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Converting 4 to 20mA Linear Signal to and from Square Root Extraction Signal

Some pressure measurements are used to indirectly derive another type of measurand. One of these is the Rate of Flow of a gas or liquid. The flow rate along a closed pipe is directly proportional to the square root of the pressure drop or differential pressure between two points.

Since the relationship is non-linear, there is a greater change in flow at low pressures compared to higher ones. In order to optimise the resolution of flow measurement, the output on some differential pressure transmitters can be altered so that it is directly proportional to the flow rate rather than the differential pressure.

Featured sqrt extraction 4-20ma current loop signal related products

  • Universal Strain Gauge Bridge Input Transmitter – STRAIN - Simplify your strain measurement setup with the STRAIN Universal Strain Gauge Bridge Input Transmitter. This versatile device converts mV signals from strain gauges, load cells, and pressure transducers into 0-10Vdc, 0-20mA, or 4-20mA outputs.
  • DPT200 High One Side Overload Differential Pressure Sensor - DP transmitter for measuring pressure difference between two pressure points which can tolerate up a very high overload pressure independently on either the positive or negative side port or both together at the same time.

Linear → Sq Rt 4-20mA Conversion

The following formula can be used for converting a linear 4-20mA current loop signal to a square root extraction type:

OutputSqRt = 4mA + (4 x √ (OutputLinear – 4mA))

The following table shows values for linear to square root extraction 4 to 20 milliamp current loop signal.

Linear (mA) Square Root (mA)
4 4.00
5 8.00
6 9.66
7 10.93
8 12.00
9 12.94
10 13.80
11 14.58
12 15.31
13 16.00
14 16.65
15 17.27
16 17.86
17 18.42
18 18.97
19 19.49
20 20.00

Convert any linear measurement to sqrt extraction 4-20mA signal

Featured sq rt 4 to 20 milliamp output related products

  • Low Differential Pressure Transmitters DPS300 User Switchable Pressure Range, Volts or Current Output Low DP Sensor - The DPS 300 is a low range HVAC differential pressure sensor. The lowest possible pressure range is 0...100 pascals. 2 or 3 switchable pressure ranges, plus volts or current output are included with most standard configurations.
  • DPT200 High One Side Overload Differential Pressure Sensor - DP transmitter for measuring pressure difference between two pressure points which can tolerate up a very high overload pressure independently on either the positive or negative side port or both together at the same time.

Sq Rt → Linear 4-20mA Conversion

The formula for converting a square root extraction 4-20mA signal to a linear one is: 

OutputLinear = 4mA + ((OutputSqRt – 4mA)² / 16)

The following table shows values for square root extraction to linear 4 to 20 milliamp current loop signal.

Square Root (mA) Linear (mA)
4 4.00
5 4.06
6 4.25
7 4.56
8 5.00
9 5.56
10 6.25
11 7.06
12 8.00
13 9.06
14 10.25
15 11.56
16 13.00
17 14.56
18 16.25
19 18.06
20 20.00

Convert sqrt extraction 4-20mA signal to any linear measurement

Featured square root extraction 4-20ma signal related products

  • Universal Strain Gauge Bridge Input Transmitter – STRAIN - Simplify your strain measurement setup with the STRAIN Universal Strain Gauge Bridge Input Transmitter. This versatile device converts mV signals from strain gauges, load cells, and pressure transducers into 0-10Vdc, 0-20mA, or 4-20mA outputs.
  • Low Differential Pressure Transmitters DPS300 User Switchable Pressure Range, Volts or Current Output Low DP Sensor - The DPS 300 is a low range HVAC differential pressure sensor. The lowest possible pressure range is 0...100 pascals. 2 or 3 switchable pressure ranges, plus volts or current output are included with most standard configurations.

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Convert 4-20mA signal to…

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  • 20-4mA
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Wirelessly Measure & Log 4-20mA

Use this battery powered wireless 4-20mA wireless transmitter to transmit readings to a receiver connected to USB, RS485, RS232, cellular network or analog output

Use this battery powered 4-20mA wireless transmitter to transmit readings to a receiver connected to USB, RS485, RS232, cellular network or analog output

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