man mm 20
Contents
1. part with a switch 130 toggled to allow the appropriate signal to pass If the sensor determines the overall flow out of a room then the switch 130 is toggled to allow a zero input signal to pass through the 1 input of the switch 130 If the exhaust sensor is disposed such that only the exhaust of the room less the exhaust out of hood A and hood B is sensed then the switch 130 is toggled such that the sum of the exhaust out of hood A and hood B accomplished with summer 135 is passed through the input of the switch 130 to be added at summer 125 to the exhaust flow from the room Alternatively the delta flow set point signal can be manually set by toggling a switch 140 between PID No 1 and PID No 4 to only allow a manual flow set point signal to pass through the switches input as opposed to allowing the delta flow set point signal of PID No 1 to pass through the input of the switch 140 In the event it is desired to manually control the exhaust damper and the supply damper such that they are fully open or fully shut respectively by properly toggling switch 150 and switch 160 respectively 100 open or 0 open signal respectively is provided to the switches 1 inputs and is passed therethrough to open or close the exhaust and supply dampers respectively In this manner the room can be quickly depleted of air if for instance a fire or toxic chemical release occurs If the switch 50 and switch 60 is toggled such that the signal2. 33 Apparatus as defined in claim 31 wherein said deriva tive action factor at any given time is directly proportional to the difference between any error determined from the immediately prior sample and the current sample divided by a loop cycle time 34 Apparatus as defined in claim 31 wherein said pro portional action factor at any given time is directly propor tional to any error determined from the current sample 35 Apparatus as defined in claim 31 wherein said modu lating means comprises a motor driven blower means wherein said motor is controlled by a motor controller adapted to vary the speed of the motor said controller means generating a feed forward control signal for said modulating means and inhibiting any error signal generation in response to sash door being moved said feed forward control signal predicting the actual flow rate of air through the exhaust duct as a function of the calculated size of the uncovered portion said controller means thereafter causing the inhibiting of any error signal generation 36 Apparatus as defined in claim 35 wherein said feed forward control signal at any given time comprises an intercept value plus a slope value multiplied by a predeter mined set flow value 37 Apparatus as defined in claim 24 further including an operator panel adapted to be mounted on the fume hood in position to be observed by a person said operator panel including display means for displaying the average fac
3. 6 is a schematic representation of the laboratory control circuit 10 15 35 45 55 2 FIG 7 is schematic representation of a hood control circuit FIG 8 is with respect to elements of FIGS 6 and 7 defining them DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views and more specifically to FIG 1 thereof there is shown a schematic representation of a system 10 for controlling laboratories 12 having fume hoods 14 The system 10 is comprised of a network 16 along which information is carried Preferably the network 16 operates in the half duplex mode for instance with a two wire RS485 network The system 10 is also comprised of a controller 18 in contact with the network 16 for receiving information from and providing information to the network 16 Preferably the controller 18 includes means 24 for requesting information from each microprocessor 22 about its condition Preferably the requesting means 24 requests information from each microprocessor 22 one at a time Additionally the system 10 is comprised of means 20 for sensing a laboratory s 12 state The state of the laboratory is defined as at least the static pressure and the supply exhaust differential of the laboratory 12 and also the face velocity of the fume hood 14 in the laboratory The sensing means 20 is disposed in eac
4. a second switch block 40 with eight switches used to select a current or voltage mode for analog inputs one through eight When the switch is off the voltage mode is utilized and when the switch is on the current mode is utilized There is an analog input port 42 which receives analog input wiring i e high resolution 12 bit input devices such as flow sensors velocity sensors the static pressure sensor and the discharge air temperature sensor are hardwired connected to the analog input port 42 TB3 A processor 44 processes the information received by the microprocessor from the network 16 and sensors in the laboratory 12 and also provides information concerning the respective laboratory 12 to the network 16 A universal input wiring input port 46 receives analog digital input wiring i e low resolution 8 bit and digital input devices such as the room temperature sensor sash position sensors the humidity sensor and the emergency contacts are hardwired to input port 46 TB1 A third switch block 48 with eight switches is used to select thermister support for the universal input port 46 inputs one through eight The memory for the microprocessor 22 includes an execu tive eprom 50 a nonvolatile ram 52 an application eprom 54 and an expansion eprom ram 56 The executive eprom 50 contains the basic operating routines of the microprocessor Input output communications diagnostics and initializa tion routines as well as the utili
5. from switch 260 is provided to the PID No 5 and PID No 6 If the sash mode is chosen then the signal received from summer 250 is passed to the FF input of PID No 5 and PID No 6 The feed forward offset signal is based on the parameters of the system such as the duct configuration and hood size The ultimate purpose of the feed forward gain and feed forward offset being provided to the set point signal in the sash mode is to allow the exhaust damper to properly compensate for the situation where the sash area and thus the damper is suddenly changed The exhaust damper lags in time in terms of how it compensates for this change in sash area In order to eliminate or minimize the offshoot that the exhaust damper experiences from the sudden change in the sash area the signal received by input FF causes the exhaust damper to move to the desired course position The PID No 5 and PID No 6 utilizing the inputs from input MV and input SP then places the exhaust damper in an essentially fine adjustment until it arrives at a desired position The set point signal arrived at by multiplying the face velocity set point time to sash area in the sash mode is also provided to PID delay 230 The PID delay 230 produces a signal based on the time it takes the damper to achieve full actuation provided through the damper delay input to the PID and based on the maximum flow through the damper when it is fully opened This delay signal is provided to switch 270
