Combination of automatic testing equipment and dosing equipment

Abstract

An automatic testing device (10) and dosing device (50) combination comprises a testing device (10) for testing the content of a selected chemical substance in district heating water in a district heating system circuit and an automatic dosing device (50) for dosing the selected chemical substance into the district heating system water. The testing device (10) comprises: a sample chamber (14) for holding a sample of district heating system water to be tested; means (16) for controlling the filling of the sample chamber (14) with district heating system water from the district heating system circuit and the emptying of the sample chamber (14) by returning the district heating system water to the district heating system circuit; at least one valve (18) for isolating the sample of district heating system water from the heating circuit during testing; and an optical testing device, including a light source (20) and a detector (22), for measuring optical properties of the sample of district heating system water isolated in the sample chamber (14) to determine whether the level of the selected chemical substance in the water is greater than a predetermined threshold level.

Description

[0001] Divisional application

[0002] This application is a divisional application of application number 2018800611764, filing date July 27, 2018, and entitled “Measuring the Concentration of Corrosion Inhibitors in Water of Central Heating Systems”. Technical Field

[0003] The present invention relates to measuring the level of chemicals in a sample, and in particular to measuring the level of corrosion inhibitor chemicals in water in a central heating system. Background Art

[0004] It is well known that damp central heating systems are subject to internal corrosion. The steel on the inner surface of the radiator, in the presence of water circulating through the system and of oxygen (which is inevitably dissolved in the water to a certain extent), tends to rust. Due to corrosion, particles can break off from the damaged inner surface of the radiator and are gradually carried into the system water. These particles can then cause damage to the boiler, particularly modern high-efficiency boilers which have very narrow channels in the heat exchanger. The presence of particles can also reduce the efficiency of heat transfer, leading to higher fuel consumption.

[0005] Therefore, dealing with this problem is important to prevent premature boiler failure, as well as ensuring efficient operation. The amount of particulate contamination in the system water can be reduced by using a magnetic filter which continuously captures particles and removes them from the system fluid. Filters are available which can effectively remove both magnetic and non-magnetic particles - see for example GB2508257.

[0006] However, using a magnetic filter alone will not prevent corrosion, and therefore will not solve the problem of generating magnetic particles in the first place. In systems that are particularly prone to corrosion, the volume of particles added to the system water may exceed the rate at which they can be removed by a magnetic filter with reasonable use intervals. Best practices to ensure that the system is efficient and reliable therefore include dosing the system water with inhibitor chemicals to reduce corrosion, thereby reducing the rate at which particulate contaminants accumulate in the system water. In principle, a sealed system with inhibitor dosing properly can remain stable for many years. However, factors vary between systems, which means that inhibitor chemicals will be diluted and / or degraded over time. One way to simply deal with this is to use a "rule of thumb" and top up a system with inhibitor, for example adding one bottle every 12 months. Overdosing the inhibitor moderately is unlikely to cause any technical problems, but it is expensive to add inhibitor unnecessarily.

[0007] The present invention aims to solve this problem by providing a method of testing whether water in a district heating system has been correctly dosed with inhibitor chemicals. Summary of the invention

[0008] According to the present invention there is provided a testing apparatus for testing the level of a selected chemical substance in district heating system water in a district heating system circuit, the apparatus comprising:

[0009] a sample chamber for holding a sample of the central heating system water to be tested, the sample chamber being connected to the central heating system circuit to allow fluid to flow between the central heating system circuit and the sample chamber;

[0010] means for controlling the filling of the sample chamber with district heating system water from a district heating system circuit, and the emptying of the sample chamber;

[0011] at least one valve to isolate a sample of the central heating system water from the heating circuit during the test; and

[0012] An optical test device including a light source and a detector for measuring optical properties of a sample of district heating system water isolated in a sample chamber to determine whether the level of a selected chemical in the water is greater than a predetermined threshold level.

[0013] The apparatus of the present invention allows for automatic on-site sample testing of district heating system water to determine whether it is dosed with the correct level of a selected chemical. The selected chemical is typically a corrosion inhibitor, although it is possible through embodiments of the present invention to monitor the concentration of other types of chemicals in district heating system water if desired. By using the apparatus of the present invention, the system can be kept dosed with the correct level of inhibitor to limit corrosion without wasting inhibitor.

[0014] Preferably the sample chamber is emptied by returning the central heating system water to the central heating system loop. This ensures that there is no pressure loss in the central heating system loop. If the volume is small enough, in some embodiments it may be acceptable to empty the water to the sewer after the test, but this will inevitably lead to a loss of system pressure over time, and a topped up system will result in dilution of the inhibitor chemistry.

