Facts
In a previous test, the concentration of large particles of CMP slurry tends to increase in bellows and diaphragm pumps, whereas no increase was observed with a Levitronix^® pump.
Large particles can lead to filter clogging, which results in a decreased filter lifetime.

Test conditions
A Levitronix^® BPS-4 pump, a diaphragm pump, and a bellows pump were evaluated for their effect on filter lifetime. Each pump was used to circulate approximately 28.5 liters of Cabot Semi-Sperse^® 12 slurry at a flow rate of approximately 29.5 lpm (7.8 gpm). A 10” Mykrolis Planargard^® CMP3 filter was installed downstream of each pump. The pressure drop across each filter, representing a correlate of filter lifetime, was monitored and compared. The tests were continued until the pressure drop across the filter increased by at least 10 psig or more than 10,000 turnovers were achieved.

Results
The pressure drop measured with the bellows and diaphragm pumps were approximately 15 and 5 times higher than those experienced with the Levitronix^® pump. The Levitronix^® pump was the only pump to reach 10,000 turnovers without the pressure drop increasing to 10 psig.

Increase in ∆P across each filter for all 3 pump tests