User`s Manual - Buck Research Instruments LLC
Contents
1. BUCKRESEARCH INSTRUMENTS L L C MODEL 1011C HYGROMETER OPERATING MANUAL 1011 HYGROMETER rec um OFF DEW POINT COOL BALANCE December 2009 BUCK RESEARCH INSTRUMENTS LLC PO Box 19498 Boulder CO 80308 Copyright 2008 Buck Research Instruments LLC All rights reserved TABLE OF CONTENTS 1 0 INTRODUCTION 1 1 General Operational Description 1 2 Brief Physical Description 1 3 Specifications 1 4 List of improvements from the 1011 1 5 Acknowledgment 2 0 CONTROLS CONNECTORS AND MAJOR COMPONENTS 2 Sensing Unit 2 2 Control Indicator Unit 2 3 Power Unit 2 4 Cables 2 5 Optional Accessories 3 0 INSTALLATION p 18 3 Unpacking Procedure 3 2 Initial Operation Check 3 3 Installation on Aircraft 3 4 Leak Check 3 5 Pressure Within Sensor 3 6 Cabling 4 0 OPERATING INSTRUCTIONS 4 Initial Setup 4 2 System Operation 4 2 Time Response 4 2 2 Mirror Cleanliness 4 2 3 Supercooled Dew Points 4 2 4 Low Frost Points 4 2 5 Pressure Effects 4 2 6 Typical Response to Humidity Changes 4 2 7 Mirror Flooding 4 3 Operation while Parked or off the Aircraft 5 0 PREVENTIVE MAINTENANCE AND TROUBLESHOOTING 5 Periodic Inspection 5 2 Cleaning System Optics p 5 p 24 p 29 FIGURES 1 Model 1011C Dew Point Hygrometer System 2 Depression capability 3 Dew Point Sensing Unit 4 Control Indicator Unit 5 Power Unit External 6 Power Unit Internal 7 Sensing2. If 1011C 15 balanced and controlling output is 5 V else output 1s 0 V Note this 1s listed as RTD in the manual C Balance Vbal 0 10 V range Output of signal from optics 1011C 1s balanced and controlling on dew or frost when Vbal is close to 5V E PRESSURE for Pressure sensor option Vpress 0 10V range Press mb 100 Vpress 1 6 64 G TEMPERATURE Dew Point Vdf 0 10V range Tdf range 75 to 450 Tdf 12 5 Vdf 75 B D F H are all corresponding ground connections for the outputs listed above APPENDIX 6 Use of fan heat sink or heater on sensor The 1011 sensor has a Molex connector on the sensor that can be used to connect either to the heat sink and fan assembly or to a heater that 15 embedded under the white insulation on the side of the sensor There 1s also a Molex connector that 15 attached across a 35 Ohm resistor that 1s inside the Power unit that needs to be installed or removed depending upon how the Molex connector on the sensor is connected The heat sink and fan are recommended only for use in the laboratory and not on the aircraft If the heat sink and fan are attached make sure that the PTC fuse is not plugged into the Molex connector that 1s across the 35 Ohm resistor attached to the chassis The heater is recommended for use only on the aircraft When using the heater the PTC fuse must be installed across the 35 Ohm resistor inside the Power unit BUCK RESEARCH INSTRUMENTS ALL DIMENS
3. y lt g 19 99 002 aE 09 00106 H lt e NY e 60 eo 20 90 FIGU RE 16 WATER VAPOR CONVERSIONS 34 e AA ES E EK E gt HEEE EEEE iS He NGH A ELE EI qat qus dq E IDR SII SE RE ZIA ES HERE ER SERE d E NER ND BESSER ek ee E N 4 EEA Ci EE e LI 2 E CORR CT Ee ET EL Lequel NM E EDEN EAE Cp ee ee Or SE NEM QE NNI a o H m o i v vi m i vi e od qu ur T i C T T in Figure 13 Vapor Pressure e vs Dew Point or Saturation Vapor Pressure vs Temperature 35 n m 25 E 7 ZEE m cH Hp tt tS M de Eres UO M F 2 M 2 3 d 4 Dew Point Figure 14 Absolute Humidity vs Dew Point 36 z e LA a 2 v ul o Li 2 ke ul 5 x n SN 40 60 80100 ICH CE g
4. X 9 Fahrenheit 7 9 S AS RO 24 SS 6 2 0 e 3 9 x48 Dew Point 0 2 o Ki Temperature 8 lt ife S y Centigrade 86 7 IO 2 e grade 2 O gt 2 S u n 8g 9 ee f x ba a conversions are 2 2 NE 2 Ly sed on ideal gas behavior gt oe amp d 3 2 ALIGN STRAIGHT E gt ES c e 2 78 d S 2 e AND CENTER MARK EE Ns 2 9 o 2 3 SY 8 7 25 ONOTHERSCALES VALUES e x2 z9 _ of 8 d Nj x 2 a ES 3 X gt S 1 SS p ER i gt 2 9 Yi H SG ss CE m ita 4 5 J lt 4 KE i e 2 2 D 8 7 e wz _ 0 e N m amp p d ER e o F eo mumemcExmemo LE 9 e ERA A ATA L EASTERN ES D CORPORATION ES 36 MAPL dii 2 E ST WATER TOWN MASS 02172 e ih e x e S 5 2 m gt p Qa o i B v 2 9 lt e f 9 a e 3 e 19 S C 9 9 e 4 9 CH 5 E o wW e M Ki A v d e 5 e ei der Q Q _ 167 v e CA ce 9E 0t vv ev 9 Ce e i 2 e 4 2 My v 5 8010 99 4 1 AS 00 04 6 Pu e
5. 5 232 0 32 C C A LED display Variable see Sect 4 2 1 0 08 v C 0 C 0 10 vdc 5 K ohms 0 1 C 28 vdc 2 5 A max 80 to 60 40 to 60 40 to 60 450 knots 45 000 feet 1 5 atmospheres 2 50 4 25 3 26 3 26 5 88 6 38 6 06 12 0 1 5 Ibs 1 25 Ibs 3 25 Ibs 6 0 oz 10 feet DEW POINT C 170 Loo 80 60 40 Percent 32 Relative 20 Humidity 100 50 20 20 A 10 5 60 2 100 120 f 18 4 68 FROST POINT F 2933040 62 90 110 430 150 SENSOR BODY TEMPERATURE FIGURE 2 Depression Capability 10 1 4 NOTE TO USERS OF 1011B SYSTEMS The following 15 a list of 1mprovements made 28 VDC operation RS 232 data output Improved accuracy 0 1 degree C over entire range Improved servo control reducing oscillations by a factor of 10 Improved cooling of at least 20 degrees C Faster and more accurate response at low dew points because of nickel plating Software upgradeable by end user Optional pressure sensor input and mixing ratio output 9 Autobalance feature automatically compensates for reduced mirror reflectivity caused by contamination 10 Service Mirror LED illuminates to indicate mirror contamination is too great and mirror needs to be cleaned 11 D F Point LED which illuminates when a dew or frost point 1s reached RS 232 output only 1 5 ACKNOWLEDGMENT Dav