[0015] Preferably there is a single flow passage between the sample chamber and the district heating system circuit to allow fluid to pass in both directions between the district heating system circuit and the sample chamber.

[0016] The sample chamber is preferably transparent to light, at least within the operating range of the optical test device. This allows the optical test device to be mounted outside the sample chamber. In one embodiment, the sample chamber is made of borosilicate glass. Preferably, the optical test device and the sample chamber are enclosed by a light-proof cover, or at least a cover that substantially blocks any wavelengths that would interfere with the optical test device.

[0017] The means for controlling the filling and emptying of the sample chamber may be in the form of a piston. Preferably, the piston comprises a wiper seal which seals the inside of the sample chamber. The piston may be retracted to draw water from the central heating system circuit into the sample chamber, kept retracted while the test is being carried out, and then extended to empty the sample chamber and return water to the central heating system circuit. The sample chamber is emptied after each test operation to prevent dirt in the water from accumulating on the sample chamber surface and darkening the light-permeable sample chamber.

[0018] Where a piston is used, a valve for isolating the sample during testing may be integrated into the piston so that when the piston is in the fully retracted position, after water has been drawn into the sample chamber, a sealing element on the piston seals the inlet to the sample chamber, preventing further flow between the sample chamber and the central heating system circuit.

[0019] A piston with an integrated valve may include a necked section in front of the piston top to connect the valve to the piston while allowing water to flow around the necked section into the sample chamber. Alternatively, the piston may include a groove along one side (in principle, this can be considered an asymmetric necking of the piston in front of the piston top). In either alternative, the necked section of the piston will be present in the sample chamber during testing. Therefore, the shape and optical properties of the necked piston need to be selected so that the necked section of the piston does not interact with the optical test device, or any interaction is predictable so that it can be systematically explained, or insignificant enough to be ignored. A slotted piston / asymmetric necked piston allows the necked portion of the piston to be located in a position that is "invisible" to the optical test device.

[0020] As an alternative, a valve independent of the piston may be provided. For example, an electric ball valve may be provided between the central heating system circuit and the sample chamber.

[0021] Preferably, the test process is fully automated, with the control means being adapted to draw water into the sample chamber (e.g. by operating an electric piston), seal the sample chamber by closing the valve (if the valve is to be operated independently of the piston), test the sample using the optical test device, including determining whether the level of the selected chemical is acceptable, and then opening the valve and draining the chamber. Preferably, there may be a time delay of, for example, ten minutes, between closing the valve and testing the sample. This is to allow for any particulate contaminants in the sample to settle, while the sample is held in a static test chamber so that any particles suspended in the system water do not affect the readings of the optical test device.

[0022] In some embodiments, a filter may be provided between the sample chamber and the central heating system to prevent particles from entering the sample chamber. However, this approach has some problems, including increased power consumption due to the resistance caused by the filter when operating the piston.

[0023] Alternatively, a magnet may be provided to attract any magnetic particles that may be entrained in the water to be tested. Preferably, the magnet is movable between an in-use position and an inactive position, wherein the in-use position is located where the magnet produces a magnetic field in the sample chamber, and the inactive position is located where the magnet is away from the sample chamber and does not produce a significant magnetic field in the sample chamber. During the test, once the sample chamber is sealed, the magnet may be brought to the in-use position. Any magnetic particles in the sample chamber will then be attracted to the magnet and removed from the body of water in the sample chamber, thereby cleaning the water. Once the test is completed, the magnet may be moved to the inactive position and the magnetic particles will return to the water.

[0024] The use of a removable magnet to temporarily maintain the magnetic particles ensures that the water is cleared of magnetic particles during the test. This, coupled with allowing the water to settle for a few minutes before testing, ensures that turbidity does not affect the test process. At the same time, as the magnet is removed after the test, magnetic particles do not accumulate in the sample chamber. The device is not intended to permanently remove magnetic particles from central heating system water, it is envisaged that it will be used in conjunction with a magnetic filter on a heating system circuit that is regularly cleaned. However, the provision of a removable magnet ensures that low levels of magnetic particles remaining in the system water will not interfere with the test process.

[0025] Preferably, the magnet is arranged outside the sample chamber, the magnet in the use position is arranged on the outer wall of the sample chamber, and the magnet in the inactive position is arranged at a position outside the sample chamber and separated from the wall of the sample chamber. The magnet can be mounted on a rotating arm to facilitate movement between the use position and the inactive position. When the piston is operated to draw fluid into and out of the chamber, the rotating arm can be arranged to rotate automatically so that when the chamber is full, the magnet is in the use position, and when the chamber is empty, the magnet is in the inactive position.

