Reference Manual
00809-0100-4022, Rev AA
July 2002
Model 4600
4-4
Determining Calibration
Frequency
Calibration frequency can vary greatly depending on the application,
performance requirements, and process conditions. Use the following
procedure to determine calibration frequency that meets the needs of your
application.
1. Determine the performance required for your application.
2. Determine the operating conditions.
3. Calculate the Total Probable Error (TPE).
4. Calculate the stability per month.
5. Calculate the calibration frequency.
Sample Calculation
Step 1: Determine the performance required for your application.
Step 2: Determine the operating conditions.
Step 3: Calculate total probable error (TPE).
Step 4: Calculate the stability per month.
Step 5: Calculate calibration frequency.
Required Performance:
1.1% of span
Transmitter:
Model 4600G, Range 4
Calibrated Span:
4000 psig
Ambient Temperature Change:
50 °F
TPE =
= 0.572% of span
Where:
Reference Accuracy =
± 0.25% of span
Ambient Temperature Effect =
ReferenceAccuracy
(
)
2
TemperatureEffect
(
)
2
+
0.03
URL
×
Span
-------------------------------
1.0
+
per100
°
F
2
---------------------------
±
Stability = ±0.5% of span for 3 years = ±0.0139% of span per month
Cal. Freq.
Req. Performance
TPE
–
(
)
Stability per Month
-----------------------------------------------------------------------
1.1%
0.57%
–
(
)
0.0139%
------------------------------------------
36 months
=
=
=
NOTE
Temperature Effect is specified per 100°F, divide by 2 for 50°F temperature change.
= ±0.515% of span
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