The Basics of Air Sampling StepbyStep SKC Inc

The Basics of Air Sampling Step-by-Step SKC Inc.

Before you begin an air sampling program. . it is important to determine your objectives. What do you want to accomplish? SKC Inc.

STEP #1 -Determine why you need to do air sampling Let’s review WHY air sampling is typically done. SKC Inc.

REASONS TO DO AIR SAMPLING TO ENSURE COMPLIANCE WITH REGULATORY STANDARDS Including Both Occupational and Environmental Standards SKC Inc.

REASONS TO DO AIR SAMPLING TO ENSURE PRODUCTIVITY OF THE WORKFORCE l l SKC Inc. Air sampling coupled with effective communication and control measures can keep workers healthy and improve employee morale. Healthy, happy workers are more productive.

REASONS TO DO AIR SAMPLING TO CHOOSE THE PROPER PERSONAL PROTECTIVE EQUIPMENT SKC Inc. l l Direct-reading instruments will allow for selection of appropriate PPE in the field. Historical databases on exposure levels will allow for selection of appropriate PPE for future tasks.

REASONS TO DO AIR SAMPLING TO EVALUATE THE EFFECTIVENESS OF ENGINEERING CONTROLS SKC Inc. l l Exposure reductions achieved from ventilation systems, scrubbers, or other devices can be documented. OSHA requires employers to control exposures through engineering controls or work practices if feasible.

REASONS TO DO AIR SAMPLING TO EDUCATE WORKERS ABOUT THE IMPORTANCE OF SAFE WORK PRACTICES SKC Inc. l Direct-reading instruments can be used to show workers the difference in exposure levels when safe work practices are used in their jobs.

REASONS TO DO AIR SAMPLING TO PERFORM EPIDEMIOLOGY STUDIES Epidemiology is the study of disease as it spreads and involves large groups of people. SKC Inc. Organizations often conduct research using air sampling data to reveal the relationship between a specific chemical agent and the onset of disease.

REASONS TO DO AIR SAMPLING TO DETERMINE THE SOURCE OF LEAKS SKC Inc. l l Direct-reading instruments can be used to determine leak points around piping, pumps and other equipment. Some instruments have ultra-sensitive leak detection modes to determine “hot spots”.

REASONS TO DO AIR SAMPLING TO ESTABLISH REGULATED AREAS FOLLOWING A LEAK OR SPILL SKC Inc. Collecting grab samples will allow for the documentation of chemical levels at various distances from the leak or spill and the establishment of appropriate controls.

REASONS TO DO AIR SAMPLING TO AVOID FUTURE LITIGATION Chemical exposures that are *Within acceptable levels and *Determined using validated, reliable methods Will reduce employers’ liability. SKC Inc.

THIS PRESENTATION FOCUSES ON AIR SAMPLING For the purposes of evaluating worker exposure levels l Using sampling media that requires subsequent laboratory analysis l SKC Inc.

Step #2 -Determine How Your Chemicals of Interest Are Regulated This will determine the type of sample you need to collect. There are three categories of exposure limits: 1. 8 -hour time-weighted averages (TWAs) 2. Short-Term Exposure Limits (STELs) 3. Ceiling Values SKC Inc.

8 -Hour TWAs Reflect the Average Full-Shift Exposure All the high concentrations and low concentrations are averaged with respect to time. SKC Inc.

8 -Hour TWAs Are Calculated as Follows: TWA =C 1 T 1 +C 2 T 2+C 3 T 3. . . +Cn. Tn _____________ 8 where: C=Concentration of contaminant T= Incremental exposure time SKC Inc.

STELs Are defined as 15 -minute average exposures which should not be exceeded at any time during a workday even if the 8 -hour TWA is within acceptable levels. SKC Inc.

Ceiling Values Are concentrations that should not be exceeded during any part of the workday-not even for an instant. Ceiling values are usually best determined with direct-reading instruments. SKC Inc.

STEP #3 -CONSULT WITH A QUALIFIED LABORATORY A qualified analytical laboratory can assist you in choosing sampling methods most appropriate to the environment being sampled. SKC has a list of laboratories accredited by the American Industrial Hygiene Association for customer reference. SKC Inc.

STEP #4 -CHOOSE AN AIR SAMPLING METHOD US AGENCIES THAT PUBLISH AIR SAMPLING METHODS l National Institute for Occupational Safety and Health (NIOSH) l Occupational Safety and Health Administration (OSHA) l Environmental Protection Agency (EPA) SKC Inc.

STEP #7 READ ON FOR FURTHER INFORMATION The following slides describe sampling using a variety of sampling media: l Sorbent Tubes l Filters l Impingers l Sampling Bags l Passive Samplers SKC Inc.

