Pest control system

Abstract

A method of pest control which includes heating the affected area to a temperature which is lethal for the pests being exterminated, and maintaining this elevated temperature in the zone for a predetermined period of time. The treatment is undertaken after determining the air flow parameters for the treatment zone, so as to be able to determine the CFM requirements for achieving a requisite air flow rate of between 0.5 and 70 air changes per hour in the treatment zone. Heated air is introduced to the treatment zone at the requisite air flow rate and at an initial temperature of at least about 240° F., with the temperature in the treatment zone being elevated at a predetermined rate until the air temperature reaches a predetermined set point. Once the predetermined set point temperature is reached within the treatment zone, the introduced heated air is adjusted to an eradication temperature and maintained in such a condition for a predetermined period of time sufficient to eradicate respective pests within the treatment zone.

Description

FIELD OF THE INVENTION

The present invention relates generally to a method for exterminating pests by thermal treatment of enclosed pest-occupying zones, wherein the zone is treated with heated air under controlled conditions for a period of time sufficient to achieve extermination of the pests. The term “pests” is intended to refer generally to creatures such as insects, mammals, reptiles, and the like, but may also include some other undesirable but non-toxic forms of matter such as certain types of bacteria, molds, and viruses.

BACKGROUND OF THE INVENTION

In the past, various techniques have been employed to exterminate pests, including the introduction of toxic or lethal gases, such as those used in typical fumigation techniques including methyl bromide, phosphine, or the like. These techniques involve certain risks to personnel, as well as to the environment, and hence are not readily undertaken without necessary precautions. Some are environmentally unfriendly. On the other hand, the present invention involves a technique for treating the zone or area thermally, with this technique being effective while creating little if any danger to the ambient atmosphere or the environment. Delays resulting from extended periods of venting are also avoided.

The technique of the present invention is adaptable for use in a wide variety of structures and enclosures. This includes zones which are situated within older structures, as well as more modern structures. The magnitude of the volume requiring treatment poses few problems or limitations, while it is appropriate that the heat generating equipment be properly sized. Also, the process may be undertaken utilizing conventional fuels including natural gas, propane, steam, electricity, or combinations thereof.

It has been discovered that the extermination and sterilization process of the present invention is useful in many different applications. Each of such applications require a unique set of operating parameters for effectively treating the target pests. As such, it is desirable to adjust relevant operating conditions to provide an effective yet energy efficient eradication system.

Certain applications, such as food sterilization processes, have been found to respond to thermal eradication parameters substantially different than that proposed in previously developed systems. As such, it is a primary object of the present invention to provide a thermal pest control system that is particularly adapted to treat pests in a variety of applications with a high degree of efficiency.

SUMMARY OF THE INVENTION

In accordance with the present invention, a technique is provided wherein heat is provided utilizing heated air, with the heated air being delivered or discharged to the treatment zone at a variable temperature and at a volume rate sufficient to achieve between about 0.5 and 70 air changes per hour. The variable discharge air temperature is preferably provided to most efficiently and quickly reach and maintain a target eradication temperature within the treatment zone. As such, heated air is preferably initially discharged to the treatment zone at a temperature of about 240° F. at a desired volume rate. Once the desired eradication temperature, such as at least about 120° F., is reached, the discharge temperature from the heating unit is lowered to a desired temperature set point for a predetermined period of time necessary to achieve a 100% treatment effectiveness.

Additionally, the treatment zone temperature is ramped-up from the normal temperature at a desired rate to reach a temperature sufficiently high to be lethal to the relevant pests. The ramp-up temperature rate may be set at, for example, about 10° F. per hour, with this ramp-up rate being sufficient to trap pests, particularly mammals or reptiles before they are able to escape the zone. Higher or lower temperature ramp-up rates, however, may be employed, as desired per application. The ramp-up temperature rate must also be maintained below a predetermined upper threshold in order to avoid structural damage due to induced thermal stresses within the treatment zone.

The term “lethal temperature” is intended to refer to a temperature which is sufficient to provide a kill for the pest. In this connection, a temperature of about 120° F.-130° F. is generally adequate, however some pests may require a slightly higher temperature to be effective.

