Abstract:
A substance detection device including a chemical substance analyzer, including, a conduit, and a membrane, wherein the membrane extends across a cross-section of the conduit, wherein the membrane is positioned to have one side and an analysis side opposite the one side, wherein the substance detection device is adapted to direct a portion of a chemical substance to the one side through the conduit, the substance detection device further including a particle separation apparatus, including a particle collection device having a collection chamber containing a first fluid and including an outlet, wherein the outlet is in fluid communication with the conduit such that particles directed through the outlet travel through the conduit and chemical substances which may be on those particles directed through the outlet are transferred to the membrane by interacting with the one side of the membrane.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     UK (GB) Priority Patent Application 0724128.4, a United Kingdom patent application filed under the “Applicant(s)/contact point” name of SMITHS DETECTION-WATFORD LIMITED” on Dec. 11, 2007, disclosing apparatus and methods of clearing a blockage, including the specification, drawings, claims and abstract, is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Detectors are sometimes used in the field of analytical instruments for detecting chemical substances, including explosive substances and/or nuclear, biological and chemical warfare (NBC) agents. 
     Apparatuses for and methods of performing an analysis of a chemical substance, including an analysis utilizing ion mobility spectrometry (IMS), are known. Often, these apparatus/methods including parameters which enhance an amount of the chemical substance available for analysis, thus improving the macroscopic sensitivity of the analysis. An increased concentration of substance available for analysis, which can be deposited on a membrane of an ion mobility spectrometer (IMS) system, in turn, increases the macroscopic sensitivity of the analysis by allowing additional sample chemical to pass through the membrane of an IMS system for analysis, due to the additional amounts of sample transferred to the membrane. 
     Apparatuses for and methods of performing an analysis of a chemical substance often utilize particle separators to separate particles from a gas (such as air). Particles often are collected for analysis using inertial separators, such as cyclones. See, e.g., U.S. Pat. No. 6,508,864. Generally, inertial separators operate by using a combination of forces, such as centrifugal, gravitational, and inertial, to separate particles from the gas in which they are contained. For cyclones, particles generally are separated using centripetal force. Specifically, cyclonic motion causes the particles to separate from the gas and impact a wall of the cyclone that can be wetted with a liquid, such as a suspension buffer. The particles are then removed from the cyclone in a fluid-particle mixture. The particles can exit through an outlet in the chamber and into a conduit extending from the outlet. 
     Because inertial separators use relatively small volumes of fluid and small diameter fluid conduits (e.g. tubing or other sample collection means), inertial separators, including cyclones, can be prone to blockages. The blockages can be caused by large particles lodged in a conduit or smaller particles aggregating to cause a blockage in a conduit. 
     Blockages can be removed or prevented by several means. For example, some inertial separators use filters to prevent particles from entering the fluid conduits. Filters capture the particles that are of interest, however, so they cannot simply be excluded, because such exclusion could interfere with the function of the inertial separator. Syringes also can be used to manually remove blockages. For example, an operator uses a syringe to manually inject an amount of fluid into the conduit closest to the chamber of the inertial separator. The fluid dislodges any particles blocking the outlet of the conduit. The dislodged particles can be flushed back out through the sample conduit and dispersed in a larger volume of fluid retained in the inertial separator. Eventually, the particles exit the inertial separator through the outlet and into an analysis device. These methods of preventing and clearing blockages suffer from several limitations. Specifically, filters can hinder the efficient collection of particles. Syringes require an operator to attend to the device and remove blockages when they occur. This is problematic, because inertial separators are often left running unattended for prolonged periods. Thus, blockages go undetected and unresolved because manual injection systems require an operator to detect a blockage and to initiate a blockage clearance procedure. 
     SUMMARY 
     Accordingly, there is a need for improved blockage removal devices that can be used, for example, in the field of analytical instruments, including, but not limited to trace detection of chemical, narcotic, explosive, and biological detection. According to a first embodiment of the present invention, there is a substance detection device, comprising, a chemical substance analyzer, including, an ion mobility spectrometer, a desorber, a conduit, and a membrane, wherein the membrane extends across a cross-section of the conduit, wherein the membrane is positioned to have a desorber side in gas communication with the desorber and an analysis side opposite the desorber side, wherein the substance detection device is adapted to direct portion of a chemical substance to the desorber through the conduit so that at least a portion of the entrained chemical substance is transferred to the membrane by interacting with the desorber side of the membrane, wherein the membrane is adapted to diffuse at least a portion of the chemical substance transferred to the membrane through the membrane to the analysis side, and a particle separation apparatus, including a particle collection device having a collection chamber containing a first fluid and including an outlet, wherein the first fluid is a sample fluid containing particles collected by the particle collection device, a first fluid distribution system adapted to direct the first fluid from the particle collection device through the outlet to flow along a first flow path in a first flow direction, a detector adapted to detect a change in a flow rate of the first fluid directed in the first flow direction indicative of a blockage at the first flow path, wherein the apparatus is adapted to automatically direct an unblocking fluid to flow along the first flow path in a second flow direction opposite the first flow direction upon the detection of the change in the flow rate indicative of a blockage at the first flow path to remove the blockage at the first flow path, the chemical interacting with the one side of the membrane, wherein the outlet is in fluid communication with the conduit so that particles directed through the outlet travel through the conduit and substances which may be on those particles directed through the outlet are transferred to the membrane by interacting with the desorber side of the membrane. According to one embodiment, there is provided an apparatus including a flow path for a fluid, a device for detecting a blockage associated with the flow path, a pump arranged to supply fluid such that the fluid flows along a first path in a first direction, and a device for redirecting flow from the pump in response to detection of a blockage so that it flows along the first path in an opposite direction to clear the blockage in the first path. According to another embodiment, there is provided a particle collection system including a particle collection device having an inlet for airborne particles, a fluid inlet, a device for supplying a fluid to the fluid inlet and an outlet for a solution of fluid and particles, a conduit extending from the outlet along which the solution of fluid and particles flows from the outlet in a first direction, a device for extracting the solution of the fluid and particles from the outlet, a device for detecting a blockage to the flow from the outlet, wherein the system is arranged such that detection of a blockage causes a flow of fluid along the conduit in an opposite direction to the outlet to push the blockage out of the outlet. 
     In some embodiments, the particle collection device preferably includes a cyclone. According to another embodiment, there is provided a cyclone system including a cyclone having an inlet for airborne particles, an inlet for a sample collection solution and outlet for a mixture of sample collection solution and particles, a first pump operable to supply sample collection solution to the sample collection solution inlet, a second pump operable to draw the mixture along a conduit for collection, the second pump being reversible on detection of a blockage to pump fluid back along the conduit to the cyclone inlet, and a switchable connection between the first pump and the conduit so that the first pump is operable on detection of a blockage also to supply sample collection solution to the conduit. Some embodiments may include a separate waste pipe extending from the cyclone to the second pump so that fluid pumped back into the cyclone via its outlet can be removed via the waste pipe. 
     According to another embodiment, there is a method of automatically removing blockages, including the steps of supplying a fluid to apparatus using a first pump, operating a second pump to draw fluid from the apparatus along a conduit in a first direction, detecting a blockage to flow of fluid along the conduit, reversing the second pump and causing the first pump to supply fluid directly to the conduit so that fluid is caused to flow in the opposite, second direction along the conduit and thereby remove the blockage to flow by the combined effect of the two pumps. 
