$ 96.31
Extech CO250 Portable Indoor Air Quality CO2 Features: Checks for Carbon Dioxide (CO2) concentrations Calculates statistical weighted averages of TWA (8 hour time weighted average) and STEL (15 minute short term exposure limit) Maintenance free NDIR (non-dispersive infrared) CO2 sensor CO2 Guidelines: Non-Enforced Reference levels: 250 – 350 ppm – background (normal) outdoor air level 350- 1,000 ppm – typical level found in occupied spaces with good air 1,000 – 2,000 ppm – level associated with complaints of drowsiness and poor 2,000 – 5,000 ppm – level associated with headaches, sleepiness, and stagnant, stale, stuffy air. Poor concentration, loss of attention, increased heart rate and slight nausea may also be >5,000 ppm – Exposure may lead to serious oxygen deprivation resulting in permanent brain damage, coma and even Regulatory exposure limits: ASHRAE Standard 62-1989: 1000ppm: CO2 concentration in occupied building should not exceed 1000ppm. OSHA: 5000ppm: Time weighted average over five 8-hour work days should not exceed 5000ppm Building bulletin 101 (Bb101): 1500ppm. UK standards for schools say that CO2 at averaged over the whole day(i.e. 9am to 3.30 pm) should not exceed 1500ppm. Germany, Japan, Australia, UK…: 5000ppm, 8 hours weighted average in occupational exposure limit is 5000ppm. Extech CO250 Specifictions: Function Range Resolution Accuracy CO2 0 to 5000ppm 1ppm ±(%5rdg 50ppm) 5000 to 9999ppm 1ppm Not specified Pressure dependence: 1.6% reading per kPa deviation from normal pressure, 100kPa Temperature -10 to 60°C14 to 140°F 0.1° ±0.6°C/0.9°F Humidity 0.0 to 99.9% 0.1% ±3%(10 to 90%)±5%(< or > 10 to 90%) Wet Bulb -5 to 60°C23 to 140°F 0.1° Calculated from RH and Temperature Dew Point -20 to 60°C-4 to 140°F 0.1° Display Triple LCD with backlight Sensor Type CO2: NDIR (non-dispersive infrared) technology Humidity: Capacitance sensor; Temperature (air): Thermistor Operating Conditions 0 to 50C (32 to 122F); < 95% RH non-condensing Storage Conditions -20 to 60C ( -4 to 140F); <99% RH non-condensing Power Supply 4 x 1.5V ‘AA’ batteries or AC adaptor (9V/1A) Battery Life approx. 24 hours (alkaline batteries) Dimensions / Weight 200 x 70 x 57mm / 190g
