What is nPB?
Why Is It in Bromothane™?

"Normal Propyl Bromide" is the full chemical name for the active ingredient in Bromothane™ solvents. Based on the element bromine, nPB is a unique liquid selected by MicroCare and Great Lakes Chemical to be the cornerstone upon which the Bromothane™ family of cleaners is built.

Bromine is a halogenated material. It is related chemically to the other halogens, which means they are all in the same column on the periodic table of the elements (if you're interested, see col. 17 on the right-hand side of the table). Other halogens include chlorine, fluorine and iodine. Notice they are all good cleaners. That's what makes Bromothane™ a great replacement for the chlorinated solvents like perc and TCE, the old CFC cleaners, and more modern ozone-depleting hydrochlorofluorocarbons like HCFC-141b and HCFC-225, and the fully-fluorinated materials (PFCs).

The Bromothane™ solvents have impressive technical specifications. Consider the following general details:

Unique physical properties include a high density, low viscosity and low surface tension. These attributes, combined with its nonflammable nature, chemical stability, thermal stability and ease of recovery make nPB an ideal choice for a broad range of applications. By itself, it is a very aggressive solvent and the solvency can easily be enhanced by use of appropriate azeotropes of alcohols, hydrocarbons, etc.

• Bromothane™ Carries a Very Conservative Toxicity Rating • 

Some customers have questions about the toxicity of nPB solvents, specifically the very conservative threshold limit value of 10 ppm established for the Bromothane™ solvents. In order to maximize worker safety, MicroCare and Great Lakes Chemical have imposed upon ourselves and our customers a toxicity rating of 10 parts per million (ppm). However, early in 2005 and after years of research and deliberations, the American Conference of Industrial Hygienists (ACGIH) finally finalized and established a "Threshold Limit Value" (TLV) of 10 parts-per-million for an eight-hour time-weighted workday. This TLV applies to the "Bromothane™" brand solvents sold by MicroCare and to all other versions on nPB marketed by other companies under their own brand names.

TLVs established by the ACGIH have long been recognized as the "official" value that most health professionals reference when looking for guidance on exposure limits. The establishment of a new TLV is a lengthy, open, peer-reviewed process. Persons having views contrary to the proposed ratings are given years to provide new information or other data that is persuasive enough to change the proposed standard. Apparently nobody had enough convincing evidence to cause the TLV committee to move up or down from 10 ppm.

According to the ACGIH web site, "The American Conference of Governmental Industrial Hygienists (ACGIH®) is a member-based organization and community of professionals that advances worker health and safety through education and the development and dissemination of scientific and technical knowledge...For over 60 years, ACGIH® has been respected for its dedication to the industrial hygiene and occupational health and safety industries. [ The ACGIH mission is ] to provide essential, cutting edge information to government, academia, and corporate facilities throughout America, Canada and countries abroad."

The decision on the TLV of nPB was not without controversy. For example, MicroCare and our supplier of Bromothane, Great Lakes Chemical, have asserted for years the proper TLV should be 10 ppm. All of MicroCare's literature and customer support are based upon this exposure level. Other companies had urged higher threshold levels, as high as several hundred ppm, but the ACGIH chose to disagree with their findings.

In fact, one trade association went to court in an attempt to block the publication of the ACGIH standard. In a Nov. 30, 2004 press release, the ACGIH noted that the case involved ACGIH's proposed toxicity ratings on n-Propyl Bromide. But the court found the lawsuit was without merit. The chairman of ACGIH's board, Vickie L. Wells, MS, CIH, CSP, stated, "We stand by our [ACGIH's] policies, procedures and processes. We stand by our recommended Threshold Limit Values, and the fairness and thoroughness of the system used in their development and dissemination."

• The Bromothane™ Product Stewardship Program • 

To accommodate the unusual requirements of this relatively low exposure limit, MicroCare has established a comprehensive product stewardship program. This program is designed to ensure that you and your workers can use the Bromothane™ solvents safely and cost-effectively for years to come.

MicroCare strongly recommends users should satisfy their own curiosity and concerns with thorough research into the chemistry. In addition, users should review the FAQs about the chemicals, their proper use, issues surrounding flammability, toxicity, skin contact, eye contact and/or accidental ingestion, and safe handling and storage. If other questions remain, please feel free to contact MicroCare.

As with all solvents, workers should wear gloves and eye protection when using these products.

In terms of regulatory issues, nPB is listed in most national chemical inventories, such as TSCA in the U.S., ELINICS in Europe, Chemical Substances Control Law (MITI/MHW) in Japan, DSL (notified) in Canada, NICNAS in Australia, and TCCL in Korea. In the U.S., nPB is not a hazardous air pollutant (HAP), and not subject to NESHAP regulation. Spent nPB is is not a listed RCRA waste (however, the stabilizers are, and any contaminants might be). NPB is not included in the SARA Title III Section 313 list of toxic chemicals, and is not subject to SARA Title III (EPCRA) reporting requirements but the stabilizers used in Bromothane™ solvents are SARA reportable.

NPB is an excellent choice for environmental reasons. NPB is proposed to be accepted by the U.S. Environmental Protection Agency (EPA) under the Significant New Alternatives Policy (SNAP) program as a substitute for ozone-depleting substances. But all nPB-based products are classified as volatile organic compounds (VOC) by the EPA. These cleaners do not comply with the stringent South Coast Air Quality Management District (SCAQMD) regulations of California, which require a VOC content of less than 50 g/L of solvent.

MicroCare is proud of our Bromothane™ products and the cost-effective cleaning they deliver. However, as with almost any industrial product, Bromothane™ cleaners must be used properly if they are to be safe and cost-effective. We are proud that we introduced the product years ago with a recommended exposure level of 10 ppm; we are proud that we have helped customers keep worker exposures at a safe level; and we are proud that the Bromothane™ line is one of the fast-growing product groups at MicroCare.

• The Benefits of Using Bromothane™ •

Bromothane™ solvents are ideally suited for use in vapor degreasers because of of the solvent's low viscosity and high density, which results in enhanced cleaning. The benefits this produces include:

• fast cleaning,

• short cycle times,

• compatible with ultrasonics if required,

• excellent cleaning of hard-to-clean shapes, even in holes and blind vias,

• fast drying, so the parts come out dry,

• lower temperatures (compared to aqueous systems),

• low energy consumption,

• no surfactants or saponifiers, which can require additional rinsing and waste treatment processes,

• small machine footprint and inexpensive cleaning machines, and

• enhanced safety because the solvents are nonflammable.

In short, Bromothane™ solvents are great choices for precision cleaning and defluxing.  

Updated: March 22, 2005
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