Key Technical Specifications
- Measurement Principle: Tunable Diode Laser Absorption Spectroscopy (TDLAS)
- Laser Type: Single-mode diode laser (Room temperature operation)
- Measurement Method: Non-contact, in-situ cross-stack measurement
- Environmental Compensation: Automatic correction for pressure and temperature variations
- Communication Interfaces: Ethernet TCP/IP, OPC Server, PROFIBUS, Modbus
- System Integration: Connects to AO2000 Central Unit (supports up to 4 modules per rack)
- Hazardous Area Certifications: ATEX, IECEx, CSA (Zone 2 / Division 2)
- Maintenance Feature: Transmission output signal for predictive maintenance
- Calibration: Automated via integrated calibration cell or process air (no test gas bottles required)
Product Introduction
Stack monitoring usually means dealing with clogged filters, contaminated sample lines, and endless calibration headaches. The AO2000 LS25 eliminates that mess by shooting a single-mode diode laser straight across the duct. It uses TDLAS to pick out one specific gas absorption line in the near-infrared spectrum, ignoring everything else. I’ve deployed these in dirty environments where extractive analyzers choked on particulates within a week. This thing just sits there, firing away without touching the gas.Engineers stick with this module because it actually delivers on the “low maintenance” promise. You don’t need a closet full of calibration gas bottles; it uses process air or an internal cell. It also automatically compensates for the wild temperature and pressure swings you get in industrial stacks. One thing to keep in mind: this specific revision is highly sensitive to optical window fouling, so if your stack is heavily saturated with oil mist, plan on installing a high-flow purge system. Otherwise, the data is rock-solid.
Quality SOP & Tech Pitfalls
Before any LS25 leaves our bench, it goes through a brutal validation protocol. We start with a visual and counterfeit check, inspecting the optical windows and connector pins under magnification. Next, it goes on a live test rack where we verify Ethernet handshakes and laser sweep functionality. We use a Fluke 115 to check insulation resistance and power supply ripple. Finally, we log the exact firmware version and seal it in anti-static packaging.Here is where people mess up: Forgetting to configure the external temperature and pressure sensor inputs. The LS25 will happily output a concentration value without them, but it will be completely wrong because the gas density changes. I once spent four hours troubleshooting a “drifting” analyzer on a kiln exhaust, only to realize the previous tech forgot to wire the PT100 temperature sensor. The laser was perfect; the math was just blind. Also, never open the transmitter housing while it’s energized in a hazardous area. The manual says wait 3 minutes for purging. Don’t skip it.
Installation & Configuration Guide
- Pre-Installation: ⚠️ Lock out and tag out the power. Verify the stack is safe to access. Take high-resolution photos of the old wiring and DIP switch settings before touching anything.
- Removal: Label every wire at the transmitter and receiver units. Release the DIN clips carefully. If dealing with an Ex-rated unit, ensure no combustible dust has accumulated inside the housing before opening.
- Installation: Copy all DIP switch and jumper settings exactly from the old unit. This prevents 90% of startup communication failures. Seat the LS25 module firmly onto the AO2000 backplane and lock it down.
- Power-On & Testing: Apply 24V DC and verify the power LEDs. Check the Ethernet link status on the AO2000 Central Unit. Download the configuration and verify the transmission signal is within the normal optical range before trusting the concentration output.
Compatible Replacement Models
- ✅ Drop-in Replacement: AO2000 LS25 (Exact match. Ensure firmware version is equal to or newer than your existing Central Unit).
- ⚠️ Software Compatible: AO2000 LS25 (Older Rev C vs Newer Rev D). Hardware is identical, but requires a firmware update on the AO2000 Central Processing Unit. Estimated labor: 30 minutes for flash and reboot.
- ❌ Hardware Mod Required: ABB ACF5000 (FTIR Technology). Requires entirely new rack, wiring, and CEMS certification. Only advise this if you need to measure 10+ components simultaneously and are doing a full system overhaul.
Frequently Asked Questions (FAQ)
Can I hot-swap this module if the AO2000 is running?
No. While the AO2000 supports hot-swapping I/O cards, the LS25 is a high-power optical device. Pulling it under power can cause a voltage sag on the backplane that might reboot the CPU. Always schedule a brief maintenance window.Why is my transmission signal dropping over time?
99% of the time, it’s dirty optics. The LS25 measures transmission as a maintenance indicator. If it drops below the threshold, your purge air flow is too low, or the stack has heavy particulate. Clean the windows and verify your purge flow is at least 20 l/min.Do I really need to connect the external temp and pressure sensors?
Yes. The TDLAS algorithm calculates concentration based on gas density. If you leave those inputs floating, the analyzer assumes standard lab conditions. In a 400°C stack, your reading will be off by a massive margin. Wire the sensors.Can I use standard test gas to calibrate this?
Not easily. Because it’s an in-situ cross-stack analyzer, you can’t just inject gas into a port. You have to use the optional integrated calibration cell or perform a span calibration using process air. Read the manual on the auto-calibration routine before attempting it.Is this unit safe for Zone 1 hazardous areas?
No. The standard LS25 is certified for Zone 2 (or Division 2). It relies on a “non-incendive” safety concept and requires purging if opened. If you need Zone 1, you are looking at a completely different, heavily purged enclosure. Check the nameplate Ex marking before installing.My AO2000 CU says “Module Mismatch.” What gives?
You probably dropped in a newer LS25 into an old Central Unit running outdated firmware. The CU doesn’t recognize the new module’s signature. You need to upgrade the AO2000 CU firmware first. It takes about 15 minutes via Ethernet.
