GB2335036A - Flow cell assembly - Google Patents

Abstract

A flow cell assembly for a monitoring apparatus has a flow cell arranged to hold a fluid sample and a heater element arranged to heat the fluid sample to a predetermined temperature; the flow cell and the heater element being assembled together by assembly means in an assembly-position, wherein the assembly means is manually transferable to a disassembly-position. The assembly means is typically a threaded ring 56 which engages a threaded portion of the heater element or cell.

Description

2335036 A Flow Cell Assembly The present invention relates to flow cell

for use in, for example, a monitoring apparatus f or monitoring the level of a substance in an aqueous stream. In particular. but not exclusively, the present invention relates to a monitoring apparatus which monitors the level of contaminants in an aqueous stream.

There are a number of known apparatus for monitoring the levels of a substance within an aqueous stream such as the EIL 8230 Series produced by ABB Kent-Taylor Limited and the Tytronics FPA 800.

The present invention seeks to provide further flow cell assemblies.

According to-a first aspect of the present invention there is provided a flow cell assembly for a monitoring apparatus comprising a flow cell arranged to hold a fluid sample and a heater element arranged to heat the fluid sample to a predetermined temperature. the flow cell and the heater element being assembled together by assembly means in an assemblyposition, wherein the assembly means is manually transferable to a disassembly-position. Thus the maintenance of the apparatus is greatly simplified as there are no tools necessary.

Preferably, the assembly means comprises a threaded ring which engages a threaded portion of the heater element or flow cell. This allows reliable sealing of the assembly, but not being prone to accidental disassembly.

in a preferred embodiment of the present invention there is provided a support housing on which the heater element and flow cell are mounted. The heater element advantageously comprises a two-part element.

To prevent accidental burns being occasioned on users, the assembly means is thermally insulated from the heating is element and/or the heating element is thermally insulated on all surfaces which would otherwise be externally exposed.

Normally, the flow cell is advantageously included in a monitoring apparatus.

Preferably the monitoring apparatus comprises a monitoring apparatus for monitoring the level of a substance in an aqueous stream, comprising a substancedetector means, a fluid pump arranged to pump selectively either a calibration-aliquot or a sample-aliquot from the aqueous stream to the substance-detector means, and a control means arranged to control the monitoring apparatus and collect information from the substance-detector means. wherein the control means includes a first memory area arranged to store a plurality of driver-routines and a second memory area arranged to store a plurality of taskoperators, each task-operator selectively operating one or more driver-routines in a predetermined manner.

A monitoring apparatus of the above described type has the significant advantage that the control of the apparatus is split between generic functions and task specific functions. This allows the generic functions to be contained within a structure that can be incorporated into a range of different monitors and only the task-specific control element having to be specifically designed for the particular monitor. This can significantly reduce production costs.

Preferably the driver-routines are generic for a plurality of substances and/or a plurality of detection principles. The task-operators will normally be specific for the substance being monitored. The present invention is particularly advantageous when the driver-routines are generic for different types of detection principle, for example for ion selective electrodes and for colorimetric 1 1 1 measurements. This allows the various monitors to share components on seemingly quite diverse monitors.

It is particularly preferred if the substance to be monitored is selected from the group consisting of ammonia or ammonium ions; chlorine or chloride ions; colour; conductivity; copper or copper ions; dissolved oxygen; oxygen or oxygen ions; flow; fluorine or fluoride ions; hydrazine; iron or iron ions; manganese; methane; nitrate; pH; phosphate; Redox (ORP) silica; suspended solids; temperature; turbidity; and water hardness. The f irst memory area will preferably include drive-routines for more than one of said group of substances, e.g. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 or 22 of said substances'. In fact the monitoring apparatus of the present invention may monitor any one of the fifty-six water supply parameters set forth in the Water Supply (Water Quality) Regulation 1989 which are listed below:

The Water Supply (Water Quality) Regulations 1989 list a total of 56 parameters. For each parameter prescribed concentration or value is given. This relates to the maximum or minimum concentration which must not be exceeded. The table below should be used in conjunction with the Water Supply (Water Quality) regulations 1989.