6. led 72 when flashing indi 10 15 35 45 55 65 4 cates that the microprocessor 22 is operating properly A third led 74 when indicates that the microprocessor 22 is transmitting data to the controller 18 A fourth led 76 indicates when the microprocessor 22 is receiving data There is a jumper block 78 with two pins When the jumper block 78 is installed a termination resister is posi tioned for the RS485 network 16 The microprocessor 22 connects to the network 16 through the network connection port 80 The controller 18 as shown in FIG 4 which is a sche matic representation of the network configuration includes a module 82 FIG 5 shows a module 82 and is a schematic representation of the module 82 The module 82 includes a module processor 84 for providing the proper instructions to the various laboratory 12 microprocessor 22 via the network 16 as well as for receiving information to better maintain the overall system 10 from the various microprocessors 22 and the laboratories 12 The module 82 also includes a reset button 86 a system task led 88 and a communications led 89 The reset button 86 is used to reset the communication module 82 without resetting the entire STAR controller 18 The system task LED 88 is lit to indicate that the commu nication module 82 task is currently being serviced The communication LED 89 is lit when the communication module 82 is idle i c not transmitting There are also por
7. means said fume hood controller means controlling the modulating means to increase the flow rate thereof to a predetermined maximum said room controlling means controlling the air supply to the room to modulate the flow of air into the room whereby the differential pressure in the room is within the range of about 0 05 and 0 1 inches of water lower than a reference pressure outside of the room so that any outwardly opening door can be opened by a person inside the room and the differential pressure will not normally force any inwardly opening door open 19 A system as defined in claim 17 wherein said prede termined emergency flow rate is the maximum flow rate 20 A system as defined in claim 17 wherein said fume hood controller means operates to provide said predeter mined emergency flow rate at a high flow rate for a prede termined time and then reduce the flow rate thereafter 21 A system for controlling the differential pressure within a room such as a laboratory or the like of the type which has one or more exit doors which can open either inwardly or outwardly of the room the room being located in a building having a building heating and air conditioning apparatus including a central monitoring station the room having a plurality of fume hoods located within it the fume hoods being of the type which have at least one moveable sash door adapted to at least partially cover the opening as the fume hood sash door is moved each of
8. of each laboratory having a fume hood providing information corresponding to the state of each laboratory with a fume hood to a perspective micro processor associated with each laboratory providing information to a respective microprocessor from a controller at a remote location and maintaining a respective laboratory in a predetermined state with the microprocessor based on the information received from the controller and the information cor responding to the state of each laboratory 8 A method as described in claim 7 wherein the sensing step includes the steps of sensing a static pressure and a supply exhaust differential of the respective laboratory and a face velocity of a respective fume hood and wherein the step of providing information corresponding to the state of each laboratory includes information about the static pres sure and a supply exhaust differential of the respective laboratory and the face velocity of a respective fume hood 9 A method as described in claim 8 including after the step of providing information to a respective microprocessor there is the step of providing information to the controller by the respective microprocessor 10 A method as described in claim 9 wherein the step of providing information to the controller includes the step of requesting information by the controller from a microprocessor and the step of providing the information by the microprocessor to the controller only when the contro
9. supply damper The error signal from PID No 3 is also provided to a maximum switch 110 which is involved with the control of the supply damper The control of the supply damper will be discussed below The second procedure that can be used to control tem perature is for the temperature set point to be manually inputted into the SP input of PID No 3 This is done by toggling a switch 115 disposed between the PID No 2 and 10 15 35 45 55 60 6 PID No 3 of the lab control diagram such that its 0 input passes the manual temperature set point signal as opposed to the 1 input of the switch 115 with respect to the first procedure which passes the error signal from PID No 2 By choosing the manual temperature set point input the signal provided by PID No 2 is eliminated and a fixed temperature set point is then provided to the PID No 3 The subsequent operation of the second procedure for controlling tempera ture in the room is the same as the operation of the first procedure described above for controlling the temperature starting from PID No 3 In order to control the static pressure and the delta flow in the room a space pressure set point signal is provided to input SP of PID No 1 The actual space pressure is provided to input MV of PID No 1 An error signal corresponding to the difference in these signals is then produced from PID No 1 and is the delta flow set point signal provided to input SP of PID No 4 Reca
10. which if the sash mode is being utilized is then provided directly to the hold input of PID No 5 and PID No 6 The signal received at the hold input prevents the PID No 5 764 579 9 5 and PID No 6 from calculating the fine adjustment of the exhaust damper for a period of time determined by the signal provided at the hold input until the course adjustment has had time to reposition the exhaust damper After the time period has passed then the fine tuning of the exhaust damper position is allowed to continue using the MV input and SP input of PID No 5 and PID No 6 The control sequence provides for control of either face velocity for velocity control or face velocity multiplied by sash area for flow control Accordingly at least the following features are provided 1 Fume hood air velocity control for safety of the operator and or integrity of the experiment process 2 Control of room pressure to maintain safety or to prevent contamination 3 Control of room temperature and humidity for comfort and for process requirements 4 Integration of velocity pressure and climate control with a direct digital control system The sash area of a fume hood is calculated from a formula which permits several methods of measurement which derive their input from a universal input connected to some type of sensor usually a multi turn potentiometer connected to a drum or puliey which is directly attached to the sash The formula takes i
11. 04135 4831 8008 114100 JAVA 13138 E 301243 31425 1 9 11 1930 NIV9 2 9 NIV9 7 011804084 W008 394VH2S 19 5 764 579 Sheet 6 of 8 Jun 9 1998 U S Patent 89 913 Osi 001 104100 8331990 renis 1081802 81 T 08470006 80 5370023 1 0 114100 8348 0 414405 H 091 29 A 5013 114405 95418104135 80134819 8012 3 31925 NIV9 11 830 NIYI 19893111 NIYO 11011409084 8 114 104100 JAWA 9 411002 45 18104135 31101 101344 31425 NIV9 3ATIVATU3Q 1199 19393131 1199 011804084 5 764 579 Sheet 7 of 8 Jun 9 1998 U S Patent 2913 114100 8348 0 I 0 0228 02 i AV130 834 0 0 vi13g MOIS 41120 13178545 30189340 0 o QuvMyOo3 0333 lt 2001 y3uv HSVS 33 98 014 3 S 018 8 18109135 112013 3393 A112013A US YS 801343 31 25 NIV9 3 11 830 013 002 ALT2013A NIV9 1v8231NI NIYO 7 011904044 U S Patent Jun 9 1998 Sheet 8 of 8 5 764 579 A C dux B B 1 4A IF 0 THEN D B IF 1 THEN D TRUE HOLD FOR C A B SECONDS D B E MAXIMUM OF C OR D FIG 8 5 764 579 1 SYSTEM FOR CONTROLLING LABORATORIES WITH FUME HOODS FIELD OF THE INVENTION The present invention is related to systems for controlling laboratories with fume hoods More specifica
