Spirax Sarco Orifice Plate System

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Spirax Sarco Orifice Plate System
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How they work....
Flow
dp
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Orifice calculations...

• The pressure drop across an orifice plate is used
  to derive the rate of flow using..................
  .....
• BS 1042
• ISO 5167
• ASME MFC - 3M (1989)
• Flow K dP

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Orifice Plate Output
Flow Error 11
Flow Error 21
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Traditional M240G system
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Pressure transmitters FCX-A/CII
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Pressure transmitters FCX-A/CII

• Both Types use
• Measuring cell with floating sensor
• Floating silicone sensor in the cell neck, to
  improove the static pressure, overload and
  temperature characteristics.
• Protection diaphragm in the cell body allows an
  overload pressure corresponding to the maximum
  static pressure without damage of the sensor.

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Pressure transmitters FCX-A/CII

• Capacitance silicone sensor
• The micro machined silicone sensor is based on
  the capacitance measuring principle. Capacitance
  C1 C2 change with applied differential
  pressure.
• Cell protected from temperature variation by
  silicon fabrication and minimmal physical size.
• Stress forces are balanced by floating cell
  design.

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Pressure transmitters FCX-A/CII

• Matching Convolutions reduce volume
• Convolutions are machined on the body.
• Diaphragm is electron beam welded to the body
• Diaphragm is pressed to body.
• Benefits
• No damage on over pressure
• Improved Temperature Spec
• Reduced Stress

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ORIFICE PLATE FLOWMETERS

• Advantages
• Low cost, especially on large sizes
• No need for recalibration
• Widely accepted
• Disadvantages
• Poor turndown (41 typical)
• Long installations
• Subject to wear.