Video: Rapidox 7100

Video transcript

What this analyser measures, why it is built to stay connected to a process, and how to wire it to the gas line and to the control system. A process atmosphere is not checked once a shift. Biogas, a furnace or a glove box change by the hour, so the analyser has to stay connected, measure without stopping, and talk to the plant. Up to 7 gases measured at the same time, with their calorific value where the gas carries energy. Six analogue outputs in voltage and 6 in current,

6 alarm relays, and 4 gigabytes of memory: about a year of data. The combination is built to order: infrared, electrochemical, thermal conductivity, tunable laser, zirconia and capacitance sensors, each for the gases it suits. Not every combination is possible, because some sensors react to other gases. For biogas and syngas, the calorific value is calculated live from the composition, following IS 069 76. A pulverised fuel option reports the combustion ratio and the PF factor,

from carbon monoxide and carbon dioxide. On the front there are only 4 things: the 7 inch touchscreen, the USB socket for the data, the flow adjuster, and the mains switch. The bench version adds a swing handle, which sets the viewing angle. Everything that ties it to the plant is at the back: the mains inlet with its fuses, 3 terminal strips for voltage outputs, current outputs and alarm relays, two serial ports,

the thermocouple input, and the gas outlet and inlet. The gas connections are at the back. The sample passes through whichever filters it needs, and into GAS IN, in FEP or stainless tube. GAS OUT goes to extraction, with nothing restricting it: the gas leaving the analyser may be toxic. Then the signals. The analogue outputs to the PLC or SCADA. The alarm relays to their loads, always in matched pairs.

SERIAL one to a computer or a PLC, SERIAL two to a multiplex unit, the thermocouple to its socket, and mains, last. Switch on, and readings appear after about a minute; an infrared sensor still warming up shows Wait. Press Start Pump and set the flow with the knob. From a pressurised source, leave the pump off: the gas flows through on its own. Each analogue output is assigned to a gas and scaled, linear or logarithmic.

Each of the 6 alarms has its set point, rising or falling, a hysteresis against chattering, and a relay that is normally open or closed. It can sound, turn the reading red, and latch until someone resets it. For the control system there is Modbus RTU, and it works both ways: the PLC reads up to 14 channels and the fault bits, and it can reprogram the alarms, the outputs and the pump speed. Every parameter is logged, from once a second to once an hour, in one file per day, and 4 gigabytes hold about a year.

Any date range goes to a USB stick, as a file that opens in Excel. With a multiplex unit, one analyser watches up to 15 points. The multiplex opens one sample line at a time and sends it on to GAS IN, and a lead to SERIAL two lets the analyser run the sequence. Switch the multiplex on first, so the analyser detects it. To calibrate, zero with fresh air, or zero air for carbon dioxide. Then apply a span gas, enter its value, and press Cal once the reading is flat. On some models, an automatic option keeps

the gases connected and calibrates on a timer. With toxic gases, vent the outlet and wear a personal gas alarm. No oxygen above 30%, unless the unit is oxygen clean. Keep water from condensing inside and the rear fan clear. And change the default passwords at commissioning. Biogas, syngas and hydrogen production. Glove boxes and inert gas blanketing. Heat treatment of metals. And medical, food and research gas analysis.

Gas analysis, from Amperis.