Clairair's technology includes a wide range of sensing techniques including optical, catalytic, solid state, photochemical, ion and thermal methods. We make extensive use of 3D CAD, multilayer PCB and software compilers in developing products.
Find Out More

As an independent sensor company we understand customers sometimes need a customised approach for a sensor, a circuit or a software application. We are pleased to provide a custom service to meet such requirements.
Find Out More

The application of various sensing techniques leads to an ongoing program of product development. Clairair gas sensor products are backed up with extensive applications support.

Find Out More

NEWS

New: CiriusX OEM transmitter provides selectable 4-20mA source and sink output
The latest issue of our CiriusX OEM 4-20mA transmitter provides a link selectable 4-20mA source or sink output. The sink output requires a minimum of 5V at the terminal block. The CiriusX can be easily customised with a user signon displayed during startup. The highly flexible operating system allows easy setup of custom ranges or sensor types via the RS232 port and provides an easy to use interactive menu.

High Resolution Autoranging IR sensors
High resolution in itself is nothing special, after all a pure analog signal has the ultimate resolution. However, a voltage output generated by digital techniques is limited by digital resolution of software (be it a lookup table or floating point mathematics) and by the digital to analogue conversion resolution. For instance, a 14 bit D/A conversion with a 2.5V reference would be able to resolve down to 0.15mV which for a 0.4V - 2.0V concentration range is equivalent to 0.01% of full scale; a 16 bit D/A conversion potentially resolves to 0.0025% of range. Single precision floating point mathematics resolves to 1.42x10^-14 which if it could be converted to analogue would be effectively as fine a resolution as a pure analogue signal. But if a 12 bit A/D is used to originate the numbers going into the mathematics then with a 2.5V reference the limit is 0.6mV so even with a linear relationship the input values are only good to 0.02% and with nonlinear signals the resolution varies with signal. High resolution does not mean high accuracy, a resolution of 0.01% compared to an output variation of 0.1% or 10% of reading demonstrates that. The patented CiriusV range of voltage output sensors have always had the ability to drop the output resolution as low as 0.0025% of range but generally the output is rounded off to a more meaningful level in line with the repeatability. 

Autoranging is different. Like an autoranging DVM the CiriusV range now has the ability to autorange so resolution and output variation at the low end of a range can be enhanced by applying higher resolution mathematics and not just by dropping a rounding value. This allows a higher resolution, tighter fit at the lower end of the range whilst maintaining a normal resolution fit at higher levels. For example a CiriusV1 hydrocarbon sensor can be configured for 0-100% volume methane to resolve to 0.01% at levels below 10% and automatically switch ranges above that to resolve to 0.1% whilst maintaining a low output variation across the entire range. The CiriusV2 CO2 sensor can be configured to resolve to 10ppm at levels below 5,000ppm and autorange to resolve to 50ppm above that and up to 5% volume whilst also maintaining a low output variation across the entire range. Any configuration within the patented CiriusV sensor range can now be made autoranging.

Latest MEMS detectors used in Cirius CO₂ sensors
Cirius CO₂ sensors are now supplied with the latest in infrared radiation detectors. The detectors are MEMS devices  and produce very high signal levels that allow us to provide CO₂ sensors with high sensitivity, better signal to noise and flexibility to cover wide concentration ranges. The sensor outputs are modified internally to appear the same as a standard JFET detector output so no customer circuit changes are needed. The Cirius2 sensor can resolve to 10ppm CO₂ below 1000ppm whilst still being ideal for ranges of 0-5% volume and even higher. The absorbance curves show typical span values for both the 0-5000ppm and 0-5% volume ranges to be 0.35 and for 0-5% volume the exponent of 0.9 and power term of 0.6 are very similar to the IR11BD. The Cirius3 high range CO₂ sensor response over the range 0-100%volume CO₂ is not saturating at high levels and this allows enhanced resolution at the high concentration end of the scale.  The typical span for the Cirius3 sensor over 0-100%volume CO₂ is also 0.35, around 50% higher than some competitor sensors .

High performance Cirius HC sensor tests
The new optic which is now in production for the Cirius range of sensors continues to provide high performance characteristics as we carry out more and more tests. The Cirius1 hydrocarbon sensor is extremely reproducible in terms of signal size and has a sensitivity of typically 11% absorbance drop in 5% volume methane. The 0-5% volume methane absorbance curve has an exponent of 0.2369 and a power term of 0.666, very similar to the IR13BD, with a typical span in excess of 0.2.  For 0-100%volume methane the exponent is 0.032 and power term is 0.5, again very close to the IR13BD and we have a high span value of typically 1.5. Hydrocarbon responses are also strong,  0-100%lel pentane for example has an absorbance curve with a typical span of 0.25, an exponent of 0.0084 and a power term of 1.0 which shows the sensor following the Beer Lambert law nicely in this case.

First light on new optic
After 3 months development on 3D CAD and another couple of months working with a prototyping supplier we have successfully tested a new optical design and first light occurred in early July 2010. Fully compliant with our patent, the new optic provides extremely high optical throughput and gives us the opportunity to extend the ranges of various gases we can detect whilst providing higher intrinsic resolution. Faster gas access is also incorporated and furthermore it allows us to also use a wider range of detectors which offer various benefits depending on the application. To the user there is little change, the specification of the sensors remains the same. We like to think of this as a third generation optic, the first generation being a scatter/normal throughput format, the second generation being a focussed format. This optic is quite different yet is still protected by our existing patent.

Thanks to Hogtronix!!
Our site was attacked by something nasty in June and Hogtronix picked it up and dealt with it brilliantly. They had to take us off line for a day while their teams in England and Spain moved us and rebuilt the site, checking overnight that everything was stable. As they say, they are superheroes and this is a great example of the fantastic support they give. Thankyou Hogtronix!!

Snow scenes January 2010
The heavy snow over England caused many traffic problems but did result in some nice winter scenes. Here are views of the snow at Clairair and the adjacent Little Braxted church.

Our history, location and background:
Clairair was established at Little Braxted Hall in the autumn of 2006 with the aim of providing an independent alternative source for infrared gas and other sensor types. 

Our location  is in a tranquil part of the Essex countryside yet adjacent to the A12 trunk road leading to central London about 40 miles away. On site is a stunning mediaeval church originating from 1120 where (Rev) Lawrence Washington, ancestor of George Washington (father of the USA), preached in the 1600's. 

Clairair Ltd was officially launched at the Sensor+Test exhibition in Nuremberg in May 2007 with the initial introduction of the Cirius range of NDIR gas sensors, having attained ISO9001 accreditation just prior to the launch. The UK patent for the technology behind the Cirius range of sensors was granted in December 2009.

Dr. Alan Doncaster is the Director of Clairair Ltd. Alan has a PhD in thermochemical kinetics, is a member of the Royal Society of Chemistry and is a Chartered Chemist. He has several years experience in gas sensing and has developed a wide range of gas sensors and associated support products over that time, with a number of gas sensor patents being published.