6. APPENDIX 1 1011C PIN DATA OUT A DEW POINT INDICATION FLAG 5 dew point B COMMON C BALANCE D COMMON E PRESSURE F COMMON G TEMPERATURE Dew Point H COMMON J HEATER NOT USED K SHIELD RS 232 2 Rx 3 Tx 5 Ground POWER 28 VDC B 428V Return C Chassis Ground B and C are wired together on the cable if supplied PRESSURE to connect up an external pressure sensor A Heater Power 28 VDC optional B Heater Return optional D Pressure blue wire from 4 20 mA sensor Power 16 VDC red wire from 4 20 mA sensor J Pressure do not use with 4 20 mA sensor K Ground do not use with 4 20 mA sensor When using 0 5 or 1 5 VDC sensor you must use D E J and or the sensor will not work Calibration instructions are available by request from Buck Research Instruments LLC Attach shield of cable to strain relief of connector using spade lug or ring terminal Recommended cable Belden YR27540 S 18 AWG CLA e CABLE W 2 POWER SENSOR MODEL 1011C LE Black N18 AWG d gt TF 2 Brown 18 je Orange 2 DEL N titti i S Iny SI L M K R 1 Cut back wire and shielding Red Green pair also Black wire from both Green Black and Yellow Black before stripping and tinning 2 Tie all shield drain wires together at each end and connect to pin J 3 If using
7. Fitting Spare to allow choice of right side or left side operation EDET X Zo lt n de Vet Figure 6 Power Unit Internal SECTION 3 INSTALLATION 31 UNPACKING PROCEDURE l Remove system components from shipping containers and situate near a 28 VDC power source If possible save shipping containers for future use 2 Make sure that all system components are accounted for Figure 1 3 Ascertain they are properly matched by serial number or have been calibrated together 4 Visually inspect exterior of system components and interconnecting cables for damage If damage 15 evident take appropriate action for corrective maintenance and repair as required 5 Record serial numbers 3 2 INITIAL OPERATIONAL CHECK Before mounting on the aircraft it 1s advisable to give the system an initial bench check to verify that it works properly and to become familiar with its operation See Section 4 3 for operation off the aircraft 3 3 INSTALLATION ON AIRCRAFT Sensing unit The sensor is normally located on the aircraft fuselage mounted through the exterior skin with the inlet fitting exposed to the airstream Other locations such as a boom can also be used The pressure field along the side of an aircraft in flight varies with location and may be greater or less than the ambient or static pressure Attempt to locate the sensor at a point where the pressure is reasonably near static pressure A side mount is
8. Unit If practicable mount so that the front panel 1 accessible during flight Make sure function switch 5 1 is in OFF position Connect cable Cable Length Standard cable lengths may be extended as follows on special order Sensing unit to power unit 3 feet 1m standard may go to 50 feet Control Indicator to power unit 3 feet 1m standard may go to 150 feet It 1s essential that cables be identical in quality and configuration to that of original equipment or the cable specified the drawings Specifically that there are 7 pairs of shielded 24 gauge wires and 2 pair of shielded 18 gauge wires contained in the cable used for connecting between the power unit and the control indicator unit and the cable used for connecting the power unit to the sensor unit It would also be acceptable to make a cable using 9 separate cables that are shielded twisted pair 7 of them 24 gauge and 2 of them 18 gauge and wrapping them together Make sure that there 1s an overall braided shield surrounding these cables and attached at both ends to the connector Use of non standard cable may cause operational problems and make the unit more susceptible to noise and electrostatic discharge sensor Body Temperature There 15 a trade off involved in the degree to which the sensor body 15 thermally coupled to the outside ambient temperature If it 1s held closely to outside temperature the thermoelectric cooler will have the lightest cooling load and t
9. Unit Mounting and Assembly 9 Sensing Unit Internal 9 Flow Test Fixture Hookup 10 System Response Characteristics Appendix Figures 11 1011C Wiring Diagrams 12 Water Vapor Conversions 13 Vapor pressure vs dew frost point 14 Absolute humidity vs dew frost point 15 Effect of pressure on dew point 16 Aspirating Fixture Hookup 17 1011C Hygrometer Complete p 31 2 p 33 p 34 p 35 p 36 p 37 p 38 LIST OF TABLES Number Title 1 1011C Connectors 2 Dew Point to Frost Point Conversions 3 Dew Point Error Due to Pressure Change in Sampling System APPENDIXES 1 1011C Pin 2 Humidity Conversion Equations 3 Warranty 4 5 232 outputs 5 Data outputs 6 Fan or heater connector on sensor p 39 p 40 p 41 p 30 p 42 p 44 p 45 p 46 p 47 SECTION 1 INTRODUCTION 1 1 GENERAL OPERATIONAL INSTRUCTIONS The 1011C is a high performance condensation type hygrometer designed for airborne measurement of dew and frost point temperatures The system 15 capable of measuring dew frost points between 75 C and 50 C over a wide range of temperatures pressures and airspeeds The 1011C is a complete update of the 1011 hygrometer incorporating many new features described below The instrument operates on the chilled mirror principle mirror 15 thermoelectrically cooled until it reaches a temperature at which condensation begins to form the dew or frost point and 1s then held at that temperature the presence of condensation 15 s
