Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
1998-11-16
2001-03-06
Warden, Jill (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C422S068100, C422S078000, C422S081000, C436S062000, C435S286100, C435S286500, C435S286600, C435S287100, C435S287500
Reexamination Certificate
active
06197256
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a device for analyzing fluid samples consisting of a sample chamber containing at least one testing device, which comprises a control and analysis device and a filling and draining device, through which, respectively, a fluid sample taken from a quantity of fluid is fed into the sample chamber and removed from it.
A typical area of application for such testing equipment is in waste water analysis. In this type of application, a fluid sample is taken from the waste water and tested in the sample chamber. Frequently, a reagent is added in the sample chamber and its reaction with the fluid sample is completed and measured. Gas-selective or ion-selective sensors, pH sensors, photo-optical sensors, and other sensors are commonly used for tests performed inside the sample chamber. A gaseous reaction product which develops during the reaction can be fed into a measuring device designed specifically for measuring this product, such as a CO
2
detector (published journal article by M. Levermann, “TOC Testing in an On-line Process”, publication “Chemie, Umwelt, Technik” [Chemistry, Environment, Technology], 94, pages 12-15).
To fill the sample chamber, the fluid sample must be conveyed from the available quantity of fluid, such as waste water, through a supply line
An unavoidable feature of such testing, particularly of waste water samples, is that deposits form in the fluid lines used to fill and drain the sample chamber. Unless they are routinely flushed—a relatively expensive procedure—there is a risk that these lines may become clogged.
Consequently, the objective of the invention is to design a device of the type specified initially in such a way that the sample chamber can be easily filled and drained without running the risk of clogging the fluid lines and incurring the substantial expense of rinsing.
SUMMARY OF THE INVENTION
According to the invention, this objective is solved in that the sample chamber is arranged in a measuring buoy immersible in a quantity of fluid and is connected to the outside of the measuring buoy via a chamber opening, that at least one testing device is arranged in the measuring buoy, and that the filling and draining device exhibits a gas exchange apparatus with which a gas which displaces the fluid sample is fed into and removed from the sample chamber.
Moving the sample chamber from a measuring device located outside the fluid to a measuring buoy immersible in the quantity of fluid eliminates the need for fluid lines which tend to become clogged. The sample chamber located inside the fluid being tested can be directly filled and drained without the need for any fluid lines.
As at least the section of the measuring buoy that contains the sample chamber is immersed into the fluid being tested, removing the gas in the sample chamber is sufficient for filling the sample chamber, i.e., by opening the sample chamber to the atmosphere, in the simplest case. The hydrostatic pressure of the fluid surrounding the measuring buoy forces the fluid sample into the sample chamber. To empty the sample chamber, a pressurized gas, such as air, is supplied by the gas exchange device to press the fluid sample out of the sample chamber. The intensity of the gas supply can be chosen so as to produce turbulence in the fluid sample in the sample chamber, thereby effectively rinsing and cleaning the sample chamber and the chamber opening with very simple means. This essentially eliminates clogging of the chamber opening.
The control and analysis device can be positioned in a remote location relative to the measuring buoy and be linked to the buoy by cables or lines. If need be, reagents and/or gases are—in addition to electric measuring signals and, if applicable, electric control impulses or an electric power supply—transported via lines that connect the measuring buoy with the remotely placed control and analysis device. Compared to the transport of fluid samples, the transport of these materials is completely unproblematic and does not lead to the risk of contamination or clogging. Alternatively, the control and analysis device can also be arranged in the measuring buoy.
Preferably, at least one reagent dosing device, which opens into the sample chamber and is connected to a reagent source located outside the measuring buoy via a hose assembly, is arranged in the measuring buoy. As a result, the types of tests that require the chemical reaction of the fluid sample with one or more reagents—which is often the case in waste water analysis—can also be performed in the sample chamber. As there is no risk of the transport lines for fluids or gaseous reagents becoming clogged, these lines can also be installed across relatively large distances between the measuring buoy and a supply unit.
Preferably, the gas exchange device exhibits a gas pump arranged in the measuring buoy and connected to the sample chamber which can be connected to a gas source located outside the measuring buoy via a hose assembly. As this type of hose assembly is also not subject to the risk of clogging, it can easily be installed across larger distances.
According to a preferred embodiment of the invention, the sample chamber opening may open into a settling chamber with a hole in its bottom which is arranged underneath the sample chamber in the measuring buoy. It may be necessary to separate the solid matter component prior to analysis, particularly when analyzing the aqueous component of activated sludge in a sewage treatment plant. The settling chamber connected upstream from the sample chamber is used to hold the fluid sample during a filling pause, so that the activated sludge settles or concentrates in the lower portion of the settling chamber before the fluid sample, which has been pre-cleaned in this manner, is allowed to enter the sample chamber.
To control this filling process over time, a fill level sensor is preferably positioned near the chamber opening connecting the settling chamber to the sample chamber and is connected to the control unit for the gas exchange device. The fill level sensor is used to determine when the settling chamber is full. When this occurs, the filling process is interrupted so that the sludge component can settle in the settling chamber. This filling process is resumed once this preset time period has expired.
To analyze activated sludge in which gas bubbles are constantly rising, it has proven to be advantageous to place a deflection object at a distance from the floor opening of the settling chamber which extends beyond the perpendicular projection of the perimeter of the floor opening on all sides. This deflection object prevents gas bubbles from entering the settling chamber and the sample chamber.
According to another advantageous embodiment of the invention, the sample chamber is linked to a gas supply line for a reaction gas, the chamber opening can be locked by means of a valve, and a gas discharge line with a locking valve runs from the sample chamber to an analysis device located at a distance from the measuring buoy. This makes it possible to subject the fluid sample drawn into the sample chamber to a reaction with the reaction gas when the chamber opening is locked, and to subsequently remove this reaction gas from the measuring buoy and convey it to a remotely positioned analysis device, so that the necessary analysis can be completed there.
REFERENCES:
patent: 4089209 (1978-05-01), Grana et al.
patent: 4314969 (1982-02-01), Arthur et al.
patent: 4763537 (1988-08-01), Scott et al.
patent: 5197340 (1993-03-01), Jones
patent: 5695719 (1997-12-01), Lynggaard et al.
patent: 5708220 (1998-01-01), Burge
patent: 5993742 (1999-11-01), Binz et al.
Bex Kalh
Burns Doane Swecker & Mathis L.L.P.
ISCO Inc.
Warden Jill
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