substantially solid matrix for the reinforcement. Other additives may also be included in the polyurethane resin composition, such as fillers, pigments, plasticizers, curing catalysts, UV stabilizers, antioxidants, microbiocides, algicides, dehydrators, thixotropic agents, wetting agents, flow modifiers, matting agents, deaerators, extenders, molecular sieves for moisture control and desired colour, UV absorber, light stabilizer, moisture absorbents, fire retardants and release agents.
By the term “polyol component” it is meant a composition that contains a plurality of active hydrogen or OH groups that are reactive towards the polyisocyanate component under the conditions of processing. The polyol component of the polyurethane resin composition may comprise polyether polyols and polyester polyols. Polyols described in U.S. Pat. No. 6,420,493 (which is incorporated herein by reference) may also be used in the polyurethane resin composition described herein. The polyol component may include, but is not limited to, a polyether polyol, a polyester polyol, or a mixture thereof. The polyester polyol may be, but is not limited to a diethylene glycol-phthalic anhydride based polyester polyol. The polyether polyols may be, but is not limited to, polyoxyalkylene polyol, propoxylated glycerol, branched polyol with ester and ether groups, amine initiated-hydroxyl terminated polyoxyalkylene polyol and mixtures thereof.
By the term “polyisocyanate component” it is meant a composition that contains a plurality of isocyanate or NCO groups that are reactive towards the polyol component under the conditions of processing. The polyisocyanate component of the polyurethane resin composition may comprise aromatic isocyanate, aliphatic isocyanate or the mixture of aromatic isocyanate and aliphatic isocyanate. Polyisocyanates described in U.S. Pat. No. 6,420,493 may also be used in the polyurethane resin composition described herein.
By the term “aliphatic isocyanate” it is meant an isocyanate in which NCO groups are either attached to an aliphatic center or not attached directly to an aromatic ring. It is also within the scope of the present disclosure that the term “aliphatic isocyanate” means an isocyanate in which the NCO groups are attached to an aliphatic center. Aliphatic isocyanates described in U.S. Pat. No. 6,420,493 may be used in the resin compositions described herein. Aliphatic isocyanates may include, but are not limited to, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexane-4,4′ diisocyanate (Desmodur W), hexamethylene diisocyanate trimer (HDI Trimer), isophorone diisocyanate trimer (IPDI Trimer), hexamethylene diisocyanate biuret (HDI Biuret), cyclohexane diisocyanate, meta-tetramethylxylene diisocyanate (TMXDI), and mixtures thereof. The aliphatic isocyanate may include a polymeric aliphatic diisocyanate, for example, but not limited to a uretidione, biuret, or allophanate polymeric aliphatic diisocyanate, or a polymeric aliphatic diisocyanate in the symmetrical or asymmetrical trimer form, or a mixture thereof, which typically does not present a toxic hazard on account of extremely low volatility due to very low monomer content. The aliphatic isocyanates may be hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) or a mixture thereof, and may be a mixture of aliphatic hexane 1,6-diisocyanato-homopolymer and hexamethylene diisocyanate (HDI). Hexamethylene diisocyanate polyisocyanates described in EP-A 668 330 to Bayer AG; EP-A 1 002 818 to Bayer AG; and WO 98/48947 to Valspar Corp (which are incorporated herein by reference) may be used in the aliphatic isocyanate resin composition described herein.
By the term “aromatic isocyanate” it is meant an isocyanate in which NCO groups are attached to an aromatic ring. Aromatic isocyanates described in U.S. Pat. No. 6,420,493 may be used in the resin composition described herein. Aromatic isocyanates may include, but are not limited to, methylene di-p-phenylene isocyanate, polymethylene polyphenyl isocyanate, methylene isocyanatobenzene or a mixture thereof. The aromatic polyisocyanate may include from about 30% to about 60% by weight, or any amount therebetween, of methylene di-p-phenylene isocyanate, from about 30% to about 50% by weight, or any amount therebetween of polymethylene polyphenyl isocyanate, with a balance of methylene isocyanatobenzene.
