1. Spirax Sarco Orifice Plate System
7 November, 2018

2. How they work.... Flow dp 7 November, 2018 www.coulton.com
When a fluid flows through a restriction it creates a pressure drop . If the flow increases , the pressure drop increases, and the maximum pressure drop will occur at the maximum flowrate. The pressure drop will be zero when there is no flow.
However at 50% of the flow, orifice plates do not produce 50% of the pressure drop. Or put another way , the differential pressure that is produced by an orifice plate is not linear to the flow rate. dp
7 November, 2018

3. 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
7 November, 2018

4. Orifice Plate Output Flow Error 1:1 Flow Error 2:1 7 November, 2018
If the DP transmitter makes an error in the measurement of the pressure drop, different errors in the flow reading will be produced dependent on which part of the meter range is being used. This error will be introduced even if the square root extraction is included in the transmitter.
7 November, 2018

5. Traditional M240G system
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6. Pressure transmitters FCX-A/CII
Silicon Sensor
Dual Temperature Compensation
Eprom
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7. 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.
7 November, 2018

8. 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.
7 November, 2018

9. 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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10. 7 November, 2018 www.coulton.com
The Spirax Sarco M410 Orifice plate package is supplied as a complete package, this ensures that all of the required components for each metering station are supplied together.
The package is labeled to identify all of the components that are being supplied against each application.
7 November, 2018

11. ORIFICE PLATE FLOWMETERS
Advantages:
Low cost, especially on large sizes
No need for recalibration
Widely accepted
Disadvantages:
Poor turndown (4:1 typical)
Long installations
Subject to wear.
7 November, 2018