Pneumatic bladder pumps operate with a unique, gentle action ideal for low-flow sampling. Timed on/off cycles of compressed air alternately squeeze the flexible bladder to displace water out of the pump, and release it to allow the pump to refill by submergence, without creating any disturbance that could affect sample chemistry. Bladder pumps run easily at low rates for extended times, without the problems of other devices.
• No overheating of high-speed electric pump motors, which can alter samples and ruin the pumps.
• No churning action, like that of bailers or inertial-lift samplers that increase turbidity.
• No suction to cause degassing of dissolved volatile contaminants.
The bladder prevents contact between the pump drive air and the sample, and the downwell equipment is permanently dedicated to each well, so both samples and the well are protected from disturbance or the danger of cross-well contamination.