Replacing normal propyl bromide

Due to legislation around the safe use of normal propyl bromide (nPB), any business still using this solvent in its cleaning and degreasing process must find a replacement. Also known as solvent 1-bromopropane, nPB is commonly used in cleaning and degreasing processes for the aerospace, precision engineering, medical, optical, and electronic industries. The hazardous substance can damage fertility and harm unborn children.

nPB has been registered as a substance of very high concern (SVHC) under Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH), which regulates the supply and use of chemicals in Europe. As such, nPB has been placed on Annex XIV, and a sunset date of July 4, 2020, has been set. After this date, its use is banned, unless authorization has been granted and the business has a permit for a specific use.

If you’re still using nPB, now is the time to act. Depending on whether it is a straightforward conversion or a full equipment replacement, selecting an alternative can be time consuming. In 2017, we worked with leading aerospace manufacturer BAE Systems to replace the nPB they were using with a safer solvent.

The challenge

BAE Systems approached us to assess its existing process to see how to use a safer, alternative solvent, at which point we also discussed additional benefits including efficiency and cost savings.

To assess their existing cleaning processes, we arranged a site visit to inspect the Solvac vapor degreasing systems at two of their facilities. We performed a full system inspection to ascertain suitability of the systems for conversion to Opteon SF79, a cleaning fluid chosen for its performance, ultra-low global warming potential (GWP), recyclability, reusability, safety, and ease of use.

Our objectives were to test the equipment for suitability and compatibility for use with SF79, as well as the general condition of the equipment and any opportunities to reduce solvent usage. The customer found that their solvent use was very high and they knew that reductions would improve their environmental impact as well as save costs.

Before using nPB, both of BAE’s systems used Trichloroethylene (Trike) to flush pipework using long narrow tanks suited to this application. They each had a flushing rig and filtration, and originally had carbon absorption/deabsorption systems fitted.

The existing Solvac systems used more than 1 metric ton of solvent per year, meaning they both required a permit from the local authority for continued use, further increasing costs for the company.

Due to the legislation around the safe use of Trike and nPB, these systems were fitted with over-tank canopies and safety interlocks to ensure operators were not exposed to solvent vapors. One of the systems also had a parts-per-million (ppm) meter fitted, which restricted the front door from opening until the level of solvent had dropped to less than a specified level. This, as well as additional safety features, protected operators, and reduced emissions.

Results

While there were minor issues with the system, these could be addressed, and Opteon SF79 was a suitable replacement. This has now been fully implemented at two locations, while the third is currently transitioning to the new product.

Since switching solvents, BAE has achieved the cleaning performance expected while also significantly reducing its environmental footprint. As SF79 doesn’t have the acidity issues of nPB, BAE’s usage fell significantly because fewer cleanouts were required. And, it’s safe and easy for operators to use.

Speaking about the results of the change to SF79, BAE’s Engineering & Governance Lead says, “The transition from nPB to SF79 was relatively straightforward and quick, and communication was good throughout. Fraser Technologies also had a much stronger relationship with the manufacturer than we did, which was especially helpful during the process.

“Due to a reduction in manufacturing throughput, we cannot confirm an exact reduction in annual usage, and therefore cost savings and environmental footprint. However, emissions monitoring that we undertook following the introduction of SF79 showed a reduction in volatile organic compounds to the atmosphere compared with the previous solvent. The product’s lower GWP will also contribute to reducing the environmental impact of our site operations.

“Overall, changing to SF79 has been a positive experience and it has helped us to achieve our safety, health, and environmental objectives.”

Fraser Technologies

About the author: Graham Fraser is managing director of Fraser Technologies. He can be reached at sales@frasertech.co.uk.