3.3 Batch and continuous lubricating systems When the oil in use shows signs of sludging, it is drained off, the clean oil is pumped into the system and the cycle re started The purifier is used on the continuous system all the time, except for the short period when the batch of oil from the dirty oil tank is being purified3.3 Batch and continuous lubricating systems • When the oil in use shows signs of sludging, it is drained off, the clean oil is pumped into the system and the cycle re￾started. • The purifier is used on the continuous system all the time, except for the short period when the batch of oil from the dirty oil tank is being purified