APSA-370 Ambient Sulfur Dioxide Monitor


The APSA-370 is a device for the continuous monitoring of atmospheric SO2 using UV fluorescence. The APSA-370 employs an proprietary, internal dry-method sampling device to achieve the highest levels of sensitivity and accuracy. The dry-method, due to its minimal maintenance requirements capability of continuous monitoring and instantaneous analysis of gas in its unaltered state, has been a preferred method for monitoring the atmospheric pollution.

AP-370 Series product literature


  • The APSA-370 uses an innovative detector and a new optical system for low background, high sensitivity (0.05 ppm F.S.), and greatly improved stability.
  • The fluorescent chamber design gives measurements with minimum influence from moisture.
  • The unit has built-in aromatic hydrocarbon cutter with a selective transmission membrane. This reduces the influence of interference components. Coupled with HORIBA's unique flow-path, it also makes it possible to extend the working life of the cutter and to take measurements effects of sample flow variations.
  • In comparison with the FPD method, the APSA-370 design is (1) highly selective for SO2, (2) requires no supplemental gas, and (3) gives linear output.
  • Compensation for the lamp's luminous energy decline guarantees prolonged calibration stability.
  • The sample inlet has a built-in Teflon filter.

Manufactured by HORIBA



UV fluorescence (UVF)


SO2 in ambient air


Standard ranges: 0-0.05/0.1/0.2/0.5 ppm; auto range ~ manual range selectable; can be operated by remote switching.
Optional (measurable) ranges: 4 ranges selectable from 0-10 ppm, within 10 times range ratio;
auto range ~ manual range selectable; can be operated by remote switching.


±1.0% of F.S.


±1.0% of F.S.

Sample gas flow rate

Approx. 0.7L/min


Measured value, range, alarm, maintenance screen


During AIC, zero calibration error, span calibration error, temperature error in catalyzer, etc.

On-screen messages are available in four languages

English, German, French, and Japanese.


• 0-1 V/0-10 V/4-20 mA, to be specified (2 systems: either (1) momentary value and integrated or (2) moving average value)
• Contact input/output
• RS-232C


100/110/115/120/220/230/240 VAC, 50/60 Hz (to be specified)


430(W) x 550(D) x 221(H) mm


Approx. 19 kg.


AP-370 series Air Pollution Monitor Brochure uploaded on 2013/12/20 (PDF:1.2MB)