DeFelsko PosiTector CMM IS, Instruction Manual

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within the Calibration Check Chamber when not in use. The
Calibration Check Chamber and Saturated Salt Solution are
designed in accordance with ASTM E104 to maintain a constant
relative humidity. Per ASTM F2170, the Calibration Check
Chamber and Saturated Salt Solution maintain a constant relative
humidity of 75% (at 25° C) and keeps the probe in a ready-to-use
condition.
ASTM F2170 requires calibration to be verified within 30 days
prior to use. Power-up the probe by inserting a battery, positive
(+) side up. Probe calibration is verified by inserting a probe into
the Calibration Check Chamber, connecting to either the
PosiTector App or a PosiTector Advanced gage body and
taking a measurement (after allowing the probe at least 1 hour to
acclimate to the present environment). Probes should report a
relative humidity within 2% of the humidity value listed in Table 1
for the corresponding temperature. To simplify the verification
process, we recommend using the Cal Check function of the
PosiTector App or PosiTector Advanced . The Cal Check
function automatically determines whether a probe is reading
within tolerance.
Probes should be allowed to acclimate for at least 24 hours within
the Calibration Check Chamber and Soluble Salt Solution before
calibration is checked.
It is important to maintain a constant temperature within the
Calibration Check Chamber. Relative humidity variation due to
temperature fluctuation for the Calibration Check Chamber is
shown in Table 1.
Table 1
Extracted from Table A1.1,
Equilibrium Relative Humidity Values
for Selected Saturated Aqueous Salt
Solutions (ASTM E104)
Example Tolerance Calculation:
At 25° C, the Soluble Salt Solution relative humidity range is
75.3% ± 0.2. Including the ±2% relative humidity tolerance
specified in ASTM F2170, a probe would be considered to be in
tolerance if it measured between 73.1 – 77.5 %.
When the Saturated Salt Solution (Boveda) is completely
dry, it will solidify. They should be replaced while there is still
moisture present and before they are completely solid.
NOTE:
t °C t °F
Sodium
Chloride (RH%)
5 41 75.7 + 0.3
10 50 75.7 + 0.3
15 59 75.6 + 0.2
20 68 75.5 + 0.2
25 77 75.3 + 0.2
30 86 75.1 + 0.2
35 95 74.9 + 0.2
40 104 74.7 + 0.2
45 113 74.5 + 0.2