     In one embodiment, there is provided an apparatus as disclosed above and/or below, comprising a particle collection device having a collection chamber containing a first fluid and including an outlet, a first fluid distribution system adapted to direct the first fluid from the particle collection device through the outlet to flow along a first flow path in a first flow direction, the first flow path including the outlet, a detector adapted to detect a change in a flow rate of the first fluid directed in the first flow direction indicative of a blockage at the first flow path, wherein the apparatus is adapted to automatically direct unblocking fluid to flow along the first flow path in a second flow direction opposite the first flow direction upon the detection of the change in the flow rate indicative of a blockage at the first flow path to remove the blockage at the first flow path. 
     In another embodiment, there is an apparatus as disclosed above and/or below, wherein the detector comprises a flow rate meter selected from the group consisting of a variable area flow rate meter, an electromagnetic flow rate meter, a coriolis flow rate meter, a caliometric flow rate meter, a pitot tube flow rate meter, a differential pressure flow rate meter, a thermal conductivity flow rate meter, a vortex shedding flow rate meter, an ultrasonic flow rate meter, a turbine flow rate meter, an optical flow rate meter, and a rotary gear flow rate meter. 
     In another embodiment, there is an apparatus as disclosed above and/or below, wherein the unblocking fluid comprises the first fluid which has passed through the particle collection device. In another embodiment, there is an apparatus as disclosed above and/or below, wherein the unblocking fluid comprises a sample collection solution that has not passed through the collection chamber of the particle collection device. 
     In another embodiment, there is an apparatus as disclosed above and/or below, wherein upon the detection of the change in the flow rate indicative of a blockage at the first flow path, the apparatus is adapted to reverse the direction of the first fluid flowing along the first flow path to flow along the first flow path in the second flow direction, the unblocking fluid comprising the first fluid flowing along the first flow path in the second flow direction. 
     In another embodiment, there is an apparatus as disclosed above and/or below, wherein upon the detection of the change in the flow rate indicative of a blockage at the first flow path, the apparatus is adapted to direct a second fluid to flow along the first flow path in the second flow direction, the unblocking fluid comprising the second fluid flowing along the first flow path in the second flow direction. 
     In another embodiment, there is an apparatus as disclosed above and/or below, including a particle collection device having a collection chamber containing a first fluid and including an outlet, wherein the first fluid is a sample fluid containing particles collected by the particle collection device, a first fluid distribution system adapted to direct the first fluid from the particle collection device through the outlet to flow along a first flow path in a first flow direction, a detector adapted to detect a change in a flow rate of the first fluid directed in the first flow direction indicative of a blockage at the first flow path, wherein the apparatus is adapted to automatically direct unblocking fluid to flow along the first flow path in a second flow direction opposite the first flow direction upon the detection of the change in the flow rate indicative of a blockage at the first flow path to remove the blockage at the first flow path. 
     In another embodiment, there is an apparatus as disclosed above and/or below, wherein the detector comprises a flow rate meter selected from the group consisting of a variable area flow rate meter, an electromagnetic flow rate meter, a coriolis flow rate meter, a caliometric flow rate meter, a pitot tube flow rate meter, a differential pressure flow rate meter, a thermal conductivity flow rate meter, a vortex shedding flow rate meter, an ultrasonic flow rate meter, a turbine flow rate meter, an optical flow rate meter, and a rotary gear flow rate meter. In another embodiment, there is an apparatus as disclosed above and/or below, wherein the unblocking fluid comprises the first fluid which has passed through the collection chamber. In another embodiment, there is an apparatus as disclosed above and/or below, wherein the unblocking fluid comprises a sample collection solution that has not passed through the collection chamber of the particle collection device. In another embodiment, there is an apparatus as disclosed above and/or below, wherein upon the detection of the change in the flow rate indicative of a blockage at the first flow path, the apparatus is adapted to reverse the direction of the first fluid flowing along the first flow path to flow along the first flow path in the second flow direction, the unblocking fluid comprising the first fluid flowing along the first flow path in the second flow direction. In another embodiment, there is an apparatus as disclosed above and/or below, wherein upon the detection of the change in the flow rate indicative of a blockage at the first flow path, the apparatus is adapted to direct a second fluid to flow along the first flow path in the second flow direction, the unblocking fluid comprising the second fluid flowing along the first flow path in the second flow direction. 
     In yet another embodiment, there is an apparatus as disclosed above and/or below, wherein upon the detection of the change in the flow rate indicative of a blockage at the first flow path, the apparatus is adapted to reverse the direction of the first fluid flowing along the first flow path to flow along the first flow path in the second flow direction, the unblocking fluid comprising (i) the first fluid flowing along the first flow path in the second flow direction, and (ii) the second fluid flowing along the first flow path in the second flow direction. In another embodiment, there is an apparatus as disclosed above and/or below, wherein the second fluid comprises a sample collection solution that has not passed through the collection chamber of the particle collection device. In another embodiment, there is an apparatus as disclosed above and/or below, wherein the apparatus includes a sample collection solution supply system adapted to supply sample collection solution to the collection chamber of the particle collection device in an absence of the detection of the change in the flow rate indicative of a blockage at the first flow path, wherein the apparatus is adapted to, upon the detection of the change in the flow rate indicative of a blockage at the first flow path, supply sample collection solution that has not passed through the collection chamber of the particle collection device as the second fluid and direct the second fluid to flow along the first flow path in the second flow direction. In another embodiment, there is an apparatus as disclosed above and/or below, wherein the first fluid distribution system includes a first pump adapted to pump the first fluid flowing along the first flow path in the first direction, the sample collection solution supply system includes a second pump adapted to pump the sample collection solution from a supply of the sample collection solution into the collection chamber of the particle collection device, the apparatus is adapted to reverse a direction of the first fluid flowing through the first pump to pump the first fluid along the first flow path in the second flow direction, the apparatus is adapted to maintain a direction of the sample collection solution flowing through the second pump while directing sample collection solution which has not passed through the collection chamber of the particle collection device to a location, with respect to a partial fluid circuit that includes the outlet and the first pump, between the outlet and the first pump, wherein the sample collection solution that has not passed through the collection chamber of the particle collection device, being the second fluid, combines with the first fluid to form the unblocking fluid and to flow along the first flow path in the second flow direction. In another embodiment, there is an apparatus as disclosed above and/or below, wherein the first fluid distribution system includes a sample pump adapted to operate at a first pump speed to pump the first fluid flowing along the first flow path in the first direction, the sample collection solution supply system includes a buffer supply pump adapted to operate at a variable pump speed to pump the sample collection solution into the particle collection device, the apparatus is adapted to reverse a direction of the first fluid flowing through the sample pump and increase the speed of the sample pump to a second pump speed, to pump the first fluid along the first flow path in the second flow direction, the absolute value of the second pump speed being greater that the absolute value of the first pump speed, the apparatus is adapted to maintain a direction of the sample collection solution flowing through the buffer supply pump while increasing the speed of the buffer supply pump over the variable pump speed while directing sample collection solution that has not passed through the collection chamber of the particle collection device to a location, with respect to a partial fluid circuit that includes the outlet and the first pump, between the outlet and the first pump, wherein the sample collection solution that has not passed through the collection chamber of the particle collection device, as the second fluid, combines with the first fluid to form the unblocking fluid and to flow along the first flow path in the second flow direction. 