1+ Parameters Expression of results Concentration or value (Maximum unless otherwise stated) Colour mQ/VIPt/Co scale 20 Turbidity (including suspended solids) Formazin tubidi units 4 Odour (including hydrogen sulphide) Dilution number 3 at 25 C Taste Dilution number 3 at 25 C Temperature C 25 Hydrogen ion pH value 9.5 (5.5 minimum) Conductivity PS/cm 1500 at 20 C Chloride Cl mgfi 400 Calcium Ca mgA 250 Total hardness Ca mgA 60 (minimum) Alkalinity HC2,mg11 30 (minimum) Sulphate SOjngfl 250 Magnesium Mg mgA 50 Sodium Na mgA 150 Potassium K mgn 12 Dry res due mgn"Co scale 1500 (after drying at 180 C) Nitrate NO3 mg/l 50 Nitrite NC)mgA 0.1 Ammonium (ammonia and ammonium ions) NHtmgA 0.5 Kjeldahl nitrogen N m911 1 Oxidizability (permanganate value) QZ M911 5 Total organic carbon C mgn No significant increase over that normally observed Dissolved or emulsified hydro-carbons ligA 10 (after extraction with petroleum ether):

mineral oils Phenols CIgHjOH g/1 0.5 Surfactants ag/1 200 (as lauryl sulphate) Aluminium AJ.0g11 200 Iron Fe.49A 200 Manganese MnAgA 50 Copper CUAII 3000 Zinc ZnPg/1 5000 Phosphorus P10911 2200 Fluoride Fnil 1500 Silver Agogfi 10 Arsenic Ashg/1 50 Cadmium Cdligli 5 Cyanide CNp911 50 Chromium Crnli 50 Mercury HW,911 1 Nickel NiAgli so Lead PbogA so Antimony Sbh/1 10 Parameters Expression of results Concentration or value (Maximum unless otherwise stated) Selenium SeOg/1 10 Boron BpgA 2000 Barium B aM 1000 Pesticides and related products: Pgn 0.1 a) individual substances Pg/1 0.5 b) total substances (i) Polycidic aromatic hydrocarbon (ii) 011 0.2 Benzo 3,4 pyrene ngA 10 Tetrachloromethane -.d/gli 3 Trichloromethane An 30 Tetrachloroethane;C911 10 Substances extractable in chloroform mg/I dry residue 1 Total coliforms number/100 mi 0 Faecal coliforms number/100 mi 0 Faecal streptococci number/100 mi 0 Sulphite-reducing clostridia number/20 mi <1 Colony counts numberll mI at No significant increase over 22t or 371,- that normally observed (1) The sum of the detected concentrations of individual substances (ii) The sum of the detected concentrations of fluoranthene, benzo 3.4 fluoranthene, benzo 11.12 fluoranthene, benzo 3.4 pyrene, benzo 1.12 perylene and indeno (1,2,3 -cd) pyrene (0 Preferably, the monitoring apparatus further includes a user input device arranged to transfer user commands to the control means. As the driver- routines are common regardless of the specific type of monitor. this has the advantage that the user input will -inherently follow the same format which is advantageous with users using a variety of the monitor.

Additionally or alternatively, the monitoring apparatus for monitoring the level of a substance in an aqueous stream comprises a substance - detector means,, a fluid pump arranged to pump selectively either a calibration- al iquot or a sample-aliquot from the aqueous stream to the substance-detector means, and a control means arranged to control the monitoring apparatus and collect information from the substance-detector means, wherein the substance-detector means monitors samples over time and the control stores a number predetermined of monitored results, the apparatus further including an output device arranged to selectively display either a single result (e.g.the most recent result) or a plurality of said results at one time.

The monitoring apparatus can thus advantageously allow the user to control how the results are displayed. Although previously the known monitoring apparatus could output the results to a chart plotter or the like, this did not allow ready manipulation on the data. The present invention thus provides a way that the user can manipulate the historical information or merely display current information.

In a preferred embodiment, the plurality of said results is selected from the results collected over a first time period and the results collected over a second time period. Thus. the user can choose to display, for example, the results over a twenty-four hour time period and can then make an assessment whether there is a particular trend 11- to daily levels of the monitored substance and if there are any abnormalities in this trend. Alternatively, the user can display a shorter time period, e.g. two hours, to see if an abnormal situation which is being corrected is reversing towards the normal levels for the monitored substance or if further correction is necessary. Such manipulations were not readily undertaken when the monitoring apparatus had to be hooked to a discrete device and the data manipulated on this discrete device.

Preferably, the plurality of said results are displayed as a graph; such a graphical output is preferred because the user can then readily interpret the information.

