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
DPS Low Differential Pressure Transmitter - Ultra low differential pressure transmitter for HVAC applications with 4-20mA current loop or amplified voltage output signal in pressure ranges from 0.1 mb up to 1 bar differential. 
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
- DPS Low Differential Pressure Transmitter - Ultra low differential pressure transmitter for HVAC applications with 4-20mA current loop or amplified voltage output signal in pressure ranges from 0.1 mb up to 1 bar differential.
- 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
- DPS Low Differential Pressure Transmitter - Ultra low differential pressure transmitter for HVAC applications with 4-20mA current loop or amplified voltage output signal in pressure ranges from 0.1 mb up to 1 bar differential.
250″wc Orifice plate flow measurement dp transmitter - This differential pressure (dp) transmitter can be used to measure the difference in upstream and downstream flowing pressure either side of a orifice plate.