12. 6 PID No 2 also receives in its set point SP input a room temperature set point signal which corresponds to a desired room temperature The PID No 2 provides an error signal corresponding to the difference between the room temperature and the room temperature set point This error signal provided by PID No 2 is then used as the temperature set point input which is provided to the SP input of PID No 3 The PID No 3 also receives a discharge temperature signal through its MV input which corresponds to the temperature of the air entering the room through the supply damper PID No 3 then provides an error signal that corresponds to the error between the discharge temperature and the temperature set point This error signal from PID No 3 is then used to control the reheat valve The output of PID No 2 can optionally be used to control an auxiliary reheat valve if one is present in the room The control of the reheat valve can be better understood with the following examples If the error signal for instance from PID No 3 indicates that the discharge temperature is not yet hot enough to obtain a desired temperature in the room then the reheat valve will open further to allow additional heat to be supplied to the air flow passing into the room through the supply damper If the error signal from PID No 3 is for instance too high then the reheat valve is caused to allow less heat to be provided to the flow of air into the room through the
13. OCESSOR 2 22 22 FIG U S Patent Jun 9 1998 Sheet 2 of 8 5 764 579 SYSTEM TASK LED MICROPROCESSOR 88 RESET A ES 84 BUTTON L oi 86 FIG 5 U S Patent Jun 9 1998 Sheet 3 of 8 5 764 579 N V i wood gt no er oc gt ol A lt 29 FIG 3 66 E c oo Uu I e e 22 AB CD 147 78 74 70 54 e 76 U S Patent Jun 9 1998 Sheet 4 of 8 5 764 579 ENCLOSURE 2 8 FIG 4 5 764 579 Sheet 5 of 8 Jun 9 1998 U S Patent 89913179 91979 913 9 94 ISQVHX3 WNHIXI 8013 ISOVRX3 1101 STIVIS 08343081 015 4 DX 0 0 Hi DS 514405 16133113 1 9 31141830 LSAVHXS 008 19101 1 8013 4 OOOH He E 1 014 180813 Get cef ker Tom 021 18104135 MODS IWONYW J 192 8013 418405 11104135 013 38155384 32 45 A I 013 91130 014 IGS MOld 1130 454102115 55384 33445 101393 31433 01293 11025 NIV9 1830 NIV9 14193111 195 1 011809080 2801 844431 398 2510 1081802 W008 39NVH2SIQ 062 458165 4831 1 104135 4831 39NVHOS G 001 iwi 1057 d lt Nid 30 NIV9 TWHOTIWT 301 NIV 19101109099 28 ald 4 31 WOO Qe 43 181
14. United States Patent McMasters et al 54 SYSTEM FOR CONTROLLING LABORATORIES WITH FUME HOODS 75 Inventors David C McMasters Monroeville David M Fisher Pittsburgh Bruce D Arnold Murrysville all of Pa 73 Assignee American Auto Matrix Inc 21 Appl No 591 541 22 Filed Oct 1 1990 51 Int CL sees BOSB 15 02 52 U S Cl 364 131 454 59 454 61 454 62 454 340 58 Field of Search 364 131 132 364 133 137 138 454 56 61 62 340 56 References Cited U S PATENT DOCUMENTS 4 040 042 8 1977 Mayer 4 160 407 7 1979 Duyin 454 61 4 528 898 7 1985 Sharp et al sss 454 61 4 557 184 12 1985 Orii et al 4 706 553 11 1987 Sharp et al sss 454 61 4741257 51988 Wiggin et al 454 59 4 773 311 9 1988 Sharp nen 454 56 5 090 309 2 1992 Ahmed aon 454 58 5 090 304 2 1992 Egbes et al one 454 59 5 092 227 3 1992 Ahmed et al 454 59 OTHER PUBLICATIONS SOLO FX Preliminary Production Description dated Nov 14 1988 SOLO FX by American Auto Matrix copyrighted in 1989 MICROPROCESSOR 2 MICROPROCESSOR 22 US005764579A Patent Number 5 764 579 1451 Date of Patent Jun 9 1998 NETWORK by American Auto Matrix dated Spring Summer 1989 SOLO FX Hood Lab Control by American Auto Matrix dated about Jan 1989 Face Velocity Control Systems bro
15. a predetermined maximum said room controlling means controlling the air supply to the room to modulate the flow of air into the room whereby the differential pressure in the room is within the range of about 0 05 and 0 1 inches of water lower than a 5 764 579 13 reference pressure outside of the room so that any outwardly opening door can be opened by a person inside the room and the differential pressure will not normally force any inwardly opening door open 22 system as defined in claim 21 wherein said prede termined emergency flow rate is the maximum rate 23 A system as defined in claim 21 wherein said fume hood controller means operates to provide said predeter mined emergency flow rate at a high flow rate for a prede termined time and then reduce the flow rate thereafter 24 Apparatus for controlling the air flow through a fume hood to maintain a predetermined average face velocity through an uncovered portion of an opening of a fume hood of the type which has at least one moveable sash door adapted to cover the opening as the fume hood sash door is moved the fume hood being in communication with an exhaust duct for expelling air and fumes from the fume hood said apparatus comprising means for detecting the position of each moveable sash door and generating a position signal that is indicative of the sash door position means responsive to said position signals for calculating the size of the uncovered portio
16. aid controller means generating a high filter loading signal responsive to said differential pressure signal exceeding a predetermined value 13 Apparatus as defined in claim 12 further comprising means for generating a warning indication in response to said high filter loading signal being generated 14 Apparatus as defined in claim 13 wherein said warning indication generating means comprises a means for provid ing a visual indication 15 Apparatus as defined in claim 13 wherein said warning indication generating means comprises a means for provid ing an audible indication 16 Apparatus as defined in claim 12 wherein said con troller means is adapted to increase the flow of air through said fume hood to compensate for said filter loading in response to receiving said high filter loading signal 17 A system for controlling the differential pressure within a room such as a laboratory or the like of the type which has one or more exit doors which can open either inwardly or outwardly of the room the room being located in a building having a building heating and air conditioning apparatus including a central monitoring station the room having a plurality of fume hoods located within it the fume hoods being of the type which have at least one moveable sash door adapted to at least partially cover the opening as the fume hood sash door is moved each of the fume hoods having an exhaust duct that is in communication with an exhaust appar
