Vartech's process calibrator range covers three instruments - a full temperature and process calibrator, a dedicated loop calibrator, and a precision V/mA signal calibrator - each aimed at a different part of instrumentation maintenance work. Choosing the right one comes down to what signal types you actually need to source and measure.
Full Process Calibrator or Dedicated Loop Calibrator?
The V 7220 R is the broadest instrument in the range - a 5-digit source-and-measure calibrator covering DC voltage, resistance, and thermocouple (multiple T/C types) and RTD (2-wire/3-wire/4-wire) simulation. This is the right instrument when your maintenance work spans multiple sensor types - temperature transmitters, RTDs, thermocouples and general process signals - from a single calibrator. The V 7221 B is more specialised: a dedicated 5-digit loop calibrator that sources 0-30 mA DC and measures ±35 mA / ±35 V DC, with sawtooth and triangle wave output for testing a loop's dynamic response - the right choice when your work is specifically 4-20 mA current loop calibration and verification rather than broader temperature sensor work.
Precision V/mA Calibration - The MS 7221
The MS 7221 is a 4½-digit V/mA process signal calibrator purpose-built for 4-20 mA loop work - sourcing and measuring 0-24 mA DC loop current and 0-10 V DC, with 0.015% mA accuracy and a built-in 24 V loop supply. That accuracy figure matters directly: when you're calibrating a transmitter or verifying a control loop's accuracy against a specification, the calibrator's own accuracy needs enough margin over the device under test that the measurement itself isn't the limiting factor. The built-in 24 V loop supply is a practical convenience - it means the calibrator can power a 2-wire transmitter loop directly during a bench check, without a separate loop power supply.
Calibrator accuracy vs. device-under-test accuracy
Portability for Field Calibration
All three Vartech calibrators are handheld, battery-powered instruments with torch and backlight - built for field calibration work (checking a transmitter in situ on a process line) rather than requiring a bench setup. This matters for instrumentation technicians who need to walk a plant's transmitter population and calibrate or verify each one in place, rather than removing instruments to a lab bench.
Quick Reference by Use Case
- Multi-sensor-type calibration work (T/C, RTD, DCV, resistance): V 7220 R.
- Dedicated 4-20 mA loop calibration with dynamic waveform testing: V 7221 B.
- Precision V/mA calibration with built-in loop supply: MS 7221.
CIE Instruments is an authorised distributor for the full Vartech process calibrator range. See our general guide on process calibrators, or contact us to match a calibrator to your loop and sensor types.