Fluid flow control device

Abstract

A fluid flow control device has a set of at least two control valves 4, each valve 4 having first, second, and third ports (21, 22,23, fig 4) and an actuator 3 to switch the control valve 4 between fi

Description

Field of the Invention The present invention relates to a fluid flow control device and a method of controlling 5 fluid flow. Specifically, the present invention relates to a device and method to control the flow of a fluid, for example a gas, from multiple sources. Background Automatic analysis of methane (CH4) composition and carbon dioxide (C02) io composition for low biogas flow conditions, such as those towards completion of Biochemical Methane Potential (BMP) tests are challenging due to the low volume of fluid which is released from a reactor, and the high degree of accuracy required for measurements. For example, the volume of fluid from one reactor may be less than 7 ml. This fluid has to be carried to a sensor in a fluid channel, which may be a few 15 millilitres in volume. There is also a need to measure multiple channels using a single probe or sensor, whilst ensuring no residue of a previous read is counted, and to account for the effect of increased back pressure on calibration values of existing volume displacement cells. In addition, a system designed to deal with low-volume fluid flow and composition analysis may also be required to maintain the ability to 20 measure other important gas components of interest, such as H2S, if required. Further, it is often desirable to achieve such systems at low cost. 05 03 25 Summary According to a first aspect of the invention, there is provided a fluid flow control device comprising: a set of at least two control valves, each valve having a first, second, and third ports and an actuator configured to switch the control valve between first and 5 second states, wherein in the first state the first port is in fluid communication with the second port, and in the second state the first port is in fluid communication with the third port. The fluid flow control device further comprises a controller arranged to control the actuators of the control valves such that at any given time, one of the at least two control valves is selected to be in the first state and the rest of the at least two io control valves is in the second state. Thus, the controller can control the flow of a fluid, for example a gas, from multiple sources to, for example, a manifold, wherein the second ports are connectable to a respective port on a manifold. This may allow for the measurement of fluid from one of 15 multiple sources, while any fluid from the remaining sources is vented outside the device. Venting the remaining sources of fluid may have the effect of reducing the pressure in fluid transport channels of the device, which may increase measurement accuracy. 20 In the first state, the third port may be closed. In the second state, the second port may closed. Only one of the at least two control valves may be selected to be in the first state. 25 The device may comprise a manifold having a plurality of inlet ports and an outlet port, wherein each second port is fluidly connected to a respective inlet port. There may be a one way valve arranged between each second port of the control valves and the respective inlet port of the manifold, preventing fluid flowing from an inlet port 30 of the manifold to a respective second port of the control valve. The device may further comprise a sensor, wherein the outlet port of the manifold is connected to a sensor. 35 In the second state, the third port may be fluidly connected to a vent. 05 03 25 That is, when a control valve is in the second state, fluid may be released from the control valve. The sensor may be a fluid flow sensor. The sensor may be a material sensor, for 5 example a methane sensor or a carbon dioxide sensor. There may be a one way valve arranged between the outlet port of the manifold and the sensor, which may allow for fluid to travel only from the outlet port of the manifold to the sensor, and may prevent fluid form flowing from the sensor to the outlet port. io The actuator may be an electromechanical actuator. For example, the electromechanical actuator may be solenoid. The control valves may be solenoid control valves. 15 The at least two control valves may be zero-pressure valves. This may have the effect of reducing the pressure in channels carrying fluid in the device, which may increase measurement accuracy of the system or device. The first and second states of the at least two control valves may be stable states. The at 20 least two control valves are bi-stable. That is, the control valve may remain in either first or second state without being powered, either continually or sporadically, to do so. The at least two control valves may be latch valves. The controller may be a microcontroller. The controller may be operatively connected 25 to one or more relay modules. Each relay module may control the state of one or more of the at least two control valves, for example by controlling their respective actuators. The controller may be arranged to receive a signal from one or each of a set of two or more mass flow sensors, each mass flow sensor corresponding to a respective control 30 valve. The mass flow sensor may be a tumbler mass flow sensor and the signal may indicate that the tumbler has overturned, released gas and is in a new stable state. Thus, the controller receiving the signal from the mass flow sensor indicates that fluid will be 35 received at the first port of the respective one of the set of two or more control valves. 