GB2505658A

GB2505658A - Slow Release Fluid System for Pressurised Fluid Container

Info

Publication number: GB2505658A
Application number: GB201215863A
Authority: GB
Inventors: Bruce Wigton
Original assignee: Midmos Solutions Ltd
Current assignee: Midmos Solutions Ltd
Priority date: 2012-09-05
Filing date: 2012-09-05
Publication date: 2014-03-12
Also published as: GB201215863D0; WO2014037694A2; WO2014037694A3

Abstract

A slow fluid release system for a pressurised fluid (e.g. Carbon Dioxide) container 12 comprises a release with a porous element 18 as a flow impeder. The porous element may be a plastic (such as a porous polytetrafluoroethylene (PTFE)), ceramic or metal element, and may give a flow rate below 10 ml/min, with a hollow puncture pin 16 release. The porous element may be positioned over and/or within a conduit running through the release, and the system may have an indicator 22 showing when the container needs replacing (i.e. the container is empty or no fluid is flowing); and the system may have a latching solenoid incorporating permanent magnets to control fluid release. The system may be used in an insect trap with a timer and battery, with a pit to trap insects. Also disclosed is a method of forming a porous element by sintering porous plastics with a filtration capacity below 20 µm.

Description

A CONTROLLED FLUID RELEASE SYSTEM AND AN INSECT TRAP OR MONITOR

INCORPORATING SUCH A RELEASE SYSTEM

[0001] This invention relates to a fluid release system capable of releasing a fluid, such S as an insect attractant, for example, a gas, such as, carbon dioxide, over a period of at least a few days, and preferably at least 5 days, more preferably still a week. It also relates to an insect trap or monitor incorporating such a system, and more particularly to a trap or monitor designed to capture bed bugs.

[0002] Also envisaged are a method for slowing the release of a fluid from a pressurised container which comprises impeding the fluid flow from the container through the use of a porous metal, ceramic or plastics element and a method of forming a slow release porous metal, ceramic or plastics element comprising compressing sintered porous metal, ceramic or plastics having a filtration capability of below 20pm by at least 10%. The element may be compressed as a whole or in part, for example, about it's periphery. Sintered porous metal or ceramic elements (which may be "coined") are also referred to as spargers, and are defined by their pore size, typically ranging from 0.1 to 200pm.

[0003] The elements used in the practice of the present invention use pore sizes smaller than 100pm, more particularly smaller than 20pm and often smaller than 10pm.

BACKGROUND

[0004] Fluids, either liquids (often volatile liquids) or gasses are often used as attractants in the capture of insects. However, replacing the attractant frequently e.g. daily, is labour intensive making it impractical and not cost effective, particular where traps are field based or in relatively inaccessible places.

[0005] Common attractants used in insect traps, particularly those for blood sucking insects, include the gas, carbon dioxide, which has been used extensively with flying insects, such as, mosquitos, but has also been used as an attractant for bed bugs -either alone or in combination with other attractants.

[0006] Whilst for the capture of mosquito's it is practical to use large gas cylinders (filled with a fluid in e.g. Kg quantities) with expensive, multi-component regulators, where gas release can be controlled in a phased and timed manner, miniaturisation has not been considered practical, as controlled release from small volume containers or cartridges (i.e. those filed with a fluid in quantities of under 250g), in a manner allowing for several days of attractant release has not hitherto proved possible.

[0007] One of the main problems to be overcome is how to control the flow rates from a small cartridge or cylinder (such as. but not limited to one with a 38g. 16g or 12g capacity) to rates below 40m1/min, more preferably still less than 20m1/min, more preferably still less than 10m1/min and most preferably 2-8m1!min.

[0008] For some applications, gases are released through semi-permeable membranes, such as low density poly ethylene (LOPE). However, such porous materials have not been used under such high pressures (typically above 100 PSIG) or for the applications contemplated by the present invention.

[0009] A typical application would be to release carbon dioxide from a pressurised cylinder where the carbon dioxide is liquefied and at a pressure in the order of over 100 P51G. typically 900 P51G. and is released to atmosphere at a rate of about 4mllmin. At this rate a 16g cartridge would release its content over a period of 24-36 hours and if released in a timed manner (e.g. 2 release periods of 4 hours per day) could have an effective use period of 7 days.

[0010] If one were to use a LOPE it would be necessary to use a material with a thickness of 0.001 inch and a diameter of 0.375 inch and it would not be possible to provide a mechanism for such a diaphragm which allowed release and was not damaged bythepressure.

BRIEF SUMMARY OF THE DISCLOSURE

[0011] In accordance with a first aspect of the present invention there is provided a slow fluid release system (10) for a container (12) containing a pressurised fluid (14) comprising a release (16) characterised in that it further comprises a flow impeder mechanism, in the form of a porous (18) element.

