National Institute for Occupational Safety and Health

“ Average recovery for 18 samples over the range of 1780 to 6970 mg/ m 3 was 100 %. In breakthrough tests at 80% relative humidity, the sampler retained 15.4 mg of chlorodifluoromethane when sampling at 0.025 L/min from atmospheres containing 7000 mg/m 3. The desorption efficiency of chlorodifluoromethane from activated charcoal averaged 0.96 in the range 0.53 to 10.4 mg per sample. ”

“ Methylene chloride is an irritant, can be absorbed through the skin, and is a suspect carcinogen [4] . Prepare samples in a hood.
SAMPLING: 1. 2. 3. 4.
Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.01 and 0.05 L/min for a total sample size of 1 to 4 L. Separate and cap the tubes. Pack securely for shipment in an insulated container with bagged refrigerant. ”

“ A silylated glass wool plug precedes the front section and a 3-mm urethane foam plug follows the back section. Pressure drop across the tube at 1 L/min airflow must be less than 25 mm/Hg. Tubes are commercially available. 2. Personal sampling pump, 0.01 to 0.05 mL/min, with flexible connecting tubing. ”