Silicon Diaphragm (only for gases) |
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Principle |
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A strain sensitive resistor (strain gauge) is formed
on a silicon chip. When pressure is applied in the
direction of the arrow, the silicon chip deforms and the
resistance value of the strain sensitive resistor (strain
gauge) changes. A change in pressure is thereby
converted into an electrical signal.
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Structure |
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Silicon diaphragm type
AP-30 Series
(Reference: Keyence products)
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Mechanical type(Bourdon tube type, etc.) |
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| Pressure is applied directly to
the silicon diaphragm through
the pressure port, and is
detected. |
Pressure applied to the inside
of the Bourdon tube expands or
contracts the entire tube, and
moves the pointer. |
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Features |
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| Pressure sensors fit into two basic categories, electronic
and mechanical. Previously, mechanical sensors like the
Bourdon tube, etc., were used. However, since they
have a short service life, electronic pressure sensors
that feature long service life, high accuracy, and high-speed
response have become popular. |
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Stainless Diaphragm Type (Gas/Liquid Multi-purpose Type) |
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Principle |
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| Changes in pressure are converted into electrical signals if the resistance on the stainless diaphragm is distorted by passing through the diaphragm. |
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Structure |
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Single diaphragm type
AP-50/80A series
(Keyence) |
Double diaphragm type |
 |
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| Voltage is directly detected using the distorted resistance of a thin film semiconductor which was integrated into the stainless diaphragm. |
The voltage received by the thin stainless diaphragm is transmitted to the silicon diaphragm sensor through silicon oil, etc. |
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Features |
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| The stainless diaphragm types are largely divided into single diaphragms and double diaphragms. Traditionally, the double diaphragm type has been commonly used. However, it lacks durability and reliability because of its thin diaphragm and the enclosed silicon oil's volume can fluctuate easily depending on the temperature. The single diaphragm type solves all these problems with its simple structure and improved durability and reliability. |
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