[0012] Preferably the element is a porous metal, ceramic or plastics element, most preferably porous plastics, particularly polytetrafluoroethylene.

[0013] Preferably the porous plastics element restricts the fluid release to below 30m1/min, more preferably less than lOmI/min. Oepending on the material selected this will typically be achieved using a material with a pore size of less than 2Opm, and more preferably less than 10pm.

[0014] The porous element is preferably positioned directly or indirectly over and! or within a conduit running through a puncture pin.

[0015] A favoured porous plastic is a porous polytetrafluoroethylene (PTFE), such as that manufactured by Porex Technologies as PMO13O, a material having a pore size of 1-2pm, a porosity of 30%, an air flow of 0.5-2.3 l!hr!cm2, a water intrusion pressure of 1030-2070 mBar, and a thickness of 3mm. Of course other porous plastics or porous ceramics or metals may be used.

[0016] Alternatives include other porous plastics that are currently used as filtration devices, with known particle limiting characteristics. These are frequently manufactured using powdered plastics which are sintered. By controlling the powder particle size and pressure during sintering pore size can be controlled such that the filtration characteristics or diffusion characteristics can be controlled. These plastics can be formed into various geometries including sheets and rods making them suitable for the claimed use as a gas impeder, where slow release under pressure is required. Exemplary porous metals and ceramics include those obtained Mott Corporation or Refractron Technologies Corp and will be familiar to those skilled in the art.

[0017] To slow the gas flow further these, in particular, porous plastics may be further compressed. For example, a standard porous plastics rod, such as a 1 inch rod of 0.25 inch diameter with a 10pm filtration capability, may be inserted into a conduit, compressed to, for example, 50% of its volume, and "locked" in a compressed or partially compressed form. Compression further impedes the gas flow through the material.

[0018] In a favoured embodiment the system further comprises an indicator capable of indicating when the container needs replacing (i.e. it indicates that it is empty of fluid and! or no fluid is flowing).

[0019] Preferably the system further comprises a mechanism for timed release of the fluid. In a preferred embodiment a latching solenoid is provided to open and close fluid flow across the outlet. Use of a latching solenoid (incorporating permanent magnets) preserves battery life as energy is only required to move the latching cover between its open and closed positions.

[0020] Timed opening and closing may be controlled via, for example, a printed circuit board or equivalent means, a timer and a battery.

[0021] The system components may be incorporated into a trap or monitoring device to provide for efficient (slow release) delivery of an attractant, particularly, but not exclusively, carbon dioxide.

[0022] In accordance with a second aspect of the present invention there is provided an insect trap or monitor (100) comprising the slow fluid release system (10) of the invention.

[0023] In accordance with a third aspect of the present invention there is provided a method for slowing the release of a fluid from a pressurised container (12) which comprises impeding the fluid flow (26) from the container through the use of a porous element (18).

[0024] In accordance with a forth aspect of the present invention there is provided a method of forming a slow release porous plastics element comprising compressing sintered porous plastics having a filtration capability of below 2Opm by at least 10%.

[0025] Preferably the porous plastics element has a filtration capability of below 10pm.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which: Fig 1 is a cross sectional view of a regulator assembly according to a first aspect of the invention; Fig 2 is an exploded view of the regulator assembly of Fig 1; and Fig 3 is an exploded view of a bed bug trap or monitor incorporating the regulator assembly of the invention.

DETAILED DESCRIPTION

[0027] Fig 1 illustrates a slow fluid release system (10) comprising a container (12) (neck pad shown) in the form of a cartridge containing a pressurised fluid (14)! in this case liquid carbon dioxide, fitted with a gas impeder (18) in the form of a porous plastics element.

[0028] The cartridge is a 16g cartridge, with a length of 88mm and a diameter of 22mm.

An alternative cartridge is a 38g cartridge, with a length of 120mm and a diameter of 30mm. The liquid carbon dioxide is typically held at a pressure of 900PSIG.

[0029] In use the carbon dioxide is released from the cartridge by puncturing a cartridge seal (not shown) with a hollow puncture pin (16) which pierces the seal as it is screwed over the neck of the cartridge allowing gaseous carbon dioxide to escape under pressure through a conduit (20) in the puncture pin. To prevent the exemplary fluid, carbon dioxide gas, escaping at too fast a late it's release is slowed I impeded by the provision of the porous plastics element (18), which is fitted over (and! or within) the conduit (20) in or extending from the puncture pin (16) leading from the cartridge (12).

[0030] As can be seen more clearly from Fig 2 the system (10) comprises a housing (36) into which the various components fit. A rubber seal (38) sits over the puncture pin (16) such that, in use, a seal forms between the cartridge neck and the housing when the cartridge is punctured by screwing the mechanism into the cartridge.

