CHANNEL BLOCK AND DISTRIBUTOR BLOCKS
The choice of glass contact refractory material for the forehearth and distributor largely determines the service life of the forehearth and distributor and it therefore needs to be selected to match the anticipated life of the melting furnace. A combination of PSR-333 for the forehearth channels and PSR-993 for the distributor glass contact blocks is often the perfect combination.
PSR has a long history in the manufacture of blocks and channels for the glass melting furnace and their experience in cutting and grinding large refractory shapes enables them to meet tight dimensional tolerances. All PSR’s channels and glass contact blocks are diamond polished on specially designed sequential cutting and grinding machines.
PSR-333 11.25% ZrO2
PSR-333 is the principal refractory material used for forehearth channel blocks. Essentially the same composition as used for feeder expendables its excellent corrosion resistance has been proven over more than 30 years of supply to thousands of forehearths and it is easily capable of achieving a campaign life in excess of 10 years, subject to operating conditions. Its low thermal conductivity both inhibits corrosion at the channel joints and minimises heat losses through the channel base and walls, and the absence of glassy phase in the refractory matrix eliminates it as a source of ‘cat-scratch’ cord.
PSR-993 99.7% Al2O3
PSR-993 is a dense bonded alumina refractory material specially developed for the distributor and forehearth. With 99.7% Al2O3, and containing only alpha alumina, PSR-993 has equivalent corrosion characteristics to fused cast α-β alumina. Being manufactured by the slip casting process PSR-993 is not subject to the shrinkage cavities or casting scars associated with fused cast refractories and offers fused-cast alumina refractory performance for a bonded refractory price.
Glass contact sidewall blocks and bottom tiles in PSR-993 are the ideal solution for the distributor, and the complete absence of glassy phase removes the risk of ‘cat scratch’ cord associated with fused cast AZS refractory materials.
PSR-993 is also often used in the forehearth where the demand for high quality glassware demands a high purity alumina glass contact refractory and it is commonly used as an alternative to fused cast AZS or fused cast α-β alumina channel blocks.