The polyurethane resin composition may have a OH:NCO mixing ratio, by volume, from about 1.0:5.0 to about 5.0:1.0, or any amount therebetween, for example a mixing ratio of 1.0:4.0, 1.0:3.0, 1.0:2.0, 1.0:1.0, 2.0:1.0; 3.0:1.0, 4.0:1.0 or any ratio therebetween.
The present disclosure also contemplates the addition of an aliphatic polyurethane composite material top coat or other suitable material to enhance durability and service life of the pole shield. Such materials may be useful for providing a tougher outer surface that is extremely resistant to weathering, ultraviolet (UV) light, abrasion and can be coloured for aesthetics or identification. An aliphatic isocyanate thermosetting polyurethane resin may be used in a top coat or outer layer(s) of the sheet of composite material. The aliphatic isocyanate thermosetting polyurethane resin top layer may have a higher concentration of aliphatic isocyanate than the thermosetting polyurethane resin used for the remainder of the pole shield. Aliphatic isocyanates polyurethane resin has superior resistance to weathering and UV rays, however aliphatic isocyanate resin is generally more expensive than other resins, such as aromatic polyisocyanate polyurethane resin. A pole shield having one or more outer layers of an aliphatic isocyanate polyurethane composite material and an inner core made from a different composite material with a lower concentration of aliphatic isocyanate therein beneficially possesses UV stability and superior abrasion resistance, while being less expensive to produce than a pole shield manufactured with a homogenous distribution of aliphatic isocyanate polyurethane throughout the pole shield.
The sheet or sheets of composite material may be manufactured using filament winding, which is a well-known process for the production of composites. However, other methods may also be used to produce the sheet of composite material, such as, but not limited to, pultrusion, resin injection molding, resin transfer molding and hand lay-up forming applications. A typical filament winding process is described in CA 2,444,324 and CA 2,274,328 (both of which are incorporated herein by reference). Fibrous reinforcement, as described herein, for example, but not limited to glass, carbon, or aramid, is impregnated with the polyurethane resin described herein, and wound onto an elongated mandrel, which may be cylindrical or tapered to produce sheet of composite material respectively. Different shaped mandrels may also be used to produce pole shields having different shapes, such as rectangular, triangular and the like.
The resin impregnated reinforcement may be wound onto the mandrel in a predetermined sequence. This sequence may involve winding layers of the composite material at a series of angles ranging between 0° and 90°, or any amount therebetween, relative to the mandrel axis, for example, at an angle of 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, or any amount therebetween. The direction that the reinforcement is laid onto the mandrel may affect the eventual strength and stiffness of the finished pole shield. Other factors that may affect the structural properties of the manufactured pole shield include varying the amount of reinforcement to resin ratio, the wrapping sequence, the wall thickness, the type of reinforcement (such as glass, carbon, aramid), and the ratio of the polyol component to the polyisocyanate component (the OH:NCO ratio) of the polyurethane resin composition. The structural properties of the pole shield can be engineered to meet specific performance criteria. In this way, the construction of the sheet of composite material can be configured to produce a finished pole shield that is extremely strong and of a suitable flexibility for installation around a pole structure.
Once the resin has set or cured, the sheet of composite material may be removed from the mandrel and may be slit longitudinally along its length to provide a pole shield with a slit or opening as shown in
The sheet or sheets of composite material may be made of a single layer of composite material, such as a layer of composite material laid down by filament winding or extruded by pultrusion. Alternatively, the sheet of composite material may include a plurality of layers of the composite material which are laid down by filament winding or by an alternative process such as pultrusion and bonded or joined together or laid down one on top of the other to form the sheet of composite material. The sheet of composite material therefore, comprises one or more than one layer of the composite material, such as, but not limited to, between two to twelve layers of the composite material, for example, 3, 4, 5, 6, 7, 8, 9, 10 or 11 layers. A pole shield made from a plurality of layers of the composite material may beneficially better protect and support the pole structure which it surrounds than a pole shield made from a single layer.
The thickness of the sheet of composite material may vary depending on where, and for what purposes, the pole shield will be used. For example, the sheet of composite material 16, 116 may be about 0.2 mm to about 20.0 mm thick, or any amount therebetween, for example, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 mm, or any thickness therebetween.
