Thermo Scientific 146i, Instruction Manual

Page: 228 / 340

Servicing
Pressure Transducer Calibration (Photometer option)
7-40 Model 146 i Instruction Manual Thermo Fisher Scientific
4. Remove the two pressure transducer retaining screws and remove the
pressure transducer.
5. Install the new pressure transducer assembly by following the previous
steps in reverse.
6. Calibrate the pressure transducer. Refer to the “Pressure Transducer
Calibration” procedure that follows.
Pressure Transducer
Calibration
(Photometer option)
An error in the zero setting of the pressure transducer does not introduce a
measurable error in the output concentration reading. Therefore, if only a
barometer is available and not a vacuum pump, only adjust the span setting.
A rough check of the pressure accuracy can be made by obtaining the
current barometric pressure from the local weather station or airport and
comparing it to the pressure reading. However, since these pressures are
usually corrected to sea level, it may be necessary to correct the reading to
local pressure by subtracting 0.027 mm Hg per foot of altitude.
Do not try to calibrate the pressure transducer unless the pressure is known
accurately.
Use the following procedure to calibrate the pressure transducer.
Equipment Required:
Vacuum pump
1. Remove the cover.
WARNING The service procedures in this manual are restricted to qualified
service representatives.
If the equipment is operated in a manner not specified by the manufacturer,
the protection provided by the equipment may be impaired.
Equipment Damage Some internal components can be damaged by small
amounts of static electricity. A properly grounded antistatic wrist strap must
be worn while handling any internal component.