05 03 25 The controller, on receiving a signal from the mass flow sensor, may be configured to send a signal to the actuator of the respective control valve to arrange the respective control valve in the first state. 5 The controller may be configured to send a signal to the remaining actuators (that is, the actuators which are not the respective actuator of the mass flow sensor sensing a signal) to arrange their respective control valves (that is, those not corresponding to the mass flow sensor from which the signal is received) in the second state. io The first port may be connectable to a source of gas. For example, the source of gas maybe a bottle, a canister, or a reactor. The reactor may be an anaerobic reactor. According to a second aspect of the invention, there is provided a method of operating the device of the first aspect, the method comprising: causing a first actuator in a 15 plurality of actuators to be in a first state; causing the rest of the actuators to be in a second state. Each actuator is configured to switch a control valve between first and second states, each valve having a first, second, and third ports, wherein in the first state the first port is in fluid communication with the second port, and in the second state the first port is in fluid communication with the third port, each second port 20 connectable to a respective inlet port of a manifold. Wherein causing the actuator(s) to be in either a first or a second state comprises sending a signal to the actuator. The signal may be received from a mass flow sensor. 25 The signals specifying the first and second states and the arrangements of the control valves into first and second states may happen simultaneously. The method may further comprise measuring a property of any fluid released from the second port of the control valve in the first state. The property7 may be, for example, 30 volume or composition. For example, if the fluid is a gas, the presence or concentration of methane or carbon dioxide may be measured. According to a third aspect of the invention, there is provided a computer program comprising instructions which when executed by one or more processors causes the one 35 or more processors to perform the method of the second aspect. 05 03 25 According to a fourth aspect of the invention, there is provided a computer program product comprising a computer-readable medium storing the computer program of the third aspect. 5 According to a fifth aspect of the invention, there is provided a module configured to perform the method of the second aspect. The module may be a hardware module. According to a sixth aspect of the invention, there is provided a monolithic integrated circuit comprising: a processor subsystem comprising at least one processor and io memory: and the module of the fifth aspect of the invention. According to a seventh aspect of the invention, there is provided a system comprising: the device of the first aspect and an integrated circuit of the sixth aspect arranged to control the device. 15 The integrated circuit maybe a digital integrated circuit. The integrated circuit may include memory. The memory may be volatile memory such as DRAM or SRAM. The memory7 maybe non-volatile memory, such as EPROM, EEPROM, NOR flash or NAND flash. The integrated circuit may be a micro integrated circuit, such as a 20 microprocessor, microcontroller or signal processing chip. The integrated circuit may be a microcontroller with embedded Flash memory. The integrated circuit may be a processor without embedded Flash memory. The integrated circuit may be a system-on-a-chip (SoC). The integrated circuit may a logic integrated circuit, such as application-specific integrated circuit chip, standard logic or display driver. The 25 integrated circuit may be a fixed-logic integrated circuit. The integrated circuit may include a field-array gate array (FPGA). The device may further include connectivity7 modules, such as wireless connectivity modules or local area network connectivity modules, such as Bluetooth modules, WiFi 30 modules and the like. The connectivity modules may- be configured to retrieve data from a server, such as a cloud server. 