     In another embodiment, there is an apparatus, wherein the apparatus is adapted to determine that the detector has detected a change in the flow rate of the first fluid directed in the first direction indicative of a blockage at the first flow path when at least one of (i) a flow rate of the first fluid flowing in the first flow path decreases by a predetermined regime, and (ii) no movement of the first fluid between two locations in the first flow path is detected. In another embodiment, there is an apparatus as disclosed above and/or below, wherein the apparatus includes a sample dispensing container including an overflow outlet, a supply of the sample collection solution, a waste container, a sample pump, and a sample collection solution supply pump adapted to pump sample collection solution from the supply of the sample collection solution, wherein the first fluid is a sample from the particle collection device which includes particles collected in the particle collection device, wherein the apparatus is adapted to direct, prior to detection of the change in the flow rate indicative of a blockage at the first flow path, the first fluid into the sample dispensing container, and wherein upon the detection of the change in the flow rate indicative of a blockage at the first flow path, the apparatus is adapted to: disconnect the supply of the sample collection solution to the collection chamber of the particle collection device and to connect the supply of the sample collection solution to the first flow path to allow sample collection solution to flow from the supply of the sample collection solution, while bypassing the collection chamber of the particle collection device, to the outlet of the particle collection device; increase a speed of the sample collection solution supply pump adapted to pump sample collection solution from the supply of the sample collection solution; reverse the direction of the sample pump and increasing the speed of the sample pump so that the speed of the sample pump has an absolute value that is greater than an absolute value of the sample pump speed just prior to the detection of the change in the flow rate indicative of a blockage at the first flow path; and pump, using the sample pump operating in the reversed direction and at the increased speed, waste solution from the waste container of the apparatus into the overflow outlet of the sample dispensing container such that sample stored in the sample dispensing container is forced out of the sample dispensing container and flows towards the outlet of the particle collection container so that the first fluid flowing along the first flow path flows along the first flow path in the second flow direction, wherein the first fluid and the second fluid combine to form the unblocking fluid flowing along the first flow path in the second flow direction. 
     In another embodiment, there is provided a method disclosed comprising, during a first temporal period, obtaining the apparatus of claim  9 , the apparatus further including a sample dispensing container including an overflow outlet, a supply of the sample collection solution, a waste container, a sample pump, and a sample collection solution supply pump adapted to pump sample collection solution from the supply of the sample collection solution, wherein the first fluid is a sample from the particle collection device which includes particles collected in the particle collection device; during the first temporal period, directing the first fluid into the sample dispensing container; during the first temporal period, detecting, using the detector, a change in a phenomenon indicative of a blockage at the first flow path; during the first temporal period, disconnecting a supply of the sample collection solution from the particle collection device and connecting the supply of the sample collection solution to the first flow path and directing the sample collection solution to flow from the supply of the sample collection solution while bypassing the collection chamber of the particle collection device to the outlet of the particle collection device; during a second temporal period after the first temporal period, increasing a speed of the sample collection solution supply pump to a speed greater than a speed of the sample collection solution supply pump during the first temporal period to pump sample collection solution from the supply of the sample collection solution; during the second temporal period, reversing the direction of the sample pump from a direction of the sample pump during the first temporal period and increasing the speed of the sample pump so that the speed of the sample pump has an absolute value that is greater than an absolute value of the sample pump speed during the first temporal period; during the second temporal period, pumping, using the sample pump operating at the reversed direction and increased speed, waste solution from the waste container of the apparatus into the overflow outlet of the sample dispensing container, such that sample stored in the sample dispensing container is forced out of the sample dispensing container and flows towards the outlet of the particle collection container so that the first fluid flowing along the first flow path flows along the first flow path in the second flow direction, wherein the first fluid and the second fluid combine to form the unblocking fluid flowing along the first flow path in the second flow direction. 
     In another embodiment, there is provided a method, wherein the particle collection device is a cyclone separator device, the method further comprising, during the second temporal period, utilizing the sample pump and the sample collection solution supply pump to push a blockage material at the first flow path causing a blockage at the first flow path into the particle collection device such that a volume comprising sample collection solution and blockage material collects in a cyclone chamber of the cyclone separator device. 
     In another embodiment, there is a method disclosed above and/or below, further comprising: during a third temporal period after the second temporal period, opening a waste outlet connected to the cyclone chamber; during the third temporal period, reversing the direction of the sample pump from the direction of the sample pump during the second temporal period and increasing the speed of the sample pump so that the speed of the sample pump has an absolute value that is greater than an absolute value of the sample pump speed during the second temporal period; and during the third temporal period, sucking the volume from the cyclone chamber through waste outlet to the waste container utilizing a suction generated by the sample pump operating at the reversed direction of the sample pump reversed the second time. 
     In another embodiment, there is a method disclosed above and/or below, further comprising: during the third temporal period, halting further sample collection solution flow from the supply of the sample collection solution bypassing the collection chamber of the particle collection device to the outlet of the particle collection device; and during the third temporal period, directing the sample collection solution to flow from the supply of the sample collection solution into the sample pump while bypassing the collection chamber of the particle collection device so as to clear material in a flow path extending from the first flow path to at least one of the sample pump, the waste container, and the sample dispensing container. 
     In another embodiment, there is a method disclosed above and/or below, further comprising: during a third temporal period after the second temporal period, reversing the direction of the sample pump from the direction of the sample pump during the second temporal period and increasing the speed of the sample pump so that the speed of the sample pump has an absolute value that is greater than an absolute value of the sample pump speed during the second temporal period; during the third temporal period, preventing flow through the first flow path in the first flow direction and the second flow direction; and during the third temporal period, directing the sample collection solution to flow from the supply of the sample collection solution into the sample pump while bypassing the collection chamber of the particle collection device while operating the sample collection solution supply pump at the increased speed so as to clear material in a flow path extending from the first flow path to at least one of the sample pump, the waste container, and the sample dispensing container. 
     In another embodiment, there is a method disclosed above and/or below, further comprising: during a fourth temporal period after the third temporal period, re-enabling flow through the first flow path in the first flow direction and the second flow direction; during the fourth temporal period, increasing the speed of the sample pump above the speed of the sample pump during the third temporal period; and during the fourth temporal period, halting the sample collection solution from flowing from the supply of the sample collection solution into the sample pump while bypassing the collection chamber of the particle collection device, and operating the sample collection solution supply pump at the increased speed so as to flush the volume from the cyclone chamber through the outlet to the waste container. 
     In another embodiment, there is an apparatus disclosed above and/or below, comprising a particle collection device containing a first fluid and including an outlet, a first fluid distribution system adapted to direct the first fluid from the particle collection device through the outlet to flow along a first flow path in a first flow direction, the first flow path including the outlet, a detector adapted to detect a change in a flow rate of the first fluid directed in the first flow direction indicative of a blockage at the first flow path, and an unblocking means for automatically unblocking a blockage at the first flow path. 
     In another embodiment, there is provided a method disclosed above and/or below, comprising: during a first temporal period, collecting particles utilizing a cyclone particle collector in a first fluid, the first fluid being located in a collection chamber of the cyclone particle collector including an outlet; during the first temporal period, directing the first fluid through the outlet to flow along a first flow path in a first flow direction, the first flow path including the outlet; during the first temporal period, automatically detecting a change in a flow rate of the first fluid directed in the first flow direction indicative of a blockage at the first flow path; during a second temporal period after the first temporal period, automatically direct unblocking fluid to flow along the first flow path in a second flow direction opposite the first flow direction upon the detection of the change in the flow rate indicative of a blockage at the first flow path to remove the blockage at the first flow path; and during a third temporal period after the second temporal period, automatically directing the first fluid through the outlet to flow along the first flow path in the first flow direction. 
