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Testo 338

Contact Instrument Solutions


The Testo 338 is an electronic smoke pump that enables the busy combustion engineer to quickly measure the levels of soot an engine is producing during planned or regular maintenance schedules.

Available in two configurations, with or without Bluetooth communications capabilities, the Testo 338 is easy to use, compact, robust fast to operate - by the touch of a button, and can link to printers via it's IRDA port for record retention. Typical applications for the Testo 338 include; diesel power or heating engines; shipping companies and dockyards; industrial engines; mining and prospecting; construction machines and land-moving vehicles.


  • Handy and robust, making it easily possible to carry to the desired application site
  • Determination of soot concentration (mg/m3) as well as Filter Smoke Number (FSN) or Bosch number
  • Easy one-handed operation
  • Direct analysis and display of measurement values, optional on-site printout of data with Testo fast printer


Soot concentration:

Measuring range 0 to 70 mg / m³

Resolution 0.01 mg / m³

Accuracy < 1.5 mg / m³ (0 to 5 mg / m³), < 1.25 mg / m³ + 5 % of mv (5 to 70 mg /m³)

FSN Bosch Number:

Measuring range 0 to 2.5 *

Resolution 0.01 *

Accuracy < 0.08 FSN *

*at reference conditions 1000 mbar, + 25 °C

General technical data:

Protection class IP 40, TopSafe

Interface IRDA / optional Bluetooth

Memory 200 measuring values

Storage battery type Lithium ion

Battery life Approximately 4 hrs continuous operation

Application temperature Individual measurements up to + 500 °C

Max. pos. press. / flue gas 300 mbar*

Test sample volume 0.4 litres (range: 0 to 0.3 FSN); 0.2 litres (range: 0.2 to 2 FSN)

Measurement period ˂ 60 s per measurement cycle

Flow-through measurement Differential pressure sensor

Optical sensor Opacity of the filter load in %

*at higher pressures, a higher measurement inaccuracy occurs

Support documents

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Testo 338 electronic smoke pump user manual.pdf Testo 338 electronic smoke pump user manual
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Testo 338 electronic smoke pump data sheet.pdf Testo 338 electronic smoke pump data sheet
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