[0026] The selected chemical is in most cases a corrosion inhibitor, although the level of other chemicals can be measured using the device according to the present invention. In many embodiments, the optical test device can indirectly measure the level of the selected chemical because the tracer chemical will first be added to the corrosion inhibitor (or other selected chemical) and it is the tracer chemical that is directly measured by the optical test member. The tracer chemical can be selected to have a similar stability to the selected chemical (i.e. any degradation of the tracer chemical is approximately the same as the degradation of the selected chemical), so that the detection of a certain amount of the tracer chemical in the system water reliably indicates the presence of a certain amount of the selected chemical. A fluorescent dye tracer that has been found to have a good effect on typical corrosion inhibitors is 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (PTSA). This fluorescent dye is quite stable in typical inhibitor chemicals under the temperature conditions of typical heating systems. PTSA exhibits fluorescence at 405nm when excited with a 375nm light source. In typical inhibitors, it has been found that a tracer concentration of 200-400mg per liter of corrosion inhibitor is sufficient. When dosed correctly, this will result in a tracer concentration of approximately 0.8-1.6mg per litre of system water. An 'acceptable' inhibitor level is typically around 0.8mg tracer per litre of system water. When lower levels of tracer are detected, the unit should indicate that a top-up of inhibitor is required.

[0027] An embodiment of an optical test device suitable for measuring fluorescence includes a light source for exciting (tracer) chemicals - such as the PTSA used as described above, where the excitation light source needs to emit at least at 375nm, and a detector for detecting the emission wave of the emitted light - in this embodiment at 405nm. The intensity of the emitted light detected at 405nm is directly proportional to the concentration of the fluorescent tracer chemical in the sample, so a determination can be made simply based on whether the intensity of the detected light exceeds a threshold.

[0028] Preferably, the excitation light source is an LED and the detector is a photodiode. In one embodiment, the excitation light source and the detector are placed at an acute angle to each other, facing the substantially cylindrical borosilicate glass sample chamber. Alternatively, the light source and the detector can be arranged at an obtuse angle, perpendicular to each other or directly opposite each other.

[0029] Depending on the excitation light source and detector used in a particular embodiment, it may be necessary or desirable to include a filter before the detector to allow only light emitted from the fluorescent tracer to pass through and limit any interference from the excitation light source. Preferably, narrow band LEDs are used, but it is possible to use wider bandwidth excitation light sources and filters on the emitter and / or detector to reduce cost.

[0030] The optical property of PTSA measured by the device is fluorescence. However, alternative embodiments of the invention are also envisaged using different tracers or intrinsic optical properties of the chosen chemical, where the optical property measured is, for example, absorption or phosphorescence.

[0031] It is envisaged that the device will operate automatically to carry out the test, for example once every two weeks or once a month. This frequency is sufficient to ensure that the central heating system is not left with insufficient inhibitor for any significant period of time, but in the test intervals the device can be powered by a battery, for example a PP3 battery, which will last for a reasonable period of time.

[0032] A calibration element may be arranged in the sample chamber. Preferably, the calibration element is automatically moved into the sample chamber when the sample chamber is emptied and is moved out of the sample chamber again when water is pumped into the sample chamber for testing. In a preferred embodiment, the calibration element is provided as part of a piston so that when the piston is extended, the calibration element moves into the sample chamber. In one embodiment, the calibration element is a plastic part treated with a coating that causes it to fluoresce at a known and constant intensity, which fluorescence has similar characteristics to the tracer chemical used. Typically, calibration is performed as part of an automated test cycle, prior to each and all sample tests.

[0033] The device may output the test results as simply as, for example, a red LED which illuminates to indicate insufficient inhibitor concentration, and a green LED which illuminates to indicate sufficient inhibitor concentration. It is envisaged that more advanced embodiments will be able to transmit the test results, for example wirelessly via NFC or Bluetooth (RTM) or WiFi or other radio frequency communication technology, or via a wired communication channel. Some embodiments may be integrated into the boiler of a central heating system, in which case they may transmit the test results to a boiler data management system.

[0034] Some embodiments may include data storage means for storing historical test results that may be read out on an output device or downloaded to another device.

[0035] In some embodiments, the apparatus may include an inhibitor reservoir and means for introducing the inhibitor into the district heating system water. When the test indicates that the inhibitor concentration is too low, the system may automatically dose to restore the correct inhibitor concentration.

[0036] Alternatively, a separate dosing device may be provided on the same heating system, including an inhibitor reservoir and means for introducing the inhibitor into the central heating system water, the test device being arranged to communicate with the dosing device to cause dosing of the system water in response to a test result indicating that dosing is required. Ideally, when an insufficient inhibitor concentration is detected, an electronic signal (wired or wireless) may be sent by the test device to the dosing device to cause dosing of the system water.

