<Appendix 1.>
A-1
IM 02C01B04-01EN
Appendix 1. 80A Pneumatic Amplifier
(Part No. F9138YA)
The function of the pneumatic amplifier is to convert
a small change in the input signal (an air pressure
signal) to a large change in the output signal.
Typically a 0.07 kgf/cm
2
(0.07 bar, 7 kPa, or 1 psi)
change in the input will produce approximately a 0.8
kgf/cm
2
(0.8 bar, 80 kPa, or 12 psi) change in the
output.
A1.1 Principles of Operation
The air supply enters the pneumatic amplifier
through a port on the surface of the instrument on
which the amplifier is mounted. The input signal
(nozzle pressure) enters the amplifier through
another port and acts on the diaphragm. Since the
stem valve is mounted on the diaphragm, the two
move in unison.
As the input signal increases, the stem pushes
against a ball valve which in turn moves a flat
spring, allowing the supply air to enter the amplifier
body. Further motion of the stem valve, causes it
to close off the exhaust port. Thus, when the input
pressure increases, the stem (exhaust) valve
closes and the supply valve opens; when the input
decreases, the stem valve opens and the supply
valve closes. This varies the pressure to the output.
F001.ai
Input
Flat spring
mounting screw
Ball valve
Supply air
Output
Exhaust
Tension adjustment
Diaphragm
Flat spring
Exhaust valve
Stem valve
Supply air valve
Figure A1. Cross Sectional View
A1.2 Cleaning the Pneumatic
Amplifier
Should the pneumatic amplifier require cleaning,
remove it from the instrument. Loosen the two
cover screws and the spring mounting screw to
disassemble the pneumatic amplifier. Clean the
disassembled parts with a suitable solvent (do not
allow solvent to contact the gasket) and dry them
carefully with compressed air. When reassembling
the pneumatic amplifier, all corresponding holes
must line up and all outside edges must coincide
with other edge of the amplifier body casting.
Tighten all screws.
F002.ai
Cover
screw
Cover
Gasket
Diaphragm
Body
Ball
Flat spring Flat spring
mounting screw
Figure A2. Exploded View
CAUTION
After reassembling the amplifier, perform a
calibration with the calibrator. (Refer to section
A1.3)
