The Gastec 9P Nitrogen Dioxide Detector Tubes are designed for sensitive, low-level measurement of nitrogen dioxide (NO2) in air using a compatible automatic air sampling pump.

The 9P provides a quantitative measuring range of 0.02 to 0.20 ppm, with a detection limit of 0.004 ppm under the specified sampling conditions. The tube uses a colorimetric reaction that produces a white-to-orangish brown color change for visual determination of nitrogen dioxide concentration.

Each box contains 10 detector tubes for 10 tests.

Automatic Air Sampling Pump Required

IMPORTANT: Gastec 9P Nitrogen Dioxide Detector Tubes require a compatible automatic air sampling pump capable of maintaining the specified flow rate and sampling time for proper measurement.

Compatible Pump: Gastec GSP-501FT Automatic Air Sampling Pump

The 9P is an automatic air sampling pump detector tube and should not be treated as a standard hand-pump detector tube. Accurate measurement requires drawing 3,000 mL of air through the tube at 100 mL/min for 30 minutes.

Do not substitute a standard manual Gastec detector tube pump for the required automatic sampling method.

Measurement & Sampling Specifications

Measurement Range	Sampling Rate	Sample Volume	Correction Factor	Sampling Time
0.02–0.20 ppm	100 mL/min	3,000 mL	1	30 Minutes

The Gastec 9P requires a continuous sampling rate of 100 mL/min for 30 minutes, providing a total sample volume of 3,000 mL. The correction factor is 1 under the specified sampling conditions.

Product Specifications

Brand: Gastec
Tube Type: Nitrogen Dioxide Detector Tube for Automatic Air Sampling Pump
Part Number: 9P
Gas Measured: Nitrogen Dioxide (NO2)
Measurement Range: 0.02–0.20 ppm
Detection Limit: 0.004 ppm at 3,000 mL (minimum detectable concentration; not part of the quantitative measuring range)
Sampling Rate: 100 mL/min
Sample Volume: 3,000 mL
Correction Factor: 1
Sampling Time: 30 Minutes
Color Change: White → Orangish Brown
Operating Temperature: 0–40°C (32–104°F), temperature correction required
Operating Humidity: 0–90% RH, humidity correction not required
Relative Standard Deviation: 10% for 0.02–0.06 ppm; 5% for 0.06–0.20 ppm
Quantity: 10 Tubes
Tests per Box: 10
Shelf Life: 30 Months
Pump Requirement: Compatible Automatic Air Sampling Pump Required

Low-Level Nitrogen Dioxide Measurement

The Gastec 9P is designed for applications requiring sensitive measurement of relatively low concentrations of nitrogen dioxide (NO2) in air.

Its 0.02–0.20 ppm measuring range provides quantitative nitrogen dioxide measurements when the tube is used according to Gastec's specified sampling procedure.

The 0.004 ppm detection limit represents the minimum concentration capable of producing a detectable reaction under the specified conditions. It is not the lower end of the quantitative measuring range and should not be interpreted as a 0.004–0.20 ppm measuring range.

During sampling, nitrogen dioxide reacts with the tube reagent to produce a visible white-to-orangish brown color change.

Common Applications

Gastec 9P Nitrogen Dioxide Detector Tubes may be useful for low-level NO2 air monitoring applications including:

• Industrial Hygiene & Occupational Air Monitoring — Measuring low-level nitrogen dioxide in applicable workplace environments.

• Combustion & Exhaust Monitoring — Evaluating NO2 in environments affected by combustion processes or exhaust emissions.

• Chemical & Industrial Facilities — Monitoring applicable work areas where nitrogen dioxide may be generated, used, or released.

• Environmental Air Monitoring — Measuring low concentrations of NO2 in applicable atmospheric investigations.

• Indoor Air Quality Investigations — Evaluating nitrogen dioxide where combustion sources or other NO2-generating processes may be present.

• Laboratory & Research Applications — Low-level nitrogen dioxide measurement under appropriate testing conditions.

• Leak & Emission Investigations — Evaluating suspected nitrogen dioxide releases or emissions.

• Industrial Safety & Maintenance — Checking applicable areas where occupational NO2 exposure may occur.

Operating Conditions

The Gastec 9P can be used from 0 to 40°C (32 to 104°F); however, temperature correction is required.

The tube can be used from 0 to 90% relative humidity without humidity correction.

Gastec specifies a relative standard deviation of 10% from 0.02–0.06 ppm and 5% from 0.06–0.20 ppm.

Always follow the temperature correction instructions provided in the official Gastec 9P instruction manual when determining the final concentration.

Possible Interferences

Gastec identifies several coexisting substances that should be considered when interpreting 9P measurements.

Carbon monoxide, nitric oxide, carbon dioxide, acetone, p-dichlorobenzene, n-decane, aromatic hydrocarbons, and formaldehyde are listed as producing no interference under the manufacturer's specified test conditions.

Chlorine: At concentrations of 0.10 ppm or less, Gastec lists no interference with the measurement; however, chlorine itself may produce a reddish-brown color beginning at approximately 0.08 ppm.

Ozone: At concentrations of 0.04 ppm or less, Gastec lists no interference with the measurement; however, ozone itself may produce a pale-yellow color beginning at approximately 0.1 ppm.

Coexisting gases and vapors should always be considered when interpreting detector tube results.

Important

A compatible automatic air sampling pump is required for correct use of the Gastec 9P Nitrogen Dioxide Detector Tubes.

For the 9P, accurate measurement depends on maintaining a continuous 100 mL/min sampling rate for 30 minutes, producing a total sample volume of 3,000 mL.

Do not use a standard manual detector tube pump in place of the required automatic sampling method.

Always follow Gastec's official instructions for the 9P detector tube and automatic sampling pump, including the required flow rate, sample volume, sampling time, temperature correction, operating conditions, interference information, and procedures for interpreting results.

Compatible Pump: Gastec GSP-501FT Automatic Air Sampling Pump

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