SOP 6. Real-time PM10 Monitor

 

Introduction

 

The TEOM instrument (TEOM 1400a Ambient Particulate (PM-10) Monitor) is a continuous PM monitoring device designated by USEPA as an equivalent method (EPA Designation No. EQPM-1090-079) for PM10 (10 microns sized particles and under) and used extensively in state and national PM2.5 monitoring networks. The acronym TEOM stands for “Tapered Element Oscillating Microbalance,” an inertial measurement technique that operates on changes in the resonant frequency of an oscillating element as a function of increases in particle mass collected on a filter attached to the element. Changes in the element’s resonant frequency are sampled electronically in quasi-real time, providing both continuous and time-averaged measures of mass accumulation that are directly proportional to instantaneous and time-averaged mass concentrations in air, respectively. The device operates at an industry-standard, volume-controlled flow rate of 16.7 L/min so that it can be outfitted with a variety of commercially available pre-separator inlets suitable for measuring PM10, PM2.5 or any other size fraction of interest.

 

Switching Instrument on/off

 

Since the airflow is maintained at a constant volume, corrected for local temperature and barometric pressure, the operation of this monitor requires that the temperature and pressure sensors are connected for proper temperature and pressure readings and flow corrections.

 

Turn on unit

 

Supply power to the instrument by plugging in the power cord to 120 VAC, and pressing the power button on the front panel of the TEOM control unit. The main screen (four-line display) will soon appear after showing the name of the instrument. Turn on the pump to draw the sample streams by plugging in the power cord to 120 VAC. The monitor waits at least 30 min after being powered up to compute the first mass concentration data.

 

Turn off unit

 

Press the power button on the front panel of the TEOM control unit. The four-line display becomes blank. Turn off the vacuum pump by pressing the power button and disconnect the control unit from 120 VAC by unplugging the power cord.

 

Status Line on Main Screen

 

Whenever a status code other then “OK” is shown on the display, the instrument automatically turns on the “Check Status” light on the front of the control unit. The information displayed on the main screen includes status condition, operating mode, A/O 1 mode, RS-232 mode, protection, and time. For example, the screen will show the following line at 8:11 AM:

 

OK      4+        51%     NU      08:11

 

Status condition:

OK      Normal operation

M         No frequency signal

T          Temperature(s) outside of operational bounds

F          Flow(s) outside of operational bounds

X         Filter nearing capacity—exchange filter

 

Operating mode:

1                    Temperature/flow stabilization

2                    Begin TM computation

3                    TM computed, begin MR/MC computation

4                    Normal operating mode

S          Set up mode

X         Stop all mode

 

 

A/O 1 mode:

(Blank) Analog output 1 normal definition

+                      Analog output 1 used for status watch

 

XX%               Filter loading (percent)

 

RS-232 mode:

N         None

P          Print online

R          R&P protocol

A         AK protocol

G         German network protocol

S          Storage to printer

F          Fast storage output

 

Protection:

U         Unlocked

L          Low lock

H         High lock

 

XX:XX            Current time (24-hr format)

 

 

Using the keypads and software

 

User should refer to Section 4.5 of the operating manual and become familiar with the incorporated menu-driven software and keypads.

 

Filter Storage and Exchange

 

The measurements must be conducted with TEOM filter cartridges that are made of Teflon-coated glass fiber filter paper. Filters should be stored inside the sensor unit for easy access and to keep them dry and warm. Do not handle new filter with your fingers. Instead, use the filter exchange tool and follow the procedures given in the operating manual. Keep the sample pump running to facilitate filter exchange. Use the two pockets on the right side of the mass transducer (inside) to store the next two new TEOM filters, for pre-conditioning and removal of excessive moisture build-up prior to use.

 

System Operation after Power Failure

 

The system resets itself when power is regained, and enters the same RS-232 mode as before. All operating parameters are maintained in the system’s battery backed-up CMOS memory.

