Diaphragm pump.
https://www.emergency-wash.org/water/en/technologies/technology/diaphragm-pump
👉🏼 PDF: https://app.box.com/s/p897s59kl0w0kg5o21300q75sdnhlj5d
A Diaphragm Pump is a positive displacement pump that displaces a fixed amount of water per cycle. Diaphragm Pumps use a flexible diaphragm to force fluid through the pump and are mainly applicable in the recovery phase.