SAMPLING OF STACK EMMISION BY STACK SAMPLER

1.0       Objective:

            The objective of this Standard Operating Procedure is to lay down the procedure for operating the Stack sampler.

2.0       Scope:

            This SOP covers operating procedure of stack sampler .

3.0       Responsibility:

The responsibility to follow the Operating procedure is of the Analyst.

4.0       Procedure:

Pre-sampling: Procedure

1. Before attempting to operate the instruments the user must gain familiarity with the flow schematic of the instrument and principal of the operation by going through the figures.
2. Verify that interconnections are OK as per the given figure no. A
3. Required gases for testing and as per gases scrubbing solution are loaded into the impinger bottles.
4. For sampling requirement of power single phase 220 V A.C.

Leak check before the start of sampling.

Selection of Filter Medium:

5. Temperature of the flue gases is the major factor in determining/selection of the type of the filter medium to be used.
6. If the temperature is below 150ºC cellulose thimble is used and above 150ºC in that case only glass micro fiber thimble can be used.
7. Cellulose filtration thimbles can be used for “IN-STACK’’ sampling of flue gases up to a stack temperature of 120ºC while glass micro fiber thimbles allow operation up to 500ºC.
8. After each sampling the probe must be backwashed with acetone to collect the particulates that may have been deposited on the probe walls. These particles must then be recovered by evaporating the solvent and their weight added to that of particles collected on the thimble.
9. While sampling flue gases containing moisture or condensable, care must be taken to minimize the length of probe out side the stack so that the flue gas do not cool down beyond their dew point resulting in significant amount of condensation before the filter assembly.

Preparing the Thimbles:

1. Prior to sampling filter medium must be dried and weighed. Cellulose/GF
filtration thimbles, particularly, are quite hygroscopic and must be dried in an oven at
100ºC for at least 30 minutes. On removal from the oven they must be allowed to
cool in a dedicator and weighed.
2.After sampling both thimbles must be dried prior to final weighing.

Loading of the Thimbles:

1. Pre-weighed thimble should be loaded into the filter holder for particulate sampling.
2. Open the thimble holder by unscrewing the front end.
3. Keep the filter casing down and hold the front end in your left hand.
4. Unscrew the screw mounted on the ‘‘U’’ shaped clamp to make sufficient space for thimble.
5. Slip the thimble slightly inwards.
6. Tighten the screw keeping the thimble straight.

Sampling Procedure:

1. First measure the temperature and velocity with the help of AMP 602 (refer fig. no. B)
2. Check that the flow control knobs 3 LPM & 30 LPM are in OFF condition by rotating the valves in clockwise direction.
3. Insert the probe pipe into the chimney’s porthole.
4. Start the vacuum pump.
5. Open the flow control valve on the 3 LPM flow meter slowly to set up the gas-sampling rate. Then open the valve on the 30 LPM and adjust the air flow for Particulate mater as calculated, for sampling in iso-kinetic condition.
6.  Always set up flow in the 3 LPM flow meter first and then in the 30 LPM flow meter. Similarly while terminating the sample, shut off the 30 LPM flow meter first and the 3 LPM flow meter last.
7. At the end of the sampling time, withdraw the probe and shut off the power to the system.

Setting Up APM 620 for Measuring SPM:

1. For sampling particulates sampling at isokinetic sampling rate must be performed.
2. Calculate the average stack gas velocity and selection appropriate traverse point where the tip of the sampling probe can be located for obtaining a representative sample.
3. Select a suitable nozzle and sampling rate using the graphs in Fig. No. A or the equations given in Calculation.

Records:

The records should be recorded in the ‘Field Data Sheet’.

Calculations:

      1)   Velocity (V) in m/s       =       0.1882 × √H × Tk

                          Where,

                           H          =     Meter Reading

                           Tk         =    Temperature in Kelvin

                           0.1882   =    Factor of velocity meter kit.

       2)    Iso Kinetic Sampling Flow Rate       =      1.9002 × V × Ta

                                                                                             Ts

                            Where,

                            1.9002   =    Factor of the nozzle of the probe of sampling kit.

                             V          =    Velocity (m/s)

                            Ta         =     Ambient temperature (K)

                            Ts         =      Stack Temperature    (K)

5.0 History of Revision:

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