10. cable that has Belfoil instead of braided shield put large braided shield over the outer jacket of entire cable solder a wire and lug on each end of braid and attach to strain relief screw on connector ITEM 1 ITEM 2 WIRE SIDE VIEW WIRE SIDE VIEW Figure 11 Wiring Diagrams Recommended cable Belden YR27540 A ets a E 7 77 INDICATOR POWER D pere moner 1011c 4 e I E Orange NA Ce fee eZ er 18 AWG D fei Notes 1 Cut back wire and shielding on Red White and Green Black also Black from White Black before stripping and tinning 2 Tie all shield drain wires together at each end and connect to pin J 3 If using cable that has Belfoil instead of braided shield put braided shield over the entire cable solder a wire and lug on each end and attach to strain relief screw on connector ITEM 2 ITEM 1 WIRE SIDE VIEW WIRE SIDE VIEW Wiring Diagrams Continued water Vapor Pressure mm H 9 00 01 ep 90199 19 si oo Parts per Million Water Va g0 by Volume pp Por S 1009 t One A my goo at One Atmosphere 000 NS 909 Pounds of Water 2 Ka d 5009 Million Cubic Feet Bac 9 and One Atmos 60 o 273 008 y S 499 400 Milligrams of Water 0 gt a 9 2 per 7 9 o 9 49 G 60 F ang 0001 VA oy F FEM S 2 X S Qew Point Temper
11. take a reading just before clearing allow sufficient time to reform a stable layer afterwards MAX COOL switch allows the operator to determine whether there is adequate cooling when the system is operating at very low frost points Momentarily switch to MAX COOL and observe the dew frost point display If the indicated temperature drops there is reserve cooling capability 4 2 5 Pressure Effects The 1011C system will display the Dew Frost Point at the pressure that the sensor chamber is exposed to The location of the sensor probe on the aircraft can influence the pressure Attaching an altimeter and comparing it with the aircraft altimeter is a convenient way of accomplishing this The dew point temperature is a function of the sample gas pressure If the pressure of the gas 15 increased or reduced from atmospheric pressure the dew point is correspondingly increased or decreased It 15 general practice to assume unless stated otherwise that dew point is with respect to atmospheric pressure To calculate dew point error due to pressure change refer to Appendix 1 4 2 6 Typical Response to Humidity Changes In level flight the system should track the Dew Frost Points very well Typical responses to step changes are shown in Figure 9 However be cautious about readings under the following conditions Icing conditions Sudden transition from low to high dew points Particularly with rise in ambient temperature typical o
12. the mirror surface then reduce the vapor pressure in accordance with Raoult s Law As the concentration increases with time the saturation vapor pressure of the liquid solution decreases and the control loop responds by elevating the mirror temperature to maintain a vapor pressure that 1 equilibrium with the partial pressure of the water vapor in the atmosphere The displayed dew point therefore drifts upward with respect to the true dew point Because the measurement error increases gradually it often goes undetected This condition 1s most easily detected by noting the indicated dew point cleaning the mirror balancing the detector then measuring the dew point again If the new reading 15 lower than the first reading there 15 probably soluble material present in sufficient quantity to cause a measurement error Gaseous Contaminants a gaseous material were present which had a higher condensation temperature than that of water even if present in very low concentrations the system control loop will eventually control on that material rather than on water The system then displays the condensation temperature of that material not water Such material would accumulate on the mirror only while chilled Fortunately while such a situation could arise in an industrial environment it is normally not a problem in the natural atmosphere An exception might be when flying through emissions from a power plant or industrial smokestacks Minim
13. 00 x r x P 622x103 r x es 100 x rho x Tk 216 7 x es rho Absolute humidity rho 216 7 x f1 DP Tk DP 216 7 x e Tk e 0 2167 x rx P 622 001 x r x Tk r 216 7 x RH x es 100 x Tk RH mixing ratio by volume ppmv 2 mixing ratio by weight ppmw x M W of gas 18 02 grains Ib r x 0 007 Precipitable cm per km rho 10 NOTE 1 f1 DP and f2 e are variations on vapor pressure formulations found in Buck A J Appl Met 20 pp 1527 1532 1981 They are given by e vs DP or es vs DP EF x aw x exp bw DP dw x DP DP cw over water EF x ai x exp bi DP di x DP DP ci over ice DP vs eor T vs es f2 e dw 2 x bw s bw S 4 x s dw 1 2 over water di 2 x bi 5 bi S 4 ci x s di 1 2 over ice where aw 6 1121 ai 6 1115 bw 18 678 bi 23 036 cw 257 14 279 82 dw 234 5 di 333 7 s e EF In aw or ai 1 1074 7 2 P 0 0320 5 9 x 10 6 T 1 1074 2 2 0 0383 6 4 x 10 6 where P is in millibars and T is in 9C NOTE 2 RH is defined here using es with respect to ice below freezing However RH is also frequently defined using es with respect to water even below freezing NOTE 3 These conversions are intended for use with moist air rather than pure water vapor They therefore include EF the enhancement factor which corrects for the slight departure of the behavior of w
14. IONS INCHES Dep DIMENSIONS SENSOR 4 CONTROL INPICATOR CONTROL INDICATOR 49 BUCK RESEARCH INSTRUMENTS DIMENSIONS IOII C POWER UNIT ALL DIMENSIONS IN INCHES 8 9 MOUNTING HOLE PATTERN B ir rr 9 i 4 Mounting hole diameter 0 207 x 4 for 10 screws for direct mounting or for optional Barrymounts