05 03 25 Brief Description of the Drawings Certain embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure i is a schematic block diagram of a device used to control fluid flow; 5 Figure 2 is a schematic block diagram of a device used to control fluid flow; Figure 3 is a schematic block diagram of a device used to control fluid flow; Figure 4 is a schematic block diagram of fluid flow paths of the fluid flow measuring device; Figure 5 illustrates a first multichannel manifold; 10 Figure 6 is a vertical cross-section of eight mass flow sensors and their connections to a perspective view of a plurality of bioreactors; Figure 7 illustrates a top view of a second multichannel manifold; Figure 8 illustrates a side view of the second multichannel manifold; Figure 9 illustrates a bottom view of the second multichannel manifold; 15 Figure 10 illustrates a vertical cross-section of the second multichannel manifold; Figure 11 illustrates a perspective view of the second multichannel manifold; Figure 12 illustrates a perspective view of the second multichannel manifold; Figure 13 illustrates a bottom view of the second multichannel manifold; Figure 14 illustrates a top view of the second multichannel manifold; 20 Figure 15 illustrates a vertical cross-section view of the second multichannel manifold; Figure 16 illustrates a first side view of the second multichannel manifold; Figure 17 illustrates a second side view of the second multichannel manifold; Figure 18 illustrates a first horizontal cross-sectional of the second multichannel manifold; 25 Figure 19 illustrates a second horizontal cross-sectional of the second multichannel manifold; Figure 20 illustrates a third horizontal cross-sectional of the second multichannel manifold; and Figure 21 is a process flow diagram of a method of operating a fluid flow measuring 30 device. 05 03 25 Detailed Description Referring to Figure 1, a system 1 for measuring the volume or composition of a fluid is shown. 5 The system 1 can be used for Residual Biogas Potential (RBP) and Biochemical Methane Potential (BMP) testing. The system 1 includes a controller 2, for example a microcontroller, and one or more actuators 3i, 32,3.-,,34,---, 3n. The actuator 3 maybe an electromechanical actuator, e.g. 10 a solenoid valve, hydraulic or pneumatic actuator. Each actuator 3 is arranged to control a respective control valve 4i, 42,43,44, ---, 4n- Each actuator 3 may operate more than one control valve 4. The control valve 4 may be a zero-pressure valve, for example, a zero-pressure solenoid valve, or a zero-pressure latching valve. This may have the effect of reducing the pressure in channels carrying fluid in the device, which may 15 increase measurement accuracy of the system 1 or device. The actuators 3 may be controlled via a relay driver 5 which includes one or more relay modules 6 for relaying a signal from the controller 2 to the one or more actuators 4. The relay driver 5 may include a second controller 7 which may receive the signal from the 20 first controller 2 and send a signal to control each of the one or more relay modules 6. The first controller 2 (also referred to simply as “controller”) may include a processor 8, for example a central processing unit (CPU) or a graphics processing unit (GPU), a sensor reader 9, a wireless controller 10, for example a Blue Tooth or WiFi controller, 25 memory 11, for example, dynamic random-access memory (DRAM) and static randomaccess memory (SRAM), and data storage 12 which may take the form on non-volatile memory, for example NVRAM. The first controller 2 maybe operatively connected to one or more sensors 15, for 30 example, a methane (CH4), carbon dioxide (C02), and flow rate sensors. The first controller 2 is connected to an interface 16 via the wireless controller 10. The interface 16 may be a local area networked (LAN) computer which is capable of displaying data from the sensor in real-time or near real-time. The data from the sensors 15 may be downloaded onto the interface 16 (e.g. computer) for further processing. The sensors 15 35 may also be connected to the controller 2 via the wireless controller 10. The controller 2 05 03 25 and the sensors 15 may be connected via a suitable cable. The controller 2 may also include a clock (not shown), and a level shifter (not shown). Referring to Figure 2. a second example system 12 is shown. In the second system 12, the 5 wireless controller 10, memory 11, data storage 12, clock 17, and level shifter 18 may be separate modules to the controller 2 and are operatively connected to the microprocessor 2. The controller 2 maybe operatively connected to one or more flow sensors 19, for 10 example, a mass flow sensor and be configured to receive a signal from the flow sensor 19. Referring to Figure 3, the controller 2 is connected to four relay modules 6b 62, 63, 64, each relay module 6 is connected to four actuators 3 and each actuator 3 controls one 15 control valve 4. Thus, in this example, sixteen control valves 4 may be controlled by one controller 2. Additional relays 6, actuators 3 and control valves 4 maybe added to a suitable controller 2. Referring to Figure 4, each control valve 4 is a three-way control valve having a first 20 