Preferably, the monitoring apparatus further includes graphical interface arranged to display information for user. This is particular advantageous because the graphical interface will inherently be very similar between different monitoring apparatus which share the generic platform of the first embodiment of the present invention. This is preferred by users of the apparatus.

The invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 illustrates a monitoring apparatus of the present invention; Fig. 2 is an exploded view of a flow cell assembly for use with the present invention; Fig. 3 shows a cross section through the flow cell assembly of Fig. 2 along the section AA of Fig. 4; Fig. 4 shows a top plan view of the flow cell assembly of Fig. 2 with the heating element and heat sensor shown in dotted outline; Fig. 5 shows a side view of the flow cell assembly of Fig. 2; Fig. 6 shows a sample pot holder f or use with the present invention; Fig. 7 shows a pump assembly suitable f or use with the present invention; i i is Figure 1 shows a particularly preferred design of the present monitoring apparatus incorporating all aspects of the present invention. The apparatus is housed within housing 10. This housing includes a recessed portion 28 which is covered by a transparent door 32 mounted on hinges 30. Within this recessed portion 28 the main mechanical components of the monitoring apparatus are contained, namely the flow cell 16 fluidly connected to the pump 18 which has selective input means 20. The various components are thus easily accessible for maintenance operations through the door 32.

The housing 10 also includes the device 12 which comprises the graphical output device and graphical user interface. This will normally have three or more lines of display. User inputs 14 are provided below the graphical output device 12. External connector ports 24, 26 are shown illustratively on the side of the housing 10.

Turning now to Figures 2 to 5 which show details of the flow cell assembly 16. The assembly 16 comprises a support bracket 54 through which a temperature sensor 64 and a heater element 62 are fitted. The aluminium heater elements 52 are split into two parts, namely a lower element 52L and an upper element 52U. The lower element is shaped to fit on the support bracket 54 juxtaposed to a flow cell housing 50 also fitted to the support housing 54. The f low cell housing 50 is sealed by 0-rings 68. The lower heater element 52L and the flow cell housing 50 are fixed to the support bracket 54 by means of a finger ring 56 which tightens on to the lower heater element 52L. The upper heating element 52U fits within the finger ring 56 and is surrounded by an insulating ring 58 to reduce heat transferral from the upper heater element 52U to the finger ring 56 and is also covered by an insulating plate 60 to reduce hot parts which could be touched by an operator. A probe can be fitted through openings in the insulating cover 60, 52U and 52L to extend into the flow cell 50 in a channel formed therein. In the present example this probe would be in the form of an ion selective electrode which can then be brought into contact with the aqueous stream for monitoring the presence of the substance, for example in a sample pot as shown in Figure 6. The Figures 3 to 5 show various constructional details of the flow cell assembly which is particularly preferred in the present invention. One of the major advantages of this flow cell assembly 16 in the present invention is that routine maintenance to the heating elements, flow cell, etc. can be undertaken without the need for removal of the flow cell from the monitor apparatus. This does not require any special tools as the flow cell can be disassembled to a sufficient degree simply by undoing the finger ring 56.

The f low cell assembly 16 is mounted on to the housing with gasket 66 extending therebetween. As you will see, the flow cell does not have any electronics contained therewithin but the heater element is operatively connected to the control means (described in detail hereinafter) as is the temperature sensor 64.

of course, previously known flow cells could also be used but this is not preferred. Advantageously, embodiments of the invention (not shown) will adopt other detection principles such as colorimetric measurement.

The pump assembly is shown in Figure assembly as a peristaltic pump, though of course a diaphragm pump could alternatively be used or any other suitable pump apparatus.

Suitable pumps are readily available, f or example Watson 1,0 is Marlow Limited produce a "micro cassette" pump head, manufacturers reference 304MC3 can be used and preferably this would be modified to a two-channel device as a threechannel device is not required for the present invention. Preferably the pump will be mounted in a way that it can be simply removed from within the recessed portion 28, for example it can be mounted on a bayonet fitting. The pump -will be supplied with the fluid to be monitored through tubing arrangement shown as item 20 in Figure 1. Normally these tubing arrangements will collectively provided a first calibration fluid (for low end calibration), a second calibration supply (for high end calibration) and normally would supply the samples from the aqueous stream being monitored. Please note that the calibration supplies will normally be permanently connected to the apparatus to facilitate automatic calibration on a regular basis.