     In another embodiment, there is an apparatus comprising a particle collection device containing a first fluid and including an outlet, a first pump adapted to pump the first fluid from the particle collection device through the outlet in a first direction along a first flow path in fluid communication with the outlet, a detector adapted to detect a change in a flow rate of the first fluid pumped in the first direction from the outlet indicative of a blockage at the first flow path, wherein the apparatus is adapted to change the direction along the first flow path of the first fluid upon the detection of the change in the flow rate indicative of a blockage at the first flow path. 
     In another embodiment, there is an apparatus including a blockage clearing apparatus, comprising a second pump for pumping a second fluid from an outlet; a detector for detecting a blockage in the outlet, and wherein upon detection of the blockage, the second pump reverses direction such that the second fluid moves along a first path in a second direction to push the blockage out of the outlet. 
     In another embodiment, there is an apparatus, wherein the detector comprises a flow rate meter selected from the group consisting of a variable area flow rate meter, an electromagnetic flow rate meter, a coriolis flow rate meter, a caliometric flow rate meter, a pitot tube flow rate meter, a differential pressure flow rate meter, a thermal conductivity flow rate meter, a vortex shedding flow rate meter, an ultrasonic flow rate meter, a turbine flow rate meter, an optical flow rate meter, and a rotary gear flow rate meter. 
     In another embodiment, there is an apparatus wherein the flow rate meter of the detector comprises at least a first sensor and a second sensor. In another embodiment, there is an apparatus wherein the second fluid comprises a sample particle and a first fluid. In another embodiment as disclosed above and/or below, there is an apparatus wherein the second direction is a direction opposite that of a first direction. 
     In another embodiment as disclosed above and/or below, there is an apparatus wherein the first sensor and the second sensor comprise a bubble sensor, the first sensor and the second sensor are configured to determine a flow rate, and the flow rate is a function of the time it takes a bubble to move from the first sensor to the second sensor. 
     In another embodiment, there is an apparatus wherein the blockage exists if the flow rate decreases to a value at or below a predetermined value. 
     In another embodiment, there is an apparatus wherein the blockage exists if there is no measurable flow rate for at least 10 seconds. 
     According to another embodiment, there is an apparatus, wherein the apparatus is a particle collection system comprising a particle collection device, wherein the particle collection device comprises a particle inlet for receiving particles, a fluid inlet for receiving a fluid, and an outlet for receiving a second fluid; a first pump for pumping the fluid to the fluid inlet such that the fluid moves along a first path in a first direction, a first conduit for receiving the second fluid from an outlet; a second pump for pumping the second fluid from the outlet; and a detector for detecting a blockage at the outlet; wherein upon detection of the blockage, the second pump reverses direction and the first pump supplies fluid to the first conduit such that the second fluid moves along the first path in a second direction to push the blockage out of the outlet. 
     In another embodiment, there is an apparatus, wherein the second fluid comprises a sample particle and the fluid. In another embodiment, there is an apparatus wherein the speed of the first pump increases when the detector detects the blockage, the speed of the second pump increases when the detector detects the blockage, or the speed of both the first and second pumps increase when the detector detects the blockage. In another embodiment, there is an apparatus as disclosed above and/or below wherein the sample particle collection device comprises a cyclone. 
     In another embodiment, there is an apparatus as disclosed above and/or below wherein the first pump operates the fluid to the fluid inlet of a first valve. In another embodiment, there is an apparatus as disclosed above and/or below, wherein the first valve connects to a second conduit, wherein the second conduit connects to a needle, and wherein the needle projects into the particle inlet. 
     In another embodiment, there is an apparatus as disclosed above and/or below, wherein the cyclone comprises a and wherein the cyclone connects to an impeller or a blower. 
     In another embodiment, there is an apparatus wherein the chamber comprises a first portion and a second portion and wherein the first portion is closed. 
     In another embodiment, there is an apparatus further comprising a sixth conduit, wherein the fluid pumped into the cyclone through the outlet travels through the sixth conduit. 
     In another embodiment, there is an apparatus wherein the fluid travelling through the sixth conduit enters the waste conduit, and wherein the waste conduit extends to a second container. 
     In another embodiment, there is an apparatus wherein a volume enters the particle detection device when the blockage enters the particle collection device. In another embodiment, there is an apparatus wherein the second pump reverses direction so that the volume in the particle collection device is forced into the second container. 
     According to another embodiment, there is a method as disclosed above and/or below, wherein the method removes blockages, comprising supplying a fluid to a blockage clearing apparatus using a first pump; operating a second pump to draw the fluid from the blockage clearing apparatus along a conduit in a first direction; and reversing the second pump and causing the first pump to supply the fluid directly to the conduit, wherein the fluid moves in a second direction such that removal of the blockage occurs 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the embodiments as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate different embodiments and, together with the description, serve to describe exemplary embodiments. 
         FIG. 1  is a schematic of the particle collection system before a blockage occurs. 
         FIG. 2  is a schematic of the particle collection system at a preliminary stage of blockage clearance. 
         FIG. 3  is a schematic of the particle collection system at a later stage of blockage clearance. 
         FIG. 4  is a schematic of another embodiment of a particle collection system at a preliminary stage of blockage clearance. 
         FIG. 5  is a schematic of the another embodiment of the particle collection system at a intermediate stage of blockage clearance. 
         FIG. 6  is a schematic of the another embodiment of the particle collection system at a later stage of blockage clearance. 
         FIG. 7  is a schematic of another embodiment of the particle collection system. 
         FIG. 8  is a schematic of another embodiment of the particle collection system. 
     
    
    
     DETAILED DESCRIPTION 
     Unless otherwise specified, “a” can refer to one or more. For example, “a outlet” can refer to “one or more outlets” unless otherwise specified. 
     Unless otherwise specified, the description of one or more components does not preclude additional components. For example, the description of an apparatus including A, B, and C includes an apparatus including A, B, C, and D. 
     Unless otherwise specified, “and” and “or” are used interchangeably. For example, a device having “A or B” can have both “A” and “B,” and a device having “A and B” can have only “A” or “B.” 
     As used herein, “particle collection device” refers to any device used to collect sample particles. Inertial separators are one type of particle collection device. Settling chambers, baffle chambers, and centrifugal collectors (also known as cyclones) are examples of some inertial separators. Cyclones can be single-cyclone separators or multiple-cyclone separators. 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. An effort has been made to use the same reference numbers throughout the drawings to refer to the same or like parts. 
     According to a first embodiment, examples of which are shown in  FIGS. 1 ,  2 , and  3 , a particle collection system  70  comprises a particle collection device  1 , a first pump  12 , a first conduit  23 , a second pump  14 , and a detector  41 . 
     As shown in  FIG. 1 , the particle collection device  1  can include a fluid inlet  75 , a particle inlet  10 , and an outlet  14 . The particle inlet  10  receives particles. The particle collection device  1  can be any particle collection device, such as a cyclone. The cyclone can be connected to a blower or impeller at the particle inlet  10  or at a first outlet  17  so that air is drawn into the cyclone. 
     The fluid that enters the fluid inlet  75  can be pumped by the first pump  12  to the fluid inlet  75 . Alternatively, the fluid can enter the fluid inlet  75  without the aid of the first pump  12 . The first pump  12  can pump fluid in a first direction or a second direction. When no blockage is detected, the first pump  12  operates in the first direction along a first path. The first pump  12  can operate at any suitable speed. For example, the first pump can operate at any speed above 0 rpm. In one embodiment the pump can operate at a speed from 20-200 rpm. In another embodiment, the pump can operate at a speed below 70 rpm. The second direction is opposite the first direction. The first pump  12  can be any pump, such as, for example and without limitation, a rotary, bellows, peristaltic, centrifugal, diaphragm, impeller gear. In one embodiment, the pump can be a rotary pump such that the first direction corresponds to clockwise movement, and the second direction corresponds to counterclockwise movement, for example. 