The sheet or sheets of composite material of the pole shield beneficially provides a lightweight structure that generally displays superior strength and durability compared to the strength and durability associated with the wood, steel or composite pole structures around which the pole shield is intended to be installed. The sheet of composite material may also be designed to be of sufficient flexibility to conform to the shape of the pole structure that it is installed around. The composite material does not rust like steel and typically does not rot or suffer microbiological or insect attack as is common in wood pole structures. The composite material generally acts as a moisture-shield and protects the underlying pole structure from the effects of moisture damage. Furthermore, the composite material, in contrast to natural products (such as wood), is engineered so the consistency and service life can be closely determined and predicted. The composite material (or at least the outer layer(s) of the sheet) may be chosen for its UV resistant properties. Still further, the composite material (or at least the outer layer(s) of the sheet) may be chosen for its fire resistant properties.
By “fire resistant properties” it is meant that the composite material has some resistance to fire. For example, the sheet of composite material may be able to withstand fire exposure for at least 50 seconds or more, for example between 50 and 250 seconds or any time in between such as 180 seconds as provided in the example given below. The temperature of the fire exposure that the sheet of composite material is able to withstand may be at least 500° C. or more, for example between 500 and 1200° C. or any temperature in between, for example between about 1000° C. and 1200° C. The energy of the fire exposure that the sheet of composite material is able to withstand may be at least 3000 kWs/m2, for example between 3000 and 20000 kWs/m2 or any amount in between. The composite material of the pole shield of the present disclosure generally self-extinguishes once the flame source is removed. It is thought that this self-extinguishing property provides fire resistant properties to the pole shield.
A pole shield comprising composite material with fire resistant properties may beneficially be used to surround pole structures, such as a wood or composite utility pole, in fire prone areas. A pole structure with a pole shield is more likely to withstand the effects of wild fire compared to a pole structure without the pole shield. Although the pole structure may sustain some damage as a result of wild fire exposure, as evidenced in the examples disclosed below, the pole structure will typically remain standing after the fire exposure.
In the examples given below, unprotected wood poles exposed to simulated wild fire conditions for severe durations of 120 seconds and extreme durations of 180 seconds, were consumed by flames to the point of failure. Wood poles, protected by a pole shield according to the embodiments disclosed herein when tested under severe conditions of 120 second fire exposure, sustained only minor surface charring and did not exhibit any loss of strength. Although wood poles protected by a pole shield tested under extreme conditions of 180 second fire exposure did fail, it is rare for wild fires conditions to go above 90 seconds duration. Composite poles protected by a pole shield according to the embodiments disclosed herein when tested to fire exposure for severe durations of 120 seconds and extreme durations of 180 seconds all survived intact. Subsequent full-scale bend testing of these composite poles resulted in no reduction in ultimate failure strength or stiffness.
In some embodiments, the pole shield circumferentially extends around the outer surface of pole structure such that pole shield is in direct contact with the outer surface of pole structure. In such an embodiment, the pole shield may be secured in positioned on the pole structure to provide contact with the structure, using a suitable fastener as described above. In an alternative embodiments, the pole shield extends circumferentially around the outer surface of pole structure but does not actually contact pole structure. In these embodiments, there is a gap between the outer surface of pole structure and pole shield, which can be filled with materials to provide further impact or fire resistance to pole structure. Materials, such as, without limitation, sand, foam, rocks, gravel, soil or any other suitable material, may be used. Furthermore, such an embodiment of the pole shield may be useful as a casing or structure for holding backfill materials to provide further structural support to pole structure.
