Diaphragm pumps include mechanical and hydraulically actuated pumps for higher flow rates and solenoid and stepper motor actuated pumps for lower flows. Watson-Marlow Bredel's pumps offer reduced equipment costs for new installations, plus simple drop-in replacement to upgrade existing diaphragm installations to low-pulse peristaltic flow with cheaper running costs.   Diaphragm pumps depend on two or more ball valves, which are prone to wear and clogging. Diaphragm installations need ancillary equipment such as strainers to filter unexpected solids, plus gas venting systems to avoid gas-locking. Watson-Marlow Bredel's pumps do not rely on valves and can pump entrained gas, naturally released by chemicals such as sodium hypochlorite.
The output of diaphragm pumps can be controlled by adjusting stroke length or stroke speed (where possible). Turndown (the ratio of minimum to maximum speed) is severely limited by a minimum stroke length of 30%, needed to reduce accuracy problems. The diaphragm pump also needs constant pressure to maintain consistent flow, dictating the use of a back-pressure valve.
Watson-Marlow Bredel peristaltic pumps score on all counts:
- No valves
- No ancillary equipment
- High turndown ratio
- One-minute maintenance
- Drop-in replacement
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