• Measure and read DC voltages
  • Calibrate recorders in live loops
  • Ranges: Up to 20V
  • Accurate to ±0.02%
  • Simulate pH probes into transmitters & analyzers
  • Measures up to 60 VDC
  • EZ-DIAL double click menu
  • Backlight easy-to-read display

This is the recommended replacement for the following Altek Calibrators:

  • Altek 135 Process Voltage Calibrator
  • Altek 235 Process Voltage Calibrator

What's in the Box

  • NIST calibration certificate (no data)


The PIE 235 Process Voltage Calibrator checks, calibrates and measures voltage instruments. The 20V range has an extended span of up to 24V giving you a portable source for powering your loops. The PIE 235 has a pH simulator used to verify proper operation of pH devices before you place a probe into a calibrated buffer.

The PIE 235 can easily set any value with the adjustable DIAL plus store any three output settings for instant recall with the EZ-CHECK switch. 2, 3, 5 & 11 steps automatically increment output in 100%, 50%, 25% or 10% of span plus continuous ramp. Set step/ramp time to 5, 6, 7, 8, 9, 10, 15, 20, 25, 30 & 60 seconds.


Here's how some of our customers use this product...

Calibrating Data Recorders

The Background: Our customer is a manufacturing facility that currently uses a number of data recorders to monitor processes throughout their facility. They seek a means to perform annual calibrations on these recorders.

The Problem: They currently have an older calibrator that is bulky and not reliable.

The Solution: We recommended the PIE 235 process voltage calibrator for this application. The PIE 235 allows the customer to preset three output settings, enabling them to verify 0, 50 and 100% of the recorder’s input. This allows the customer to quickly calibrate the recorders they have at a much faster rate.