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1.0 Introduction
Setra’s Model 730 capacitance manometer is a temperature compensated, absolute pressure
transducer designed for accurate and repeatable vacuum measurements. Various full scale
ranges are available from 10 Torr up to 1000 Torr. The units of measurement may be specified
in Torr (mmHg), mBar, kPa, or PSIA.
The Model 730 operates from a 12-30 VDC power supply and provides a 0-10 VDC signal
output that is linear with pressure and independent of gas composition. It can also be supplied
with a 0-5 VDC output, which operates from 9-30 VDC power supply. The Model 730 is pin
for pin compatible with competitive capacitance manometers. Superior EMI/RFI performance
is achieved by the use of a metal case in conjunction with surge and ESD suppression
components and RFI filtering on the inputs and outputs. The Model 730 has easy access to
multi-turn potentiometers for fine zero adjustments. Inconel is used for all wetted materials
for compatibility with corrosive gases. A wide range of process connections are available.
The high accuracy pressure sensing element used in the Model 730 is Setra’s variable
capacitance sensor. A centrally located feedthrough assembly supports a circular electrode in
close proximity to the back surface of the diaphragm. Together, the electrode and diaphragm
form a variable capacitor within a small reference vacuum chamber. As the pressure increases,
the diaphragm deflects and the gap between the electrode and diaphragm reduces, causing
an increase in the capacitance. This change in capacitance is detected and converted to a
highly accurate linear DC electronic signal by Setra’s high frequency precision diode bridge
circuit.
Excellent zero stability and barometric insensitivity is achieved through the patented sensor
design. The Model 730 sensor contains no fragile or complex parts as found in ceramic based
capacitance manometers. The all welded construction eliminates stability issues inherent in
other designs due to frictional contact between dissimilar materials.
2.0 Mechanical installation
Remove all packaging material and the protective flange cover and visually check the Model
730. If the Model 730 appears damaged, notify Setra Systems or your supplier immediately.
Retain packaging materials for inspection. Do not use if damaged. If the Model 730 is not
going to be used immediately, then replace the protective flange cover and store in an area
where the temperature range is controlled between -20 to +85°C.
The Model 730 can be mounted in any orientation on the vacuum system. To avoid the buildup
of debris or condensible material in the measurement cavity of the Model 730 (which may
cause measurement errors), we recommend that you install the Model 730 vertically with the
tube facing down. Outline drawings showing the external dimensions are shown in Figure 1.
