Chart Recorders in Modern Process Plants: Still Relevant?
Yes. Chart recorders in process plants are still relevant wherever a plant needs a continuous, tamper-evident record of pressure or temperature that works without external power, networks, or software. Paperless recorders and data loggers have taken over many jobs, but mechanical chart recorders remain common at wellheads, pipelines, and remote sites where simplicity and reliability matter more than connectivity.
What Is a Chart Recorder Used For?
A chart recorder draws a continuous trace of a process variable on paper, so anyone can see what happened over a given period by looking at the chart.
• Pressure: wellhead, pipeline, and vessel pressure over hours or days.
• Differential pressure: filter condition and flow across an orifice plate.
• Temperature: furnaces, heat treatment, sterilisation, and storage.
• Other variables: flow, humidity, and pH in plants where recorders are wired to transmitters.
The result is a graph that shows peaks, dips, and timing at a glance, which is why recorders are used both for operations and for later investigation of upsets.
What Types of Chart Recorders Are There?
Chart recorders come in three main paper formats, and the format decides how the record is stored and read.
1. Circular chart recorders: a rotating paper disc, compact and enclosed behind glass, best for a known cycle such as 24 hours or 7 days.
2. Strip chart recorders: a long paper strip moves beneath one or more pens, suited to continuous processes and long unbroken records.
3. Roll chart recorders: similar to strip recorders, with the paper stored on a roll inside a fully enclosed case.
Circular charts must be changed more often, but the disc format is easy to file and compare day by day.
What Are Circular Chart Recorder Applications in Plants?
A circular chart recorder suits any process where the record is reviewed per day or per week.
• Wellhead and gas-measurement sites: a 24-hour or 7-day chart gives one clean record per period.
• Batch processes: a disc matched to the cycle time shows the whole batch on one chart.
• Utilities: boiler pressure, compressed-air pressure, and cooling-water temperature.
The Barton 242E, for example, is a 12-inch circular chart recorder with pressure and/or temperature elements and mechanical chart drives of 2 hours/8 hours or 24 hours/7 days.
What Are Strip Chart Recorder Applications?
A strip chart recorder is chosen when the process runs continuously and a long, uninterrupted trace is more useful than a single disc.
• Laboratories: test and analysis work that needs a graphic record of an input.
• Process measurement: continuous signals from transmitters, such as temperature or flow.
• Process upsets: industrial strip recorders often have two chart speeds, so a faster speed can follow a disturbance in detail.
Strip charts are less common in oil and gas field work than circular charts, but they remain useful where trends are studied over long continuous runs.
What Is the Difference Between a Paperless Recorder and a Chart Recorder?
A paperless recorder stores readings electronically and shows them on a screen, while a chart recorder prints them with a pen on paper.
• Storage: paperless units keep data in memory or on a USB or network drive, so there are no pens, ink, or charts to replace.
• Channels: paperless models record many inputs on one display, whereas a pen recorder is usually limited to one or two pens.
• Power: a mechanical chart recorder needs no mains power or network, and a battery-driven version can run unattended.
• Verification: a paper chart can be read without software, while electronic records need the right software and, in regulated industries, controls such as audit trails and secure access.
• Cost over time: paper recorders have ongoing costs for charts and pens, while paperless units cost more up front but have fewer consumables.
For a plant that wants to keep a paper record already accepted by auditors, a chart recorder avoids the validation work that paperless systems usually bring.
How Does a Digital Data Logger Compare With a Chart Recorder?
A digital data logger records measurements at set intervals into memory and is read out later on a computer, rather than being read directly.
• Resolution: loggers can sample every second or faster and store thousands of readings, far more than a pen trace.
• Analysis: data exports to a spreadsheet for trending, alarms, and reports.
• Immediacy: a chart recorder shows the trace at the instrument, with no download needed.
• Reliability in the field: a mechanical recorder has no firmware, battery-backed memory, or software to fail.
Falling logger prices have pushed them into jobs recorders once held, but many sites keep a chart recorder alongside as an independent, readable backup.
Why Do Oil and Gas and Process Sites Still Specify Chart Recorders?
Plants keep specifying them for three practical reasons: independence, simplicity, and accepted records.
• No external utilities: fully mechanical recorders need no mains power, which suits remote and hazardous locations.
• Direct reading: operators and inspectors can read the chart on site without a laptop.
• Accepted evidence: a dated paper chart is a long-standing form of record for pressure and temperature history.
• Wide ranges: the Barton 242E range covers pressures from 0–25 psi up to 0–6,000 psi, with 316 stainless steel pressure elements for tougher service.
General Tech Services supplies chart recorders from brands such as Barton (Sensia) and Ralston, backed by more than 30 years of engineering experience in the UAE.
How Do You Choose a Process Chart Recorder?
Choosing the right chart recorder starts with the measurement and the review period, not the brand.
1. Variable: pressure, temperature, or both on a two-pen model.
2. Range: pick a range so that normal operation falls in the middle of the scale, not at the top.
3. Chart drive: mechanical (24 hours/7 days or 2 hours/8 hours) or battery-driven with selectable speeds.
4. Mounting: pipe, wall, or panel mounting to suit the location.
5. Wetted materials: 316 stainless steel or other elements for the process fluid.
6. Records policy: check whether your quality system accepts paper or requires electronic records.
How Should a Chart Recorder Be Calibrated?
A chart recorder should be checked against a traceable reference at least once a year and after any shock or overpressure event.
• The pen position is compared with a reference gauge or calibrator at several points across the range.
• The clock or chart drive is timed over a full revolution to confirm it matches the chart.
• A recorder that has seen pressure beyond its range should be checked immediately, since the sensing element may have shifted.
General Tech Services offers ISO/IEC 17025 accredited pressure and temperature calibration, so recorders can be supplied and recalibrated by the same provider.
FAQ: Chart Recorders in Process Plants
Q: Are chart recorders still used today? Yes. They remain common in oil and gas field sites, utilities, and laboratories wherever a simple, power-independent paper record is wanted.
Q: Can a paperless recorder replace a chart recorder? Often, yes, especially when many channels or software trending are needed, but regulated sites must make sure electronic records meet their quality system.
Q: How long does one chart last? It depends on the chart drive: common choices run 24 hours or 7 days per rotation, with 2-hour and 8-hour options for short tests.
Q: What is the difference between a one-pen and two-pen recorder? A one-pen unit records a single variable, while a two-pen unit records two, such as pressure and temperature, on the same chart.
Q: Do chart recorders need electricity? Mechanical models do not, as the clockwork drives the chart. Electric and battery-driven versions are also available.
Get the Right Chart Recorder for Your Plant
Whether you need a single-pen pressure recorder for a pipeline or a two-pen pressure and temperature unit, General Tech Services stocks genuine chart recorders from trusted brands. Pair them with pressure gauges or pressure calibration kits and systems, or get in touch for advice and a quote.
Talk to us (UAE): +971 6 5436933
