SOP 3
Chemiluminescence Ammonia analyzer (TEI Model 17C)

Description and Principle of Operation

The chemiluminescence NH₃ analyzer (Model 17C, Thermal Environmental Instruments (TEI), Franklin, MA) is a combination NH₃ converter and an NO-NO₂-NO_x analyzer. Ammonia in the air sample is oxidized to nitric oxide (NO) with a catalytic converter at 875°C. The NO is further oxidized by gas-phase titration with ozone (O₃) in the analyzer’s reaction chamber, producing nitrogen dioxide (NO₂) in an excited state (Equation 1). At reduced pressure created by a vacuum pump, some of the excited NO₂ molecules emit radiation as they return to a lower energy state. With excess O₃, the intensity of the radiation is proportional to the concentration of NO.

NO + O₃ ® NO₂ + O₂ + hv (1)

where O₂ is oxygen and hv represents photons, particles of light energy, or radiation energy that is generated by moving electric charges. The emitted radiation is detected by a photomultiplier tube (PMT), which in turn generates an electronic signal that is processed into a gas concentration reading. Sample air is drawn at a flow rate of 0.6 L/min from the converter into the NH₃ analyzer through a particulate filter, a glass capillary, and a solenoid valve. The solenoid valve routes the sample either directly into the reaction chamber (NO mode), through the molybdemum converter and the reaction chamber (NO_x mode), or through the catalytic converter and the reaction chamber (N_t mode). The NH₃ analyzer’s full scale is adjustable up to 200 ppm. It has a lower detectable limit of 1 ppb. Its precision is 0.5% of full scale and the 0 to 90% response time is 120 s with 10 s averaging (TEI Model 17C Chemiluminescence NH₃ Analyzer Instruction Manual). Ammonia concentration is calculated based on the difference between the readings obtained by the N_t and NO_x modes. The response time of the instrument is decreased if operated only in the N_t mode. Additionally, the costs of NH₃ scrubbers required with the NO and NO_x modes are avoided.

Calibration

1. Calibration Gases

Zero air, nitric oxide (NO) in N2 and [JN1] NH₃ in air are used to calibrate the instrument. However, if the instrument is operated only in the N_t mode, then NO is needed only to periodically assess the need to maintain the converter by testing its efficiency.

2. Zero and Span Check Procedure for Analyzer Only

• Record calibration date and time in the lab notebook.
• Detach the NH₃ inlet tube including the filter from the existing sampling manifold. Close the pipe adapter of the sampling manifold with a cap or plug.
• Attach the NH₃ analyzer inlet tube including the filter to a calibration manifold.

Zero Gas Check

1. Close regulator valve on the zero gas cylinder

2. Open main valve on zero gas cylinder

3. Insert the 1/8” ID tubing (from the gas cylinder) into the calibration manifold connected to the valve; then open the regulator valve to allow gas flow. Zero gas is now flowing from the cylinder to the analyzers

4. Adjust regulator valve until vent airflow is about 1 L/min (read from bottom of ball of the vent monitoring flow meter installed in outlet of calibration manifold). This provide a little extra zero air to the analyzers and keep the pressure inside the manifold close to the atmospheric pressure.

5. Record time and analyzer display in lab notebook after display is stabilized (typically 5 to 10 minutes).

6. Press MENU button on the NH₃ Analyzer

a. Select calibration press ENTER

b. Select calibrate zero press ENTER

c. When reading is stable, press ENTER to zero the analyzer

d. Press RUN

7. Close regulator and remove tubing from zero gas cylinder.

Span Gas Check (NO)

1) Close regulator valve on span gas cylinder

2) Open main valve on span gas cylinder

3) Insert 1/8” ID tubing (from the gas cylinder) into the calibration manifold connected to the valve; then open the regulator valve to allow gas flow

4) Adjust regulator valve until calibration manifold exhaust airflow is 1 L/min (read from bottom of ball of the flow meter).

5) Record the time and analyzer display on the lab notebook after display is stabilized (typically 5 to 10 minutes).

6) Press MENU on the NH₃ Analyzer

a. Select calibration press ENTER

b. Select NO press ENTER

c. Set NO value to the certified concentration of the calibration gas

d. When readings are stable press ENTER

e. Press RUN

7) Close regulator and remove tubing from gas cylinder

Span Gas Check (NH₃)

1) Close regulator valve on span gas cylinder

2) Open main valve on span NH₃ cylinder

3) Insert 1/8” ID tubing (from the gas cylinder) into the calibration manifold connected to the valve; then open regulator valve to allow gas flow

4) Adjust regulator valve until gas flow is 1 L/min (read from bottom of ball of the flow meter).

5) Record the time and analyzer display on the lab notebook after display is stabilized (typically 5 to 10 minutes).

6) Press MENU on the NH₃ Analyzer

a. Select calibration press ENTER

b. Select NH₃ press ENTER

c. Set NH₃ value to concentration of the calibration gas

d. When readings are stable press ENTER

e. Press RUN

7) Close regulator and remove tubing from gas cylinder

Post Calibration

Reattach the filters to the existing gas sampling system.

Check and close main valves on all cylinders

Calibration of the NH₃ analyzer is complete

Maintenance (to be completed)

List of Spare Parts (to be completed)

Vacuum Pump (TEI p/n 9456, cost was $1,841 on January 2002)

KNF Neuberger

KNF Double Headed Vacuum Pump (PU 425-NO26.3-8.90)

2 Black Forest Road
Trenton, NJ 08691
609-890-8600

Vacuum Pump (alternative less expensive source .. $588 on January 2002)

Pump needs to provide 29 inches of mercury dead head

Part No. LAA-V104-NQ

Clean Air Engineering

500 W. Wood Street, Palatine, IL 60067

1-800-553-5511 ext. 2222

Vacuum Pump repair kit # K425 9XTP  ($41 from KNF Neuberger)

Manufacturer Contact Information

Thermo Environmental Instruments (www.thermoei.com)

8 West Forge Parkway

Franklin, MA 02038
Tel:  (508) 520-0430 ext. 6812
Fax: (508) 520-1460

Sales: Souphin A. Sithideth, Inside Sales Engineer, e6812, E-Mail:  SSithideth@thermoei.com
Service: Barry Pepin, Service Engineer, e6908, E-Mail:  Bpepin@thermoei.com

Calibration Record Sheet for TEI Model 17 Ammonia Analyzer

Date of Calibration: __________________ Calibrated by: __________________

Time	Items	Unit =	Notes
: :	Vacuum pressure, (mm Hg)
	Ozonator airflow (L/min)
	Sample airflow (L/min)
: :	Zero air applied	---	Cylinder P: ___ psi
: :	Time switch on	---
: :	Nt Reading (ٱ PC, ٱ Analyzer)
: :	Nt Reading (ٱ PC, ٱ Analyzer)
: :	Reset to zero gas	^Yes/No
: :	NO (______ ppm) applied	---	Cylinder P: ___ psi
: :	Nt Reading (ٱ PC, ٱ Analyzer)
: :	Nt Reading (ٱ PC, ٱ Analyzer)
: :	Reset to span gas	^Yes/No
---	New coefficient
: :	NH3 (______ ppm) applied	---	Cylinder P: ___ psi
: :	Nt Reading (ٱ PC, ٱ Analyzer)
: :	Nt Reading (ٱ PC, ٱ Analyzer)
: :	Reset to span gas	^Yes/No
---	New coefficient
: :	New coefficient saved	^Yes/No
: :	Time switch off (5 min/10 min)	---
: :	Connect analyzer back to sampling system.
Note:

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[JN1] NH3 measurement will be set at 0-50 ppm.