port 21, a second port 22 and a third port 23. The control valve 4 can switch between first and second states. In the first state the first port 21 is in fluid communication with the second port 22, and in the second state the first port 21 is in fluid communication with the third port 23. For clarity, only the first control valve 4t of Figure 4 has the first port 2ii, the second port 221 and the third port 231 labelled. The control valve 4 may be 25 bi-stable, for example, the first and second states of a control valve 4 may be stable states. That is, the control valve 4 may remain in either first or second state without being powered, either continually or sporadically, to do so. The control valve 4 may be a latch or latching valve, for example, an LHL series control solenoid valve, e.g. LHLA1221411H, which is a three-way latching valve. 30 The control valve 4 may be a magnetically latched control solenoid valve. The control valve may be an ultra-low power consumption valve, for example, as low as 5.5 mJ per switch. The control valve 4 may have low heat dissipation. If the control valve 4 is a latch valve, moving the valve form one state to another (i.e. the latching movement) 35 may require only momentary pulses of current to switch to and remain in each flow 05 03 25 state. While held in a specific flow state for an extended period of time, the control valve 4 may not consume power, may not generate heat, or may not produce noise. Each first port 21 is connected to a respective source of fluid 25, for example a gas 5 source. The fluid source 25 may be a reactor, for example a bioreactor that releases gas or gases from a biological reaction. The gases released from the bioreactor may include methane (CH4) and carbon dioxide (C02). There may be a plurality of fluid sources 25 in one fluid source unit 26, for example, a static batch reactor system. If the source of fluid is a bioreactor, for example a bioreactor bottle containing fluid e.g. a digestate, 10 each fluid source 25 may also include a respective agitator (not shown) or “stirrer”. The agitator stirs the digestate so that is it homogenous. The fluid from each fluid source 25 then enters a respective flow sensor 19. Fluid flow sensors may take any suitable form for example, they may be differential pressure flow 15 sensors, or thermal mass flow sensors. If the fluid is gas, each flow sensor 19 can take the form of a gas tumbler having a housing which contains a pivoted trapezoidal block and which is partially filled with water. As gas enters the tumbler, it is trapped under the block which is initially in a rest position. A volume of gas begins to collect and starts to lift one side of the block. This continues until a sufficiently large volume of gas has 20 been collected which tilts the block enough to allow the volume of gas to escape. The block returns to its rest position (i.e. it tumbles) and the process is repeated. The volume of gas needed to tip the block is known and by counting each time the block tumbles (for example using a magnet connected to the block and a reed switch), the total volume of gas can be calculated. 25 The fluid flow sensors 19 may be housed in a single block 29. Each second port 22 is connected to a respective inlet 31 of a multichannel manifold 32. The multichannel manifold 32 may have any number of inlets, for example, eight, or 30 sixteen inlets. The multichannel manifold has one outlet 33 through which fluid from one of the inlets flow out of the multichannel manifold 32. Optionally, there may be a one-way valve 34 between the second port 22 and the inlet 31 of the multichannel manifold 32 to prevent fluid flowing form the multichannel manifold 32 towards the control valve 4. 05 03 25 The third port 33 is connected to a first vent 35, for example, if the fluid is a gas, the vent may be in fluid communication with the atmosphere around the system. Alternatively, the vent maybe connected to a collection bag (not shown), or alternative fluid waste deposit. A one-way valve (not shown) may also be connected to the third 5 port 23 to prevent fluid entering the valve 3 from the vent 35. The outlet 33 is connected to at least one sensor 15, for example a methane (CH4) or a carbon dioxide (C02) sensor. Optionally, there may be a one-way valve 36 between the outlet 33 and a first sensor 15. At least one sensor 15 is connected to a second vent 37 10 and, optionally, a one-way valve 38 may be connected between the second vent 37 and the at least one sensor 15 to prevent fluid from the vent flowing into the sensor 15. The second vent 37 has a similar function and may have a similar constructions to the first vent 35. 