[0037] In addition to the optical test device for determining whether the concentration of the selected chemical is acceptable, the apparatus may also include a test device for testing the turbidity, pH and / or conductivity of the central heating system water in the sample chamber. Turbidity can be measured with an optical test device, particularly an emitter and detector, which can operate over a relatively wide spectrum. Ideally, the turbidity test is carried out shortly after the water is pumped into the sample chamber, before any suspended particles have time to settle. Turbidity provides a measure of the level of particle contamination, and excess may indicate that the magnetic filter in the system has reached capacity and needs cleaning. If a removable magnet is provided, the turbidity test can be carried out when the magnet is in the inactive position. In some embodiments, a turbidity measurement can be made when the magnet is in the use position and a turbidity measurement can be made when the magnet is in the inactive position, and the difference between the two measurements is used as an indication of the turbidity level due to the magnetic particles. pH and conductivity can be measured by probes of known types, which require contact with the water in the sample chamber. It is important to ensure that the pH of the system water is low enough so that its alkalinity does not attack aluminum surfaces within the system, such as aluminum radiators or boiler heat exchangers. Conductivity can be used to measure the level of dissolved salts in system water, which can lead to scale formation.

[0038] According to a second aspect of the present invention, there is provided a method for testing water in a district heating system for a concentration of a selected chemical substance, the method comprising:

[0039] A sample of the central heating system water is drawn into the sample chamber;

[0040] Wait a period of time to allow suspended solids to settle out of the water in the sample chamber;

[0041] activating an optical testing device including a light source and a detector to measure an optical property of the sample to determine whether the level of a selected chemical in the water is greater than a predetermined threshold;

[0042] Empty the sample chamber.

[0043] Preferred / optional features of the second aspect of the invention are set out in claims 33 to 43.

[0044] According to a third aspect of the invention, there is provided an automatic dosing device for dosing chemicals into water in a central heating system, the dosing device comprising a fitting for permanently connecting the dosing device to a central heating system circuit, a chemical reservoir, a channel in the fitting between the central heating system circuit and the chemical reservoir, a valve in the channel, and a component for introducing chemicals from the chemical reservoir into the central heating system circuit in response to an electronic signal.

[0045] According to the first aspect of the invention, the electronic signal may be a signal from a test device. When the signal indicates that dosing is required, the chemical substance will be introduced from the reservoir into the district heating system circuit through the channel. When dosing is not required, the valve in the channel will be closed so that the reservoir is not in flow connection with the district heating system circuit.

[0046] A testing device working in conjunction can test the inhibitor concentration, and in response to a signal from the testing device, the dosing device can add inhibitor to the system to correct the insufficient concentration.

[0047] In one embodiment, the chemical reservoir is in the form of a syringe having a piston driven by an electronic actuator. In this embodiment, the valve may be a non-return valve which allows fluid to flow from the reservoir to the central heating system circuit, but not in the other direction. When the piston is extended into the syringe, fluid is forced from the reservoir through the non-return valve and through a passage in the fitting into the central heating system. Operating the syringe piston causes an increase in pressure in the syringe, which causes the non-return valve to open and allow fluid to flow into the central heating system circuit.

[0048] The actuator can be a motor. The motor can rotate a drive screw, which in turn moves the arm linearly, pressing the back of the plunger into the syringe, adding chemical to the system.

[0049] In an alternative embodiment, the reservoir is pressurized to a greater static pressure than the central heating system and the valve is an electric valve or another electronically actuated valve. For example, a solenoid valve may be suitable for some embodiments. In this embodiment, the valve may be opened for a period of time in response to an electronic signal, which will cause fluid to flow from the high pressure reservoir and into the low pressure central heating system.

[0050] The reservoir may be provided in the form of a pressurised canister including a press-open valve on the nozzle. When mounted to the dosing equipment, the canister may be held on a seat so that the valve on the canister nozzle is permanently open when the canister is mounted. The seat is at the entrance to the equipment passage. Fixing the canister in place may be achieved by a clamping arrangement which pushes the canister onto the seat and holds it in place. When the valve on the canister nozzle is permanently open it becomes an electronically actuated valve which controls the flow of fluid from the canister into the central heating system circuit. However, when the canister needs to be removed and replaced, the valve on the canister nozzle will close with the canister removed.

[0051] Preferably a switch or sensor is provided to detect when the tank has been removed and inhibit operation of the electronically actuated valve to ensure that the electronically actuated valve remains closed when the tank is not installed. Alternatively or additionally, a one-way check valve may be provided to prevent fluid from flowing out of the central heating system circuit when the tank is removed or depressurized.