15. RECT INCEDENTAL OR CONSEQUENTIAL DAMAGES OF ANY KIND 45 APPENDIX 4 RS 232 Data Stream and Pin Out for 1011C Aircraft Hygrometer Pin Out 2 Rx Data In 3 Tx Data Out 5 Ground 9600 baud 8 N 1 parity Use included null modem cable to connect to computer running Hyperterminal or similar serial port emulator software 14354 14 23 0 0 56 0 33 00 05 08 2003 17 47 08 14060 13 95 0 0 54 0 33 00 05 08 2003 17 47 09 13721 13 69 0 0 52 0 33 00 05 08 2003 17 47 10 13342 13 40 0 0 50 0 33 00 05 08 2003 17 47 11 Balance mirror temperature flag pressure PWM mirror board temp date time Balance number that indicates how close the servo 15 to being balanced and a dew frost point being measured on the mirror Mirror temperature temperature on the mirror surface Flag Indicates the following 0 normal operation dew or frost point achieved on mirror 2 balance mode Pressure pressure in mb if sensor installed 255 to 255 Indicates how much heating or cooling being applied to mirror Mirror Indicates the following 0 mirror normal 1 mirror contaminated and will need cleaning soon Board temp temperature on main circuit board Date Date in month day year Time 24 hr time 469 APPENDIX 5 1011C DATA OUT VOLTAGES AND CONVERSIONS Data Out Conntector Pins A DPI Dew point indication binary output of 0 V or 5 V
16. advisable to avoid pressure changes with change of aircraft pitch and to avoid rain while parked Avoid prop wash and areas of large local pressure changes such as wing surfaces behind radar domes and struts etc It is usually safe to mount the sensor near the static instrument ports as they are located at or near a point of static pressure In pressurized aircraft try to avoid locating immediately downstream of windows or other cabin penetrations that might have slight leaks and thereby affect the air being sampled A forward location allows a somewhat better penetration of the aircraft boundary layer by the probe and so is somewhat preferable although usually not critical The inlet fitting is designed for use on either the right or the left side of the aircraft but not both The consequence of mounting on the wrong side of the aircraft is upward pointing inlet and exhaust holes and the likelihood of collecting liquid water in the sensor The sensor should be mounted as shown in Figure 7 Initially orient the sensor so the inlet fitting points downstream parallel to the airstream with the inlet and exhaust holes pointed downwards As soon as practical adjust for proper flow and pressure change in the cavity according to Section 3 5 Power Unit Wire up cables and connect the proper cables they are coded to prevent mismatch 28VDC must be used Using any other power will damage the unit and void the warranty Control Indicator
17. ater in air from that of a pure gas NOTE 4 The definitions f1 and f2 for ice agree with an extrapolation of NBS values down to 120 deg C within 0 5 44 APPENDIX 3 WARRANTY Manufacturer warrants that the items delivered shall be free from defects latent and patent in material and workmanship for a period of one year after acceptance of the specific goods by Buyer or within 30 days of receipt of the item whichever comes first The Buyer s sole and exclusive remedy under this warranty shall be limited to repair or replacement Defective goods must be returned to the Manufacturer promptly after the discovery of any defect within the above referenced one year period Transportation expenses to return unit to Manufacturer shall be borne by the Buyer Return shipping to Buyer shall be borne by Buyer for valid warranty claims This warranty shall become inapplicable in instances where the items have been misused or otherwise subjected to negligence by the Buyer NOTWITHSTANDING ANY OTHER PROVISION OF THIS CONTRACT NO OTHER WARRANTIES WHETHER STATUTORY OR ARISING BY OPERATION OF LAW EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO THOSE OF MERCHANTABILITY OR FITNESS FOR PARTICULAR PURPOSE SHALL APPLY TO THE GOODS OR SERVICES PROVIDED HEREUNDER OTHER THAN THE REPAIR AND REPLACEMENT WARRANTY ABOVE SELLER SHALL IN NO EVENT BE LIABLE TO BUYER OR ANY THIRD PARTY FOR ANY DAMAGE INJURY OR LOSS INCLUDING LOSS OF USE OR ANY DIRECT OR INDI
18. drift Additionally the temperature is measured with an analog to digital converter ADC that 15 calibrated each time the instrument is turned on and 15 not susceptible to drift like the analog electronics in the old 1011B instrument and therefore does not need a calibration plug Three Cables or six Connectors a Data Connector and a Power Connector connect the various system components and provide input power Optional Accessories which further increase versatility and ease of use are described in Section 2 6 Note The 1011B hygrometer was originally developed and produced by General Eastern Instruments This operating manual originated at General Eastern and many of the drawings are reproduced by their courtesy Figure 1 Dew Point Hygrometer System shown with optional cables 1 3 SPECIFICATIONS Dew point range Accuracy Response time Outputs Analog Dew point Control voltage Minimum load impedance Digital display resolution Power Input Operating Limits Operating temperature range Sensing Unit Control Indicator Unit Power unit Airspeed nominal Altitude nominal Pressure Limit Dimensions in inches Sensing Unit Diameter max Length with inlet fitting Control Indicator unit Height Width Depth Power unit including shock mount Height Width Depth Weight 165 Sensor Control Indicator Power unit Cables 75 to 50 nominal see also Figure 2 0 1