17. at their O inputs are passed therethrough then the signals from PID No 4 or from the maximum switch 10 is passed to the exhaust or supply damper respectively Optionally to maintain a minimum air flow into a room which provides for a minimum number of air changes for a given time per hour in a room the output signal from switch 110 is received by both scaler 162 and switch 164 if it is desired not to maintain a minimum air flow then switch 164 is set to 0 and the output from switch 110 passes directly to switch 160 Scaler 162 receives a minimum and maxi mum air flow range Scaler 162 then scales the output signal from switch 110 to be in an aliowable air flow range The output signal from scaler 162 is then provided to the SP input of PID No 8 The MV input of PID No 8 receives a supply flow signal indicating the supply flowing through the supply damper and outputs a signal to switch 164 which is then provided to the supply damper The humidity control is accomplished by PID No 7 receiving through MV input the humidity sensed by a humidity sensor in the room The humidity set point is predetermined and provided to the SP input The output of PID No 7 controls a cooling valve based on the level of humidity in the room If the humidity is too high then the cooling valve is opened further This causes the room temperature to drop thus causing the humidity in the room to drop The control sequence with respect to the flow of air th
18. ation with an exhaust duct for expelling air and fumes from the fume hood said apparatus comprising means for detecting the position of each moveable sash door and successively generating a position signal that is indicative of the position of each sash door means responsive to said position signals for calculating the size of the uncovered portion of the opening means for successively generating an actual flow signal that is indicative of the actual flow of air through the exhaust duct modulating means for varying the flow of air through the exhaust duct responsive to a control signal being received from a controller means controller means responsive to said position signals and said actual flow signal for controlling the flow modu Jating means said controller means either generating a control signal value that maintains a predetermined minimum flow rate or generating a desired flow rate signal as a function of the calculated size of the uncovered portion said desired flow rate signal corre sponding to a flow rate that is sufficient to maintain the predetermined average face velocity through the uncovered portion of the opening said controller 5 764 579 17 18 means generally continuously comparing said desired 52 Apparatus as defined in claim 51 wherein said mea flow rate signal with successive instantaneous sample surement samples are taken generally every 100 millisec values of said actual flow signal and generating an
19. atus for expelling air and fume from the room said system comprising a fume hood controller means for controlling a flow modulating means associated with each fume hood and its associated exhaust duct to provide the greater of the flow required to maintain a predetermined minimum flow through said exhaust duct or to maintain a desired face velocity through the uncovered portion of the opening said flow modulating means associated with each fume hood and adapted to control the air flow through the fume hood a first emergency switching means located adjacent each fume hood adapted to be activated by a person in the event of a chemical spill or the like said switching means providing a signal to said fume hood controller means to control the flow modulating means to achieve a predetermined emergency flow rate and providing a signal to the central monitoring station indicating an emergency condition 18 A system as defined in claim 17 further including a second emergency switching means located outside of the room room controlling means for controlling at least the volume of air that is supplied to the room from the heating and air conditioning apparatus of the building 10 15 25 35 45 55 12 said second emergency switching means providing an emergency signal to said room controlling means and to the fume hood controller means of at least some of the fume hoods in response to a person actuating said second switching
20. chure by Anemostat copyright 1984 Yamato Clean Benche product description brochure Envirotrak A Laboratory Air Flow Control System from Anemostat dated Aug 1985 Total Lab Control for the 90 s TLC 90 Anemostat copyrighted in 1988 Information Disclosure Statement Declaration of Linda Diss and attachments thereto Information Disclosure Statement Declaration of Richard Fish and attachments thereto Primary Examiner Reba L Elmore Assistant Examiner Thomas E Brown Attorney Agent or Firm Reed Smith Shaw amp McClay 57 ABSTRACT system for controlling laboratories having fume hoods comprising a network along which information is carried The system is also comprised of a controller in contact with the network for receiving information from and providing information to the network Additionally the system is comprised of means for sensing a laboratory s state The sensing means is disposed in each laboratory There is additionally a microprocessor disposed in each laboratory for receiving information concerning the laboratory from the respective sensing means and the controller in order to maintain the laboratory in a predetermined state and to provide information about the laboratory to the controller 54 Claims 8 Drawing Sheets MICROPROCESSOR 22 0 5 Patent 9 1998 Sheet 1 of 8 5 764 579 18 I6 CONTROLLER REQUESTING MEANS MICROPROCESSOR MICROPROCESSOR MICROPR
21. d external supply to pass to the supply damper output It is the greatest of these four signals which controls the supply damper This way for instance if more heat is to be provided to the room in order to increase the temperature of the room then the supply damper will also increase the flow of heated air into the room If the signal from PID No 4 is greatest than the signal from PID No 3 due to for instance the static pressure or the delta flow being increased then the supply damper will provide a greater flow of air to the room in order to increase the static pressure or the delta flow With respect to the delta flow signal provided to the MV input of PID No 4 the signal is essentially the difference between the supply flow into the room and the exhaust flow out of the room The exhaust flow out of the room is determined one of two ways In the event that a sensor determines the overall exhaust flow from a room then this value is subtracted from the supply flow into the room at subtractor 120 to yield the delta flow of the room If the exhaust flow sensor is disposed such that it only determines exhaust flow out of the room but does not determine the exhaust flow out of the room from a hood A and a hood B then the total exhaust flow is determined by adding the exhaust flow out of the room plus the addition of the exhaust flow out of hood A and hood B at summer 125 5 764 579 7 aforementioned is reduced to practice
22. e velocity being calculated for the associated fume hood and for displaying other status information relative to the opera tion of the apparatus 5 764 579 15 38 Apparatus as defined in claim 37 wherein said opera tor panel includes means for placing said controller in one of two modes of operation one mode being a day mode and the other a night mode said controller means including memory means for storing information relative to the operation of said apparatus said controller means being adapted to receive separate predetermined average face velocity values for each of said day and night modes 39 Apparatus as defined in claim 38 wherein said opera tor panel includes connector means adapted to be connected to a computer means of the type which has a keyboard the computer means being capable when connected to the operator panel of defining parameters and operating values of the fume hood to which the apparatus is to control 40 Apparatus as defined in claim 39 wherein said param eters and operating values include the number of sash doors and the possible movement of such sash doors the physical dimensions of the sash doors and of the opening of the fume hood the average face velocity for day and night modes 41 Apparatus as defined in claim 24 wherein said means for calculating the size of the uncovered portion of the opening comprises computing means located within said controller means 42 Apparatus for controlling the ai
