SafEye Quasar

Three Series, Two Technologies, Three Gas Types

Replace the existing model table with:

The gas decides the series, and the path length decides the model. Each model covers a different distance band, so the beam can be matched to the site.

Infrared is used for hydrocarbons because they absorb infrared. Ultraviolet is used for hydrogen sulphide and ammonia because they absorb in the UV band. It’s the same family approach and commissioning method, using a different part of the spectrum.

Spectrex Invented This

This explains why the range behaves the way it does.

Early open path gas detectors were plagued by false alarms. Sunlight, flare stacks, arc welding and lightning all put radiation into the beam, and detectors couldn’t tell that apart from gas.

Spectrex invented the xenon flash lamp design that solved it. The source fires a very powerful signal for a very short time, at set intervals. The receiver only responds to signals of that intensity and speed, and ignores background radiation. It’s a physical solution rather than a software one, which is why the immunity holds.

Performance in All Weathers

An open path beam crossing a site collects whatever’s in the air: dust from a haul road, sea fog, tropical rain, snow, or vibration shifting the alignment. All of it reduces the signal reaching the receiver.

The Quasar’s high power xenon lamp compensates for changing weather, including rain, fog, mist and snow. The optics are thermostatically heated to stop ice and snow building up, and to prevent condensation on the lenses. It operates from -55°C to +65°C.

No Unrevealed Failures

The Quasar 900 is designed so a fault can’t go unnoticed. In normal operation, the output is 4 to 20 mA, depending on the gas concentration. Below 4 mA, it signals a fault (1 mA) or beam blockage (2 mA).

A continuous self test also gives a pre warning (3 mA) when the detector is still working but needs attention, for example when the transmitter or receiver is misaligned, or deposits are building up on the optics. That allows maintenance without downtime. The 950 and 960 have a 3 mA maintenance call too.

An internal data logger on the Quasar 900 keeps a detailed record of the last 100 events.

SIL 2 and Certification

All three series are approved to SIL 2 under IEC 61508 by TÜV. That matters when the detector forms part of a safety instrumented function, rather than sitting alongside one.

Certification also covers ATEX and IECEx, with FM performance testing and DNV approval for the Quasar 900. The 950 and 960 are certified Ex d e ib IIB+H2 T4 Gb, with Ex tb IIIC for dust.

Built for Offshore

The 950 and 960 source and detector housings are 316L stainless steel, with an electropolished finish. The circuit boards are conformal coated and protected against vibration.

That’s aimed at a particular set of conditions: salt air, constant vibration from rotating plant, washdown, and a maintenance regime where getting to a detector is expensive. Electropolished 316L resists pitting corrosion, and conformal coating keeps humidity off the electronics.

For Australian coastal, offshore and North West Shelf work, that’s the difference between a detector that lasts and one that becomes a maintenance item.

One Person Can Commission It

Open path detectors traditionally need two people, one at the source and one at the receiver, with a radio.

The Quasar can be aligned and commissioned by one person. After a coarse adjustment by eye, a telescope is fitted for fine adjustment to get the strongest signal. An intrinsically safe handheld unit handles diagnostics, calibration and configuration, connecting quickly to the detector or over HART on the mA line.

On the Quasar 900, built in calibration means there’s no need for manual adjustment or test gas. Each detector comes with methane, propane and ethylene calibrations as standard, selectable in the field.

Reading LEL Metres, With a Worked Example

Open path readings for hydrocarbons are in LEL metres, which measures the total gas along the beam rather than the concentration at one point. It takes a moment to get used to, and it changes how alarms are set.

Take a gas cloud at 20% LEL sitting across 7 metres of the beam. The reading is 20% LEL x 7 metres, which gives 1.4 LEL metres. Against a typical low alarm of 1 LEL metre, that alarms comfortably.

Now take the same 20% LEL cloud across only 2 metres. That reads 0.4 LEL metres, and doesn’t reach the alarm. The concentration is the same, but the quantity of gas in the beam isn’t.

That’s why open path detection complements point detection, rather than replacing it. Open path tells you gas is present across an area. Point detectors near likely leak sources tell you where it’s coming from.

Where It’s Used

Refineries and petrochemical plant, offshore platforms and FPSOs, LNG production and storage, gas filling and distribution terminals, gas transport and pipelines, chemical processing plants, wastewater treatment works and digesters (for hydrogen sulphide), ammonia refrigeration engine rooms and cold stores, fertiliser production and storage, and perimeter and boundary monitoring.