Referring now to
Referring now to
Each tapered pole shield 100 is hollow and has an open top (or first) end 112 and an open bottom (or second) end 114 with the cross-sectional area of top end 112 being less than the cross-sectional area of bottom end 114. To form pole shield stack 200, bottom end 114 of pole shield 100 A is mated with top end 112 of pole shield 100 (as shown in
The present disclosure therefore contemplates that pole shield 100 be configured such that two or more than two pole shields may be stacked one on top of the other to form a pole shield structure. In one embodiment of the pole shield structure, the top or first end 112 of lower positioned pole shield 100 slips into, or is matingly received within, the bottom or second end of higher positioned pole shield 100A to a predetermined height to provide elongated vertical pole shield stack 200. In an alternative embodiment of the pole shield structure, the bottom or second end 114 of higher positioned pole shield 100A slips into, or is matingly received within the top or first end 112 of lower positioned pole shield 100. The overlaps of these joint areas may be predetermined so that adequate load transfer can take place from one pole shield and the next. This overlap may vary throughout pole shield stack 200, generally getting longer as the pole shields descend in order to maintain sufficient load transfer when reacting against increasing levels of bending moment. The joints may be designed so they provide sufficient load transfer without the use of additional fasteners, for example press fit connections, bolts, metal banding, screws, nails and the like. However, it is within the scope of the present disclosure that a fastener be used to secure two pole shields together, if desired and there may be no overlap of the poles shields in the stack. The internal dimensions of lower positioned pole shield 100 may greater than the external dimensions of higher positioned pole shield 100A such that a portion or the whole of pole shield 100A nests within pole shield 100 when not assembled for ease of transportation and storage.
In alternative embodiments, the cylindrical pole shield or any other shaped pole shield may be stacked one on top of the other and fastened by overlapping and/or through the use of fastener(s). When pole shields are stacked together to form pole shield stack, they behave as a single structure able to resist forces and to protect pole structure from damage and to provide structure support to pole structure. As described above, the height of pole shield stack can be varied simply by adding or removing pole shield(s) from pole shield stack.
The present disclosure further provides a series or kit including a plurality of pole shields. The pole shields may be of different sizes. The largest pole shield may have a greater internal dimension than the external dimensions of the next largest pole shield, such that at least a portion of the smaller pole shield nests within the larger pole shield. In one embodiment, the whole of the smaller pole shield nests within the larger pole shield. Additional pole shields may be provided that are gradually smaller in size. In this way, the two or more than two pole shields that make up a pole shield stack can be nested one within the other. The nested pole shields offers handling, transportation and storage advantages due to compactness and space saving.
The series or kit may be used to construct pole shield stack 200 whereby the pole shields may be configured so that the top (or first) end 112 of the first or largest pole shield 100 fits inside or is matingly received within the bottom (or second) end 114 of the second or smaller pole shield 100A. Alternatively, the bottom (or second) end 114 of the second or smaller pole shield 100A may be configured so it will fit inside or is matingly received within the top (or first) end 112 of the first or largest pole shield 100. In alternative embodiments, the kit may include cylindrical pole shields 10 or other different shaped pole shields which can be stacked one on top of the other for construction of a pole shield stack or structure.
Referring now to
In use, therefore (as hereinbefore described), the pole shield of the present disclosure may beneficially protect a pole structure from damage and may also provide additional structural support, especially for leaning or rotting pole structures. The composite material of the pole shield may be selected to include fire suppression qualities. Furthermore, the durability and strength of the composite material may help to support and protect a pole structure from breakage from ice or wind loading. Further, in desert areas, the pole shield may help protect a pole structure from the constant barrage of sand. Still further, the pole shield may help protect a pole structure from moisture, rain, UV damage, bacteria, insects, borers, woodpeckers and other pests, and may thereby reduce the usage of chemicals for treating pole structures. The composite material of the pole shield may also be selected to provide electrical insulation, and therefore can be used as an electrical insulating barrier around steel pole structures. As described above, if the pole shield is positioned away from the outer surface of a pole structure, the gap between the pole structure and the pole shield can be filled in with materials, such as without limitation, sand and foam, to provide impact resistance. Furthermore, with a gap between pole structure and pole shield, the pole shield can be used as a structure or casing for holding backfill materials. The pole shield may also be easier and cheaper to replace if damaged compared to replacing a damaged pole structure, for example, if the pole shield is damaged in a fire, it can be replaced without having to replace the whole pole structure.
The International Crown Fire Modeling Experiment (ICFME) in the Northwest Territories (NWT) of Canada, was conducted between 1995 and 2001. During this period, 18 high-intensity crown fires were created and studied by over 100 participants representing 30 organizations from 14 countries. The ICFME provided valuable data and insight into the nature and characteristics of crowning forest fires, which greatly assisted in addressing fire management problems and opportunities affecting both people and ecosystems.
