Collecting and Testing Dust (continued)

Finding A Qualified Test Lab

A few independent test laboratories have dust collection experience, and some equipment manufacturers also offer testing. Before selecting a lab, review these questions with potential vendors:

How much does testing cost?

Independent labs may charge anywhere from $300 to $10,000, depending on the scope of the testing. Some manufacturers offer free testing as a value-added service to customers. Find out whether you are obligated to buy a dust collector if the manufacturer conducts tests for you.

How long does testing take?

The testing usually takes no more than a day to complete, but additional time is need to prepare a written report. Ask whether you are allowed to visit the lab during testing: You may find it useful to participate in the test process.

What kinds of tests are available?

Find out how many "small-sample" or "bench" test procedures typically are used to evaluate dust samples and whether full-scale testing is available.

What samples or other materials will be needed to run the tests?

Bench testing requires only a 1-pint dust sample in an airtight container. For full-scale testing, a 55-gallon drum of dust is needed. Proper collection of the sample is important to make sure that it represents the state in which the filter will collect it. If you have an existing dust collector, a dirty bag or cartridge is an ideal sample.

The lab also should ask you to provide detailed application data. This data may include information on the process generating the dust, operating requirements, airflow and pressure-drop conditions, temperature and humidity, space constraints, and more. Without application data, no context exists for your test program, which means less-valid test results.

What type of reports and recommendations will be provided?

Based on test data and your application input, you should receive a recommendation that includes filter type (i.e., bag or cartridge), media type, and air-to-cloth ratio (defined as the velocity of the gas stream through the filter media). Lab application engineers also can recommend the proper dust discharge equipment design, including hopper angle and rotary airlock versus screw conveyor, and advise you on what will be needed to get the dust out of the collector.