TWO GENERAL TYPES OF SAMPLING TECHNIQUES l Active Sampling l Passive SKC Inc. Sampling

ACTIVE SAMPLING. . . is the collection of airborne hazards by means of a forced movement of air by an air sampling pump through the appropriate sampling media. The pump is used to collect and/or concentrate the chemical of interest onto the sampling media. SKC Inc.

THREE KEY ELEMENTS OF ACTIVE SAMPLING A sampling pump Something to pull or push air l The sampling media Something to pull or push the air through l A calibrator Something to indicate how much air has been pulled or pushed l SKC Inc.

A NOTE ABOUT PUMP CALIBRATION Calibration means to set and verify the flow rate of the pump. Calibration should be done before and after every sample that you take. Flow rates are measured in ml/min or l/min. SKC Inc.

ELECTRONIC PUMP CALIBRATOR SKC Inc.

AN IMPORTANT SAMPLING PARAMETER THAT MUST BE SUPPLIED TO THE LABORATORY IS THE AIR VOLUME. This is determined by multiplying the pump’s flow rate in ml/min or l/min by the sampling time in minutes. SKC Inc.

ACTIVE SAMPLING OF GASES AND VAPORS Many sampling methods require the use of sorbent tubes for sampling gases and vapors. A sorbent tube is a small glass tube normally filled with two layers of a solid sorbent material. SKC Inc.

SORBENT TUBE SKC Inc.

COMMON SORBENT MATERIALS Activated Charcoal l Silica Gel l Tenax l XAD-2 l Chromosorbs l The sorbent used to collect specific chemicals will be specified in the sampling method. SKC Inc.

TO COLLECT A SAMPLE WITH SORBENT TUBES The end tips of the tube are broken and a known volume of air is drawn through the tube using an air sampling pump that has been calibrated to the flowrate specified in the sampling method. Airborne chemicals are trapped by the first layer with the back-up layer assuring complete removal of chemicals from the air. SKC Inc.

SORBENT TUBE SAMPLING TRAIN SKC Inc.

AFTER SAMPLE COLLECTION The tube is capped and sent to a qualified laboratory for analysis. There the sorbent is removed and the trapped chemicals are extracted using either solvents or heat and identified and quantified using gas chromatography or other laboratory equipment. SKC Inc.

ACTIVE SAMPLING OF GASES AND VAPORS In some cases, it may be desirable to collect the entire air sample in a special bag designed for that purpose. This type of sample is termed a grab or instantaneous sample. SKC Inc.

GRAB SAMPLES Are usually taken for short periods of time to indicate peak airborne concentrations l Can be used to determine TWA exposures in areas where chemical levels remain constant l SKC Inc.

TO COLLECT A SAMPLE WITH SAMPLE BAGS Pumps with an exhaust or pressure port can be used to push air into a sampling bag that is connected to the pump with teflon tubing. l Alternatively, bags can be placed into a chamber which is evacuated using a pump to fill the bag by negative pressure. l SKC Inc.

FILLING A BAG BY POSITIVE PRESSURE SKC Inc.

FILLING A BAG BY NEGATIVE PRESSURE SKC Inc.

AFTER SAMPLE COLLECTION Bags containing the sample can be analyzed in the field using direct reading instruments. l Bags can also be shipped to the laboratory where they can be analyzed by gas chromatography or other laboratory equipment. SKC Inc. l

ACTIVE SAMPLING OF GASES AND VAPOR S Some chemical hazards such as acids, ozone, chlorine and formaldehyde can be sampled using impingers. Impingers are specially designed glass bottles that are filled with a collection liquid specified in the sampling method for specific chemicals. SKC Inc.

IMPINGERS SKC Inc.

NOTES ABOUT IMPINGERS In some cases, the impinger nozzle is fritted or modified with thousands of small holes. This disperses the air and allows for better contact between the air sample and the impinger liquid. SKC Inc.

TO COLLECT A SAMPLE WITH IMPINGERS A sample pump is used to bubble air through the impinger which contains a liquid medium that has been specified in the method. The liquid will physically dissolve or chemically react with the chemical of interest. SKC Inc.

IMPINGER SAMPLING TRAIN SKC Inc.

AFTER SAMPLE COLLECTION The liquid is removed from the impinger and sent to the laboratory for analysis. l The impinger can then be cleaned and reused for future samples. l SKC Inc.

AIRBORNE PARTICULATE HAZARDS Airborne particulate hazards may include: l Dusts l Fumes l Mists l Aerosols SKC Inc.

