Kwik-Draw® Detector Tube Pump. Photo courtesy of MSA

Maintaining a safe workplace, be it a construction site, manufacturing operation or emergency response event, is a high priority for safety and health professionals. Workers are equipped with all types of personal protective equipment appropriate for the potential hazards they may encounter.

Keeping the work environment free from atmospheric contamination is also a vital concern for safety professionals. The protection of workers against toxic substances in the air is done through testing for the presence of toxic substances and through measuring the level of contamination. Gas detector tube units are a critical tool used for such worker protection screening.

Help with decisions

With so many different types of gas detector tube units available for a wide range of substances, safety and health professionals have come to rely on third-party certification to help with purchasing decisions. The SEI voluntary certification program requires participating manufacturers to undergo an extensive annual quality assurance audit, as well as initial and periodic performance testing.

It is the gas detector tube manufacturer’s responsibility to have their products conform to industry or government standards. The Safety Equipment Institute (SEI) plays the role of an independent, third party in offering testing and certification of gas detection tube units. SEI’s third-party certification program allows the manufacturer to use the SEI mark only when:
  1. The independent testing laboratory determines that the product models have successfully undergone performance tests and meet the ANSI/ISEA 102-1990 (R 2003) American National Standard for Gas Detector Tube Units – Short Term Type for Toxic Gas and Vapors in Working Environments;
  2. The quality assurance auditor completes an extensive audit of the manufacturer’s operations and determines that the manufacturer complies with the quality assurance requirements of SEI.

The quality assurance audit, conducted on location at the manufacturer’s facility, is a unique and important facet of SEI certification. Certification is not based on a one-time test, it is comprehensive and ongoing. SEI wants to ensure that products coming off the assembly line are made to the same exacting specifications as the product models tested by the independent laboratory. After the initial audit, the SEI auditor will conduct audits at least annually. Gas detector tubes are submitted for periodic compliance testing. If products not meeting the standards should be found, SEI can require a recall. This protects the buyer of SEI certified equipment in case a recall is necessary.

Value of certification

It is easy to see value in relying on SEI certification. Manufacturers’ operations usually include proprietary information normally protected closely from outsiders. “Opening the doors” requires serious consideration by the manufacturer. Voluntary participation in a third-party certification program demonstrates a manufacturer’s integrity and responsibility by showing a willingness to provide SEI auditors the access to their own facilities. The SEI program provides independent confirmation of in-house testing and quality assurance programs.

To assure objectivity in developing policies and procedures for SEI, a balanced perspective is afforded by a seven-member board of directors. The SEI board is comprised of two representatives from organized labor, an insurance company representative, two safety equipment user companies, one fire service representative and one manufacturer of safety equipment.

As an assurance to those manufacturers who come to SEI to have products certified and to those who use the certified products, SEI is accredited as a certification organization for personal protective equipment by the American National Standards Institute (ANSI) and the Standards Council of Canada (SCC). The prestigious ANSI and SCC accreditations affirm that SEI’s certification program complies with ten international guides pertaining to testing, inspection and certification.

Voiding certification

The premise for SEI’s gas detector tube unit certification program has always been that certified tube unit models consist of both sampling pump and tube from the same manufacturer. Any change made to that system voids the certification. A SEI-certified model identifies a device of the same basic design and components from a single applicant produced by the same manufacturing and quality assurance procedures that are covered by the same certification.

Any change that affects the device’s performance under the limits of the current certification constitutes the classification of a different model. A different model would require full certification testing and be subject to the existing quality control requirements as other certified models. Such changes that should affect the model’s ability to meet performance requirements of the ANSI/ISEA 102 standard are:
  1. Any change to the gas detector tube unit or components thereof, which individually or collectively affects standard sampling rate or sample volume;
  2. Basic chemical formulation change;
  3. Color change to reagent;
  4. Any change that affects interchangeability of components of certified gas detector tube units within the same manufacturer’s certified system.

Testing procedures

Manufacturers of gas detector tube units have the opportunity to certify to 21 different substances as follows: acetic acid, acetone, ammonia, benzene, carbon dioxide, carbon disulfide, carbon monoxide, chlorine, hydrogen chloride, hydrogen cyanide, hydrogen sulfide, methyl bromide, nitric oxide, nitrogen dioxide, ozone, phosphine, sulfur dioxide, toluene, trichloroethylene, vinyl chloride and xylene.

Certification testing is conducted at SEI’s contract laboratory, Clayton Group Services, an AIHA-accredited laboratory located in Novi, Mich. Sampling pumps are tested for accuracy and leakage, and 80 samples of each candidate tube are tested. Each of the detector tubes chosen is presented with a requisite volume of an accurate blend of the test standard substance. Again, the certified tube unit model consists of the sampling pump and tube from the same manufacturer.

Twenty tests are conducted at each concentration, and in each test, the length of stain (determined at point of color change) is read by three different readers against the scales of the detector tubes. The accuracy of readings must be ±35 percent at 0.5 times the threshold limit value (TLV), and 25 percent at 1.0 to 5.0 times of the gas or vapor.

Some other tests include the effects of channeling of air within the tube, perpendicularity of the zero point interface and user instructions.

Manufacturers with certified gas detector tube units are Draeger Safety, Inc., Gastec, Matheson/Kitigawa and Mine Safety Appliances Company. All SEI-certified gas detector tube units can be found on the SEI web site