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Pressure Sensors
Thermo Fisher Scientific
Note The T1 Ambient temperature sensor is readily accessible. However,
the T2, T3, and T4 sensors should be allowed to equilibrate to either
ambient or room temperature if the IMR Heating system has been active
within the past one-hour.
Three pressure sensors are included in the Model 5030 SHARP:
•
P1 orifice sensor
•
P2 pump vacuum sensor
•
P3 barometric pressure sensor
P1 measures the pressure differential across an orifice and is used for the
flow calibration. P2 measures the vacuum under the filter tape, relative to
barometric pressure. P3 directly measures the barometric pressure.
Although the Model 5030 SHARP should hold a valid calibration for up to
one year, typically it is recommended by the USEPA to visit the monitoring
site biweekly to perform a flow check for control charting.
Should an error in the flow check be significant (>7%), the error may be
caused by one of the pressure sensors (most probably P3 barometric
pressure). It would also be beneficial to control chart the P3 sensor with
each site visit. Furthermore, P3 sensor audits can be done once per quarter.
If the P3 sensor does not agree within ±10 mm Hg (±13.33 hPa) of the
auditing standard, then a calibration is required in addition to an annual
calibration. A drifting control chart from biweekly checks can define for the
user what the calibration frequency may be for the instrument and if there is
any persistent sensor drift. Should a fatal error occur with a pressure sensor,
contact the Thermo Fisher Scientific.
Note The P1 and P2 pressure sensors are factory calibrated and re-zeroed
with each filter exchange. Calibration for these two sensors can only be
done by a factory-trained technician.
The "Installation" and "Calibration" chapters provide the procedures for
re-zeroing the nephelometer. Although the nephelometer is designed to
provide a consistent optical background measurement, drift may occur
should the optics becoming coated over time. Normally an annual cleaning
of the optics by a factory-trained technician should be scheduled.
Preventive Maintenance
Model 5030 SHARP Monitor Instruction Manual
Pressure Sensors
5-5
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