MKS Baratron 740C, Manual, Page: 52 / 84

How To Check the Transducer Zero Chapter Two: Installation
42
How To Zero an Absolute Transducer
To zero an absolute transducer, you must pump the unit, with the power on, down to a pressure
less than the transducer’s resolution (0.01% of Full Scale).
Note
The zero adjustment must be made at a pressure less than the transducer’s
resolution (0.01% of F.S.).
In addition, you should position the transducer in the
same orientation as
it will be positioned when installed in your system.
Zeroing a transducer at a pressure above its stated minimum resolution creates a zero offset
relative to true absolute pressure. All subsequent readings are then linear and accurate relative to
the offset value .
Note
If your system cannot achieve a sufficiently low pressure to set the
transducer zero, you may use a vacuum leak detector with sufficient
vacuum pumping (to achieve proper zeroing pressures). In this case,
mount the transducer on the leak detector
in the same plane of orientation
as it will be during actual use .
To properly zero an absolute transducer, follow this procedure:
1. Install the transducer in a system and connect a power supply/readout.
2. Pump the system down to a pressure below the resolution of the transducer.
Refer to Table 18, page 43, for recommended pressure levels.
3. Using a small screwdriver, adjust the
ZERO
pot until the readout displays zero (0000).
Refer to Figure 12, page 41, for the location of the
ZERO
pot.