Both have their advantages. Integra® Bladder Pumps have low flow capability and ensure that no drive gas comes into contact with sample water, making them ideal, and approved by regulators worldwide for VOC sampling. Select a Bladder Pump for higher regulator acceptance and lower flow rates. Double Valve Pumps provide greater flow rates, as well as low flow capabilities, better performance in silty water, and are low maintenance, with no bladder to replace and fewer parts to decontaminate. Select a Double Valve Pump for faster purging, and operation in harsher environments.