D2 Miniature Sensors - Alphasense - #1

The world wide use of multigas portable personal safety monitors has grown since the 1970s to include an ever increasing number of industries. The one requirement in common to the majority of these instruments is the need to measure both Carbon Monoxide and Hydrogen Sulfide simultaneously.

Alphasense now offers a compact dual gas sensor which allows designers to reduce significantly instrument size and cost. The D sensor provides a unique approach to the dual gas sensor in both its size and working electrode configuration. The use of a high capacity filter over the Carbon Monoxide working electrode eliminates Carbon Monoxide cross sensitivity to Hydrogen Sulfide.

Adoption of the QD2 in portable instrument designs enables accurate factory, service and field calibration of instruments using multi-component gases without the fear of incorrect calibration of the Carbon Monoxide channel, providing reduced instrument manufacturing and service costs.

PERFORMANCE Sensitivity nA/ppm in 400ppm CO 30 to 55

Response time t₉₀ (s) from zero to 400ppm CO < 25

Zero current ppm equivalent in zero air < ± 6

Resolution rms noise (ppm equivalent) 1

Range ppm CO limit of performance warranty 1000

Linearity ppm error at full scale, linear at zero and 400 ppm CO < 40

Overgas range maximum CO for stable response to gas pulse 5000

LIFETIME Zero drift ppm equivalent change/year in lab air n/d

Sensitivity drift % change/month in lab air, monthly test n/d

Operating life months until 80% original signal (24 month warranted) 24

Sensitivity @ -20^oC % (output @ -20^oC/output @ 20^oC) @ 100ppm CO 50 to 71

Sensitivity @ 50^oC % (output @ 50^oC/output @ 20^oC) @ 100ppm CO 106 to 114 Zero @ -20^oC ppm equivalent change from 20^oC -1 to 1

Zero @ 50^oC ppm equivalent change from 20^oC -1 to 4

Filter Capacity

ppm-hours of Hydrogen Sulfide

15,000

< 5

< 50

< 0.1

< 0.1 <55

< 0.1

< 0.1

H₂S NO NO₂ Cl₂

^H2 SO₂

NH₃

sensitivity % sensitivity % sensitivity % sensitivity % sensitivity % sensitivity % sensitivity %

measured gas @ 20ppm measured gas @ 50ppm measured gas @ 10ppm measured gas @ 10ppm

H₂S NO NO₂ Cl₂

measured gas @ 400ppm H2 @ 20^oC

measured gas @ 20ppm measured gas @ 20ppm

SO₂

NH₃

Temperature range ^oC

-30 to 50 80 to 120 15 to 90 6

10 to 100

< 2

Pressure range Humidity range Storage period Load resistor Weight

kPa

%rh continuous (see note below) months @ 3 to 20^oC (stored in sealed pot) Q (recommended)

Note: Above 85% rh and 40^OC a maximum continuous exposure period of 10 days is warranted. Where such exposure occurs the sensor will recover normal electrolyte volumes, when allowed to rest at lower %rh and temperature levels for several days.

NOTE: all sensors are tested at ambient environmental conditions, with 10 ohm load resistor, unless otherwise stated. As applications of use are outside our control, the information provided is given without legal responsibility. Customers should test under their own conditions, to ensure that the sensors are suitable for their own requirements.