What do you do when your Pneumatic Pump is properly connected, yet there is no sample discharge? A simple ‘trick’ is to submerge the sample discharge line into a clear container of water. During the drive cycle you should see bubbles. An aggressive blast of bubbles can mean that there is no water available, while a steady mild bubbling indicates that the pump is operating and sample water is on the way up.
Once sample water is being discharged, you can adjust the flow rate using a pump controller. Make sure that your controller has easy to follow pre-set pumping options, such as the Solinst Electronic Control Units. This helps take the guesswork out of determining suitable drive and vent times for your Bladder Pump or Double Valve Pump.
Determining the amount of applied pumping pressure to retrieve a sample is simple. 1 psi of pressure can raise a 2.3 ft column of water, this is about half of the column height of water in feet, expressed as psi. If a Bladder Pump’s intake is at 100 ft below ground surface, you will require approximately 50 psi of pressure to get a sample. When sampling with a Double Valve Pump, this calculation is made from ground level to static water level (as a minimum, but can be made from total pump depth to maximize purging rates). Therefore, if a Double Valve Pump is 100 ft below ground surface, and static water level is at 50 ft, you can select a pressure of between 25 and 50 psi. In both cases, add an extra 10 psi to allow for line loss.