Patent Application
20160274002
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1. Field of the Invention
This invention relates to improvements in a variable volume capture device. More particularly, the present variable volume capture device that allows for capture and delivery of a representative and exact volume of liquid for online (or at-line) chemical analysis. In particular, this is intended for use on the sampling and analysis of multiple sample sources.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Many industries today use chemical processing in, for example, mining, food processing, refining, water treatment, recycling, and semiconductor manufacture, metal and plastic surface treatment, and so on. In most cases, monitoring of the process chemistry by chemical analysis is necessary to maintain the product quality and consistency. For analysis in general and for online (or at-line) chemical analysis in particular, it is usually necessary to obtain a liquid sample and to dispense it accurately. For this it is important that the sample be representative of the whole and that the amount captured and dispensed be controlled. To obtain a representative sample, particularly when different sample sources and compositions are anticipated, it is necessary to remove completely and desirable to purge out efficiently old sample. And for reasons of both obtaining a representative sample and of dispensing a consistent and accurate volume of sample, it is necessary to remove air bubbles from the sample and sample chambers. In addition, a process with multiple analyses and corresponding multiple analytical procedures can benefit from a device or system that captures and delivers variable, selectable, but still accurate, sample volumes.
Historically, mechanized syringes and burettes have worked well for some of these analytical functions. That is, they can be operated to draw (fill) any amount within their range, and likewise precisely dispense a specific amount. The Kloehn (Las Vegas, Nev.) model V6 syringe and syringe drive, for example, perform these functions and can include a valve at the syringe tip to select fluid source and destination(s) as well. But as the syringe chamber is effectively a fluidic dead-end, this is not a flow-through device and consequently sample change-over is either inefficient or incomplete. Although one could orient the unit so that the syringe tip points downward to facilitate drainage, this would defeat the air-purging that is achieved in the normal, upward direction.
A number of patents and or publications have been made to address these issues. Exemplary examples of patents and or publication that try to address this/these problem(s) are identified and discussed below.
U.S. Pat. No. 6,235,002 issued May 22, 2001 to Edward Lawrence Carver, Jr et al. discloses a Syringe for Use in Fluid-Handling Apparatus. The syringe has a housing, a substantially fixed seal, a solid or closed-tip plunger, an internal passageway formed between the housing and the plunger, and at least two ports on the housing with at least one port located at each end of the passageway for the passage of fluids and the elimination of gas. While the syringe takes a sample, there can be a cross contamination and the sample is fixed in volume.
U.S. Patent publication Number 20080060413 was published on Mar. 13, 2008 to Masao Miyamoto et al., discloses a Flow Analysis System. The deaerator comprises a liquid-containing means variable in internal volume for containing the liquid together with gas bubbles included in the liquid. While the dearator can extract a sample, the dearator only extracts a sample from a flow and not from a standing pool.
U.S. Patent Publication Number 20140219311 was published by Valerian Plotnikov et al., discloses an Isothermal Titration Microcalorimeter Apparatus and Method of Use. This patent describes an automatic pipette assembly for an isothermal titration micro calorimetry system. The pipette system is basically a single use sampling system because when a sample is taken the syringe holder can be contaminated.
What is needed is a variable volume capture device that allows for a capturing and delivery of a representative and exact volume of liquid for chemical analysis.
It is an object of the variable volume capture device to capture a variable amount of sample. The variable amount is controlled by a linear actuator that produces a variable and adjustable stroke length that capture the programmed amount of fluid into the syringe barrel. The captured fluid is then dispensed out of the syringe barrel for further testing and analysis of the captured fluid.
It is another object of the variable volume capture device to flush itself from a previous sample of fluid. If the syringe barrel is not flushed, cross contamination of test fluids can cause false readings of the captured samples. Valves located on each side of the syringe barrel allow for sample collecting, dispensing and draining to ensure that the capture device is free to collect new samples.
It is still another object of the variable volume capture device to allow for changing syringe and barrel diameters and lengths to accommodate larger or smaller ranges of samples. While the linear drive shaft can capture a variable amount of fluid with each sample, capture of small samples that have a volume of the plunger fluid path can be imprecise, whereby changing to a smaller syringe and barrel will provide greater afficiency. At the other extreme, if a large sample that exceeds the volume of a syringe barrel, a larger syringe and barrel can be utilized.
Various objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components.
There is a threaded coupling 31 that connects the linear drive shaft 30 to the plunger 40. The plunger 40 has an upper fluid port 40 where captured fluid is expelled to a drain or dispensed for testing. Within the plunger 42 is a fluid path 41 for captured fluid to travel. The bottom of the plunger 42 is retained in the syringe barrel 45 and is sealed with a plunger seal 43 at the funnel entrance 44. The bottom of the syringe barrel 45 has a syringe nose piece 46 connecting the syringe cavity to the lower fluid port 47.
Modes of Operation
In this embodiment the reservoir is a syringe barrel 45, but in general can be a cylindrical chamber with rigid walls, an opening at the top end for a plunger 42, and a smaller opening at the lower end as a fluid orifice. On the plunger 42 there is a sliding fluid seal 43 between the plunger 42 and the reservoir, such as can be made with Teflon, polyethylene, or an elastomer. In our embodiment, an elastomer O-ring was preferred as it could be readily replaced upon wear. At the lower orifice is a valve 50 used to stop or allow sample flow. It is opened, for example, during sample capture and closed during sample dispense. In some cases, when back flushing is not required, a check valve can be used for valve 50 to simplify the hardware. An upper orifice passes through the plunger 42 and optionally through additional valve(s) that select fluid destination.
An alternate first mode (prior to sample capture) is sample flush, that is, flushing with sample. This is desirable when there is a sample change over and it is necessary to remove the residual of the previous fluid. In this case the plunger 42 is positioned so as to minimize the internal reservoir volume and so minimize the flush time and volume required. This change over can be further accelerated by introducing air into the sample, which acts to break up laminar flow and push fluids out of pockets.
The typical last mode is cleanup. In this mode the reservoir 45 is emptied and/or rinsed by cycling the plunger 42 and flushing with water and/or air. Flushing in the reverse direction is especially effective and can be facilitated by a funnel shape 44 at the bottom of the reservoir.
Thus, specific embodiments of a variable volume capture device have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims.
Not Applicable.