     The first pump  12  can connect to a first two-way valve  18 . A first port  72  of the first two-way valve  18  can connect to a first conduit  19 , and a second port  73  of the first two-way valve  18  can connect to a second conduit  40 . The first port  72  of the first two-way valve  18  can be open, and the second port  73  of the first two-way valve  18  can be closed. 
     The first conduit  19  can be any suitable shape, including cylindrical. The first conduit  19  can connect to a needle  20  and a third container  11 . The needle  20  can project into the particle inlet  10  so that the contents of the needle  20  enter the collection chamber (“chamber”)  16  with the particles or any airborne particles. The third container  11  contains a fluid, such as a sample collection solution. Thus, the needle  20  can be used to provide a fluid, such as a sample collection solution, from the third container  11  to the chamber  16 . 
     The chamber  16  can contain a particle inlet  10 . The particle inlet  10  can be oriented in a direction tangential to the chamber  16  so that air is given a swirling motion about the axis of the chamber  16 . In some embodiments, the chamber  16  is oriented horizontally. Other orientations, however, of the chamber  16  are possible. For example, the chamber  16  can be oriented vertically or at an angle to the particle inlet  10 . The chamber  16  can be any suitable shape, including cylindrical. 
     The chamber  16  can have a first portion  21  and a second portion  76 . In some embodiments, the first portion  21  is closed. The first portion  21  can have a formation  22  that projects from the closed end of the first portion  21  and into the inside of the chamber  16 . The top of the formation  22  can include an outlet  13 . A wide range of diameters are possible for the outlet  13 . For example, the diameter can be less than about 0.2 mm, less than about 0.4 mm, less than about 0.6 mm, less than about 0.8 mm, less than about 1 mm, or less than about 5 mm. In an embodiment, the diameter of the outlet  13  can be about 0.8 mm. The formation  22  can be any suitable shape. For example, the formation  22  can be conical or cylindrical. 
     The outlet  13  can connect to a third conduit  23 . The third conduit  23  can be any suitable shape, such as cylindrical. A wide range of diameters are possible for the outlet  13 . For example, the diameter can be less than about 0.2 mm, less than about 0.5 mm, or less than about 1 mm. The third conduit  23  can connect to a second two-way valve  24 . The second two-way valve  24  can connect to a fourth conduit  25 . The fourth conduit  25  can be cylindrical. The fourth conduit  25  can connect to a second pump  14 . 
     A detector  41  for detecting blockages can be located along the fourth conduit  25 . Other locations for the detector  41  are also possible. For example, the detector  41  can be located along any of the other conduits described in this application. The location of the detector  41  is not important, so long as the detector  41  is able to detect blockages. The detector  41  can detect blockages in any way. For example, blockages can be detected based on a change in the rate of fluid flow, a change in pressure, or an optical change. 
     The second pump  14  can pump a second fluid from the outlet  13  along the fourth conduit  25 . When there is no blockage, the second pump  14  can pump in a direction opposite the direction that the first pump  12  operates. In some embodiments, the second pump  14  pumps in the second direction. The second pump  14  can operate at any suitable speed, such as, for example, above 0 rpm. In one embodiment the pump can operate below 200 rpm, In another embodiment the pump can operate at or below 25 rpm. Generally, the second fluid comprises particles and fluid, such as one or more buffers. 
     The second pump  14  can connect to a third two-way valve  30 . The third two-way valve  30  can have a first port  77  and a second port  78 . The first port  77  of the third two-way valve  30  can connect to a waste conduit  37 . The second port  78  of the third two-way valve  30  can connect to a first container  32  (sample dispensing container). The first port  77  of the third two-way valve  30  can be closed, and the second port  78  of the third two-way valve  30  can be open. 
     The waste conduit  37  can connect to the second pump  14  and a second container  38 . The second pump  14  can pump any waste fluid through the waste conduit  37  to the second container  38 . The waste conduit  37  can be any suitable shape, including cylindrical. 
     The first container  32  can have a container inlet  31 , a container outlet  33 , and an overflow outlet  34 . The container inlet  31  and the container outlet  33  can be located anywhere along the container  32 . For example, as shown in  FIG. 1 , the overflow outlet  34  can be located between the container inlet  31  and the container outlet  33 . The second fluid can enter the first container  32  through the container inlet  31  and exit the first container  32  through the container outlet  32 . The container outlet  32  empties into an analysis unit  15 . The container outlet  32  can directly connect to the analysis unit  15 . The container outlet  32  also can empty into a seventh conduit  79  that empties into the analysis unit  15 . The seventh conduit  79  can be any suitable shape, including cylindrical. According to one embodiment, as shown in  FIGS. 1 ,  2 , and  3  the overflow outlet  34  is located between the container inlet  31  and the container outlet  33 , so that if fluid should enter the first container  32  at a higher rate than is discharged through the container outlet  33 , it would flow out of the overflow outlet  34 . 
     The overflow outlet  33  can connect to a fifth conduit  35 . The fifth conduit  35  can connect the overflow outlet  33  to a fourth two-way valve  36 . The fifth conduit  35  can be any suitable shape, including cylindrical. The fourth two-way valve  36  can have a first port  81  and a second port  82 . The first port  81  of the fourth two-way valve  36  can be open. The second port  82  of the fourth two-way valve  36  can be closed. The fifth conduit  35  can connect to a waste conduit  37  and extends via the second pump  14  so that the waste fluid is pumped into the second container  38 . In normal operation, therefore, the fluid containing the collected particles in suspension is drawn from the particle collection device  1  to the analysis unit  15  for detection and analysis. 
     Any suitable flow rate metering mechanisms can be used. For example, a variable area flow rate meter, an electromagnetic flow rate meter, a coriolis flow rate meter, a caliometric flow rate meter, a pitot tube flow rate meter, a differential pressure flow rate meter, a thermal conductivity flow rate meter, a vortex shedding flow rate meter, an ultrasonic flow rate meter, a turbine flow rate meter, an optical flow rate meter, and a rotary gear flow rate meter. The detector  41  of the particle collection system  70  can include any amount of sensors. For example, the detector  41  of the particle collection system  70  can include a first sensor  26  or a first sensor  26  and a second sensor  27 . Any suitable sensor mechanism can be used. For example, a bubble sensor, a temperature or heat sensor, an electromagnetic sensor, a mechanical-type sensor, a chemical proportion sensor, an odor sensor, an optical radiation-type sensor, an ionizing radiation-type sensor, a non initialized-type sensor, or an initialized system sensor. 
     According to one embodiment, the detector  41  includes a first sensor  26  and a second sensor  27 . The first sensor  26  and the second sensor  27  can determine the flow rate of the second fluid along a conduit, such as the fourth conduit  25 . According to one embodiment, the first sensor  26  and the second sensor  27  are bubble sensors. Using bubble sensors, the time elapsed between detection of a bubble between a first sensor  26  and second sensor  27  is measured. The first and second sensors  26 ,  27  are a known distance apart and the flow rate is a function of the elapsed time and the distance between the first and second sensors  26 ,  27 . Deviation from an expected flow rate can indicate a blockage. A flow rate below a predetermined value can indicate that there is a blockage. A flow rate that is less than 90%, 80%, 70%, 60%, 50%, 40% 30%, 20% or 10% of a predetermined value can indicate that there is a blockage. In one embodiment, a flow rate can be derived from the amount of time that elapses between detection of a bubble between a first sensor  26  and second sensor  27  and an amount of time that increases above, for example 110%, 120%, 130%, 140%, 150% or 175% can indicate that there is a blockage. The failure to detect flow rate for a predetermined time also can indicate a blockage. For example, the failure to detect a flow rate for greater than or equal to 10 seconds can indicate that there is a blockage. In some embodiments, the absence of a flow rate for greater than or equal to 2 seconds, 5 seconds, 15 seconds, or 30 seconds can indicate a blockage. 
