The foot valve pump consists of a tube with a stainless steel ball valve and a tripod with lever. There are two sizes of ball valves: 18 millimetres external, for a tube of 12 x 16 millimetres and 12 millimetres external for the LDPE tube of 8 x 10 millimetres.
The ball valve is attached to the bottom of the tube and inserted into the monitoring well. Once submerged in water, the tube should be moved up and down relatively quickly and the water in the tube is pushed upwards. Because the tube is connected to a lever, movement is facilitated and pumping required less effort.
You can stand upright during the operation, so that an ergonomically sound movement is guaranteed. The pumping action of the foot valve pump is not based on suction, so in principle it has no water level depth limit. The lever hinges on a tripod whose height can be adjusted.
The tube connection is universal and suitable for different sizes of tubes and ball valves. The tube should have some rigidity; a polyethylene hose meets this requirement, with a preference for HDPE and over LDPE at greater depths. PTFE (polytetrafluoroethylene) tubing can also be used.
Ball valve pumps can also be connected to a pipe instead of a tube. This creates a more rigid composition, which can also be used in deeper monitoring wells.
If ball valve pumps are used for groundwater sampling, the pumping movement must take place above the filter of the monitoring well in order to prevent the sample from becoming turbid. At the same time, the ball valve should not rise above the water level when the hose is moved up and down. This causes the water to become too aerated. For more information, consult relevant standards, such as NEN5744 and NPR5741.
SCOPE OF DELIVERY
- Hand operated foot valve pump
- Tube guide
- Ball valve for external tube (18 millimetres), for tube (12 millimetres)
- PE tube diameter 12 x 16 millimetres
- Aluminium tripod
