Residual Pressure in a Sprinkler System

Definition

• Residual pressure is the amount of force that the sprinkler can create when other pressure sources are accounted for. This means that one sprinkler may be able to spray under high pressure, but the pumps being used can only produce a lower pressure range when they are all turned on at once. This is the residual pressure of the system. It may also be considered the pressure at the farthest sprinkler head from the pumping system.

Issues

• Residual pressure is important because it controls not only how much water is produced but also the radius each sprinkler can be counted on to reach, at minimum. This may not be important in other applications but when it comes to sensing and stopping fire hazards it plays a major role. Small issues such as different water storage components and aging valves can lead to large areas of ineffectivness in the system.

Tests

• When sprinkler system tests are conducted, the hydraulic demand of the sprinklers, the available water supply and the pumping mechanisms are all examined in order to gain an understanding of the residual pressure. A small change in the way water flows, drains and is pumped can change this, and vice versa. If the residual pressure drops due to water supply weaknesses or extra pipes, it usually indicates a need to rework plans and shore up water supply.

Automation

• The more advanced fire sprinkler systems have automated sensors that are used to detect pressure. This makes it easier to keep a running examination of residual pressure and to test for issues during examinations. Some systems are able to adjust pump activity to change pressure for optimal operation. Sensors can activate only certain sprinklers in the area where the fire is detected, which keeps water pressure high.