15 Referring again to Figures 1 to 4, the controller 2 is arranged to receive a signal from a mass flow sensors 19 (for example, one mass flows sensor 19 from a set of two or more mass flow sensors 19). Each mass flow sensor 19 may correspond to a respective control valve 4. Where the mass flow sensor 19 is a tumbler mass flow sensor 19, the signal from the mass flow sensor may indicate that the tumbler has overturned, released gas 20 and is in a new stable state. Thus, the controller 2 receiving the signal from the mass flow sensor 19 indicates that fluid will be received at the first port 21 of one of the set of control valves 4. The controller 2, on receiving a signal from a mass flow sensor 19, sends a signal (for example via the relay drivers(s) 5 and relay module(s) 6) to the actuator 3 of the respective control valve 4 to arrange the respective control valve 4 in 25 the first state - where the first port 21 is in fluid communication with the second port 22 and the third port 23 is not in fluid communication with either the first port 21 or the second port 22. Thus, fluidly connecting the respective gas source 25 from which the signal originated with the manifold 32, and the sensors 15. The controller 2 also sends signals to the remaining control valves 4 not corresponding to the mass flow 30 sensor 19 from which the signal is received to arrange these remaining control valves 4 in the second state - where the first port 21 is in fluid communication with the third port 23 and the second port 22 is not in fluid communication with either the first port 21 or the third port 23. Thus, gas from the remaining gas sources 25 is vented to outside the device or system 1. In this way, the controller 2 can control the flow of a fluid, for 35 example a gas, from multiple sources 25 to, for example, a manifold 32 (for example, a 05 03 25 multichannel manifold 32), and can allow gas from one gas source 25 to be measured, and can vent gas from other gas sources 25. For example, gas is released from a third fluid source 253 into the third flow sensor 193 5 causing it to tumble and send a signal to the controller 2. The controller 2 sends a signal to the third actuator 33 (e.g. via the first relay module 61) to arrange the third control valve 43 in the first state and simultaneously send a signal to all remaining actuators 31, 3a, 34, 3s, 36, —, 3n to arrange their respective control valves 4i, 42, 44,45, 46,..., 4n in the second state. This may allow for the measurement of fluid from the third fluid source 10 253, while any fluid from the remaining sources 251, 252, 254, 255,..., 25n is vented outside the device 1. Venting the remaining sources 25 of fluid, rather than closing the valve and keeping the gas in the device or system may have the effect of reducing the pressure in fluid transport channels of the device 1, which may increase measurement accuracy. 15 Optionally, if the system is to be used with a gas, there may be a desiccator 38 arranged between the gas source 25 and the sensor 15. The desiccator 38 may be for example a bottle containing silica gel, or other suitable desiccating agent, the desiccator 38 maybe a gas-drying bottle. The desiccator may reduce the humidity of the gas before the gas 20 reaches the sensor 15, prolonging the life of the sensor 15 and may also improve the accuracy of the sensor 15. Referring to Figure 5, the multichannel manifold 32 may take the form of a disc having the outlet 33 in the centre of the disc and the inlets 31 around the circumference of the 25 multichannel manifold 32. Referring to Figure 6, a fluid source unit 26 in the form of a bioreactor system includes several bioreactor bottles which are sources of gas 25. An agitator 40 stirs the fluid in the bioreactor bottles to keep the fluid homogenous. Gas from each bioreactor bottle 30 (e.g. fluid source 25) then flows to and enters a respective flow sensor 19 in the fluid flow block 29. Referring still to Figure 6, a cross-section of a gas tumbler flow measuring device block 29 having eight individual tumbler flow sensors 19 as described earlier receives gas from the bioreactor bottles. Each flow sensor 19 receives gas from a respective bioreactor gas source 25. 05 03 25 Referring to Figure 7, a top view of a circular or disc-shaped multichannel manifold 32 shows sixteen actuators 3 attached around the circumference of the manifold 32. Each actuator 3 has a respective inlet 31 and a respective vent 34 arranged in a line between the actuator 3 on the circumference and the centre of the manifold 32. In this example, 5 the vent 34 is closer to the centre of the manifold 32 than the inlet 31. Referring to Figure 8, a side view of the multichannel manifold 32 in Figure 7 is shown. Here the single outlet 33 is visible at the bottom of the manifold 32 in the centre. The outlet 33 is where the fluid exist the manifold 32 and enters a sensor 15, optionally via a 10 one-way valve 34. The side view also illustrates the location of the control valves 4 adjacent to their respective actuators 3. Referring to Figure 9, a bottom view of the manifold 32 is shown. The outlet 33 is located in the centre of the manifold 32. The control valves 4 are located around the 15 circumference of the manifold 32 adjacent to (or “below”) their respective actuator (not shown). Referring to Figure 10, a cross-section of the manifold in Figure 7 reveals the first port 21, second port 22 and third port 33 of the control valve 4. A first channel 41 connects 20 the inlet to the first port 21. A second channel 42 connects the second port 22 to the outlet 33. A third channel 43 connects the third port 23 to the vent 35. The first channel 41 and second channel 42 may make up at least part of the flow path of the first state. The first channel 41 and the third channel 43 may make up at least part of the flow path of the second state. 