While other heating equipment may be employed, direct-fired heaters are preferable. Additionally, for the process and technique to be effective, the temperature of air discharged into the treatment zone should be variable, as described above.

A ramp-up rate of up to about 10° F. per hour is most desirable, though higher temperature ramp-up rates are contemplated by the present invention as being useful in certain applications. Typically, an upper limit to temperature ramp-up rates is desired in order to preserve structural integrity of the building or enclosure. Rates substantially in excess of about 10° F. per hour may result in adverse effects to the structure and its overall integrity. By controlling the ramp-up rate within a safe range, therefore, it is possible to both trap and kill the pests in hard-to-reach places, as well as reducing the impact of adverse affects due to induced thermal stresses.

In addition to a complete kill of existing pests, the elevated temperatures provided in the treatment zone by the system of the present invention may be effective for the destruction of any eggs, larvae, pupae that may be present. Test cages may be employed to determine effectiveness of the overall thermal treatment.

The use of heated air with a certain portion originating from outside the treatment zone provides an added advantage in the extermination technique. It has been found that certain pests may be able to withstand elevated temperatures when the relative humidity within the treatment zone is relatively high. The utilization of at least some outside air is effective in holding the relative humidity of the treatment zone down to a point where the pests are not given this added measure of protection. The use of some heated outside air is also advantageous in that water vapor present within the treatment zone is being continuously driven from the zone, without being retained and/or accumulated as would be the case in a system employing full recirculation.

However, it has been found that certain applications of the pest control system of the present invention respond more desirably through the use of at least partially re-circulated air. The use of re-circulated air typically results in higher moisture content within the treatment zone, which is preferable, for example, in wood packaging heat treatment systems. In addition, the use of re-circulated air within the treatment zone accelerates the temperature ramp-up rate, and minimizes the power needed to heat the discharge air. As such, the use of re-circulated air from within the treatment zone both adds effectiveness of certain applications to the system, and enhances efficiency of the system.

Therefore, it is a primary object of the present invention to provide an improved technique for extermination of pests through thermal treatment, with the treatment utilizing predetermined mixtures of outside and/or re-circulated air heated at a variable discharge temperature for maximum effectiveness and efficiency.

It is a further object of the present invention to provide an improved technique for the extermination of pests including insects, mammals such as rats, mice and the like, as well as reptiles, wherein the technique is undertaken thermally so as to avoid use of toxic gases which may pose environmental as well as personnel hazards.

It is a still further object of the present invention to provide an improved technique for the reduction and/or elimination of some non-toxic forms of micro-organisms, including particular varieties of bacteria, molds, and viruses, wherein the technique is undertaken thermally.

It is yet a further object of the present invention to provide an effective time-expedient technique for pest extermination utilizing thermal treatment for undertaking and completing the extermination operation.

Other and further objects of the present invention will become apparent to those skilled in the art upon a study of the following specification, appended claims, and accompanying drawings.

IN THE DRAWINGS

FIG. 1 is a flow chart representing the major preliminary steps involved in defining the requirements for equipment to be utilized in the contemplated treatment process; and

FIG. 2 is a block diagram illustrating the steps to be undertaken in the pest extermination operation of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the preferred embodiment of the present invention, the thermal treatment of a zone for extermination of pests is undertaken as follows. It is believed that the recitation of steps set forth below will enable those of skill in the art to readily and effectively practice the technique.

Treatment Zone Defined

The dimensions, type of structure, as well as area of structure for heat treatment is analyzed and determined. This determination enables the technician to establish some basic guidelines for the equipment necessary to effectively handle the procedure. Accordingly, the nature of the heat source and fuel supply is determined, along with the equipment installation factors.

The step of defining treatment zone air flow is then undertaken with respect to heat movement, air distribution, placement of the equipment being utilized, and desired locations for heated air inlet and discharge. This step may generally be characterized as the determination of air flow parameters for the treatment zone.