23. e or providing a predetermined minimum flow rate 25 Apparatus as defined in claim 24 wherein the fume hood has one sash door that is moveable in a vertical direction to selectively cover and uncover the opening said detecting means comprising an elongated resistance means located adjacent the sash door adapted to be contacted at different positions along its length by actuator means asso ciated with said sash door as the door is moved vertically said position signal being generated by said detecting means comprising a voltage level that is indicative of the position of said sash door 26 Apparatus as defined in claim 24 wherein the fume hood has a plurality of sash doors that are moveable in at least a horizontal direction to selectively cover and uncover the opening said detecting means comprising an elongated 10 15 35 45 55 14 resistance means located adjacent the sash doors adapted to be contacted at different positions along its length by actua tor means associated with each sash door as each sash door is horizontally moved said position signals being generated by said detecting means comprising voltage levels that are indicative of the horizontal positions of each sash door 27 Apparatus as defined in claim 26 wherein said plu rality of sash doors are mounted in a frame means that is moveable in a vertical direction said detecting means fur ther comprising a second elongated resistance means located adjacent t
24. error onds signal having a magnitude that is directly proportional 53 Apparatus as defined in claim 51 wherein position to the sum of any calculated integration error any 5 detecting means operates to generate a position signals calculated derivative error and any calculated propor generally every 200 milliseconds tional error said controller means successively gener 54 Apparatus as defined in claim 51 wherein said con ating and outputting a control signal to said modulating troller means generates said control signal generally every means for reducing said error signal to a predetermined 100 milliseconds minimum value or maintaining said predetermined 10 minimum actual flow
25. gnal as a function of the calculated size of the uncovered portion said desired flow rate signal corresponding to a flow rate that is sufficient to maintain the predetermined average face velocity through the uncovered portion of the opening of each fume hood said controller means comparing said desired flow rate signal and said actual flow rate signal for each fume hood and generating an error signal indicative of any errors that exist by taking a plurality of successive measurement samples of said actual flow rate determining at least two distinct fac tors of said error signal from said successive samples and summing the said factors to generate said error signal said controller means outputting a control signal 10 35 45 55 65 16 to said modulating means associated with each fume hood for selectively reducing said error signal to a predetermined minimum value or maintaining a prede termined minimum actual flow 43 Apparatus as defined in claim 42 wherein said con troller means determines three distinct factors of said error signal from said successive samples and sums the said factors to generate said error signal said factors comprising a proportional action factor an integral action factor and a derivative action factor 44 Apparatus as defined in claim 42 wherein said integral action factor at any given time is directly proportional to the integral action factor calculated from the immediately prior sample multi
26. h laboratory 12 The sensing means 20 preferably includes a static pressure sensor 26 a supply exhaust differential sensor 28 and a face velocity sensor 30 disposed in each laboratory 12 as shown in FIG 2 FIG 2 is a schematic representation of the laboratory 12 There can also be included a temperature sensor 32 There is also a microprocessor 22 disposed in each laboratory 12 for receiving information concerning the labo ratory 12 from the respective sensing means 20 and the controller 18 in order to maintain the laboratory 12 at a predetermined state and to provide information about the laboratory 12 to the controller 18 Preferably the controller 18 and the microprocessors 22 maintain the respective laboratory 12 in the predetermined state by maintaining their respective static pressure and supply exhaust differential as well as the face velocity of the hoods 14 of a given laboratory 12 The controller 18 and microprocessors 22 preferably operate in a master slave relationship with the controller 18 being the master and the microprocessor 22 being the slave The master initiates all communications by sending mes sages Messages are composed for instance of data bytes transmitted serially using standard asynchronous data frames These data frames can consist of one start bit eight data bits no parity bit and one stop bit The master and each slave share the same network 16 for transmitting and receiving half duplex The master a
27. he frame means adapted to be contacted at different positions along its length by actuator means associated with said frame means as said frame means is vertically moved said position signals being generated by said detecting means also comprising voltage levels that are indicative of the vertical position of each sash door 28 Apparatus as defined in claim 24 wherein said modu lating means comprises a motor driven blower means wherein said motor is controlled by a motor in order to vary the exhaust air flow in the duct 29 Apparatus as defined in claim 24 wherein said modu lating means comprises a damper means located in the exhaust duct and actuating means for varying the position of the damper means to thereby vary the flow of air through the exhaust duct 30 Apparatus as defined in claim 24 wherein said air flow measuring means comprises a flow sensor 31 Apparatus as defined in claim 24 wherein said con troller means determines three distinct factors of said error signal from said successive samples and sums the said factors to generate said error signal said factors comprising a proportional action factor an integral action factor and a derivative action factor 32 Apparatus as defined in claim 31 wherein said integral action factor at any given time is directly proportional to the integral action factor calculated from the immediately prior sample multiplied by a loop cycle time plus any error measured by the present sample