25 Referring to Figure 11, a perspective view of a multichannel manifold 32 is shown having sixteen actuators 3, control valves 4, inlets 31 and vents 35. Referring to Figure 12, a perspective view of the manifold 32 of Figure 7 is shown 30 without the actuators 3, control valves 4, or connectors for the inlets 33 and vents 35. The ends of the first channel 41, second channel 42, and third channel 43 are shown at the circumference of the manifold 32 where the first port 21, second port 22, and third port 23 connect respectively. 35 Referring to Figure 13, a bottom view of the manifold 32 of Figure 12 is shown showing the outlet 33 in the centre of the manifold 32. 05 03 25 Referring to Figure 14, a top view of the manifold 32 of Figure 12 is shown illustrating the locations of sixteen inlets 31 and their respective vents 35. Each inlet 31 and vent 35 may have an M6 tapped thread hole for the securing of a suitable connector. 5 Referring to Figure 15, a cross-section D-D of the manifold 32 of Figure 14 shows the first channel 41, second channel 42, and third channel 43 in the cross-section. The third channel is in fluid communication with the outlet 33. The first, second, and third channel 41,42,43 diameters may be manufactured to be as small as possible, such that 10 the volume of the channels is veiy low. For example, the first, second, and third channel 41, 42,43 diameters maybe the between 1 mm, and 3 mm, for example, 1.5 mm, 1.6 mm, 1.98 mm, 2 mm, 2.5 mm to keep the volume of the channels 41, 42, 43 as small as possible. Keeping the volume of the fluid flow channels as small as possible may ensure there is minimum residue of a previous gas measurement is counted and 15 therefore may allow for increased accuracy of measurements of the gas. The first port 21, the second port 22 and the third port 23 may have the same range, or the same value of diameter as the first second and third channels 41,42,43. Referring to Figure 16, a side view of the manifold 32 of Figure 12 is shown. The ends of 20 the first channel 41, second channel 42, and third channel 43 can be seen at the circumference of the manifold 32. Referring to Figure 17, a side view of the manifold 32 of Figure 12 is shown indicating cross-sections A-A, B-B, and C-C. Referring to Figure 18, cross-section A-A of Figure 12 25 is shown revealing sixteen third channels 43 in fluid communication with the outlet 33. Referring to Figure 19, cross-section B-B reveals sixteen second channels 42. Referring to Figure 20, cross-section C-C reveals sixteen first channels 41 and part of the sixteen second channels 42. 30 Referring to Figure 21, to operate the system 1, optionally, the controller 2 received a signal from a mass flow sensor 19 (step Si). On receiving the signal, the controller 2 sends a signal to a respective actuator 3 causing the actuator 3 to be in a first state and sends a signal to the rest or remaining actuators 3 causing them to be in a second state (step S2). Optionally, a property, for example volume, or the presence or concentration 35 of a material is measured (step S3). 05 03 25 The signals may be sent simultaneously, causing the actuators 3 to be in the required states simultaneously. As explained above, when the actuator is in a first state, it causes the respective control valve 4 to be in a first state and when the actuator is in a second state, it causes the respective control valve 4 to be in a second state. 5 Modifications It will be appreciated that various modifications may be made to the embodiments hereinbefore described. Such modifications may involve equivalent and other features which are already known in the design, manufacture and use of gas measuring devices, 10 systems and component parts thereof and which may be used instead of or in addition to features already described herein. Features of one embodiment may be replaced or supplemented by features of another embodiment. Although claims have been formulated in this application to particular combinations of 15 features, it should be understood that the scope of the disclosure of the present invention also includes any novel features or any novel combination of features disclosed herein either explicitly or implicitly or any generalization thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention. 20 The applicants hereby give notice that new claims may be formulated to such features and / or combinations of such features during the prosecution of the present application or of any further application derived therefrom. 05 03 25

