VTI SGA-100 Instruction Manual

VTI Corporation
Technical Note #0008 Rev H, 3/05/08
Calibration Protocol (short version)
A. General
The performance of the VTI water sorption analyzers is checked by running standard
samples with known sorption behavior. The deliquescence point of sodium chloride
(NaCl) at 25oC and the known amount of water sorption at 80% RH at 25oC of (PVP)
Polyvinylpyrrolidone (irrespective of molecular weight), test the instrument performance.
Running these at regular intervals is strongly recommended.
B. Sodium Chloride Experimental Details
Guidelines are:
Drying conditions
Drying temperature: 25°C
Equilibrium criteria: 0.000 % W every 5 minutes
Max equilibrium time: 5 minutes
Experimental conditions
Experimental temperature: 25oC
Equilibrium criteria: 0.000mg every 5 minutes (CI and CAHN balances)
Max equilibrium time: 15 minutes for 500ccm MFC; 25 min for
instruments with <500ccm MFC.
Start % RH: 84%
Minimum % RH: 73%
Steps: Use steps 84, 80, 78, 77, 76, 75, 74, 73
Quantity of sample: 20 to 25 mg
Figure 1 shows a typical adsorption isotherm for NaCl, which deliquesces at 75.5% RH
at 25oC to become a saturated salt solution. A tolerance of ±1% is acceptable. The
deliquescence range falls between the apex of the curve (the last point where the
sample is gaining or maintaining weight) and the next point where the sample weight
decreases. The mid point of this range is computed by adding the %RH of the apex and
the %RH of the next point where the weight decreases then dividing the result by two.
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VTI TN #0008, Rev H, 3/5/08 2 of 3
Figure 1: A typical adsorption isotherm for sodium chloride (short version)
D. Polyvinylpyrrolidone Experimental Details
Guidelines are:
Drying conditions
Drying temperature: 60oC
Equilibrium criteria: 0.000% every 5 minutes (CAHN & CIE Balance)
Max equilibrium time: 60 minutes
Experimental conditions
Experimental temperature: 25oC
Equilibrium criteria: 0.001% every 5 minutes (CAHN & CIE Balance)
Max equilibrium time: 200 min
Start % RH: 10 %
Maximum % RH: 80 %
Steps: 10%, 20%, 80%
Quantity of sample: 3 to 3.5 mg

Sorption Isotherm
0
3.727888823
7.232872963
41.92790222
0
5
10
15
20
25
30
35
40
45
0 102030405060708090
%RH
Weight (% change)
Adsorption
VTI TN #0008, Rev H, 3/5/08 3 of 3
Figure 3 shows a typical adsorption isotherm for polyvinylpyrrolidone. The percentage of
weight increase is 42% (±2) at 80% (±1) RH. An uncertainty of ±2% is acceptable,
which gives an acceptable range of 40 to 44 wt %. Values can run higher (up to
46 wt %) in vacuum systems.
Figure 3: A typical adsorption isotherm for PVP
END OF PROCEDURE
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Effective Date: March 5, 2008 Approval:______________________________
Agustin Venero, Laboratory Director
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VTI Corporation
Test Procedure # 0015 Rev B, 9/18/04
SGA-100 Org Sample & Evaporator Temperature RTDs’ CALIBRATION
1.0 Scope of VTI TP 0015
1.1 The RTD Temperature Calibration procedure applies to the VTI SGA-100 models
with organic option only.
2.0 Purpose
2.1 The purpose of this procedure is to ensure that the Sample and Evaporator RTD
Temperature Probes are properly calibrated for operation.
3.0 Equipment and Documents Required
3.1 Equipment
3.1.1 Calibrated and certified traceable thermometer and probe with a minimum
range of 0°C to 100°C with a resolution of ±0.1°C or better with a display of
two decimal places or better
3.2 Documents and Software
3.2.1 RTD calibration Macro for Organic Models
3.2.2 RTD calibration spreadsheet for Organic Models
3.2.3 Microsoft Excel
4.0 RTD Calibration Process
4.1 Carefully remove the balance from the instrument.
4.2 Ensure that the instrument is powered on with all of the cables and computer
attached to the peripherals.
4.3 Print out macro spreadsheet for documenting voltages and temperatures.
4.4 With the sample door opened or removed:
4.4.1 Attach the thermometer probe tip to the Sample RTD probe tip preferably
with aluminum tape or can use aluminum heat transfer block (Suggestion:
wire Temperature probe through the hole in the rear of the balance
chamber down the sample tube)
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VTI TP #0015, Rev B, 9/18/04 2 of 2
4.4.2 Disconnect the Evaporator RTD probe from the evaporator and also install
the probe tip to the Sample RTD probe tip (Suggestion: also introduce
through the hole in the rear of the balance chamber down the sample tube)
4.4.3 Physically connect all three probe tips.
4.4.4 Plug top of sample tube hole (where the probe and Org RTD wire are going
through) with paper towel.
4.4.5 Re asseamble all acrylic panels
4.5 Change the bath to manual mode
4.6 Set the bath temperature initially to 10ºC.
4.7 Open NiDaq Test Panel on the Analog Input Card, Channel 2 (Sample RTD) and
Channel 4 (Evaporator RTD)
4.7.1 Y scale mode: Auto Scale
4.7.2 Data Mode
4.7.2.1 Strip Chart Mode
4.7.2.2 …when temperature is stable…(after the
temperature on the temperature meter is achieved,
wait 15 minutes)
4.7.2.3 Choose the one shot Mode
4.7.2.4 …take five random readings by hitting the enter
button and document to five decimal places…
4.7.2.5 Average the five readings
4.7.2.6 Document average in spreadsheet w/five decimal
points
4.7.2.7 Document temperature in spreadsheet w/two
decimal places
4.7.2.8 Set bath to 20ºC and repeat steps 4.7.2.2 – 4.7.2.7
4.7.2.9 Set bath to 30ºC and repeat steps 4.7.2.2 – 4.7.2.7
4.7.2.10 Set bath to 40ºC and repeat steps 4.7.2.2 – 4.7.2.7
4.7.2.11 Set bath to 50ºC and repeat steps 4.7.2.2 – 4.7.2.7
4.7.2.12 Set bath to 60ºC and repeat steps 4.7.2.2 – 4.7.2.7
4.8 Document accumulated numbers in macro spreadsheet
4.9 The slope and intercept will be computed along with R² which should not be lower
than .9998.
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Effective Date: September 18, 2004 _Approval: ______________________
Henry Barnard, Operations Dir
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