28. ll that static pressure and delta flow are related since static pressure is constant when delta flow is zero and static pressure is changing in the direction of increasing or decreasing delta flow when delta flow is changing Thus PID No 1 provides the delta flow set point that corresponds to the difference between the actual static pressure in the room and the desired static pressure in the room If the actual static pressure is the desired static pressure then the delta flow set point signal is essentially Zero If the actual static pressure is different than the desired static pressure then the delta flow set point signal corre sponds to this difference The actual delta flow signal in the room is provided to the MV input of PID No 4 Optionally PID No 1 can be used to directly control the supply and exhaust static pressure in a room without utilizing flow sensors by way of switch 117 PID No 4 produces an error signal corresponding to the difference in the delta flow set point signal and the actual delta flow signal This error signal from PID No 4 is then provided to the exhaust damper output The exhaust damper is accordingly moved in response to the command placed on it from the signal of PID No 4 The error signal from PID No 4 is also provided to the maximum switch 110 to which the error signal PID No 3 is also provided The maximum switch 110 allows the greatest of four signals auxiliary reheat reheat static pressure an
29. ller requests the information from the microprocessor 11 A method as described in claim 10 wherein the step of requesting information includes the step of requesting the information from the microprocessor one at a time 12 Apparatus for monitoring and controlling a fume hood of the type which has an opening and at least one moveable sash door adapted to at least partially cover the opening as the fume hood sash door is moved the fume hood having an exhaust duct for expelling air and fumes therefrom said fume hood being of the type which has a filter housing and filter means for entrapping fumes and effluents said ratus comprising means for determining the size of the uncovered portion of the opening and for generating a position signal indicative of the determined size 5 764 579 11 means for measuring the flow of air through the fume hood and generating a flow signal that is indicative of the flow of air therethrough modulating means for varying the flow of air through the fume hood responsive to a control signal being received from a controller means means for measuring the differential pressure across the filter housing and providing an electrical differential pressure signal that is proportional to the measured differential pressure and controller means responsive to said position signal and said actual flow signal for controlling the flow modu lating means to control the flow of air through the fume hood s
30. lly the present invention is related to a system for controlling laboratories with fume hoods using a network to communicate with a remote controller to control the state of the laboratory BACKGROUND OF THE INVENTION Laboratories wherein dangerous experiments or processes are performed require protections for the workers and the experiments in the laboratory One very common protection found in laboratories are fume hoods in which chemical reactions are conducted The fume hoods have air drawn out of them thus essentially preventing any toxic fumes from escaping the fume hood into the laboratory and threatening the operators The velocity of air drawn through the fume hood sash is controlled to a value high enough to maintain safety for the operator and low enough to provide non turbulent air for the experiment of process An additional protection that can be provided is to main tain the static pressure in the laboratory at a lower or higher pressure than the pressure in the surrounding corridors of the building A lower pressure would prevent contaminants from exiting the laboratory in the case of an accident A higher pressure would prevent contaminants from entering the laboratory as is the case in a clean room Also control of the laboratory climate is required both for opera tor comfort and for certain experiments or processes where strict temperature and humidity control are necessary There are many schemes and apparatuses that p
31. n of the opening means for measuring the actual flow of air through the exhaust duct and generating an actual flow signal that is indicative of the actual flow of air through the exhaust duct modulating means for varying the flow of air through the exhaust duct responsive to a control signal being received from a controller means controller means responsive to said position signals and said actual flow signal for controlling the flow modu lating means to generate the greater of a predetermined minimum flow rate signal value or a desired flow rate signal value as a function of the calculated size of the uncovered portion said desired flow rate signal corre sponding to a flow rate that is sufficient to maintain the predetermined average face velocity through the uncovered portion of the opening said controller means comparing said desired flow rate signal and said actual flow rate signal and generating an error signal indicative of any error that exists by taking a plurality of successive measurement samples of said actual flow rate determining at least two distinct factors of said error signal from said successive samples and summing the said factors to generate said error signal said controller means generating and outputting a control signal to said modulating means for selectively reduc ing said error signal to a predetermined minimum value when said actual flow rate signal exceeds said prede termined minimum flow rate signal valu
32. nd each slave must be able to enable disable their transmitters not shown so as not to interfere with other slaves trans missions The transmitter enable disable should be con trolled such that the carrier enable is switched off concur rently with the end of the final stop bit of any transmission The master arbitrates when a given slave may respond with the simple rule that a slave only transmits in response to a message uniquely directed to it See PUP guidelines A document entitled PUP Protocol Guidelines is available from American Inc Please contact the PUP Protocol Committee and request Version 6 for an example of a protocol that can be used in the system 5 764 579 3 In the operation of the preferred embodiment micro processor 22 is disposed in each laboratory 12 as shown in FIG 3 FIG 3 is a schematic representation of the micro processor 22 The microprocessor 22 is comprised of a fuse 32 which protects the microprocessor 22 from electrical overload There is a transformer 34 for converting current and voltage provided to the microprocessor 22 through the power input port 36 There is a first switch block 38 with eight switches used to select thermister support for eight analog inputs When any given switch is on moved to the right it operates as a thermister and when any given switch is off moved to the left the switch operates in a normal mode as is well known in the art There is
33. nto account several parameters which can be programmed by the user to model the specific fume hood and sash system The formula used for calculating the sash position is shown in the following equation PI SR UI 255 SD ST SR UI 255 y12 Where OA Offset Area minimum sash opening SQ FT GA Sash Width width of sash opening FT SR Pot Turns Per 100 number of turns the post has from endstop to endstop UI Universal Input 8 bit analog input which measures the pot voltage PI Pi 3 1416 SD Drum Diameter diameter of drum or pulley to which the pot is attached IN 1 ST Cable Thickness thickness of the cable used if the pot is attached to a drum which coils the cable IN This equation accounts for the added diameter of the drum caused by the coiled cable In the case of a system with a pot connected directly to a pulley the ST cable thickness attribute would be set to zero and the drum diameter would simply be SD Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims What is claimed is 1 A system for controlling laboratories having fume hoods comprising a network along which informati
