Natural Gas Pipeline Technician Found a Better Way to Calibrate Chart Recorders
The Challenges of Using Hydraulic Fluid on Natural Gas Pipelines
Todd is a pipeline technician responsible for calibrating chart recorders on a natural gas pipeline. Because the work is performed during the winter, he had several concerns about using hydraulic fluid for calibration.
His concerns included:
- Contamination: Calibrating a gas pipeline with a liquid can leave residual fluid behind, which concerned Todd since it could create a false differential pressure.
- Damage to the chart recorder: Because it was winter, Todd was concerned that residual fluid trapped in the sensing element could freeze and damage the chart recorder.
- Pressure stability: Maintaining stable pressure during calibration can be challenging when temperature and volume changes affect the hydraulic fluid.
These challenges led Todd to look for an alternative calibration approach.
The Goal: Stable, Repeatable Chart Recorder Calibration
Todd wanted a calibration approach that would address his concerns while providing accurate, reliable, and repeatable chart recorder calibration.
The Solution: Nitrogen Calibration with a Ralston Pressure Calibration Manifold
A colleague told Todd about Ralston Pressure Calibration Manifolds.
He was interested in this option because the manifolds use compressed nitrogen gas instead of hydraulic fluid, which eliminates the risk of residual fluid contamination and freezing, preventing damage to the chart recorder.
Unlike hydraulic fluid, compressed nitrogen is also very stable because it can expand to fill the test volume. This provides a more consistent pressure source for calibration and helps improve control during testing.
Todd also liked that the Ralston Pressure Calibration Manifold was part of the Ralston Quick-test™ Connection System, which includes Ralston Quick-test™ adapters and low volume microbore hoses. Together, these components were easy to set up and helped reduce gas consumption during each calibration.
The Results: Faster Setup, Stable Pressure Control
Todd connected a Ralston Quick-test™ fitting to the pressure regulator on his nitrogen bottle, one to the high side of the chart recorder, and one to his pressure reference gauge.
Using the valves and fine-adjustment control piston on the calibration manifold, he was able to dial in each test pressure point quickly and accurately.
He was especially pleased that the calibration did not waste very much nitrogen because he was using Ralston Quick-test™ Microbore Calibration Hoses.
A Better Way to Calibrate Chart Recorders on Natural Gas Pipelines
By replacing hydraulic fluid with compressed nitrogen and a Ralston Pressure Calibration Manifold, Todd improved pressure stability while eliminating concerns about residual fluid contamination and freeze-related damage. The solution also simplified calibration and reduced gas consumption.
After seeing the results firsthand, he decided to use the Ralston Pressure Calibration Manifold for future static calibrations of both chart recorders and pressure transmitters.
Build Your Compressed Gas Calibration Setup
If you’re calibrating chart recorders and pressure transmitters with compressed gas as an alternative to hydraulic fluid, Ralston has all of the components you need to improve accuracy, simplify setup, and reduce gas consumption.
