CI-PC502 Selective Hydrogen Concentration Analyzer — Interference-Free H₂ Measurement

"How much hydrogen is in this line right now?" — Why selective measurement matters

Hydrogen (H₂) is the lightest gas and has an exceptionally wide explosive range. It ignites across roughly 4%~75% in air, so knowing the concentration of leaked hydrogen accurately and in real time is itself a matter of safety. At the same time, in hydrogen production and refining lines, hydrogen purity (%) determines product quality. The problem is that many hydrogen analyzers use thermal conductivity (TCD), so the reading drifts whenever the background gas changes.

CHANG AI's CI-PC502 selective hydrogen concentration analyzer was designed to bridge exactly this gap. The CI-PC502 uses a solid-state hydrogen-specific sensor that responds only to hydrogen, measuring H₂ concentration accurately with no cross-sensitivity to other gases. Why do hydrogen production and power sites choose this "selective" analyzer? The answer lies in the sensor principle.

Hydrogen-specific solid-state sensor — Measurement principle

The CI-PC502 is equipped with a solid-state sensor that reacts specifically to hydrogen. Measurement proceeds in the following steps.

1. Sample gas is delivered to the sensor measurement chamber at a constant flow rate (recommended 1L/min).
2. The solid-state sensor responds selectively to hydrogen (H₂) only, generating a signal proportional to concentration. It has no cross-sensitivity to other gases.
3. A microcontroller digitally processes the signal (zero/span correction and linearization) and runs self-diagnostics to produce a stable reading.
4. The hydrogen concentration is shown on a 240×128 LCD and output via analog signals such as 4-20mA and RS485 (Modbus RTU) communication.

Thanks to its hydrogen specificity, the solid-state sensor's reading does not drift even when the background gas changes — the core of "Selective" hydrogen measurement. (Source: CHANG AI CI-PC502(G1) official operation manual and product datasheet)

Four standout strengths of the CI-PC502

① Hydrogen-specific selectivity — Accuracy without cross-interference

Thermal-conductivity (TCD) hydrogen analyzers measure the difference in thermal conductivity, so errors arise when background gases such as CO₂, He, or Ar change.

The CI-PC502 is different. Its solid-state sensor responds only to hydrogen (H₂) with no cross-sensitivity to other gases, reading hydrogen concentration accurately even within mixed gases.

② Wide measurement range — From trace leaks to high-concentration purity

A narrow measurement range means separate devices for leak monitoring and purity management.

The CI-PC502 supports both the low-concentration range of 0.01%~10% and the high-concentration range of 5%~99.99%, handling trace-leak monitoring and hydrogen-purity management in one unit. Display resolution is 0.01% and response time is about 30 seconds.

③ Stability and reliability — Self-diagnostics + tempered-glass protection

Field equipment is exposed to vibration, impact, and misoperation.

The CI-PC502 offers stability of about 0.2% over 7 days and full self-diagnostics, and applies tempered glass to the front window to protect the LCD and touch keys. Its menu-lock function also prevents parameter changes from misoperation. Sensor life is 2+ years and device life is 5+ years.

④ Process automation integration — Signal, communication, and storage all supported

The analog output can be freely selected from 4-20mA/0-20mA/0-1V/0-5V/0-10V/1-5V via the menu, and RS485 (standard, Modbus RTU) communication connects directly to PLC, DCS, and HMI. It also supports relay alarm outputs for 2 concentration and 4 status points, plus SD card/USB data storage.

General thermal-conductivity (TCD) hydrogen analyzer vs. CI-PC502 selective hydrogen analyzer

Industries where the CI-PC502 is essential

1. Hydrogen production processes — Detecting the volume concentration (%) of excess hydrogen in production streams
2. Power-plant hydrogen-cooled generators — Monitoring hydrogen concentration in the circulating gas of hydrogen-cooled units
3. Fertilizer & ammonia synthesis processes — Measuring hydrogen concentration in make-up and circulating gas on ammonia synthesis lines
4. Petrochemical & refining processes — Real-time monitoring of hydrogen concentration in process gas for safety and quality control
5. Ambient air & industrial vessels — Detecting hydrogen-leak concentration in sealed vessels and work spaces

CHANG AI's selective hydrogen concentration analyzer — CI-PC502

📌 CI-PC502 — Selective hydrogen concentration analyzer

The CI-PC502 is an online hydrogen analyzer installed via panel mounting. It features a 240×128 LCD, four capacitive touch buttons, and a front tempered-glass protective structure, with PT1/4 internal-thread inlet and outlet ports. When ordering, you can choose a suction pump (P) or needle valve (V) configuration; net weight is about 5.3kg.

📊 CI-PC502 technical specifications

※ Source: CHANG AI CI-PC502 product page and CI-PC502(G1) official operation manual. Specifications may vary by configuration and options; recommended calibration interval is once per year. For explosion-hazard areas, an explosion-proof model (e.g., CI-PC552-1) is recommended.

Why the CI-PC502 is the right answer for hydrogen measurement

Typical hydrogen measurement equipment hits limits in the following situations.

• Background-gas interference — Thermal-conductivity readings drift when the mixed-gas composition changes
• Split measurement ranges — Hard to cover trace leaks and high-concentration purity with one device
• Vulnerable to misoperation/impact — Reduced reliability from lack of protection/lock features

The CI-PC502 solves these limits simultaneously with a hydrogen-specific solid-state sensor (selective) + 0.01%~99.99% wide-range measurement + tempered glass/menu lock + multiple analog/RS485 integration. A single unit secures accuracy, measurement range, and process automation all at once.

Closing — Invisible hydrogen determines safety and quality

Hydrogen is colorless and odorless, yet its wide explosive range makes even a small leak a major hazard. What matters in a process is "exactly how much hydrogen is in this line right now." Only by reading H₂ accurately, without drifting with the background gas, can you trust and manage the measurement.

Are you seeing your hydrogen line's concentration accurately, without drifting with the background gas?

CHANG AI's official Korea distributor, RS Korea Co., Ltd., handles sales, repair, calibration, and technical support for the CI-PC502 and all CHANG AI products within Korea. RS Korea operates both its in-house technical team's calibration/maintenance capability and its sales team's on-site visits, processing everything from product selection consulting to sensor replacement and after-sales service through one local channel. If you'd like to learn about other CHANG AI hydrogen analyzers, see also our CI-PC562 trace hydrogen analyzer article.