ATD Cal. Lab. Information

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
Information Found Here
50Y RH Cal Procedure 50Y Temp. Cal Procedure


RH calibration for Vaisala 50Y probes.


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:
	PM	enters 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





Temp. calibration for Vaisala 50Y probes.

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.