34. on is carried a controller in contact with the network for receiving information from and providing information to the network means for sensing a laboratory s state disposed in each laboratory 10 15 35 45 55 65 10 a microprocessor disposed in each laboratory for receiv ing information concerning the laboratory from the respective sensing means and the controller in order to maintain the laboratory in a predetermined state and to provide information about the laboratory to the con troller 2 A system as described in claim 1 wherein the controller includes means for requesting information from each labo ratory about its condition 3 A system as described in claim 2 wherein requesting means requests information from each microprocessor one at a time 4 A system as described in claim 3 wherein the network operates in the half duplex mode 5 A system as described in claim 4 wherein the controller and the microprocessors maintains the respective laboratory in the predetermined state by maintaining the respective static pressure and supply exhaust differential as well as the face velocity of the hoods of a given laboratory 6 A system as described in claim 5 wherein the sensing means includes a static pressure sensor a supply exhaust differential sensor and a face velocity sensor disposed in each laboratory 7 A method for controlling laboratories having fume hoods comprising the steps of sensing a state
35. plied by a loop cycle time plus any error measured by the present sample 45 Apparatus as defined in claim 42 wherein said deriva tive action factor at any given time is directly proportional to the difference between any error determined from the immediately prior sample and the current sample divided by a loop cycle time 46 Apparatus as defined in claim 42 wherein said pro portional action factor at any given time is directly propor tional to any error determined from the current sample 47 Apparatus as defined in claim 42 wherein said modu lating means comprises a damper means located in the exhaust duct and actuating means for varying the position of the damper means to thereby vary the flow of air through the exhaust duct 48 Apparatus as defined in claim 43 wherein said mea surement samples are taken generally every 100 millisec onds 49 Apparatus as defined in claim 43 wherein position detecting means operates to generate a position signals generally every 200 milliseconds 50 Apparatus as defined in claim 43 wherein said con troller means generates said control signal generally every 100 milliseconds 51 Apparatus for controlling the air flow through a fume hood to maintain a predetermined average face velocity through an uncovered portion of an opening of a fume hood of the type which has at least one moveable sash door adapted to cover the opening as the fume hood sash door is moved the fume hood being in communic
36. putted from PID No 5 and PID No 6 and provided to switch 220 If switch 220 is not toggled to an override position then the signal outputted from PID No 5 and PID No 6 is then passed directly to the exhaust damper of the hood positioning it to be in a desired location In the event that the override mode is toggled on switch 220 then the output signal from switch 220 causes the exhaust damper to take a fully opened position and allow the maximum possible exhaust to be obtained Alternatively if the flow control is used as a basis to maintain the exhaust damper then the 0 input of switch 200 receives the sensed flow through the exhaust This signal is then passed directly through switch 200 to the MV input of PID No 5 and PID No 6 Switch 210 passes through the signal at its 0 input This signal is the sash area of the hood multiplied by the face velocity set point This resulting signal is provided to the SP input of the PID No 5 and PID No 6 The set point signal provided by multiplying the face velocity set point by the sash area is additionally fed to a PID delay 230 as well as to a multiplier 240 At the multiplier 240 the signal is multiplied by fced forward gain that provides a course adjustment signal which is received by summer 250 Summer 250 adds the course adjustment signal from multiplier 240 to a feed forward offset signal This summed signal is provided to switch 260 If the velocity mode is toggled then 0 output
37. r flow through a plurality of fume hoods to maintain a predetermined average face velocity through an uncovered portion of an opening of each fume hood each fume hood being of the type which has at least one moveable sash door adapted to selectively cover the opening as the fume hood sash door is moved each fume hood in communication with an exhaust duct for expelling air and fumes from each fume hood the exhaust ducts for each fume hood being in communication with an exhaust system said apparatus comprising means associated with each fume hood for detecting the position of each moveable sash door and generating a position signal that is indicative of the position of such sash door means responsive to said position signals for calculating the size of the uncovered portion of the opening of each fume hood means for measuring the actual flow of air through the exhaust duct in communication with each fume hood and generating an actual flow signal that is indicative of the actual flow of air through the exhaust duct modulating means associated with each fume hood for varying the flow of air through the exhaust duct that is in communication with the respective fume hood responsive to a control signal being received from a controller means controller means responsive to said position signals and said actual flow signal for controlling the flow modu lating means associated with each respective fume hood to generate a desired flow rate si
38. rough a hood 14 is based on in general coordinating the sash area of the hood 14 with the hood exhaust damper opening When the sash area is increased the damper opening is also increased in order to remove the additional volume of air that is provided to the hood because of the increased sash area and thus maintain the desired face velocity When the sash area is decreased the damper opening is also decreased in order to prevent the smaller volume of air through the smaller sash area from being drawn too quickly through the damper opening Consequently the desired face velocity is again maintained The control sequence provides for control of either face velocity for velocity control or face velocity multiplied by 10 15 25 35 45 55 8 sash area for flow control see FIG 7 If face velocity is chosen as the basis for measurement then the 1 input of switch 200 receives the velocity signal corresponding to the face velocity of the hood This face velocity signal is passed through switch 209 to the MV input of PID No 5 and PID No 6 PID No 5 controls a first hood and PID No 6 controls a second hood Additionally through switch 210 s one input is received a face velocity set point signal which is then passed through switch 219 to the set point SP input PID No 5 and PID No 6 The face velocity signal received at input MV is compared to the set point signal received at input SP and an error correction signal is out