Data collected during the ICFME experiments and from literature on wild fire events were used to gauge the severity of the simulated wild fire exposures. Observations from these studies showed gas temperatures ranging from 800-1,200° C. [1,472-2,192° F.], and total heat energy of 6,000-10,000 kW-s/m2. Most fires however are below 1,000° C. [1,832° F.] and exposure durations are rarely above 90 seconds. Wild fires in undisturbed coniferous forests are not expected to exceed 90 seconds in duration. Exposure durations in maintained overhead line right-of-way areas would not typically exceed 60 seconds. The findings from this data is shown in Table 1 below.
Pole structures being tested were stood in a vertical position, guyed or embedded to hold the poles in place, instrumented to measure temperature and heat flux and then exposed to propane fueled diffusion flames for durations that simulated severe wild fire conditions. Poles were exposed to beyond worst-case durations of 120 seconds (defined as Severe) and 180 seconds (defined as Extreme).
To ensure flame contact with the pole surface, shrouds were constructed using 20-gauge steel spiral duct of 0.60-0.91 m [24-36 in.] nominal diameter, and with an overall length of 1.5-3.7 m [5-12 ft.]. The shrouds were fitted with openings near the base to accommodate modified propane torches. Fuel was routed via electric solenoid valves to critical flow orifices, which controlled the amount of fuel introduced through the burners. The shrouds were elevated above grade level to control the air available for combustion. The mixing element in each torch was removed to cause pure propane to be expelled from the orifices, making the fuel/air mixture within the test shroud very fuel rich. This ensured that combustion product temperatures achieved a minimum target temperature of 800° C. [1,472° F.]. The combustion products flowed through the annular space between the pole and the shroud and exited the top of the shroud.
Various composite poles and wood poles with and without a pole shield were exposed to wild fire conditions. All composite poles and pole shields tested were commercially available from RS Technologies Inc. (hereinafter “RS”). After fire exposure some of the poles were full-scale bend tested (FST) to failure to observe the impact on pole strength and stiffness.
A 35 ft. [10.7 m] CL5 red pine pole was fire exposed for 120 seconds, with a maximum gas temperature of 1,040° C. [1,904° F.] and a total energy exposure of 12,200 kWs/m2.
A 35 ft. [10.7 m] CL5 red pine pole with an RSS-03 RS Fire Shield™ was fire exposed for 120 seconds, with a maximum gas temp of 1,080° C. [1,976° F.] and a total energy exposure of 14,400 kWs/m2.
A 35 ft. [10.7 m] CL5 red pine pole with a split-fit RSS-03 RS Fire Shield™ was fire exposed for 120 seconds, with a maximum gas temperature of 1,100° C. [2,102° F.] and a total energy exposure of 12,280 kWs/m2.
A RSM-07-TB-15-83962™ RS composite pole module with a split RSS-09 RS Fire Shield™ was subjected to fire exposure for 120 seconds, with a maximum gas temperature of 1,180° C. [2,156° F.] and a total energy exposure of 9,600 kWs/m2.
A 35 ft. [10.7 m] CL5 red pine pole was fire exposed for 180 seconds, gas temperatures and heat flux values were not recorded.
A 35 ft. [10.7 m] CL5 red pine pole with a split-fit RSS-03 RS Fire Shield™ (15 ft. [4.6 m] high) was fire exposed for 180 seconds, with a maximum gas temperature of 1,200° C. [2,192° F.] and a total energy exposure of 17,500 kWs/m2.
A 45 ft. [13.7 m] RS 0204™ modular composite pole without a RS Fire Shield™ was fire exposed for 180 seconds, with a maximum gas temperature of 1,100° C. [2,012° F.] and a total energy exposure of 11,988 kWs/m2.
A 45 ft. [13.7 m] RS 0204™ modular composite pole without a RS Fire Shield™ was fire exposed for 180 seconds, with a maximum gas temperature of 1,109° C. [2,028° F.] and a total energy exposure of 11,808 kWs/m2.
A 20 ft. [6.1 m] section of a 45 ft. [13.7 m] RS 0204™ modular composite pole covered with a split RSS-05 RS Fire Shield™ and the edge of the Fire Shield™ protected with an aluminum J-Channel was fire exposed for 180 seconds, with a maximum gas temperature of 850° C. [1,562° F.] and a total energy exposure of 16,540 kWs/m2.