[0052] In another alternative embodiment, the reservoir may again be provided in the form of a pressurised tank having a press-open valve on the nozzle. However, the pressurised tank may be located with the nozzle against the seat so that the nozzle is closed in the rest position. When an electronic signal is received and dosing is required, an electronic actuator may be provided to press the tank against the seat to open the nozzle and allow fluid to flow from the tank into the central heating system circuit. According to a fourth aspect of the invention, a combined testing and dosing device is provided based on the first and third aspects of the invention.

[0053] The testing and dosing equipment combination works together to protect district heating systems by continuously monitoring the concentration of corrosion inhibitors present in the system water. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to better understand the present invention and to more clearly show how it can be put into practice, preferred embodiments will now be described with reference to the accompanying drawings, in which:

[0055] Figure 1 shows a cross section through a first embodiment of a test apparatus according to a first aspect of the invention;

[0056] Figure 2 Shows Figure 1 A perspective view of the test device with the housing installed;

[0057] Figure 3 shows a cross section through a second embodiment of a test apparatus according to the first aspect of the invention;

[0058] Figure 4 Shows Figure 3 A perspective view of the test device with the housing installed;

[0059] Figure 5 Shows a perspective view of a third embodiment of the test device according to the first aspect of the present invention;

[0060] Figure 6 Shown through Figure 5 cross section of the equipment;

[0061] Figure 7 shows a cross section through a first embodiment of a dosing device according to a third aspect of the invention;

[0062] Figure 8 shows a cross section through a second embodiment of a dosing device according to a third aspect of the invention; and

[0063] Fig. 9 A cross section through a third embodiment of a medicated device according to a third aspect of the invention is shown. DETAILED DESCRIPTION

[0064] First reference Figure 1 , a first embodiment of a test apparatus according to the invention is generally shown at 10. The test apparatus 10 comprises a fitting or connector 12 for connecting the test apparatus 10 to a district heating system circuit, a sample chamber 14 for holding an isolated sample of district heating system water during testing, means for controlling the filling of the sample chamber 14 in the form of an electric piston 16 having an integrated valve 18 for sealing the sample chamber 14 when the piston is retracted, and optical test means comprising an excitation light source 20 and a detector 22.

[0065] The connector 12 is in the form of a simple T-connector, allowing district heating system water (for example) to flow into an inlet 24 and out of an outlet 26. In this embodiment, the connector 12 is symmetrical so that the inlet 24 and outlet 26 can be interchanged, i.e. with district heating system water flowing in the other direction. The connector 12 connects the sample chamber 14 to the district heating system circuit so that a sample of the district heating system water can be drawn into the sample chamber and automatically tested whenever required.

[0066] In this embodiment, the connector 12 is in the form of a reducing T, i.e. the inlet and outlet are compression fittings of 22 mm, and the branch of the T connected to the sample chamber 14 is of smaller diameter. As an alternative to a compression fitting, a push-fit fitting or any other suitable fitting may be provided for connecting the device to a district heating system circuit. Devices of different sizes may also be provided for district heating systems using pipes with a diameter greater or less than 22 mm.

[0067] As an alternative to a T-shaped connector, a Y-shaped connector may be used, or any other suitable shape.

[0068] The wall 14a of the sample chamber 14 is made of borosilicate glass, which is transparent and has a high resistance to thermal shock. The sample chamber 14 is essentially a cylindrical tube. A flow channel 28 is provided between the sample chamber 14 and the connector 12 to allow water to enter the sample chamber 14 from the central heating system circuit and then return from the sample chamber 14 to the central heating system circuit again.

[0069] To control the filling and emptying of the sample chamber 14, the piston 16 can be extended into the sample chamber to empty the sample chamber 14, or retracted to fill it. Figure 1 In the figure, the piston 16 is shown in an intermediate position; the fully extended position would be further toward Figure 1 The fully retracted position will be further toward the bottom. The piston 16 includes an O-ring pressure seal 16a, which prevents any water from entering behind the seal 16a (i.e. Figure 1 The pressure seal 16a also serves to clean the borosilicate glass wall 14a of the sample chamber 14 after each use to prevent darkening of the wall 14a and reduced light transmittance due to dirt accumulation.

[0070] In this embodiment, the piston includes an integrated valve 18. When the piston is fully retracted (i.e. Figure 1 When the valve 18 is in the center position (all the way down), the valve 18 engages the valve seat 18a to seal the sample chamber from the central heating system circuit and keep the water sample still and isolated.

