Best of both worlds
Infrared flammable gas detector with low lifetime cost

A new combustible gas detector uses infrared (IR) technology to combine good technical performance with a low total cost of ownership.

Compared to gas detectors based on catalytic sensors, the Statox 501 IR from Compur Monitors offers nearly unlimited lifetime, extended maintenance intervals and the ability to work at oxygen concentrations below 10 vol. percent, for instance in nitrogen-blanketed systems. Also unlike catalytic sensors, the Statox 501 IR is immune to poisioning by heavy metals, halogens, silicones and high concentrations of flammable gases.
The Statox 501 IR is a compact unit with a housing made from stainless steel and fiber-reinforced polyamide. The mounting bracket serves as a terminal box, so no separate connection box is required for installation. The terminal box features increased safety (EEx e), while the transmitter itself is explosion proof (Ex d). The transmitter uses a 4–20 mA current loop to transmit the signal to a control unit. This can be the dedicated Statox 501 controller or any process control system.

The sensor compartment is sealed to IP67 for reliable operation in harsh environments, while the heat produced by the IR lamp and the sensor electronics is enough to prevent condensation. This saves installation costs compared to some IR gas detector designs that require a separate heating system. Failure of an important component such as the light source or the photodetector will trigger a “system fail” alarm. This reduces maintenance and calibration costs, and is accepted by most regulatory authorities as a self-diagnostic feature, says Compur Monitors. An LED display shows the gas concentration in percent LEL (lower explosive limit). An important accessory is the calibration adapter, which allows all parameters to be checked or changed, and calibration performed, without opening the transmitter. The service menu is password-protected to prevent unauthorized access. The adapter is also equipped with a gas outlet so that it can be used for flow-through applications.
IR techniques can detect a wide range of flammable and
other gases. The more C–H bonds a molecule has, the easier it is to detect at low levels. Methane (CH4), for instance, can be measured in the range 0–4.4 volume percent, while the range for hexane (C6H14) is 0–1000 ppm. Hexane is an important reference gas for fuels such as gasoline (C5–C12), diesel (C9–C20) and kerosene (C10–C16). All these fuels are hydrocarbon mixtures, with different compositions according to how they have been manufactured. Regardless of composition, however, they can be reliably measured by the Statox 501 IR.