A 45 ft. [13.7 m] RS 0204™ modular composite pole covered with a split RSS-05 RS Fire Shield™ and the edge of the Fire Shield™ protected with an aluminum J-Channel was fire exposed for 180 seconds, with a maximum gas temperature of 1,100° C. [2,012° F.] and a total energy exposure of 15,840 kWs/m2.
A 45 ft. [13.7 m] RS 0204™ modular composite pole covered with a split RS Fire Shield™ and the edge of the Fire Shield™ protected with an aluminum J-Channel with an intentional 12.7 mm [0.5 in.] uncaulked gap below the slip joint was fire exposed for 180 seconds, with a maximum gas temperature of 1,018° C. [1,864° F.] and a total energy exposure of 13,428 kWs/m2.
A 45 ft. [13.7 m] RS 0204™ modular composite pole had the base module covered with a slip-fit RS Fire Shield™ and the second module wound with an integrated 3 mm [0.12 in.] Fire Shield™ was fire exposed for 180 seconds, with a maximum gas temp of 1,278° C. [2,332° F.] and a total energy exposure of 12,582 kWs/m2.
A 45 ft. [13.7 m] RS 0204™ modular composite pole covered with a split RS Fire Shield™ and the edge of the Fire Shield™ protected with an aluminum J-Channel with one unplugged temporary step hole in the fire exposure shroud was fire exposed for 180 seconds, with a maximum gas temperature of 1,018° C. [1,864° F.] and a total energy exposure of 11,867 kWs/m2.
A 45 ft. [13.7 m] RS 0204™ modular composite pole covered with a split RS Fire Shield™ and aluminum edge fitted with a 318 kg [700 lb] simulated transformer mounted 310 mm [12 in.] away from the pole surface plus a 1.2 m [48 in.] composite cross-arm was fire exposed for 180 seconds, with a maximum gas temperature of 1,059° C. [1,938° F.] and a total energy exposure of 12,060 kWs/m2.
The results of the severe fire exposure tests are given in Table 2 below.
All unprotected wood poles exposed to simulated wild fire conditions for severe durations of 120 seconds and extreme durations of 180 seconds, were consumed by flames to the point of failure. Wood poles, protected by an RS Fire Shield™ when tested under severe conditions of 120 second durations, sustained only minor surface charring. Post fire exposure full scale bend testing of wood poles protected with an RS Fire Shield™ did not exhibit any loss of strength. Wood poles protected with an RS Fire Shield™ and exposed to extreme wild fire durations of 180 seconds did not survive.
RS composite poles protected with an RS Fire Shield™ and fire exposed for severe durations of 120 seconds and extreme durations of 180 seconds all survived intact. Subsequent full-scale bend testing of these RS composite poles resulted in no reduction in ultimate failure strength or stiffness.
7 ft. [2.1 m] RSM-02™ RS composite module pole sections with 4 step holes fitted with silicone rubber plugs were exposed to radiant energy and fire per the ASTM “Standard Test Method for Determining Charring Depth of Wood Utility Poles Exposed to Simulated Wild Fire”. Total exposure time was 600 seconds for each test. The first 300 seconds applies 50 kW radiant energy only followed by 300 seconds of 50 kW radiant energy plus fire exposure from a 40 kW ring burner positioned at the pole base. Total energy exposure is in excess of 30,000 kWs/m2. Pole surface and gas temperatures were not measured. The following tests were carried out:
In this disclosure, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.
It is contemplated that any part of any aspect or embodiment discussed in this specification can be implemented or combined with any part of any other aspect or embodiment discussed in this specification.
While particular embodiments have been described in the foregoing, it is to be understood that other embodiments are possible and are intended to be included herein. It will be clear to any person skilled in the art that modifications of and adjustments to the foregoing embodiments, not shown, are possible.
All citations are hereby incorporated by reference.
This application is a continuation in part of U.S. Patent application Ser. No. 15/316,055 filed Dec. 2, 2016 which is a § 371 National State Application of PCT/CA2015/050497 filed May 29, 2015, which claims priority to U.S. Patent Application No. 62/006,613 filed Jun. 2, 2014.
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| Number | Date | Country | |
|---|---|---|---|
| Parent | 15316055 | US | |
| Child | 16751342 | US |