19. e is kept as close to that of ambient air as possible by proper heat sinking and insulation There is of course a trade off between response time control system stability and sensitivity to contamination 4 2 2 Mirror cleanliness It is not necessary that the mirror be microscopically clean in fact best performance will be obtained from a mirror which has been operating for a few hours after cleaning On an unscratched freshly cleaned mirror there are a relatively small number of nucleation sites on which dew or frost deposits can form and so the time it takes to collect a condensate layer at low frost points 15 increased Also overshoot occurs which cause oscillation Since proper operation of a condensation hygrometer depends strongly on the condition of the mirror surface the following discussion of the effects of various types of contaminants may be helpful Particulate Contaminants Particulate matter which is insoluble in water may accumulate on the mirror surface but usually will not affect the instrument accuracy until the mirror reflectance 1s reduced substantially and 1n many cases will improve instrument response by providing condensation sites Water Soluble Materials Materials such as naturally occurring salts which readily dissolve water are detrimental to accurate vapor concentration measurement by any condensation method These materials readily go into solution with the water condensate on
20. ecial care that the gasket 15 properly oriented to allow free flow through the sensor body Lower the pressure inside the sensor as much as possible and check for leaks The flowmeter ball should not move B If the optional aspirating kit is not available seal all ports of the inlet fitting and attach a pump and flowmeter to the pressure tap on the sensor body Check for leaks as above NOTE To ensure a good seal use Teflon pipe tape when replacing pressure port plug C If a flowmeter is unavailable the following alternate method can be used Connect the pump to the sensor by one of the above arrangements along with a shutoff valve and a pressure gauge After pumping down the sensor close the valve to seal it off and observe its recovery to ambient pressure If recovery takes 10 seconds or longer the sensor 15 adequately sealed from leaks If a leak 1s apparent locate 1s using positive pressure and a soap solution or equivalent 3 5 PRESSURE WITHIN A SENSOR sensor should not be exposed to a pressure differential greater than 1 5 atmosphere across the sensor as pressure in excess of this can destroy the seals The sensor is designed to be leak tight when the lower pressure is the sensor chamber 1 pressurized cabin with the sensor chamber at atmosphere pressure 3 6 CABLING When cables are supplied with the 101 1C and it is desired to use cables of different length than the 3 foot 1m lengths origina
21. ensed optically The signal output is a voltage corresponding to the temperature of the mirror The 1011C consists of three distinct units Sensor unit a Power unit and a Control Indicator unit The Sensor unit contains a three stage thermoelectric cooler TEC capable of reaching frost points normally encountered at altitudes up to 45 000 feet ALL PARTS OF THE 1011C CAN ONLY BE USED WITH THE 1011C NONE OF THE 10118 COMPONENTS CAN BE INTERCHANGED WITH THE 1011C The 1011C features a microcontroller based Power unit It features both voltage and 9600 baud 5 232 serial data outputs Optionally it includes a power switch and a pressure sensor input The Control Indicator unit features LEDs that indicate mirror cleanliness an LED display that shows dew frost point temperature and a blue LED that indicates whether the instrument is controlling on a dew or a frost point The instrument will operate well in most environments both on and off aircraft Although the standard configuration 1s designed for in flight operation an optional aspirating kit enables use while the aircraft 15 on the ground as well as off the aircraft a lab or other environment Startup and operation are normally very simple Excluding extreme humidity environments no in flight adjustments are required Note An aircraft 15 an exceedingly difficult platform from which to make humidity measurements because of the extreme range of environmental conditions
22. evel pressure adjust for actual pressure multiply above errors by level P actual altitude feet approximate change in psi thousand feet 10 000 3 9 20 000 2 8 30 000 2 0 10 000 1 3 50 000 0 8 60 000 0 5 mb psi 68 948 meters ft 0 3048 APPENDIX 1 HUMIDITY CONVERSION EQUATIONS Revised 7 96 Computer efficient algorithms for converting among several humidity units as used in HCON are given here They utilize vapor pressure formulations developed by A Buck 1981 DP dew or frost point in deg C e vapor pressure in millibars es saturation vapor pressure in millibars P pressure in millibars r mixing ratio by weight in ppm RH relative humidity in percent rho absolute humidity in g m3 rhos absolute humidity at saturation T temperature in deg C Tk absolute temperature in K Saturation vapor pressure es f1 T e RH Dew frost point DP f2 e f2 r x P 622 x 109 r r f2 f2 RH x f1 T 100 RH f2 rho x Tk 216 7 rho Vapor pressure e f1 DP DP rx P 622 x 103 4 r r RH x f1 T 100 RH rho x TK 216 7 rho Mixing ratio ppmw 18 02 M W of gas x 106 x e P e e 18 02 M W of gas x 106 x f1 DP P f1 DP DP 18 02 M W of gas x 106x RH x es 100 x P RH x es RH 18 02 M W of gas x 106 x rho x Tk 216 7 x P rho x Tk rho Relative humidity RH 100 x f1 DP f1 T DP 100 x e es e 1