Availability and adequacy of power and fuel supply for the heating system being employed is then determined. The requirements of the fuel supply are established by the energy available at the treatment site such as natural gas, propane, steam, electricity, or combinations thereof.

As a preliminary step, the treatment zone is analyzed and used to determine the BTU requirements. Through this step, the specific heat loss calculations may be made in order to more specifically determine the quantity and size of equipment necessary, including heaters, fans, ductwork, and the like. Placement of equipment may then be readily determined.

With the equipment in place, means are provided to provide heated air to be discharged within the treatment zone at a variable temperature during the treating process.

As described above, the temperature discharge rate from the heating apparatus is preferably variable within a pre-defined program. For example, air is preferably discharged from the heating apparatus at a temperature of about 240° F., with such air discharge temperature being maintained for a predetermined period of time necessary to reach a target eradication temperature. In many embodiments, such an eradication temperature is between about 120 and 130° F., but certain applications may require higher eradication temperatures.

In one embodiment of the invention, the discharge temperature of the air is dropped from about 240° F. to the target eradication temperature so as to maintain such eradication temperature within the treatment zone for a predetermined period of treatment time. Such an air discharge temperature drop may be performed through a single step-function, or may instead be performed through other means of temperature change. Examples of alternative temperature change mechanisms include multiple step-functions, integration techniques, and the like.

In some embodiments of the present invention, the air discharge temperature profile may be automatically controlled through the use of programmed software means operably coupled to controller means for controlling the energy input of the heater apparatus. In such a manner, a temperature profile may be pre-programmed into the software means to thereby automatically control the output of the air heater.

In a preferred example air discharge temperature profile, the initial air discharge temperature of about 240° F. is switched in a single step-function operation to a temperature consistent with a targeted eradication temperature, such as 130° F. In other embodiments, however, the air discharge temperature may be changed from an initial temperature of about 240° F. prior to reaching the steady-state eradication temperature within the treatment zone, such that the temperature within the treatment zone gradually stabilizes at a set point temperature, rather than initially overshooting the target eradication temperature and gradually decreasing to the target eradication temperature. A wide variety of other temperature profiles may be utilized by the variable air discharge temperature aspect of the present invention.

A particular advantage introduced by the variable air discharge temperature is in enhancing the efficiency of the system. In particular, significant energy is required to heat air to the temperatures required to eradicate pests. As a result, significant cost and energy savings are reaped by minimizing the air discharge temperature where possible. In this case, it has been found that a target eradication temperature need only be maintained for the predetermined period of time to accomplish a 100% pest treatment. Accordingly, temperatures within the treatment zone need not exceed the target eradication temperature for any extended period of time. The variable air discharge temperature profile of the present invention, therefore, significantly enhances efficiency without compromising pest eradication effectiveness.

It has further been found that the heated air flow rate through the treatment zone may be set according to the particular application being treated. For example, off-gassing treatment typically requires an operating temperature of 260° F., and an air exchange rate of 50-70 per hour. On the other hand, drying and mold remediation have been found to be most effective at a significantly lower air exchange rate of between about 0.5 and 3air changes per hour. In the above examples, the term “air exchange” refers to a volume of air output from the heater system, with one air exchange being equal to the volume of air within the treatment zone.

The adjustment of heated air output volume is preferably set at a minimum rate that enables a 100% eradication effectiveness. As a result, efficiency of the system of the present invention is further enhanced, due to the fact that excess heated air is not driven through the treatment zone and is, consequently, not needed to be manufactured.

A further aspect of the present invention is in the tailored modification of proportion of outside air to re-circulated air as input to the air heater apparatus. As described above, certain applications are tolerant to, and/or require elevated moisture environments during the thermal treatment process. As a result, certain embodiments of the invention preferably utilize at least some re-circulated air from within the treatment zone as input feed to the air heater discharge apparatus. Since re-circulated air typically maintains a relatively higher moisture content, the use of re-circulated air can contribute to maintaining an elevated moisture content within the treatment zone.