 

Internal Data Logging

 

Values logged internally are stored in a circular buffer, and can be viewed from the control unit (press <Store>, and select “View Storage”, or enter 08<Enter> from any screen), or downloaded over the monitor’s RS-232 port. The instrument always stores the time, date, and station number in each record in addition to the data fields selected by the user. The storage capacity is given in Fig. 4-11 of the operating manual, generally about 1.7 weeks of 8 data fields per record, using a storage interval of 10 minutes.

 

Setting Variables Stored in Data Logger

 

The <Step Screen> key toggles the instrument between the View Storage Screen and Set Storage Screen, or, pressing 09<Enter> can gain direct access to the Set Storage Screen from any screen. The first eight lines of the Set Storage Screen contain the titles of the variables currently being stored in the data logger (Program Register Codes listed in Appendix A of operating manual). The “Interval” variable defines the time (in seconds) between successive writings of data to the circular buffer.

 

Some popular program register codes:

Code

Variable

Units

008

Mass concentration

mg/m3

009

Total mass

mg

035

Filter loading

%

039

Current main flow

L/min

040

Current auxiliary flow

L/min

041

Status condition

code

057

30-min average mass concentration

mg/m3

130

Current ambient temperature

oC

131

Current ambient pressure

atm

 

 

Setting Analog Outputs

 

The instrument’s three analog output channels are accessible from the identical 15-pin connectors on the front and back panels of the control unit. Details regarding the pin assignments and voltage (VDC) of outputs are given in the operating manual (Section 5.1). To bring up the Set Analog Output Screen, press <A/O>, or select “Set Analog Output” from Menu Screen, or press 04<Enter>.

 

Downloading Stored Data into Computer

 

Connect an IBM AT-compatible computer to an RS-232 port using the provided 9-to-9 pin computer cable. Make sure the computer is logged to the proper directory and subdirectory for program execution. Type TEOMCOMM <Enter> to bring up the software. Use the “Download storage” command to download the stored data in the data logger. Ensure that the communication software is set for the same communication parameters as the instrument.

 

Other Serial Output and Two-Way Communications

 

Details of serial outputs and two-way communications (such as online printing and connecting to a computer through a modem) are given in section 6 of the operating manual.

 

Nomenclature

 

TEOM              Tapered element oscillating microbalance

TM                   Total mass

MR                  Mass rate

MC                  Mass concentration

AK                  AK protocol was developed by the German automobile industry to standardize thecommunication among instrumentation. This protocol is used in combination with the TEOMCOMM software for data logging of the system.

A/O                  Analog output

atm                   atmosphere, 746 mBar

 

 

Calibration

 

Procedures are based on routine flow auditing, leak checking, and mass calibration verification. Since the TEOM monitor can be directly mass calibrated, it can be directly quality assured using a mass standard. All QA procedures should be coordinated with routine maintenance procedures to minimize down time.

 

Flow Audit

 

A flow audit adapter is provided and the procedures are outlined in the operating manual. Both the sample flow rate and total flow rate may be checked using the flow audit adapter with a capped nut for closing the flow splitter bypass line port. It is recommended that the volumetric flow rates be within ±7% of the set points. The United States Environmental Protection Agency (USEPA) requires a tolerance of ±10% for the total flow through the PM-10 inlet. If measured flows differ by more than the stated tolerances, recheck all settings, and perform the test again. Large errors in the flow may indicate other sources of error, such as a malfunctioning flow controller, a system leak, or improper temperature and pressure settings.

 

Leak Check

 

The leak check procedures are included in the operating manual (Section 7.6). The leak check should be performed with NO sample filter attached to the mass transducer, which will prevent accidental damage from occurring to the sample filter cartridge when exposed to the high pressure drop (vacuum) in the sample line that the leak check creates. Flow rates should indicate less than 0.15 L/min for the main flow and less than 0.65 L/min for the auxiliary flow with the end of the sample line closed, if not, systematically check plumbing for connector leaks.