[0071] The excitation light source 20 and the detector 22 are provided at an acute angle to each other, facing the sample chamber 14 outside the borosilicate glass wall. An opaque molded part 30 is provided, which accommodates the borosilicate glass tube sample chamber 14 and provides fixation of the light source 20 and the detector 22. The opaque molded part 30 prevents any light from entering the sample chamber 14 from the outside, controls the incidence of light from the light source 20 onto the sample chamber, and ensures that the light source 20 and the detector 22 remain in a fixed position relative to each other to maintain consistency of measurement.

[0072] A stepper motor 32 is provided for moving the piston 16 between the retracted and extended positions on the thread. Another type of actuator, such as a solenoid valve or other linear actuator, may be suitable for use in other embodiments.

[0073] Reference now Figure 2 , shows the same embodiment with housing 34 installed. The housing substantially encloses all components of the test device 10, with only the connector 12 extending out of the housing for connection to the central heating system circuit. Figure 1 In addition to the components described and shown in the figure, the housing 34 also accommodates a control PCB and a battery for powering the device. In some embodiments, an AC / DC transformer can be provided inside or outside the housing 34 to replace the battery.

[0074] Figure 3 An alternative embodiment of the test apparatus 10' is shown. In most respects, this embodiment is similar to Figure 1 1 and like parts are marked with like reference numerals. However, instead of the valve (18) being integral with the piston (16), an alternative embodiment uses an electric ball valve 18' disposed in the connector 12 to seal the sample chamber 14 from the central heating circuit. The ball valve 18' is operated by a separate motor (not visible in the figure) rather than by the stepper motor 32 that operates the piston 16'. Figure 4 As shown, the electric ball valve (18') and its corresponding motor are mounted in a separate housing 36.

[0075] The body of the piston 16 may include a calibration element which is arranged in the sample chamber, within the "line of sight" of the optical testing device, when the piston is in its extended position.

[0076] Typically, these devices are adapted to follow a test procedure as described below. The device will typically be controlled by electronics on a control PCB, which may be enclosed in housing 34, although in some embodiments this may be externally mounted, for example if the device is to be integrated into a boiler. The control PCB may include a microcontroller, or any other suitable type of control circuit.

[0077] The process begins with the piston 16 in its fully extended position and the sample chamber empty.

[0078] First, the excitation light source 20 is turned on. This excites the fluorescent coating on the calibration element, which forms part of the body of the piston 16. The fluorescent coating emits light at a wavelength of (for example) 405 nm. The intensity of the radiation at 405 nm is measured by the detector 22. Because the intensity of the excitation light source 20 and the fluorescent properties of the coating on the calibration element are known to a certain accuracy, the measurement from the detector 22 can be used to calibrate the device 10, effectively taking into account any dirt that may have accumulated on the borosilicate glass wall 14a. Once the calibration reading is taken, the excitation light source 20 can be turned off.

[0079] The piston 16 is then retracted, drawing the water sample into the sample chamber 14. Figure 1 ), this also has the effect of moving the integrated valve 18 to meet the valve seat 18a, sealing the sample chamber 14 from the central heating system circuit. Figure 3 ), the electric ball valve 18' must be operated at this stage to seal the sample chamber from the central heating system circuit.

[0080] Once the water sample enters the sample chamber 14, it is cooled and settled for a period of time. This period of time can be 5 minutes, or 10 minutes, or another period of time. The purpose of the delay is to allow any solids to settle out of the sample so that turbidity does not affect the test results. Allowing the sample to cool may also be necessary, depending on the optical properties being tested and the chemicals used.

[0081] The excitation light source is then turned on to excite the sample. This results in fluorescence of the sample, depending on the concentration of the selected chemical. It will be appreciated that fluorescence is not the only optical property that can be used to test the concentration of the selected chemical. Absorption and phosphorescence are other potentially suitable properties.

[0082] The detector then measures the intensity of the emitted light at, for example, 405 nm (which is the desired fluorescence emission wavelength for the tracer chemical in a particular embodiment). Preferably, multiple measurements are taken, for example three times over 10 to 20 seconds. Averaging multiple measurements helps ensure consistent results. Once all measurements have been taken, the excitation light source is turned off.

[0083] After the test is completed, the electric ball valve 18' (as used herein) is opened and the piston 16 is extended to evacuate the sample chamber 14. As the piston 16 is extended, the pressure seal 16a cleans the inside of the borosilicate glass wall 14a.

[0084] The readings from the detector 22 are evaluated. In a simple embodiment, a determination is simply made as to whether the level of the chemical is acceptable. A simple output interface may include a green LED to indicate acceptable levels and a red LED to indicate insufficient levels. Alternatively, the results may be transmitted to a subsequent system, such as a boiler data management system, via a wired or wireless connection. In some embodiments, when insufficient levels are detected, an electronic signal may be sent to a dosing device, resulting in dosing the system with an inhibitor.