Moreover, the user of recycled air from within the treatment zone minimizes the amount of energy required to heat outside air to a desired air discharge temperature. The use of at least some re-circulated air, therefore, has the effect of either accelerating temperature ramp-up rate within the treatment zone, or minimizing the amount of energy input by the air heater apparatus into the feed air to reach a desired output temperature. In some embodiments, up to about 50% of the air supply to the heater apparatus is from within the treatment zone as re-circulated air. The remainder of the supply air preferably is sourced from outside the treatment zone.

Heat is provided to the air until a temperature of at least about 240° F. is reached and it is then discharged at a volume rate sufficient to ramp-up the temperature within the zone at a predetermined rate. In some embodiments, such a ramp-up rate is about 5-10° F. per hour. The volume rate is selected to be sufficient to provide for between about 0.5 and 70 air changes per hour within the treatment zone. This discharge and ramp-up rate is continued until an air temperature at least equal to the lethal temperature for the pests is achieved throughout the treatment zone. Generally, a temperature of about 120° F.-130° F. is satisfactory and constitutes an appropriate lethal temperature. The requisite temperature and air flow rate is maintained to continue providing lethal temperatures for a predetermined period of time. For some more resistant insects, such as lesser grain borers, as may be found in and around grain storage elevators and the like, the elevated temperature and air change cycles are preferably maintained for periods ranging from between about eleven hours and 24 hours. Upon reaching the desired treatment time, the heat is turned-off, and with outside air, the flow is continued for a gradual cool-down.

In order to provide a further means of determining that a sufficient lethal or elevated temperature is reached, and that the lethal temperature has been achieved for a sufficient period of time, test cages may be set in place throughout the treatment zone and monitoring of these test cages will normally be adequate to indicate the total effectiveness of the kill.

Through such a method, pests such as insects, mammals, reptiles, and the like may be effectively exterminated from within the treatment zone. Furthermore, some non-toxic varieties of household bacteria, molds, and viruses that are vulnerable to temperatures contemplated in processes pursuant to the present invention may also be reduced and/or eliminated via such a thermal treatment method. Additionally, such a method may also be effective in accelerating respective outgassing rates of some substances located within the treatment zone.

It will be appreciated, of course, that various modifications may be made in the steps undertaken and defined hereinabove, without actually departing from the spirit and scope of the invention.

Claims

1. Pest extermination by thermal treatment of enclosed pest-occupying treatment zones comprising the steps of:

(a) determining air flow parameters for the treatment zone;

(b) determining CFM requirements for achieving a requisite air flow rate of between 0.5 and 70 air changes per hour in the treatment zone;

(c) introducing heated air to said treatment zone at said requisite air flow rate and at an initial temperature of at least about 240° F.;

(d) elevating temperature in said treatment zone at a predetermined ramp rate until air temperature in the treatment zone reaches a predetermined set point;

(e) adjusting temperature of the introduced heated air to an eradication temperature; and

(f) maintaining said requisite air flow rate at said eradication temperature for a predetermined period of time sufficient to eradicate respective pests within the treatment zone.

2. The pest extermination by thermal treatment of enclosed pest-occupying treatment zones of claim 1 wherein said eradication temperature is at least 120° F.

3. The pest extermination by thermal treatment of enclosed pest-occupying treatment zones of claim 1 wherein the temperature adjustment of the introduced heated air is performed in a single step-function.

4. The pest extermination by thermal treatment of enclosed pest-occupying treatment zones of claim 1 wherein the introduced heated air is between about 50 and 100% outside air.

5. The pest extermination by thermal treatment of enclosed pest-occupying treatment zones of claim 1 wherein said predetermined set point is equal to said eradication temperature.

6. The pest extermination by thermal treatment of enclosed pest-occupying treatment zones of claim 1 wherein said predetermined set point is less than said eradication temperature.

7. The pest extermination by thermal treatment of enclosed pest-occupying treatment zones of claim 1 wherein said predetermined period of time is at least about 11 hours.

8. The pest extermination by thermal treatment of enclosed pest-occupying treatment zones of claim 1 wherein said predetermined ramp-up rate is up to about 10° F. per hour.