Busak+Shamban are supplying seals for alternative fuelling systems. They are working with major companies involved in this technology, including the main filling system expert WEH and compressor manufacturer Opcon Autorotor. Busak+Shamban engineers have developed new sealing solutions suited to the difficult conditions in these systems.
Governments are trying to lower the world’s use of fossil fuels. The primary alternative to petrol is hydrogen gas. Environmentally friendly hydrogen powered vehicles produce only water vapour, so they make ecological sense.
Because hydrogen is a very volatile fuel when in contact with oxygen, a filling system that would not fail was needed. Without this, hydrogen fuelling would never be put into operation. German company WEH has spent a large number of years on development of filling systems for alternative fuels.
The latest patented system from WEH gives the best possible safety for the user. The filling nozzle is connected tightly, until there is no pressure in the space between the inlet valve and connector. The higher the input pressure, the faster the tanks can be filled. WEH is developing a system that can fill the tank at a higher pressure than the current 450 bar. These pressures need high-performance seals, because the force to energise the seals must be as low as possible when the filling system is turned on. Also, the seals must stand up to temperatures as low as –40°C, and give a long service life with no maintenance.
This filling system for hydrogen gas from WEH utilises Busak+Shamban seals to help it perform effectively at pressures up to 450 bar and temperatures down to –40°C.
In a partnership with Busak+Shamban, engineers from WEH chose a group of seals including PTFE seals, O-Rings, Stepseal® and Glyd Ring®. These were of standard Busak+Shamban materials and specially developed materials, some of these contain up to fifty different ingredients. These seals were used with special seals for rotary transmission lead-throughs', fitted into the tank filling systems.
A suitable FKM material came from work in other low temperature applications. This is flexible at operating temperatures down to -40°C, the lowest temperature in the pump nozzle. To make sure of sealing integrity in the filling equipment after it is connected thousands of times, the material is also low friction and mechanically resistant.
Hydrogen filling stations, using WEH systems and including Busak+Shamban seals, are being built at a number of European locations. This is making the dream of hydrogen fuelled vehicles on the road, a reality.
Energy to power the vehicle is made by the chemical reaction of hydrogen and oxygen. The oxygen in the air is used, so an oxygen tank is not needed. A compressor blows air through the fuel cell where the chemical reaction takes place. Swedish compressor manufacturer, Opcon Autorotor, is one of the leading suppliers of these.
Air is injected into the cells, at over 150 cubic metres per minute. At the same time, the propeller shaft of the compressor rotates 24,000 times per minute, around its own axis. The shaft must be sealed from the compressor housing and it is vital that oil from the oil bath, does not go into the fuel cell. Even a small amount of hydrocarbon would cause damage.
Busak+Shamban engineers succeeded in designing a single seal to separate the 'air chamber' and the oil bath. This was a Turcon®Varilip® PDR seal, with two sealing lips made of different PTFE materials cased in aluminium. This 'double-acting seal' stopped air from entering the oil bath and oil leakage into the fuel cells.
The demands on the PTFE materials, specially developed by Busak+Shamban, are very high. The sealing lips must be airtight to the shaft, and work with no lubrication at speeds from 10,000 to 24,000 rpm.
Busak+Shamban Research and Development Manager, Matthias Keck stated, “We provide the sealing solutions of today but our focus is, and always has been, the needs of tomorrow. The challenge of new technologies ensures that we continue to develop innovative materials and products.”