39. rovide such control and protection to laboratories However heretofore there have been no systems that provide for integrated direct digital control of laboratories SUMMARY OF THE INVENTION The present invention pertains to a system for controlling laboratories having fume hoods The system is comprised of a network along which information is carried The system is also comprised of a controller in contact with the network for receiving information from and providing information to the network Additionally the system is comprised of means for sensing a laboratory s state The sensing means is disposed in each laboratory There is additionally a micro processor disposed in each laboratory for receiving infor mation concerning the laboratory from the respective sens ing means and the controller in order to maintain the laboratory in a predetermined state and to provide infor mation about the laboratory to the controller BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings the preferred embodi ments of the invention and preferred methods of practicing the invention are illustrated in which FIG 1 is a schematic representation of a system for controlling laboratories having fume hoods FIG 2 is a schematic representation of a laboratory FIG 3 is a schematic representation of a microprocessor FIG 4 is a schematic representation of the network configuration FIG 5 is a schematic representation of a module FIG
40. ssor based multitasking field panel for monitoring and controlling devices which include the communication module 82 More information can be found in a document entitled STAR User Manual Ameri can Auto Matrix part number 1E 04 00 0054 A laboratory is controlled by for instance the laboratory control circuit 100 as shown in FIG 6 A discussion of its control sequence follows There are preferably four ele ments of the control sequence These are temperature static pressure humidity and delta flow with respect to a room under the control of the laboratory controller 100 The four variables that can be manipulated in order to obtain the desired temperature static pressure humidity and delta flow is a supply damper which controls the amount of air flow into the room an exhaust damper which controls the amount of air flow out of the room a cooling valve which dehumidifies the air and the reheat valve which controls the amount of heat provided to the flow of air that passes through the supply damper into the room Specifically the control sequence with respect to the control of temperature in the room preferably has two possible procedures that can be used to introduce additional heat less heat or the same amount of heat into the room The first procedure utilizes a temperature sensor 32 which deter mines the room temperature and provides a corresponding signal to the measured variable MV input of PID No 2 as shown in FIG
41. the fume hoods having an exhaust duct that is in communication with an exhaust apparatus for expelling air and fumes from the room said comprising a fume hood controller means for controlling a flow modulating means associated with cach fume hood and its associated exhaust duct to provide the greater of the flow required to maintain a predetermined minimum flow through said exhaust duct or to maintain a desired face velocity through the uncovered portion of the opening said flow modulating means associated with each fume hood and adapted to control the air flow through the fume hood a first emergency switching means located adjacent each fume hood adapted to be activated by a person in the event of a chemical spill or the like said switching means providing a signal to said fume hood controller means to control the flow modulating means to achieve a predetermined emergency flow rate a second emergency switching means located outside of the room room controlling means for controlling at least the volume of air that is supplied to the room from the heating and air conditioning apparatus of the building said second emergency switching means providing an emergency signal to said room controlling means and to the fume hood controller means of at least some of the fume hoods in response to a person actuating said second switching means said fume hood controller means controlling the modulating means to increase the flow rate thereof to
42. ts 90 which connect the module 82 to the dual RS485 com munications network 16 In general for the preferred embodiment the inputs and outputs are the following Analog Inputs Space Static Pressure AI2 Supply Air Flow Exhaust Air Flow Hood A Air Flow AIS Hood B Air Flow AI6 Hood A Face Velocity AI7 Hood B Face Velocity AIS Discharge Air Temperature Universal Inputs Room Temperature 8 bit Analog UD Hood A Sash Area 8 bit Analog UI3 Hood B Sash Area 8 bit Analog UI4 External Supply Damper Humidity Input 8 bit Analog US External Exhaust Flow Input 8 bit Analog UI6 Space Emergency Contact Digital UI7 Hood A Emergency Contact Digital UI8 Hood B Emergency Contact Digital Analog Outputs AOI Supply Damper Position 2 Reheat Valve Position Exhaust Damper Position AO4 Hood A Damper Position AOS Hood B Damper Position AO6 Auxiliary Reheat Valve Position AO7 Total Exhaust Air Flow AOS Humidity Cooling Valve Position Digital Outputs DOI Space Emergency Output 002 Hood A Emergency Output DO3 Hood B Emergency Output DO4 High Limit Output 5 764 579 5 DOS Low Limit Output DO6 Digital Output 6 Unused 007 Digital Output 7 Unused DOS Digital Output 8 Unused A given module can be networked with up to 32 micro processors 22 in series as shown in FIG 4 The module 82 can be integrated into a STAR which serves as the controller 18 The STAR is a microproce
43. ty routines for the application which include but are not limited to the math functions and the PID control routines The non volatile ram 52 is used for work space for the executive and the application as well as for storage of attributes and control parameters The application eprom 54 contains the laboratory fumehood control algorithms The expansion eprom ram 56 is used for extra application algorithm storage or for extra non volatile ram storage In the present SOLO FX configuration this site is unused There is a fourth switch block 58 with eight switches that can be used as determined for a given situation The digital binary output port 60 is used to connect devices to the microprocessor for annunciating alarm conditions and for general purpose digital outputs A fifth switch block 62 with eight switches is used to select a current or a voltage mode for analog outputs five through eight of analog output port 66 There is a threc volt lithium smart battery 64 used to maintain the data in the ram 52 in the event of a power failure There is a sixth switch block 68 that has eight switches that are used for analog outputs one through four of analog output port 66 to determine whether they should be in a current or voltage mode A first led 70 indicates whether the application eprom 54 is installed in the microprocessor 22 If the led 79 is off it indicates that the application eprom 54 is installed in the microprocessor 22 A second
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