Description
This file is a temporary repository for REFERENCE INFORMATION NOTES about
using the 'NCAR/ATD' Calibration Facility.....
Steve/Kurt Please edit me!!!
Last modified: Mon. 5/16/03
50Y RH Cal Procedure | 50Y Temp. Cal Procedure | |
Operations are performed in the Thunder Scientific Temp./RH Chamber. This chamber is used for RH cals only because it does not have sufficient mixing for proper temperature cals. The temperature control it does provide is only used to profile humidities over the expected operating temp. range of the device undergoing RH cal. Re Cleaning the transducers: Decide whether to first clean the transducers with distilled h2o before doing a cal. run. This depends upon whether the operation is a 'pre-project' calibration, or a 'post-project' performance check, in which case cleaning may cause mis-estimation of possible offsets experienced in the field. For optimum 'pre-project' calibration, cleaning is normally advisable. Additional cleaning may be done in-between each temperature point, especially for the Krypton Hygrometers which tend to 'scale' during a rh profile run. ---------------------------------- Procedure: 1) Open LabView (F:) Files: (these are .vi Labview executables) TRHDataCollection This will ask what data file to write to enter something under: G:/data/project/RH-precal-snxxx TS-ManualOperation TS-DefaultProfile x=1,2,3 etc. 2) Place 50Y probes in the ThunderScientific chamber Remove TRH gortex filters, make sure 50Y sensors are connected to their assigned TRH-CPU4AD boards to ingest and process their data. Suspend the sensors in a bundle using a string on the roof of the chamber with the internal temp. probe placed in the same bundle. Close access port with 2 round foam bungs put square blue foam in doorway and close door. Start Pump, using toggle switch on the power strip under the chamber. Turn-On Chamber, power switch is on the back. 3) Connect TRH A/D Boards with each 50Y probe to Interface Board Use Berg connector cables (located under the bookshelf with board suspended up-side-down). Note: Ports assigned 0-7, left to right. We use ports 1-5 currently Turn-On 12V power supply next to the interface board. 4) Open Procomm Plus terminal on PC (Nowitna located adjacent to the chamber) Determine if TRH data is coming in: Ports COM4-COM8. Note: the TRH should have been setup for RS232 (not RS485) and broadcasting continuous data messages prior to calibration. 4 Data fields are needed for the pre-set LabView program that is used. If this is not the case; using procomm type: PMenters polled-mode of TRH AD enter AD submenu CHNL 0 1 2 3 enables 4 channels AD exit AD submenu CD start Continuous Data output MR or power cycle may be needed to restart Exit Procomm (this is optional but there could be conflict in port use with the data collection program noted below if you try to look at the same port that procomm has open) 5) Start all 3 LabView 'VI' programs noted above The screen widget may show 'Off' so use the mouse to click on the 'White Arrow' at the upper left corner. This will turn it 'black' and the widget should indicate 'running.' On 'ManualOperation' VI: use selectable values under 'control setting' to change Sat.Temp. to +15degC. Then click on the large 'Run' button in the lower left corner of the window. On 'TSDataCollection' VI: Make sure that the sensor count box (upper left) is the same # as the number of sensors in the chamber. Check 'last data scan' has real numbers coming through. Wait 1-Hour; Check Chamber LCD display to see if the 'Satur degC' is getting close to +15C (within a couple of degrees). If it is: then on PC go to 'TSManualOperation' VI, and click on "profile" button in the upper left. Look at the 'TS-DefaultProfile' VI status button turns blue (it should have been yellow previously). Wait ~28Hours. 6) Stop profile run Make certain that the profile is complete Normally the last step taken is -15degC, 90%rh. You can also check the size of the data file to see if it has data. Press 'Black' arrows in the upper left corner of all 3 windows (or perhaps the 'stop' button) Click on the 'X' button in the upper right corner on all 3 windows Note: if the program asks whether to 'save changes,' say yes. Check data file exists and has something in it: /Data/Project-Name/postcal... Turn-Off the Chamber and Compressor
Re Temp cal: The Oil Bath is used for Temperature Cals. It has a holder for 6-8 glass tube/rods which is immersed in it. Only 6 glass tube/rods are available. The 50Y's are run through the 'trh boards' using a short extension cable. There are 2 types of hoses used to help protect and fit the cables: 1 ~6" spiral wrap which is put over the cables first; then 1 ~6" tube which fits longitudinally over the spiral and creates a good fit in the glass tubes. Obviously the tubes protect the transducers / cables and create a thermal 'bond' with the oil.