23. he instrument will be able to achieve maximum performance at very low frost points high altitudes it may however become flooded on descent when the cold sensor body suddenly encounters warm moist air If on the other hand the sensor body 15 strongly influenced by the heated cabin the reverse will be true better stability on descent but reduced performance at frost points below 50 C In practice normal mounting on 20 MINS Le KEE ER ldvd2uip FOS Jk FLV S SIIGNOTT d 1404 137400 IO LN amp 255 7 NIW AMOd L37NI Nivag Ab A BS de det 9 1 NITHIT TILIA AnS 2522 NMOHS SY gt NO s 34325 ANIHIVW S s TE F 9 Figure 7 Sensing Unit Mounting Note 6 32 screws go into the mount collar which has a maximum depth of 0 375 Add this length to the total thickness of the aircraft skin and any plates used to deternine screw length 21 the aircraft skin usually works well To achieve a different balance between inside and outside temperatures insulation and or heat sinking can be applied as appropriate CAUTION Make sure the sensor has adequate heat sinking when operating in hot environments Do not operate in environments over 60 140 F 34 LEAK CHECK A Ifthe optional aspirating kit is available attach the aspirating fixture in place of the sensor inlet fitting and temporarily seal the inlet holes Take sp
24. id M McFarland at the National Center for Atmospheric Research initially developed the flow test fixture and the aspirating fixture We acknowledge with appreciation Mr McFarland s contribution in making these devices available to the user community 11 SECTION 2 CONTROLS CONNECTORS AND MAJOR COMPONENTS 2 1 SENSING UNIT Figure 3 A Inlet Fitting has inlet exhaust and water drain ports Each fitting 15 designed for use on either the left or the right side of the aircraft but not for both B Mounting collar The mounting collar has 6 holes drilled in it that are ready to be tapped for either 8 32 or M4 screws for mounting Buck Research Instruments LLC does not tap these holes unless specifically requested by the customer as mounting configurations and requirements vary from aircraft to aircraft C Connector J6 for cable leading to power unit Figure 3 Dew Point Sensing Unit 12 2 2 CONTROL INDICATOR UNIT Figure 4 Function switch S1 applies power to the various system supplies and provides the following functions OFF no power applied to any circuit DEW POINT normal operating position Allows system to maintain an equilibrium condensation layer on the mirror Initiates a balance cycle upon initial power up MAX COOL switch position that applies full cooling current to the thermoelectric cooler This is used to 1 determine whether there is adequate cooling when the system 15 o
25. ion switch to the DEW POINT position and observe the reading settle to its proper value The panel meter will read the mirror temperature as it rapidly approaches the correct dew point When the unit stabilizes the D F point LED will illuminate At dew points above 0 the system stabilizes within a few seconds the correct dew frost layer Take dew frost point readings after the D F point LED has illuminated If you connect the RS 232 output to a PC running Hyperterminal there will be a 1 in the third position of the line when the mirror temperature and balance have stabilized enough that dew or frost points are being outputted otherwise this will be a zero Please see page 45 for more details 4 2 1 Time response Time response depends a number of factors slew rate dew point flow rate and thickness setting Slew rate 15 turn dependent on dew point and depression at higher dew points and moderate depression it 15 typically 1 C second At lower dew points and or larger depressions taken as the temperature difference between the mirror and the sensor body slew rate becomes slower and be reduced to tens of minutes at its limit At low dew points response 15 also limited by the reduced availability of water molecules and the resulting slow crystal growth rate For best response 1 maximize flow to increase the rate at which water vapor is supplied or carried off and 2 make sure the sensor case temperatur
26. izing Effects of Contaminants In marine environments or other situations where contaminant levels are unusually high one may reduce the rate at which contaminants accumulate on the mirror by reducing flow and or by increasing condensation thickness 4 2 3 Supercooled Dew Points When making measurements in the frost point region of 0 to 40 C there 1s the possibility that the mirror 15 actually controlling on the supercooled dew point which 15 0 1 to 42 below the actual frost point See Appendix 1 for frost point dew point conversions This is a relatively 1mprobable situation since dew cannot exist indefinitely below 0 C and will sooner or later transform to ice To guarantee that the mirror 15 controlling on frost rather than supercooled water switch S 1 to COOL briefly to force cool the mirror several degrees lower than its previous reading Upon release of the MAX COOL switch the mirror may attempt to overshoot above 0 C causing the deposit to melt Prevent this by again switching to MAX COOL to hold mirror below 0 C This will insure that final reading will be terms of frost point 4 2 4 Low Frost Points At very low frost points it is good practice to allow the instrument to operate continuously to assure operation in the ice phase Performing a rebalance is not recommended as it could take hours for the frost layer to reform If a balance check 15 done or the mirror 1s otherwise cleared of its frost layer