ACTIVE SAMPLING FOR PARTICULATES l To sample for particulates, a filter loaded into a filter cassette will be used. l The filter diameter, type and pore size will vary depending on the chemical being sampled and will be specified in the sampling method. SKC Inc.

FILTER CASSETTE SKC Inc.

FILTER SAMPLING TRAIN SKC Inc.

AFTER SAMPLE COLLECTION Filters can be analyzed by a variety of methods depending upon the chemical: l Gravimetric-Weighing the sample before and after collection l Atomic Absorption/ICP-Performing chemical analysis to determine specific compounds l Microscopic-Counting individual fibers SKC Inc.

Some regulations require the measurement of respirable dust. Respirable dust is dust so small in size that it can get through the protective mechanisms of the human body and get down deep into the gas exchange region of the lung. To sample respirable dust, you will need to use a cyclone. SKC Inc.

RESPIRABLE DUST CYCLONE SKC Inc.

When sampling with cyclones The smaller respirable particles will be collected onto the filter for subsequent analysis. Larger particles will fall into the grit pot and will be discarded. SKC Inc.

Note About Cyclone Sampling l l SKC Inc. Be sure to calibrate your pump to the flow rate specified to achieve the desired 50% cut-point. Cut-point is the size of dust that the cyclone will collect with 50% efficiency.

NOTE ABOUT CYCLONE SAMPLING NIOSH and ACGIH recommend a 4 micron cut-point. l To achieve this cutpoint, a flowrate of 2. 5 l/min is recommended using the SKC aluminum cyclone. l SKC Inc.

INHALABLE DUST l l SKC Inc. Is a new term used to describe dust that is hazardous when deposited anywhere in the respiratory tree including the nose and mouth Includes the larger and the smaller particles

IOM SAMPLER FOR INHALABLE DUST SKC Inc.

TO COLLECT A SAMPLE FOR INHALABLE DUST Load a filter of the type appropriate for the particulate being sampled into the filter cassette of an IOM sampler. l If doing gravimetric analysis, desiccate or equilibrate the filter together with the cassette for 24 hours, then get a presample weight. l Place the cassette into the sampling head and connect it to a sampling pump SKC Inc. that has been calibrated at 2 l/min. l

AFTER SAMPLE COLLECTION Remove the cassette containing the filter from the sampling head and desiccate or equilibrate the cassette and filter again for 24 hours to get a post-sample weight. l Alternatively, chemical analysis can be done on the filter sample. l SKC Inc.

THE HEART OF AN ACTIVE SAMPLING TRAIN IS THE PUMP. For most industrial hygiene applications. GASES AND VAPORS are sampled at low flow rates to allow effective adsorption to occur onto the sorbent material. PARTICULATES are sampled at high flow rates so that airborne particles can be effectively trapped onto the filter material. SKC Inc.

LOW FLOW PUMP SKC Inc.

HIGH FLOW PUMP also with low flow capabilities SKC Inc.

PASSIVE SAMPLING. . . is defined as the collection of airborne gases and vapors at a rate controlled by a physical process such as diffusion through a static air layer or permeation through a membrane WITHOUT the active movement of air through an air sampling pump. SKC Inc.

PASSIVE SAMPLERS SKC Inc.

MOST PASSIVE SAMPLERS OPERATE BY DIFFUSION. Diffusive samplers rely on the movement of contaminant molecules across a concentration gradient which can be defined by Fick’s First Law of Diffusion. SKC Inc.

IN OTHER WORDS. . . SKC Inc. Chemicals will diffuse from an area of high concentration in the air to an area of low concentration on the sampler and the rate of diffusion for individual chemicals can be determined.

WHEN CHOOSING A PASSIVE SAMPLER Be sure that it has been tested and verified to work effectively for the chemical of interest. Otherwise, you should use a validated active sampling method for compliance purposes. l Be sure to note the sampling rate in ml/min given by the supplier along with the minimum and maximum sampling times. l SKC Inc.

TO COLLECT A PASSIVE SAMPLE Simply open the sampler at the sampling site and attach it to the worker in the breathing zone or hang in an area. l It is important that there be some degree of air movement at the sampling site. Placement of the sampler in stagnant air will cause “starvation” and will cause low results to occur. l SKC Inc.

AFTER SAMPLE COLLECTION l l l SKC Inc. Cover the sample opening to stop sample collection. Properly label the sample. Ship to the laboratory for chemical analysis.

FOR FURTHER ASSISTANCE Call your local SKC representative or the SKC corporate office at 412 -941 -9701 or (in the US) 800 -752 -8472. SKC’s technical staff is available to answer your questions. SKC Inc.

FOR FURTHER ASSISTANCE You can also get additional information by visiting the SKC home page on the world wide web at www. skcinc. com SKC Inc.