1. What is the 4-20 mA to PSI Conversion?

The 4-20 mA to PSI conversion is used in industrial instrumentation to convert a current signal (typically 4-20 mA) from a pressure transmitter to the corresponding pressure value in PSI. The 4 mA typically represents the zero scale value, while 20 mA represents the full scale value.

2. How Does the Calculator Work?

The calculator uses the standard conversion formula:

Where:

• \( mA \) — Current in milliamps (4-20 mA range)
• \( Span \) — The pressure range in PSI (Full Scale - Zero Scale)
• 4 — The zero scale current value (4 mA)
• 16 — The span of the current signal (20 mA - 4 mA)

Explanation: The formula linearly converts the current signal to the corresponding pressure value based on the instrument's configured span.

3. Importance of Current to Pressure Conversion

Details: Accurate conversion is crucial for process control, monitoring, and safety in industrial applications where pressure transmitters are used.

4. Using the Calculator

Tips: Enter the current value between 4-20 mA and the span (the difference between upper and lower range values) in PSI. All values must be valid (mA between 4-20, span > 0).

5. Frequently Asked Questions (FAQ)

Q1: Why is 4-20 mA used instead of 0-20 mA?
A: The 4 mA "live zero" allows distinguishing between a true zero signal and a broken wire or failed instrument (which would show 0 mA).

Q2: What if my instrument has a different range than 4-20 mA?
A: The formula would need to be adjusted accordingly. For example, 0-20 mA would use a different calculation.

Q3: How accurate is this conversion?
A: The conversion is mathematically precise, but the actual accuracy depends on the transmitter's calibration and linearity.

Q4: Can this be used for reverse calculation (PSI to mA)?
A: Yes, the formula can be rearranged to calculate mA from PSI: \( mA = (PSI/Span \times 16) + 4 \)

Q5: What about 3-15 PSI signals?
A: This calculator is specifically for 4-20 mA to PSI conversion. For 3-15 PSI systems, a different approach is needed.