27. lly supplied factory made cables of different lengths are available from Buck Research Instruments LLC on special order basis only Normally only the connectors are supplied for 1011 and it 1s the responsibility of the end user to make cables This 1s done because many agencies will not certify cables from outside vendors such as Buck Research Instruments LLC for use aboard their particular aircraft Cable length can generally be varied without problem However the shielding and grounding arrangement is critical and the cable used should be identical to that originally supplied or specified Section 3 3 of the manual and in the wiring diagrams If you have any questions or doubts about making your own cable please contact Buck Research Instruments LLC and we would be happy to assist you Figure 8 Sensing Unit Internal 23 Teuorado 1Teuorado 1939WN 3 5 1939W MOTA li LIV dw 4104 eunssoeig 2171825 IJBIDITV 01 Mar Figure 9 Flow Test Fixture Hookup SECTION 4 OPERATING INSTRUCTIONS 4 1 INITIAL SETUP 1 Ascertain that function switch S 1 1s in OFF position 2 Connect power unit sensing unit and control unit to their appropriate cables and to 28 VDC see Figure 13 Also connect analog or digital recording devices as desired 3 If instrument 1 to be operated while not in flight refer to section 4 4 4 2 SYSTEM OPERATION Turn the funct
28. n descent into warm moist air Under normal conditions the 1011C will handle the transition without problem but under severe transitions the sensing cavity may collect excessive water Refer to next section 4 2 7 Mirror Flooding Under conditions of abrupt transition from dry to moist conditions particularly when accompanied by a transition from cold to warm temperatures the mirror may accumulate an overload of moisture It may then take several minutes for the sensor to dry out The process can be speeded by temporarily setting the function switch of the control indicator unit to the BALance position thereby heating the mirror 4 5 OPERATION WHILE PARKED OR OFF THE AIRCRAFT The system will operate on the ground however with the sensing unit closed there will be almost no air exchange within the sensor cavity To obtain readings of ambient dew point means for supplying air to the sensor must be provided either by opening the sensor cavity or by pumping air through Three options in order f preference are 1 If you have the optional aspiration system connect it to the sensor Set the flow to about 5 SCFH 2 5 Ipm 2 If a pump and flow meter are available but no flow test fixture connect them to the sensor pressure port Set flow to 5 SCFH 2 5 Ipm 3 Remove the sensor body to expose the sensor cavity being very careful not to contaminate the cavity with dirt dust or fingerprints While shielding the cavity from ext
29. pection of the system annually or at intervals as required by the service environment and extent of use Inspection consists of the following steps Visually check for damage of system components with particular attention given to cables and connectors 0 rings and gaskets front panel switches and indicators system optics mounting hardware Clean interior and exterior of all components and tighten loose knobs and hardware as required Clean and lubricate 0 rings and gaskets with silicon grease If necessary replace any worn or damaged 0 rings or gaskets or other components 5 2 CLEANING SYSTEM OPTICS The cleaning rate for the mirror 15 a direct function of the contaminant level of the air of the operating environment In time the REBALANCE LED will stay lit after balancing This indicates that the mirror 15 getting dirty Eventually it will get dirty enough that the SERVICE MIRROR LED will light and the mirror must be cleaned to restore proper operation To clean the mirror 1 Remove the four screws from the top of the sensor and set lid aside 2 Unscrew two screws holding optics block on using supplied ball driver and lift out optics block exposing mirror 3 Clean the mirror using supplied cotton swab moistened with an approved solvent such as acetone followed by water A few light swipes 15 sufficient use only enough solvent to wet and clean the mirror 4 Reassemble the sensor by replacing optics block and lid
30. perating at very low frost points and 2 convert any supercooled water deposit to frost BALANCE initiates a balance cycle which heats the mirror to 40 C to evaporate condensation and allows system to be balanced with a dry mirror Do not leave in this position once balance routine is initiated or it will repeatedly balance mirror Switch back to DEW POINT position once REBALANCE LED lights B Digital Panel Meter allows direct readout of dew point data C D F Point LED blue LED indicates if unit has stabilized on a dew or frost point D REBALANCE LED Lights when a balance routine is performed If it stays light after balance finishes this indicates that mirror 1s becoming contaminated and will need to becleaned soon SERVICE MIRROR LED This LED flashes to indicate that mirror is too contaminated for proper operation and needs to be cleaned Main Connector 18 for cable leading to control unit Figure 4 Control Indicator Unit 2 5 POWER UNIT Figure 5 A SENSOR Connector J5 for cable to sensor B CONT IND Connector J7 for cable to Control Indicator C DATA OUT Connector 14 provides analog signal outputs D POWER IN Connector J1 for connecting 28 VDC E PRESSURE to connect to optional pressure sensor RS 232 serial data output 9600 Baud 8 N 1 The power unit is no longer furnished with a shock mounted base as we have determined that one should not be required for mo