[0085] Reference now Figure 5 and Figure 6 , another embodiment of the test device is shown at 10". This embodiment is similar to Figure 3 and Figure 4 The test device 10' is substantially the same as the test device 10', but includes a movable magnet 40. The magnet 40 is arranged at one end of a rotating arm 42, and by rotating the arm, the magnet can be moved from an in-use position in which the magnet 40 is in contact with the wall 14a of the sample chamber 14 to an in-use position in which the magnet 40 is separated from the wall 14a of the sample chamber 14. The in-use position is as follows: Figure 5 and Figure 6 shown.

[0086] The magnet in the use position contacts the exterior of the sample chamber wall 14a through the hole in the opaque overmolding. Preferably, a light-tight seal is provided to prevent light from leaking into the sample chamber. Alternatively, a light-tight outer housing may be relied upon to prevent extraneous light from leaking into the sample chamber.

[0087] like Figure 6 As most clearly shown, the swivel arm is connected to the test device body at a pivot 44. A spring 46 is provided between the pivot 44 and the magnet 40, which urges the magnet end of the swivel arm away from the wall of the sample chamber, i.e. into an inactive position. A follower 47 is provided at the other end of the swivel arm (non-magnetic). The follower 47 contacts a linear cam 48, which then moves linearly with the piston 16. When the piston 16 is retracted to fill the sample chamber 14, the linear cam 48 is positioned to lift the follower away from the test device body. By lifting the follower away from the test device body, the magnet 40 at the other end of the swivel arm contacts the wall 14a of the sample chamber 14, thereby resisting the action of the spring 46. In this way, whenever the syringe is retracted and the sample chamber is filled with liquid, the magnet 40 is positioned to contact the wall 14a of the sample chamber 14.

[0088] The magnet attracts any magnetic particles that may be entrained in the water sample being tested and prevents the entrained magnetic particles from adversely affecting the test procedure.

[0089] Reference now Figure 7 , a dosing device according to the third aspect of the invention is generally shown at 50. The dosing device comprises a fitting 52 for connecting the dosing device 50 to a central heating system circuit, a chemical reservoir 54 in the form of a syringe, and a passage 56 between the syringe 54 and the fitting 52. A non-return valve 58 is provided in the passage 56. The non-return valve 58 allows fluid to flow out of the syringe 54 and into the central heating system circuit, but prevents fluid from flowing out of the central heating system circuit and into the syringe 54.

[0090] The syringe 54 includes a piston 60 which can be extended into the syringe 54 (i.e., Figure 7 to the left in the center) to force liquid from syringe 54 through passage 56 and valve 58 and through fitting 52 into the central heating system circuit.

[0091] The syringe piston 60 can be pushed into the syringe body by an arm 62. The arm 62 includes a threaded hole. An externally threaded rod 64 passes through the hole and is fixed to one end of the shaft of a motor 66, which in turn is fixed relative to the syringe body 54. In this way, the motor can rotate the screw 64 so as to move the arm 62 linearly, extend the piston 60 to the syringe 54, and force the inhibitor chemical from the syringe 54 into the central heating system circuit.

[0092] The syringe 54 can be removed from the passage 56 so that when the syringe is empty, it can be refilled with the inhibitor chemical. After the syringe is removed, the non-return valve 58 will remain closed to prevent water from leaking out of the central heating system circuit.

[0093] Reference now Figure 8 , the dosing device of the second embodiment is generally shown at 70. The dosing device 70 also includes a fitting 72 for connection to a central heating system, a reservoir 74 containing an inhibitor chemical, a passage 76 between the reservoir 74 and the central heating system circuit, and a valve 78 in the passage 76. However, in this embodiment, the reservoir is a pressurized tank and the valve is an electric valve. In response to an electronic signal, the valve 78 opens and fluid will flow from the reservoir into the central heating system due to the greater static pressure on the reservoir side. The valve 78 can be opened for a period of time to control the amount of inhibitor chemical entering the central heating system.

[0094] The pressurized canister 74 includes a nozzle 80 with a push-open valve. A seat is provided at the entrance to the passage 76, onto which the nozzle 80 is pushed when the canister is fitted, keeping the push-open valve permanently open when the canister 74 is connected to the dosing device 70. The canister 74 is secured to the remainder of the device 70 and is pushed onto the seat by a clamp 82 extending from the fitting 72, against the seat at the entrance to the passage 76, along the outside and behind the canister. The clamp 82 may be spring loaded to allow for quick release of the canister. When the canister is removed, the valve on the nozzle 80 will close to prevent any leakage. It is envisioned that the disposable canister will be filled with the inhibitor chemical, and when the canister is empty, it will be discarded and replaced with a new, full, pressurized canister.