       FIG. 2  shows an exemplary particle collection system  70  after detection of a blockage. Upon detection of a blockage, the speed of the first pump  12  and the second pump  14  increases, the first two-way valve  18  switches, and the second pump  14  operates in the first direction. In some embodiments, the speed of the first pump  12  increases by a factor of at least 1.25, 1.5, 2, or 3. For example, the speed of the first pump  12  can increase to greater than or equal to 70 rpm. When the first pump  12  reaches the increased speed, the first pump  12  can be controlled to provide a substantially constant outlet compensated for varying environmental conditions. In some embodiments, the speed of the second pump  14  can increase by a factor of at least 1.25, 1.5, 2, or 3. For example, the speed of the second pump  14  can increase to greater than or equal to 30 rpm. 
     When the first two-way valve  18  switches, the first port  72  of the first two-way valve  18  can be closed and the second port  73  of the first two-way valve  18  can be open. Initially, the second port  82  of the fourth two-way valve  36  can remain open. 
     The closure of the first port  72  of the first two-way valve  18  can disconnect the first pump  12  from the needle  20 . When the second port  73  of the first two-way valve  18  opens, the fluid from the third container  11  can move from the first pump  12  into the second conduit  40 , through the second conduit  40  to the second two-way valve  24 , and from the second two-way valve  24  to the outlet  13 . 
     When the second pump  14  operates in the first direction, the second pump  14  can pump waste fluid from the second container  38  through the waste conduit  37  and the fifth conduit  35  into the overflow outlet  34 . As the first container  32  fills, the second fluid can leave the first container  32  through the container inlet  31 , of the first container  32 , and into the fourth conduit  25 . Once in the fourth conduit  25 , the second fluid can move from the fourth conduit  25  to the third conduit  23  and from the third conduit  23  into the outlet  13 . According to another embodiment, any suitable mechanism can pump waste through the waste conduit  37 . For example, gravity or a pump. 
     The combined effect of the pressure from the first pump  12  and the second pump  14  can push a blockage back into the chamber  16  and can cause a volume  50  of the fluid to enter the chamber  16 . The volume  50  can collect between the formation  22  and the inside surface of the chamber  16 . In some embodiments, the process illustrated in  FIG. 2  and described above takes place in less or equal to about 25 seconds, about 45 seconds, or about 60 seconds. 
       FIG. 3  shows a later stage of the particle collection system  70  after detection of a blockage. The volume  50  and the material causing the blockage can exit the chamber  16 . A sixth conduit  60  can extend from the chamber  16  to the fourth two-way valve  36 . The sixth conduit  60  can extend from anywhere along the chamber  16 . For example, the sixth conduit  60  can extend from the chamber  16  at an opening located at the bottom of the formation  22 . In some embodiments, the sixth conduit  60  is cylindrical and has a large diameter as compared to the other conduits. The sixth conduit  60  can be larger than the diameter of the fourth conduit  25  by a factor of at least 1.25, 1.5, 1.75, 2, or 3. For example, the sixth conduit  60  may have a diameter greater than or equal to 1.6 mm. 
     The third two-way valve  30  can switch so that the first port  77  of the third two-way valve  30  can be open and the second port  78  of the third two-way valve  30  can be closed. The fourth two-way valve  36  can switch so that the first port  81  of the fourth two-way valve  36  can be closed and the second port  82  of the fourth two-way valve  36  can be open. The second port  82  of the fourth two-way valve  36  can connect with the waste conduit  37  which extends to the second container  38  via the second pump  14 . 
     The second pump  14  can pump in the second direction and at an increased speed. The speed of the second pump  14  can be greater than or equal to 40 rpm, for example. The increased speed of the second pump  14  can cause volume  50  to exit the chamber  16 . The volume  50  can enter the waste container  38  through the sixth conduit  60  and the waste conduit  37 . 
     The first pump  12  can pump fluid from the third container  11 . The second two-way valve  24  can switch to prevent the fluid from flowing to the particle collection device  1  and instead direct it to flow through the second conduit  40 . The fluid from the third container  11  can move through the second conduit  40  into the fourth conduit  25 . The second pump  14  can pump the fluid from the second conduit  40  to the fourth conduit  25 . In some embodiments, the process illustrated in  FIG. 3  and described above takes place in less or equal to about 25 seconds, about 45 seconds, or about 60 seconds. At the completion of this process, the particle collection system  70  can return to the state shown in  FIG. 1 . 
       FIGS. 4 ,  5 , and  6  show another embodiment of the particle collection system  170 . The particle collection system  170  is similar to the particle collection system  70 , except the particle collection system  170  has no sixth conduit  60  and only contains two, two-way valves  118 ,  124 . A blockage can be removed by the third conduit  123 . The third conduit  123  can be any suitable shape, including, for example, cylindrical. 
       FIG. 4  shows a preliminary stage of the particle collection system  170  after detection of a blockage. The speed of the first pump  112  and the second pump  114  can increase. For example, the speed of the first pump  112  can increase to a speed of greater than or equal to 70 rpm, and the speed of the second pump  114  can increase to a speed of greater than or equal to 30 rpm. Alternatively, only one of the two pumps can increase in speed. The first pump  112  pumps in the first direction, and the second pump  114  pumps in the second direction. 
     The first pump  12  can connect to the first two-way valve  118 . The first two-way valve  118  can have a first port  172  and a second port  173 . The first two-way valve  118  can switch so that the second port  173  of the first-two way valve  118  can be open and the first port  172  of the first two-way valve  118  can be closed. Similar to the embodiment shown in  FIG. 2 , the closure of the first port  172  of the first two-way valve  118  can disconnect the first pump  112  from the needle  120 . The opening of the second port  173  of the first two-way valve  118  can allow the first pump  112  to pump the fluid from the third container  111  to the second conduit  140 , from the second conduit  140  to the second two-way valve  124 , and from the second two-way valve  124  to the outlet  113 . 
     When the second pump  114  pumps in the second direction, the second pump  114  can pump the second fluid from the second container  138  into the overflow outlet  134 . As the first container  134  fills, the second fluid can exit through the container inlet  131  and can move through the fourth conduit  125  to the third conduit  123  and from the third conduit  123  to the outlet  113 . 
     In some embodiments, the process illustrated in  FIG. 4  and described above takes place in less or equal to about 15 seconds, about 25 seconds, about 45 seconds, or about 60 seconds. A blockage can be removed from within or around the outlet  113 , from within the third conduit  123 , and/or from within the fourth conduit  125 . 
