A circulating path from a supply pipe to a filter, from the filter through a vent pipe, returning to the supply pipe is formed, and a first three-way valve is provided at the vent pipe. On the other hand, a circulating path from the supply pipe to a discharge pump, from the discharge pump through a purge...http://www.google.com.au/patents/US6238109?utm_source=gb-gplus-sharePatent US6238109 - Processing solution supply apparatus