Claims

1. A fluid flow control device comprising:a set of at least two control valves, each valve having a first, second, and third5 ports and an actuator configured to switch the control valve between first and second states, wherein in the first state the first port is in fluid communication with the second port, and in the second state the first port is in fluid communication with the third port; anda controller arranged to control the actuators of the control valves such that at io any given time, one of the at least two control valves is selected to be in the first state and the rest of the at least two control valves is in the second state.

2. The device of claim 1, further comprising:a manifold having a plurality of inlet ports and an outlet port, wherein each15 second port is fluidly connected to a respective inlet port.

3. The device of claim 2, further comprising:a sensor, wherein the outlet port of the manifold is connected to a sensor.20 4. The device of any one of claims 1 to 3, wherein in the second state, the third portis fluidly connected to a vent.

5. The device of any one of claims 1 to 4, wherein the actuator is an electromechanical actuator.

256. The device of any one of claims 1 to 5, wherein the at least two control valves are zero-pressure valves.

7. The dev ice of any one of claims 1 to 6, wherein the first and second states of the30 at least two control valves are stable states.

8. The device of any one of claims 1 to 7, wherein the at least two control valves are latch valves.35 9. The device of any one of claims 1 to 8, wherein the controller is amicrocontroller.05 03 2510. The device of any one of claims 1 to 9, wherein the controller is arranged to receive a signal from one of a set of two or more mass flow sensors, each mass flow sensor corresponding to a respective control valve.

511. The device of claim 10, wherein the controller, on receiving a signal from the mass flow sensor, is configured to send a signal to the actuator of the respective control valve to arrange the respective control valve in the first state.10 12. The device of any one of claims 1 to 11, wherein the first port is connectable to asource of gas.

13. A method of operating the device of claim 1, the method comprising: causing a first actuator in a plurality of actuators to be in a first state;15 causing the rest of the actuators to be in a second state,each actuator configured to switch a control valve between first and second states, each valve having a first, second, and third ports, wherein in the first state the first port is in fluid communication with the second port, and in the second state the first port is in fluid communication with the third port, each second port connectable to20 a respective inlet port of a manifold.

14. The method of claim 13, further comprising: measuring a property of any fluid released from the second port of the control valve in the first state.2515. The method of claim 13 or 14, wherein the property is volume.

16. A computer program comprising instructions which when executed by one or more processors causes the one or more processors to perform the method of any one 30 of claims 13 to 15.

17. A computer program product comprising a computer-readable medium storing the computer program of claim 16.35 18. A module configured to perform the method of any one of claims 13 to 15.19- A monolithic integrated circuit comprising:a processor subsystem comprising at least one processor and memory; and the module of claim 18.5 20. A system comprising:the device of any one of claims 1 to 12; andan integrated circuit of claim 19 arranged to control the device.03 25

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