       FIG. 5  shows an intermediate stage of the particle collection system  170  after detection of a blockage. The second pump  114  can pump in the first direction, and the second two-way valve  124  can switch. The speed of the second pump  114  may or may not increase from the increased speed of the embodiment shown in  FIG. 4 . Switching the second two-way valve  124  can prevent the fluid from entering the particle collection device  101  so that the second pump  114  receives a flow of fluid from the first pump  112  via the second conduit  140  and the fourth conduit  125   
     The first pump  112  can pump the fluid from the third container  111  into the second conduit  140  and from the second conduit  140  to the fourth conduit  125 . Any remaining blockage in the fourth conduit  125  can be pumped by the second pump  114  to the first container  132  and from the first container  132  to the second container  138 . In some embodiments, the process illustrated in  FIG. 5  and described above takes place in less or equal to about 15 seconds, about 25 seconds, about 45 seconds, or about 60 seconds. 
       FIG. 6  shows a later stage of the particle collection system  170  after detection of a blockage. The second two-way valve  124  can be switched. The first pump  112  and the second pump  114  each can operate in their respective first directions. The first pump  112  and the second pump  114  can operate at an increased speed. In some embodiments, both the first pump  112  and the second pump  114  can operate at an increased speed, or only one or neither can operate at an increased speed so that a larger amount of fluid is sprayed into the particle collection device  101  to wash out any remaining blockage. In some embodiments, the first pump  112  and second pump  114  operate at a speed greater than or equal to 70 rpm. The fluid pumped from the third container  111  can be pumped by the second pump  114  through the third conduit  123 , from the third conduit  123  through the fourth conduit  125 , and from the fourth conduit  125  into the first container  132 . Fluid entering the first container  132  can exit the first container  132  through the overflow outlet  134  and can be pumped by the second pump  114  into the second container  138 . In some embodiments, the process illustrated in  FIG. 6  and described above takes place in less or equal to about 15 seconds, about 25 seconds, about 45 seconds, or about 60 seconds. After this, the particle collection system  170  returns to its normal operating mode. 
     Some exemplary scenarios detailing use of some embodiments will now be described. 
     With reference first to  FIG. 1 , a system includes a particle collection device  1  having a particle inlet  10 . A sample collection solution, which can be a buffer solution from a third container  11  is supplied by a first pump  12  to the particle collection device  1  and collected samples are removed via an outlet  13  utilizing a second pump  14 , and are supplied to an analysis unit  15 . 
     The particle collection device  1  has a generally cylindrical chamber  16  (a collection chamber, which can contain a first fluid containing particles collected with the particle collection device) oriented horizontally (although alternative orientations are possible) with a particle inlet  10  opening into the chamber  16  tangentially so that air may be given a swirling motion about an axis of the chamber  16 . In some embodiments, the particle collection device  1  is connected to a blower or impeller or the like at its particle inlet  10  or at a first outlet  17 , or both, so that air is drawn through the particle collection device  1 . The buffer solution is pumped from the third container  11  by the first pump  12  to an inlet of a two-way valve  18 , which may connect via a first conduit  19  to a needle  20  projecting into the particle inlet  10 , so that the buffer solution enters the chamber  16  with the air and any airborne particles. Referring to  FIG. 1 , the first portion  21  of the chamber  16  is closed and has a formation  22  projecting axially, up which flows the mixture of buffer solution and entrapped particles. The outlet  13  is provided by a narrow axial bore of, in an exemplary embodiment, about 0.8 mm in diameter opening at the top of the formation  22 . 
     The outlet  13  connects via a first flow path, which in an exemplary embodiment can include the outlet  13  and a third conduit  23  (in an exemplary embodiment, about 0.5 mm internal diameter and part of a first flow path) to a second two-way valve  24 , which can connect to a second length of fourth conduit  25  extending to the second pump  14 . A detector  41  adapted to detect a change in a flow rate of fluid passing through the conduit indicative of a blockage at the first flow path is present, which, in the exemplary embodiment shown, comprises two bubble sensors  26  and  27  mounted at spaced locations along a first flow path, fourth conduit  25 , to detect passage of air bubbles in the tubing. 
     Initially, during operation of the particle collection device  1  to obtain samples, the second pump  14  can be rotated at a relatively low speed of about 25 rpm in a forward direction to draw the buffer and particle mixture from the outlet  13  along the fourth conduit  25 . A port of the second pump  14  connects with a third two-way valve  30 , which normally connects the second pump  14  to a container inlet  31  of a first container  32 . The first container  32  has a container outlet  33  at its lower end, which is open to allow flow from the first container  32  to the analysis unit  15 . The rate of flow from the container outlet  33  can be regulated to be suitable for the particular analysis unit  15  used. The first container  32  can have an overflow outlet  34  between the container inlet  31  and the container outlet  33  so that, if solution should enter the first container  32  at a higher rate than is discharged through the container outlet  33 , it would flow out of the overflow outlet  34 . The overflow outlet  34  connects via a fifth conduit  35  to a fourth two-way valve  36 , which, in the exemplary embodiment depicted in  FIG. 1 , connects to a waste conduit  37  and extends via the second pump  14  so that the waste solution is pumped into a second container  38 . In operation, the buffer solution containing the collected particles in suspension can be drawn from the particle collection device  1  to the analysis unit  15  for detection and analysis. 
     If a blockage should occur in or around the outlet  13  of the particle collection device  1  or its associated conduit  23  or  25 , this blockage would stop and/or reduce the flow along the fourth conduit  25  extending past the two bubble sensors  26  and  27 . Flow rate along the fourth conduit  25  utilizing the embodiment depicted in the figures can be measured based on the time taken by a bubble to flow between the two sensors  26  and  27 . If this time should increase above a predetermined value, such as 150%, this is taken as indicating a blockage. Further, a complete blockage would prevent any flow along the fourth conduit  25 , so the absence of any output from the bubble sensors  26  and  27  for a predetermined time, such as 10 second is also taken as indicating the presence of a blockage. When a blockage is detected, the system starts an automatic unblock procedure, as will now be described. 
     First, as shown in  FIG. 2 , the first two-way valve  18  is switched to disconnect the first pump  12  from a nozzle  20  and instead connect the pump to a second conduit  40 , a flow path, extending to the second two-way valve  24 . This valve  24  switches to allow buffer solution to flow from the first pump  12  to the outlet  13  of the particle collection device  1 . At the same time, the speed of the first pump  12  is increased to about 70 rpm, up from its previous variable speed, which can be controlled to provide a substantially constant outlet compensated for varying environmental conditions. 
     In this scenario, the second pump  14  is reversed and its speed increased to around 30 rpm. In this way, waste solution from the second container  38  is pumped by the second pump  14  along a waste conduit  37  and a fifth conduit  35  into the overflow outlet  34  of the first container  32 . The first container  32  fills so that fluid can be drawn out from its container inlet  31  to flow along conduits  25  and  23  to the outlet  13  along with the buffer solution direct from the third container  11 . The combined effect of the pressure from the two pumps  12  and  14  forms an unblocking fluid which can be a combination of the buffer solution and the sample fluid from the particle collection device  1  containing particles which travels in a direction opposite to the sample flow down the first flow path and acts to push the blockage back into the chamber  16  and causes a volume  50  of buffer solution to enter the particle collection device  1  to help break down and disperse the blockage material. The volume  50  collects in the annular corner between the formation  22  and the inside cylindrical surface of the chamber  16 . This takes place for about 25 seconds. 
