S-2.1, r. 14 - Regulation respecting occupational health and safety in mines

Schedule Disposition versions

2016-06-23

SCHEDULE VI

(Revoked)

O.C. 782-97, s. 29; O.C. 465-2002, s. 32; O.C. 445-2016, s. 6.

2012-09-01

SCHEDULE VI

(s. 102)

SAMPLING AND ANALYSIS PROTOCOL FOR RESPIRABLE COMBUSTIBLE DUST (RCD)

1. Principle underlying the protocol

A sample of respirable dust is taken on a silver membrane filter (0.8-micrometre pores, 25 mm in diameter). Once the sampling is completed, the filter is weighed and then placed in a furnace at 400°C for at least 1.5 hours. That temperature and the catalytic action of the silver membrane filter combine to eliminate carbon-based substances. That loss in mass is therefore equivalent to the quantity of respirable combustible dust.

2. Precision and accuracy

CONCENTRATION RANGE (RCD): 0.04 to 3.0 mg/m3 (1000-litre sample).

ACCURACY: <10% (pure diesel dust samples).

PRECISION: ±0.04 mg (on gravimetric analysis only).

3. Interference

Carbon-based mineral dust (coal, graphite).

Some sulphide mineral dusts.

4. Equipment

Personal sampler: 10 mm Dorr-Oliver nylon cyclone. Silver membrane filter 25 mm in diameter with 0.8-micrometre pores. Three-piece plastic cassette with backup pad.

Personal sampling pump. Flexible plastic tube to connect the pump to the cassette.

Flowmeter.

Furnace equipped with automatic temperature control system. Fire-proof glass or stainless steel plates for filters.

Electrobalance (0.01 mg readability).

5. Sampling

The flow of the sampling pump shall be calibrated at 1.7 litres per minute using the flowmeter. When using a cyclone, the flow must be fixed at 1.7 litres per minute under the actual temperature and pressure conditions of the sampling site. Calibration of the flow is done with the entire sampling device (pump, tube, cyclone, filter cassette).

The sampling flow shall be measured at the end of sampling and the difference compared to the initial flow shall be less than 5%.

The sampling volume shall range from 400 to 1,000 litres.

Sampling shall focus on the total duration of the shift.

Once the sampling is completed, the cassette shall be plugged and sent to the laboratory for analysis.

6. Analysis

Using tweezers, the filter shall be withdrawn from the cassette case making sure not to touch the dust deposit. The filters to be analyzed shall be placed in the same clean room as the balance for an acclimatization period of at least 2 hours.

After that period, each filter shall be weighed at least twice. If the difference between the 2 readings is 0.03 mg or more, a third reading is required. The mass of the filter is the average of the masses that differ by 0.02 mg or less.

The filters shall be placed on heating plates, which shall then be inserted into the furnace. The position of the filters shall be carefully recorded using a diagram on which each filter is identified and its position in relation to the others indicated (identification marks on filters may burn off during the heating process).

The furnace shall be heated to 400°C. A timer equipped with an audible alarm may be used to indicate the end of the heating period, which shall be at least 1.5 hours at a temperature of 400°C.

At the end of the heating process, samples shall be removed from the furnace. They may be removed from the plates if it can be done safely. Otherwise, it is recommended to wait until the plates have cooled. Filters may sometimes tend to adhere to the plate. A scalpel blade inserted between the filter and the surface while holding the filter with tweezers usually frees the filter without damaging it.

Filters shall then be placed in the same place as the balance for 2 hours. Filters shall be re-weighed as described in the second paragraph.

The mass of respirable combustible dust is the difference between the final mass obtained pursuant to the sixth paragraph and the initial mass obtained pursuant to the second paragraph.

7. Quality control

The accuracy of the furnace temperature reading shall be periodically verified by using an independent electronic thermometer.

The balance shall be calibrated at the beginning of each weighting session using the manufacturer’s directions for internal calibration. Thereafter, every 3 months or more if needed, the accuracy of the balance shall be checked using NIST Class S weights. Every year, the balance shall be cleaned and its accuracy checked again using ANSI/ASTM Class 1 weights.

The calibration of flowmeters shall be done by a laboratory which shall file certificates demonstrating that the calibration procedures comply with NIST Standards.

Analytical and sampling blanks shall be analyzed at the same time as the other samples. The loss in mass of analytical blanks should never exceed 0.04 mg and that loss in mass shall be applied as a correction factor.

O.C. 782-97, s. 29; O.C. 465-2002, s. 32.