The control of the monitoring apparatus is controlled by control means (not shown) except by means of the input/output device connected thereto as Unit 12, 14. The control means comprises a process instrumentation platform which provides a standard CPU, LCD display, four button input, Ram, Rom, real-time clock, RS232/485 port, SPI, and I'C f acilities. This stand alone unit contains all the necessary control functions for running the operator. Many of the control functions are implemented via software as this provides a convenient way to allow f or updating and implementing these routines. The invention is described with reference to a particular series of ion selective electrode monitors (ISE 1000) though of course other measurement principles and adaptations can be readily made by the skilled person.

The control means operate by interactions of two distinct programme parts. Firstly there is a generic range of software applications provided as a library of functions 1 ( is within the software "kernel". The various drivers and control routines provided within the kernel are designed to be generic through a great variety of different monitors.

Each monitor is then provided with application software tailored for the particular monitoring activity of a particular installation. These application software will call upon routines from the kernel as required by the monitoring activity and will be controllable by user input. important in providing the user with information to control the apparatus, , the graphical interface 12 will provide information on options available to the user who can then select the appropriate options by means of the input devices 14. There is the inherent advantage of using the common platform that the nature of inputting commands and the types of inputs to be made will be standardised across all types of monitors using the generic platform.

The generic platform provides a communication port 24 for connection to an output chart logger or the like. In addition, the control means also includes a communication port 26 which allows communication to the control panel via a PC or even modem linkup. This is particularly advantageous when the control means, as in the present embodiment, is provided with as f lash memory f or containing the various programme structures. In this way the apparatus can be maintained, updated or inspected by remote linkup through a modem. This is of particular importance in the present invention as often the devices of the present invention are located in geographically diverse places and do not have operators who can attend to these high level maintenance operations. The use of f lash memory thus allows many of these functions to be done remotely without the need f or on site presence. Clearly this is economically and commercially advantageous to both users and suppliers of the monitoring apparatus.

1 Preferably, the control means is also provided with I1C functionality although units may be connected by simple peripheral interface. The VC interface will allow units to be introduced into the unit and be automatically recognised and incorporated within the control structure without specific input from a user. This is of particular importance if, for example, a further function is required to the unit which was not required when f irst produced. For example, if the unit requires "fieldbus".functionality such a "fieldbus" unit can be mounted in the housing 10, connected to the control board which would then interrogate this new unit, determine its purpose and incorporate it to within the control structure. This greatly simplifies updating and renovation of the equipment.

The details of the software implementation, for example the software presentation of the kernel, can be amended, expanded upon or altered as required for a particular monitoring apparatus or a range of monitoring apparatus. The present invention has been implemented from software products available to the skilled person. The basic programming of the platform may, for example,, be accomplished using software available from Accelerated Technology,, Inc., Nucleus PLUS - Borland Paradigm Port80186. Individual designs of screens, etc. was undertaken by graphic designers to present the information in a userfriendly way.

Details of the basic operation and control of the preferred embodiment of the invention will be readily apparent and the skilled person can readily adapt for other monitoring applications.

1.5

Claims (1)

1. CLAIMS:

   1.

   is A flow cell assembly for a monitoring apparatus comprising a f low cell arranged to hold a fluid sample and a heater element arranged to heat the f luid sample to a predetermined temperature; the flow cell and the heater element being assembled together by assembly means in an assemblyposition, wherein the assembly means is manually transferable to a disassemblyposition.

   2. The f low cell assembly where the assembly means comprises a threaded ring which engages a threaded portion of the heater element or flow cell.

   3. The flow cell according to Claim 1 or Claim 2, further including a support housing on which the heater element and flow cell are mounted.

   4. The flow cell according to Claim 1, Claim 2 or Claim 3, wherein the heater element comprises a two-part element.

   5. The f low cell according to any one of the preceding claims, wherein the assembly means is thermally insulated from the heating element.

   6. The f low cell according to any one of the preceding claims, wherein the heating element is thermally insulated on all surf aces which would otherwise be externally exposed.

   A monitoring apparatus including a flow cell according to any one of claims 1 to 6.

   1 14- 8. A flow cell assembly as hereinbefore described and/or illustrated in the accompanying drawings.

   9. A monitoring apparatus as hereinbefore described and/or illustrated in the accompanying drawings.