[0095] Reference now Fig. 9 , the chemical dosing device of the third embodiment is generally shown at 90. The dosing device includes a fitting 92 for connecting to a central heating system circuit, a reservoir 94, which is a pressurized tank with a push-open valve on the nozzle in this embodiment, similar to the tank (74) of the second embodiment, a passage 96 in the fitting between the tank 94 and the central heating system circuit, and a non-return valve 98 in the passage 96. The tank 94 is provided with a nozzle 100, which is located at the entrance of the passage 96. When the tank 94 is pushed to the entrance of the passage 96, the valve on the nozzle 100 will open, and the chemical will pass through the non-return valve 98, enter the passage 96, and then enter the central heating system circuit 92.

[0096] The canister 94 is secured to the entrance of the passage 96 by a clamping and actuating arrangement 102. One end of the clamping and actuating arrangement is secured to the fitting. A retractable element 104 extends from the fitting 92 and extends along the outside of the canister 94 (at Fig. 9The push-open valve is formed by a retractable element 104, which is located below the tank 94 in the middle) and then behind the tank, which holds the tank 94 from the rear. By retracting the retractable element 104, the nozzle 100 of the tank is pushed onto the seat at the entrance of the passage 96 to open the push-open valve. The retractable element 104 is retracted by an actuator 105. The actuator can be a motor with a threaded rod, or alternatively, the actuator can be a solenoid valve or other linear actuator. The actuator operates in response to an electronic signal to retract the rod, push the tank 94 toward the entrance of the passage 96, and dose the heating system with inhibitor chemicals from the tank 94.

[0097] The test device and dosing device can work together to protect the heating system. When the test device detects an insufficient amount of inhibitor chemical in the central heating system, it sends an electronic signal to the dosing device, causing the system to be dosed with inhibitor, thereby correcting the dosing level before serious corrosion is allowed to occur. In some embodiments, the test device and dosing device can be incorporated into a single housing and / or can share a single fitting for connection to the central heating system loop.

[0098] The embodiments described above and shown in the figures are merely examples of how the invention may be put into practice. Various modifications will be apparent to the skilled person. The invention is defined in the claims.

Claims

1. A combination of automatic testing equipment and dosing equipment, including: A test device and an automatic dosing device for testing the level of selected chemical substances in district heating system water in a district heating system circuit, the test device comprising: a sample chamber for holding a sample of the central heating system water to be tested, the sample chamber being adapted to be connected to a central heating system circuit to allow fluid to flow between the central heating system circuit and the sample chamber; means for controlling the filling of the sample chamber with district heating system water from the district heating system circuit and the emptying of the sample chamber by returning the district heating system water to the district heating system circuit; at least one valve for isolating a sample of the district heating system water from the district heating system circuit during testing; as well as an optical test device including a light source and a detector for measuring an optical property of a sample of the central heating system water isolated in the sample chamber to determine whether the level of a selected chemical in the water is greater than a predetermined threshold level; The automatic dosing device is used to dose a selected chemical substance to the central heating system water, the dosing device comprising a fitting for permanently connecting the dosing device to the central heating system loop, a chemical substance reservoir, a fitting passage between the central heating system loop and the chemical substance reservoir, a valve in the passage, and a member for introducing the chemical substance from the chemical substance reservoir into the central heating system loop, wherein the test device is suitable for sending an electronic signal to the dosing device to cause the dosing device to dose the chemical substance into the central heating system loop in response to a measurement on the test device indicating an insufficient concentration of the chemical substance.

2. A combination as claimed in claim 1, wherein the test device and the dosing device share a single fitting for connection to a central heating system circuit.

3. A combination as claimed in claim 1 or 2, wherein the chemical reservoir is in the form of a syringe.

4. A combination as described in claim 3, wherein the syringe has a piston that extends to the syringe body by motor operation.

5. A combination as claimed in claim 1 or 2, wherein the valve is a one-way check valve arranged to allow fluid to flow from the reservoir to the district heating system circuit, but not to allow fluid to flow from the district heating system circuit to the reservoir.

6. The combination of claim 1, wherein the reservoir is provided in the form of a pressurized tank.

7. A combination as claimed in claim 6, wherein the valve is an electric valve which opens for a period of time in response to an electronic signal to allow fluid to flow from the pressurised reservoir into the central heating system circuit.

8. The combination of claim 6 or 7, wherein the pressurized canister includes a nozzle having a push-open valve.

9. A combination as claimed in claim 8, wherein an actuator is provided, the actuator being arranged to push the can against a seat at the entrance of the passage to open a push-open valve on the nozzle of the can in response to an electronic signal.

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