     The next stage, shown in  FIG. 3 , involves removal of this volume  50  of solution with the blockage material. A sixth conduit  60  (in some embodiments having an internal diameter of about 1.6 mm) extends from the chamber  16  where it opens into the corner at the bottom of the formation  22 . The opposite end of the sixth conduit  60  connects with the fourth two-way valve  36  and is normally closed by this valve but is opened during this removal stage. A port of the two-way valve  36  connects with the waste conduit  37 , which extends to the waste container  38  via the second pump  14 . The second pump  14  is now driven forwards at an increased speed of about 40 rpm so that the volume  50  is drawn away to the second container  38  via the sixth conduit  60  and the waste line  37 . The pump  12  continues to pump buffer solution from the third container  11  but the second two-way valve  24  is now switched to prevent the buffer flowing to the particle collection device  1  and instead direct it to flow via second conduit  40  along the fourth conduit  25  to the second pump  14  to help clear any material in this conduit. This takes place for about 25 seconds in this exemplary scenario. After this process has been completed, the system returns to its normal operating mode. 
     In some embodiments, the system does not employ a sixth conduit  60  of the type depicted in  FIGS. 1 to 3 , as can be seen in the exemplary embodiment shown in  FIGS. 4 to 6 , where equivalent components to those in  FIGS. 1 to 3  are given the same numerals with the addition of 100. The system of  FIGS. 4-6  has only two two-way valves  118  and  124 , where blockage material is removed via the outlet line  123 . 
       FIG. 4  depicts the initial stage after detection of a blockage. After a blockage is detected, the pump  112  can be driven at high speed, around 70 rpm, in a reverse direction from its normal operation. The first two-way valve  118  can be switched to disconnect the first pump  112  from the nozzle  120  and instead to supply the buffer solution along the second conduit  140  to the second two-way valve  124 . This valve  124  can be set such that the buffer solution flows to the inlet  113  via the third conduit  123 . The second pump  114  also can be reversed and driven at a higher than normal speed of around 30 rpm. This causes waste solution in the second container  138  to be pumped into the overflow outlet  134  of the first container  132 . As the first container  132  fills, the solution can flow out of the container inlet  131  and back along conduit  126 , via the second pump  114  and the two-way valve  124  to add to the solution pumped to the outlet  113  from the first pump  112 . This initial flushing takes place for about 15 seconds and can be effective to push out blockages in or around the outlet  113 , or in its associated conduits  123 ,  126 . 
     In the next stage, as shown in  FIG. 5 , the direction of rotation of the second pump  114  can be reversed so that it rotates in the normal direction. The second two-way valve  124  can be switched to prevent flow to or from the particle collection device  101  so that the second pump  114  receives a flow of clean buffer solution from the first pump  112  via conduits  140  and  126 . Any remaining blockage material in conduit  126  can be flushed through via the first container  132  to the waste container  138 . This stage can also take place for about 15 seconds. 
     The final stage, shown in  FIG. 6  is to remove material from the particle collection device  101 . This can be achieved by switching valve  124  to close conduit  140  and to open the path between the outlet  113  and the second pump  114 . Both pumps  112  and  114  can be driven in their normal forward direction but at high speed, typically around 70 rpm so that a larger than usual amount of buffer solution is sprayed into the particle collection device  101  to wash out any remaining material. The solution can be drawn by the second pump  114  via conduits  123  and  126  into the first container  132  where it overflows to its container outlet  134  and is pumped to the second container  138  by the second pump  114 . This can take place for about 15 seconds, after which the system switches to its normal operating mode. 
     In some embodiments, blockages in the system can be cleared automatically, without user intervention. In some embodiments, cyclone or other systems can be operated unattended for prolonged periods. Other systems other than cyclone systems can be utilized for particle separators. Some or all features disclosed herein can be used in other particle collection systems and/or in any other arrangement where blockage is a problem and/or where filters cannot be used/are not adequate. 
     As can be seen from the Figures, in an embodiment, there is an apparatus comprising a particle collection device  1  having a chamber  16  containing a first fluid and including an outlet  13 , a first fluid distribution system adapted to direct the first fluid from the particle collection device  1  through the outlet  13  to flow along a first flow path  23  in a first flow direction, the first flow path  23  including the outlet  13 , a detector  84  including sensors  26 / 27  adapted to detect a change in a flow rate of the first fluid directed in the first flow direction indicative of a blockage at the first flow path  23 , wherein the apparatus is adapted to automatically direct unblocking fluid to flow along the first flow path  23  in a second flow direction opposite the first flow direction upon the detection of the change in the flow rate indicative of a blockage at the first flow path  23  to remove the blockage at the first flow path. 
     In another embodiment, the detector  41  comprises a flow rate meter selected from the group consisting of a variable area flow rate meter, an electromagnetic flow rate meter, a coriolis flow rate meter, a caliometric flow rate meter, a pitot tube flow rate meter, a differential pressure flow rate meter, a thermal conductivity flow rate meter, a vortex shedding flow rate meter, an ultrasonic flow rate meter, a turbine flow rate meter, an optical flow rate meter, and a rotary gear flow rate meter. 
     In another embodiment, there is an apparatus as disclosed above or below, wherein the unblocking fluid comprises the first fluid which has passed through the particle collection device and exited through outlet  13  and entered the first flow path  23 . In another embodiment, the unblocking fluid comprises a buffer solution that has not passed through the collection chamber  16  of the particle collection device  1 , having been routed around the particle collection device  1  via flow path  40 . 
     In another embodiment, there is an apparatus wherein upon the detection of the change in the flow rate indicative of a blockage at the first flow path  23 , the apparatus is adapted to reverse the direction of the first fluid flowing along the first flow path  23  to flow along the first flow path  23  in the second flow direction, the unblocking fluid comprising the first fluid flowing along the first flow path  23  in the second flow direction. In another embodiment, upon the detection of the change in the flow rate indicative of a blockage at the first flow path  23 , the apparatus can be adapted to direct a second fluid to flow along the first flow path  23  in the second flow direction (e.g., in a direction from the second two-way valve  24  towards outlet  13 ), the unblocking fluid comprising the second fluid flowing along the first flow path  23  in the second flow direction. 
     In an exemplary embodiment, the pump  14  is a sample pump adapted to pump the first fluid containing the sample from the collection chamber  16  so that the first fluid flows along the first flow path (the first flow path including at least a portion of conduit  23 ). In an exemplary embodiment, the pump  12  is a sample collection solution supply pump adapted to pump sample collection solution from a supply of the sample collection solution  11  into the collection chamber  16  of the particle collection device  1 . According to another embodiment, the pump  12  is a sample collection solution supply pump adapted to operate at a variable pump speed to pump the sample collection solution into the particle collection chamber  16  of the particle collection device  1 . 
     According to one embodiment, the sixth conduit  60  is a waste outlet where the volume  50  is drawn from the cyclone chamber  16  (the particle collection chamber  16 , when the device  1  is a cyclone—that is, in an embodiment, the particle collection device  1  is a cyclone separator device and the chamber  12  is a cyclone chamber of the cyclone separator device) through the waste outlet to a waste container  38 . 
     It is noted that the various features disclosed and described herein can be combined together in any combination that will permit the present invention to be practiced. Also, an embodiment includes any device, method or system to implement the various methods, use steps, and exemplary usage scenarios disclosed herein. It is further noted that dimensions are provide herein by way of example only and not by way of limitation. In this regard, in some embodiments of the present invention, the dimensions may vary by plus or minus about 1% to about 100%, or even more. Also, in some embodiments of the invention, the dimensions are uniformly scaled up and/or scaled down. 
     The embodiments described above have been set forth herein for the purpose of illustration and are exemplary in nature unless otherwise explicitly stated. This description, however, should not be deemed to be a limitation on the scope of the embodiments. This is especially true with respect to various specific dimensions and regimes detailed herein. Various modifications, adaptations, and alternatives may occur to one skilled in the art without departing from the claimed concept.