[0031] In manufacturing the system, the porous plastics element (18) is dropped into the housing (36) and a spacer (40) is placed there-over and the two are held in place using a lock nut (42). The process of "locking" down the porous plastics element (18) may cause it to be compress (depending on the plastics), in some cases by about 30-70%, such that the rate of diffusion through the material is slowed further.

[0032] An indicator (22) is provided to identify when the container needs replacing (i.e. it indicates that it is empty of fluid and! or no fluid is flowing). In the embodiment illustrated a coloured indicator cap (44) is provided on an indicator sleeve (46) which sits over a pin (48) which is biased by a spring (50) and held in place by a washer (52) and 0 ring (54).

When gas flows through the system the indicator cap is visible.

[0033] To extend the effective period of use, the system further comprises a mechanism for timed release of the fluid. In a preferred embodiment (see Fig 3) a latching solenoid (24) is provided to open and close fluid flow (26) across the outlet (28). Use of a latching solenoid (incorporating permanent magnets) preserves battery life as energy is only required to move the latching cover between its open and closed positions. The latching solenoid is connected to the regulator system (10) via solenoid pin (56), seal (58) and lock nut (60).

[0034] Timed opening and closing may be controlled via, for example, a printed circuit board (30), or equivalent means, timer (32) and a battery (34).

[0035] The slow fluid release system (10) forms pad of an insect monitor or trap, more particularly a bed bug monitor or trap where the attractant, carbon dioxide is released in a phased manner to the trap or monitor.

[0036] One such monitor or trap (100) is illustrated in Fig 3 and comprises a base (102) which sits on the floor and has a perimeter (104) bed bug walk way leading to a pit (106) which, in the case of a trap, may include a glue board. Above the pit there is provided a cover (108) supported by pillars (110) which extend from the pit of the base. The timed release mechanism comprises a solenoid (24), printed circuit board (30), timer (32) and battery (34). These form a unit (80) further comprising the cartridge (12). regulator system (10) comprising the porous plastics impeder element (18), indicator (22). The components of the unit (80) are housed on a board (112) with a cover (114) and sit above the trap or monitor cover (108).

[0037] The monitor or trap cover (108) may comprise a plurality of apertures (116) allowing gas to be distributed substantially evenly to the pit of the monitor or trap.

Claims

CLAIMS1. A slow fluid release system (10) for a container (12) containing a pressurised fluid (14) comprising a release (16) characterised in that it further comprises a flow impeder mechanism, in the form of a porous (18) element.
2. A slow fluid release system (10) as claimed in claim 1 wherein the porous element is a plastics, ceramic or metal element.
3. A slow fluid release system (10) as claimed in claim 1 or 2 wherein the release is a hollow puncture pin.
4. A slow fluid release system as claimed in any of the preceding claims wherein the porous element impedes the fluid flow, to a flow rate of below 1 OmI/min.
5. A slow fluid release system as claimed in any of the preceding claims wherein the porous element is positioned directly or indirectly over and! or within a conduit (20) running through the release.
6. A slow fluid release system as claimed in any of the preceding claims which is a porous plastics element.A slow fluid release system as claimed in claim 6 wherein the porous plastics is a porous polytetrafluoroethylene.
7. A slow fluid release system as claimed in any of the preceding claims further comprises an indicator (22) capable of indicating when the container needs replacing (i.e. that it is empty of fluid) and! or no fluid is flowing.
8. A slow fluid release system as claimed in any of the preceding claims further comprising a mechanism (24, 30, 32, 34) for controlling timed release of the fluid.
9. A slow fluid release system as claimed in claim 8 comprising a latching solenoid (24) to open and close fluid flow (26) across an outlet (28).
10. A slow fluid release system as claimed in claim 9 wherein the latching solenoid incorporates permanent magnets.
11. A slow fluid release system as claimed in any of the preceding claims wherein the pressurised fluid is carbon dioxide.
12. An insect trap or monitor comprising the slow fluid release system (10) of any of claims 1 toll.
13. An insect trap or monitor as claimed in claim 12 comprising a timed release mechanism incorporating a solenoid (24), printed circuit board (30), timer (32) and battery (34) together with a cartridge (12), indicator (22) and porous plastics element (18)
14. An insect trap or monitor as claimed in claim 12 or 13 further comprising a pit (106).
15. A method for slowing the release of a fluid from a pressurised container (12) which comprises impeding the fluid flow (26) from the container through the use of a porous plastics element (18).
16. A method of forming a slow release porous plastics element comprising compressing sintered porous plastics having a filtration capability of below 2Opm by at least 10%.
17. A method as claimed in claim 16 wherein the sintered porous plastics is a polytetrafluoroethylene.