Nominal size and flow

Guidelines for selection of sensor

• Min. measuring range: 0 … 1 m/s
• Max. measuring range: 0 … 10 m/s

Nominal flow velocity:

• Normal: 1 … 3 m/s
• Minimum: not permanently below 0.5 m/s
• Maximum: up to 8 m/s

Flow velocity calculation formula:

• v = (4 x Q_max) / (? x D_i? x 3600)
• v in m/s, Q_max in m?/h, D_i in m

Additional to the flow velocity check it is recommended to observe the Reynolds number (Re):

The optimal performance of the flowmeter is with a Re above 10 000, which is typical for flow velocities (water) above 0.5 m/s. Avoid an Re value between 2000 and 5000. In order to observe this and to be above the recommended 0.5 m/s flow velocity limit the sensor size must be reduced.

Re formula: Re = V x Di / Viscosity

V in m/s, Di in m, Viscosity in cSt (X x E^-6 m²/s)

Example: Viscosity for water at 20 °C = 1 x E^-6 m²/s

Inlet and outlet conditions

Recommended inlets and outlets

To maximize performance inlet and outlet must be straight. There must be a certain distance between flowmeter and bends, pumps and valves. It is also important to centre the flowmeter in relation to pipe flanges and gaskets.

Valves must always be installed after the flowmeter. The only exception is installation of the sensor in a vertical pipe. In this case a valve below the sensor is necessary to allow zero point adjustment. It is important to select a valve which does not alter the flow when fully open.

¹⁾ Inlet for FUE380 approved systems: Minimum straight inlet pipe: 1.5 m, but note further recommendations above.

Reductions

The flowmeter can be installed between two reducers (e.g. DIN 28545). At 8° the pressure drop curve below applies.

Example:

A flow velocity of 3 m/s (V) in a sensor with a diameter reduction from DN 250 to DN 200 (d₁/d₂ = 0.8) gives a pressure drop of 3 mbar.

The sensor must always be completely filled with liquid:

The following installations must be avoided:

• Installation at the highest point of the pipe system
• Installation in vertical pipes with free outlet

With partially full pipes or pipes with free outlet the flowmeter should be located in a U-shaped tube:

Installing the transducers in horizontal position is recommended:

Pressure/temperature curve to EN (DIN) flanges

Pressure/temperature curve to ANSI B16.5 flanges

Note: The pressure/temperature curves only assist in the selection of a system. No responsibility is taken for the correctness of the information. For exact data please refer to the PED requirements.

Reference conditions

To ensure continuous accurate measurement, flowmeters must be calibrated. The calibration is conducted at Siemens flow facilities with traceable instruments referring directly to the physical unit of measurement according to the International System of Units (SI).

Therefore the calibration certificate ensures recognition of the test results worldwide, including the US (NIST traceability).

Siemens offer accredited calibrations assured to ISO 17025. Siemens Flow Instruments accredited laboratories are recognized by ILAC MRA (International Laboratory Accreditation Corporation - Mutual Recognition Arrangement) ensuring international traceability and recognition of the test results worldwide.

Flowmeter calibration data are stored in the internal EEPROM of the transmitter FUS060 or FUS080.

The system accuracy refers to the following systems:

SONO 3300/FUS060, SONO 3100/FUS060¹⁾ which are typically calibrated on the frequency output.

Typical calibration reference conditions:
Fluid	Water
Fluid temperature	22 ± 5 °C
Ambient temperature	22 ± 5 °C
Supply voltage	115/230 V AC +10 … -15 %
	DC 24 V +25 … -15 %,
	AC 24 V ± 15 %
Straight inlet length	20 x Di
Outlet	3 x Di
Rangeability	0 … 1 m/s to 0 … 10 m/s
Repeatability	Better than 0.25 % in the range 0.5 … 10 m/s
Linearity (for water)
Reynolds number 1000 < Re < 5000	Better than 1 %
Reynolds number > 5000	Better than 0.5 %

¹⁾ Only systems with transmitter FUS060. For systems with transmitter FUS080 see chapter on FUS380 and FUE380.

Additional effects of deviations from reference conditions

• Current output: As frequency output (± 0.1 % of actual flow +0.05 % FSO)
• Effect of ambient temperature: Frequency/pulse output: < 0.005 % SPAN/K; Current output: < ± 0.0075 % SPAN/K
• Effect of supply voltage: 0.005 % of measuring value at 1 % change