Reference methods for measuring particulate matter and lead emissions from secondary lead smelters: section 1


Section 1: Sampling Procedures

Many of the standard sampling procedures applicable to this source are described in Report EPS 1-AP-74-1, Standard Reference Methods for Source Testing: Measurement of Emissions of Particulates from Stationary Sources. Procedure 1.6 incorporates certain modifications to the standard method and shall be used in place of Method E in the above report.

1.1 Determination of Sampling Site and Traverse Points

Method A, Report EPS 1-AP-74-1.

1.2 Determination of Stack Gas Velocity and Volumetric Flow Rate

Method B, Report EPS 1-AP-74-1.

1.3 Determination of Molecular Weight by Gas Analysis

Method C, Report EPS 1-AP-74-1.

1.4 Determination of Moisture Content

Method D, Report EPS 1-AP-74-1.

1.5 Calibration Procedure for S-Type Pitot Tube, Dry Gas Meter, Orifice Meter and Rotameter

Method F, Report EPS 1-AP-74-1.

1.6 Determination of Particulate Matter and Lead Emissions

1.6.1 Principle

Particulate matter is withdrawn isokinetically from a number of sampling points in the stack and its weight determined gravimetrically after removal of uncombined water. Sampling isokinetically means that the linear velocity of the gas entering the sampling nozzle is equal to that of the undisturbed gas stream at the sample point.

1.6.2 Apparatus

1.6.2.1 Sampling train (Figure 1).

Figure 1 : Particulate Matter Sampling Train

Particulate Matter Sampling Train

1.6.2.1.1 Nozzle. A stainless-steel nozzle with sharp, tapered leading edge is required. An equivalent nozzle made of Pyrex, Vycor, borosilicate or quartz may be used when high temperature or corrosive gases are encountered.

1.6.2.1.2 Probe. A Pyrex probe encased in stainless-steel tubing with a heating system capable of maintaining a gas temperature of at least 121°C (250°F) at the exit end, or higher if necessary, to avoid condensation during sampling, is required. Probes for sampling gas streams in excess of 315°C (600°F) shall be constructed of special glass liners such as Vycor, quartz or equivalent material. Where length or strength limitations preclude the use of a glass liner, Incoloy 825 or equivalent may be used. Water-cooled probes may be used where very hot gases capable of damaging the nozzle-probe assembly are encountered.

1.6.2.1.3 S-type pitot tube. An S-type pitot tube or equivalent is attached to monitor stack gas velocity.

1.6.2.1.4 Temperature gauge. A thermocouple or equivalent device, capable of measuring stack temperatures to within 1.5% of the minimum absolute stack temperature, is attached to the pitot tube. When stack temperatures exceeding 371°C (700°F) are encountered, appropriate shielding and aspiration shall be provided for the thermocouple. The temperature and corrosiveness of the stack gases will determine the type of thermocouple to be used.

1.6.2.1.5 Miniature cyclone (optional). A Pyrex miniature cyclone following the sampling probe and preceding the filter is used to collect the large-particulate fraction in gas streams when appreciable. The cyclone prevents the premature build-up of particulate matter on the filter medium and permits longer sampling runs than can be achieved without it. The cyclone must be maintained at a temperature of at least 107°C (225°F), or higher, if necessary, to avoid condensation.

1.6.2.1.6 Dry gas meter. A dry gas meter calibrated to within ±1% and equipped with inlet and outlet temperature indicators is used to determine sample volume. The dry gas meter follows the vacuum pump in the sampling train.

1.6.2.1.7 Orifice meter. A calibrated orifice meter is used to measure the sample flow rate. The orifice meter is connected to the outlet of the dry gas meter.

1.6.2.1.8 Differential pressure gauges. Inclined manometers or equivalent, capable of measuring pitot tube velocity pressure and the pressure drop across the orifice meter to within 0.1 mm H2O (0.005 in. H20), are required.

1.6.2.1.9 Barometer. A barometer capable of measuring atmospheric pressure to ±2.5 mm Hg (0.1 in. Hg) shall be used.

1.6.2.1.10 Filter holder. A Pyrex filter holder, 6.5 cm in diameter, with a heating system capable of maintaining a temperature of the gas sampled of at least 107°C (225°F), or higher, if necessary, to avoid condensation, is required. A filter support of porous fritted glass material or equivalent and a suitable gasket shall be used.

1.6.2.1.11 Filter. High purity glass fibre filters of 0.3μ porosity are required. The filter should contain no organic binders and should be desiccated to constant weight before use.

1.6.2.1.12 Impingers. Five Greenburg-Smith impingers are connected in series. The first, third, fourth and fifth impingers are modified by replacing the tips and impaction plate of the standard design with a 1.27-cm (½-in.) ID glass tube extending to 1.27 cm (½ in.) from the bottom of the flask. The second impinger has the standard tip and impaction plate.

1.6.2.1.13 Leakless vacuum pump. A vacuum pump capable of maintaining an isokinetic sampling rate and continuously withdrawing a portion of the stack gases through the sampling train is used. The pump is connected to the outlet of the last impinger by a vacuum line containing a vacuum gauge to measure the pump intake vacuum to within 1.25 cm Hg (0.5 in. Hg) and a coarse adjustment valve to regulate sample flow. A bypass valve is connected across the vacuum pump to allow for fine control of the sample flow.

