Hydropneumatic System

The hydropneumatic system consists of a pressure vessel and a pressure pump. The pressure vessel contains water with a pressurized air space to provide the pressure for the system. With water demand, water flows from the vessel, increasing the air space as well as decreasing air pressure. This lower pressure signals the pump to start. The pump meets the demand with the excess volume backing up in the pressure vessel. This decreases the air space and increases the pressure once again. When the upper level is reached, the pump shuts off. The newer pressure vessels have a neoprene bladder to separate the air space from the water.

These systems are common in homes with an individual well system. They typically provide adequate pressure but low volume. They are ideal for a rural water system that has a limited service area that is elevated from the main line resulting in inadequate pressure. Hollows, cul-de-sacs, and small trailer parks utilize these to increase pressure. Some water systems have small hydropneumatic stations added as the system expands. These stations are relatively inexpensive to engineer and construct and are often available as package units.

Some of the problems with hydropneumatic stations are that while they provide adequate pressure, they provide limited volume. In some instances, with the nonbladder pressure vessels, air may be forced into the water lines if the demand for water exceeds pump capacity. Also, if the air space in the vessel is lost due to leakage (waterlogging), the pressure pump will stop and start too frequently, resulting in erratic pressure and low water volume. Also, pressure will not last long during power outages.