Larson Davis CAL150 Manual - Environmental Precautions
CAL150 Technical Reference Manual
Microphone Calibration
2-5
Environmental Precautions
While the CAL150 will perform normally under a wide
variety of gradually changing environmental conditions,
some precautions should be taken when sudden changes
occur:
•
The temperature of the CAL150 should be stable. If the
temperature changes suddenly, provide a stabilization
time of at least 15 minutes. This will ensure that the
temperature compensation sensors are at the same
temperature as the rest of the unit.
•
While humidity will not affect the CAL150, avoid
condensing moisture. Also, avoid environments over
90% relative humidity because condensation can easily
take place.
•
The CAL150 is insensitive to magnetic fields. However,
the instrument being tested may not be. Therefore,
calibration should not be done near motors, dynamos,
high voltage wires, or other sources of electromagnetic
fields.
Calibrator Calibration
The American National Standards Institute states, “An
acoustical calibrator should be recalibrated at least annually
by the instrument manufacturer or an acoustical test
laboratory qualified to perform calibration.” (American
National Standards Institute. Specifications for Acoustical
Calibrators. ANSI S1.40, 2006,par. 5.2)
Larson Davis believes the frequency of recalibration
depends on the number of calibrators being used and the
number of instruments being calibrated. With this in mind,
the following guidelines are presented for your
consideration:
•
For one calibrator and one measurement instrument, the
CAL150 should be certified at least yearly.