 

Mass Calibration Verification

 

The mass transducer is permanently calibrated and never requires recalibration under normal use. However, the mass measurement accuracy of the instrument may be verified following procedures in the operating manual. R&P offers a mass calibration verification kit to help perform this procedure.

 

Maintenance

 

The lifetime of a TEOM filter cartridge depends on the nature and concentration of the particulate sampled, and the main flow rate setting (1, 2, or 3 l/min). The filter must be exchanged when the filter loading value (as shown on the status line of the main menu) approaches 100%. At a flow rate of 3 l/min, 100% filter loading generally corresponds to a total mass accumulation of approximately 3 to 5 mg of particulates. Filter lifetime at a main flow rate of 3 l/min is generally 21 days at an average PM-10 concentration of 50 mg/m3. Flow splitter adapters for 1 and 2 l/min operation are available for use in areas with higher particulate concentrations.

 

The factory recommended schedule of periodic maintenance and the schedule to be adopted for use in livestock buildings are as follows:

 

Maintenance item

Factory

APECAB

Clean external screen

-

As necessary

Clean PM-10 inlet

Upon filter exchange

Weekly

Exchange in-line filters

6 mon. or when loaded

When loaded

Clean air inlet system

6 mon.

Monthly

Leak test

Annually

Bimonthly

Mass flow controller calibration

Annually

Bimonthly

Analog board calibration

Annually

Every 5 months

Mass calibration verification

Annually

Bimonthly

 

The PM10 inlet requires regular maintenance in livestock buildings. A wire-mesh external screen was designed for the PM10 inlet to keep large dust particles out. This external screen requires cleaning every two to three days, depending on PM concentration in the air. Cleaning is accomplished by carefully removing the external screen, and, in an area downwind of the inlet unit, brushing it or cleaning with water and letting dry. After all visible dust has been removed from the external screen, carefully replace it on the PM10 head, so as not to disturb the sensor unit.

 

 

Figure. TEOM PM10 inlets with external screens. (Source: Purdue University)

 

The PM10 inlet itself should be cleaned weekly. In order to do this one must first push the <Data Stop> button on the keypad. Remove the PM10 inlet and replace it with an in-line filter to prevent excessive amounts of dust being pulled into the TEOM unit. At this point, unscrew the Acceleration Assembly from the Collector Assembly (see fig. F-1). Using a can of pressurized Dust Remover (found at most hardware and electronics retailers), spray the inlet screen on the Acceleration Assembly until clean. Then spray the inside of the Acceleration Assembly from the bottom tube. This should remove most of the dust from the screen. Also spray the internal areas of the Collector Assembly. After these have been cleaned, feel the o-rings, located on the lower part of the Acceleration Assembly and on the lower part of the Collector Assembly, for the presence of silicon grease. Grease as needed to maintain a slight layer of Silicon Grease. Carefully replace the inlet unit, and return to the control unit of the TEOM system, and press the <Data Stop> button once more. This will prevent skewed data from being recorded. It will automatically begin recording in approximately 30 min.

 

Other Notes

Flow rate through sample inlet   16.7 L/min (1 m3/hr)

Main flow rate                                      3 L/min

Temperature of sample stream  50 oC

Particulate concentration                       < 5 mg/m3 to several g/m3

 

Spare Parts and Consumables

Slow blow 2A, 250 V fuse

2A $ 250 V in-line fuse, P/N 04003419

Box of 20 TEOM filter cartridges (TX40 media), P/N 57-000397-0020

Large bypass in-line filter, P/N 57-002758

Flow controller filter, P/N 30-003097

 

Manufacturer Contact Information

 

Rupprecht & Patashnick Co., Inc.

25 Corporate Circle

Albany, NY 12203

Timothy Morphy
Assistant Product Manager
518.452.0065 voice
518.452.0067 fax
tmorphy@rpco.com (email)

 

Peggy O’Gormon

Marketing Associate

X3229, email: pogorman@rpco2.com