Laversab 6300L, User Manual

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SECTION 6
CALIBRATION
6.1
EQUIPMENT:
This calibration procedure requires the following equipment:
1. Vacuum pump.
2. Pressure supply of clean, dry air at 35 psia
3. Pressure standard having accuracy of at least 0.002 inHg up to 32 inHg and an
accuracy of at least 0.003 inHg from 32 inHg to 50 inHg.
6.2
GENERAL NOTES:
The transducers inside the 6300 are sensitive to the change in density of the medium being
used. The unit must be calibrated with Dry Air only. Calibrating with Nitrogen or any
medium other than Dry Air will give erroneous results.
Because the transducers are medium-sensitive, care must be taken to ensure that the hoses
used in the calibration system do not out-gas. Normally, PVC hoses, or refrigeration type
hoses have a tendency to out-gas. The ideal hoses to use are Teflon or Teflon-coated hoses
because they have a very low absorption and out-gas coefficient. Stainless steel hoses may
also be used.
If the wrong type of hoses are used, then the typical results obtained will show that the error
increases as the pressure increases. Also, it is very unlikely that the repeatability of the
indicated pressure will be less than 0.002 inHg at 60 inHg. If the system cannot achieve
repeatability of 0.002 inHg or less, then the most likely cause is the out-gassing of hoses.
In the following sections, the instructions call for generating a pressure of 1.000 inHg abs.
using the Pressure Standard. If your Standard cannot generate such a low pressure, then
please generate as low a pressure as possible provided it is less than 4.0 inHg abs.
The 6300 has a drift of typically 0.005 %FS per year. Therefore it needs to be calibrated once a
year to perform adequately as a calibration standard for air data equipment.