31. raneous light allow as much free ventilation as possible 50 40 DEW POINT C A LA 20 10 MANUALLY INITIATED TEST CYCLE 1 C SEC COOLING RATE 4 1 RESPONSE UPWARD AND DOWNWARD CHANGES IN DEW POINT 28 CHART SPEED 1 MIN CHART SPEED 1 MIN 0 In the manually initiated test cycle shown above the mirror heats while the function switch 5 1 is in the BAL position this case about 30 seconds Upon return ing the switch to operate the system cools at its 1 C sec rate overshoots slight ly as the dew layer forms and then re turns to the true dew point temperature The above trace shows the system s typi cal response to upward and downward changes in dew point Note that over shooting is absent the response of the system is rapid enough to insure controi the dew layer at all times As long as the dew layer does not evaporate over shooting in the response will not occur FIGURE 10 System Response Characteristics 29 SECTION 5 PREVENTIVE MAINTENANCE AND TROUBLESHOOTING A periodic inspection and preventive maintenance program will significantly improve the performance and longevity of this equipment The main items of routine maintenance are periodic inspection and mirror cleaning Maintenance of the system 15 otherwise limited to that associated with troubleshooting the system 5 1 PERIODIC INSPECTION GENERAL Perform periodic ins
32. st aircraft installations If shock mounts are deemed necessary they are made by Barry Controls and the part number is Barrymount L44 BA M 2 Use BAM for metric and for standard Install one on each corner of the Power unit using the screw holes on the blue mounting brackets on the bottom You will need a total of 4 Barrymounts HESEURE Qa Buck RESHARCH MSTRUM SER 2017 SENS POWERIN SENSOR d A 865 232 USER SERVICEAPLE PARTS INSIDE _ __ THIS UNIT CONTAINS SELF HESETTING FUSES Figure 5 Power unit 2 4 2 5 16 CABLES Six connectors and wiring diagrams or three cables are supplied power unit to 28 VDC power unit to sensing unit and power unit to control indicator unit Each connector is unique so that it 15 Impossible to accidentally connect the cables incorrectly OPTIONAL ACCESSORIES Aspirating Kit Provides airflow through the 1011C sensor when it 15 not exposed to in flight conditions It consists of an aspirating fixture which attaches to the sensor a pump a floating ball flowmeter with control valve and a length of non hygroscopic tubing with fittings The fixture attaches itself quickly and allows an operational check of the entire system the lab or on the aircraft while parked It also allows use of the system in the lab or other off aircraft environments and permits a complete leak check to be performed Inlet
33. t da NN NS SN NN KA N EN NN ANN EA ANA 8 do 22 SS DP amp PRESSURE DP 14 7 PSIA LNIOd 0 1 104 15083 2000 4000 6000 8000 19 000 200 300400 600 8001000 20 water vapor in air PART PER MILLION BY VOLUME PPM Figure 15 37 amp n 105125 404 4 Figure 16 Aspirating Fixture Hookup 38 Figure 17 1011C Hygrometer Complete 39 Table 1 1011C Connectors Power Unit 0 Control Indicator 2 2 2 PTO6E20 16P SR PTO6E14 195 SR PTO6B12 10P SR PTOGES 35 SR Control Indicator PTO6E14 18 SR PTOGE14 185 SR Table 2 Dew Point to Frost Point Conversions Below 0 C dew point hygrometers measure the frost point temperature rather than the dew point The table below permits conversion from dew to frost point For a more accurate con version consult the Smithsonian Meteorological Tables __ lt e FROST DEW FROST DEW FROST DEW POINT POINT POINT POINT POINT POINT 0 0 40 Table 3 Dew Point Error due to Pressure Change in Sampling System dew frost point approx error degrees C OC psig 70 0 46 60 0 51 50 0 55 40 0 58 30 0 65 20 0 70 10 0 71 0 0 94 10 1 01 20 1 10 These errors are calculated for sea l
34. which can occur the abruptness of changes encountered and various thermodynamic and aerodynamic considerations While the 1011C is designed using the highest standards in this type of instrument in flight situations can be encountered which will tax its limits To help assure consistently good performance a number of cautionary factors are discussed in this manual 1 2 BRIEF PHYSICAL DESCRIPTION Physically the system Figure 1 consists of a sensing unit a control indicator unit a power unit associated cabling and a maintenance unit The Sensing Unit 15 the moisture detecting device It contains a right or left hand inlet fitting a mirror sensing control optics a thermistor a TEC and associated electronics The Control Indicator Unit B 15 the user interface component and contains the on off function switch balance control and displays The Power Unit C distributes operating power to the system components and contains the circuitry that controls the thermoelectric cooler and converts mirror temperature to a suitable output signal provided at rear of unit The unit is equipped with quick remove shock mount The Maintenance kit Consistng of bottles for water and acetone cotton swabs and spare gaskets and o rings Unlike the 10118 the 1011C does not come with a calibration plug This 1s because the 1011C uses an ultra stable thermistor instead of an RTD which improves speed of response and 15 far less susceptible to
Download Pdf Manuals
Related Search