1.6.3 Reagents

1.6.3.1 Sampling train.

1.6.3.1.1 Indicating type 6-16 mesh silica gel dried at 177°C (350°F) for 2 hours.

1.6.3.1.2 Deionized or distilled water.

1.6.3.1.3 Crushed ice.

1.6.3.1.4 Cleaning solution. All glassware should be cleaned prior to use with aqua regia and rinsed several times with distilled or deionized water. Aqua regia is prepared by mixing 1 volume of reagent-grade concentrated nitric acid and 3 volumes reagent-grade concentrated hydrochloric acid.

1.6.3.1.5 Aqua regia, 5% solution. This is prepared by diluting 50 ml of aqua regia to 1 litre using distilled or deionized water.

1.6.3.2 Sample recovery.

1.6.3.2.1 Reagent-grade acetone.

1.6.3.2.2 Deionized or distilled water.

1.6.4 Procedure

1.6.4.1 Sampling train.

1.6.4.1.1 Preliminary. Select the sampling site and minimum number of sampling points according to procedures described in EPS 1-AP-74-1 (Method A). Determine the stack pressure, temperature, moisture and range of velocity pressures. Use this information to determine the size of nozzle required for isokinetic sampling. Recommended minimum nozzle size is 4.76 mm (3/16") ID.

1.6.4.1.2 Preparation of collection train. Label a filter of proper diameter, desiccate for at least 24 hours using Drierite or equivalent at 21 ± 6°C (70 ± l0°F) and weigh to the nearest 0.5 mg in a room where the relative humidity is less than 50%. The pre-weighed filter should be placed in a clean container to prevent contamination during transportation to the sampling site. Place 100 ml of 5% aqua regia in each of the first two impingers. Place 100 ml of deionized or distilled water in the third impinger and approximately 200 g of pre-weighed silica gel in the fifth impinger. Set up the sampling train as in Figure 1, but without the probe. Check the sampling train at the sampling site for leaks by plugging the inlet to the filter holder and pulling a 38-cm Hg (15-in. Hg) vacuum. If the needle on the dry gas meter moves, a leakage rate not in excess of 0.00057 m3/min (0.02 ft3/min) at a vacuum of 38 cm Hg (15 in. Hg) is acceptable. Attach the probe and nozzle. Leak check this assembly by plugging the nozzle and pulling a 5.1-cm Hg (2-in. Hg) vacuum. A leakage rate net in excess of 0.00057 m3/min (0.02 ft3/min), at this vacuum, is acceptable. Adjust the heater to provide a minimum gas temperature of 1210C (25° F) at the probe outlet.

Adjust the filter heating system to provide a temperature of 107°C (225°F) at the filter holder. Place crushed ice around the impingers. Add more ice during the run to keep the temperature of the gases leaving the last impinger as low as possible, preferably at 21°C (70°F) or less. Temperatures above 21°C (70°F) may result in damage to the dry gas meter from either moisture condensation or excessive heat.

1.6.4.1.3 Particulate train operation. To begin sampling, position the sampling nozzle at the first sampling point (traverse point). Point the nozzle directly into the approaching gas stream and secure the entire apparatus to the support system. Immediately start the vacuum pump and adjust the sampling flow rate to isokinetic conditions. Sample for at least 5 minutes at each sampling point; sampling time must be the same for each point. Maintain isokinetic sampling throughout the sampling period by making the necessary adjustments in the sampling flow rate as stack conditions change, or as the build-up of particulate matter on the filter affects the flow. Nomographs are available, or can be constructed, to aid in the rapid adjustment of the sampling rate without other computations. For each run, record the data required on the example sheet shown in Figure 2. Instrument readings shall be recorded at intervals that are consistent with the time duration established for each point. For example, if testing for a minimum of 5 minutes per point, readings should be recorded every 2½ minutes and whenever flow adjustments are necessary. The time between readings should not exceed 5 minutes. When the traverse is completed, turn off the vacuum pump and record the final instrument readings. Transfer the sampling apparatus to any additional sampling port and repeat the sampling procedure. When the test is completed, remove the sampling apparatus from the stack, disconnect the probe and repeat the leak check at the filter holder inlet according to the procedures specified in Section 1.6.4.1.2. Use the maximum vacuum achieved during the test in lieu of the 38 cm of Hg specified in Section 1.6.4.1.2.

Figure 2 : Particulate Matter Data Sheet

Particulate Matter Data Sheet
1.6.4.2 Sample recovery.

Exercise care in moving the collection train from the test site to the sample recovery area to minimize the loss of collected sample or the gain of extraneous particulate matter. Wash the interior surfaces of the nozzle-probe assembly with acetone, using a brush to remove the particulate matter adhering to the walls, place these washings in a numbered container (container 1), and cover. If a miniature cyclone was used ahead of the filter, remove it from the collection train and wash the interior surfaces with acetone; use a rubber policeman to remove the particulate matter adhering to these surfaces, and add these washings to container 1. Remove the filter from its holder, transfer to its container, and seal. Wash the interior surfaces of the filter holder preceding the filter with acetone and add the washings to container 1. Seal this container. Measure the volume of liquid in each of the first four impingers to the nearest 0.5 ml and record the results on the moisture analysis data sheet (Figure 3). Transfer the contents of the first two impingers to a second numbered container (container 2). Rinse the first two impingers, connectors and the interior surface of the filter holder following the filter with deionized or distilled water and add these washings to container 2. Seal container 2. Using a rubber policeman if necessary, transfer the silica gel from the fifth impinger to a container, and seal.

Figure 3 : Moisture Analysis Data Sheet

Moisture Analysis Data Sheet

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