Term/abbreviation |
Description |
Advanced Pressure Management |
Varying the PRV outlet pressure in response to demand and other factors in order to minimise the average zone pressure (AZP). Sometimes known as pressure modulation. |
APV |
Advanced pilot valve |
AZP point |
The point in the DMA which sees the average pressure |
AZP |
Pressure at AZP point |
AZP Sensor |
Sensor measuring and transmitting pressure at AZP Point |
Basic Pressure Management |
Installation of PRV with a fixed outlet pressure |
Controller |
Electronic controller used to control the PRV output pressure |
Critical Point |
The point in the DMA which sees the lowest pressure |
DMA |
District meter area |
FAVAD |
Fixed and Variable Area Discharge. Formula used to calculate effect of pressure on leakage |
IP68 |
Watertight enclosure down to a specified depth (i2O equipment designed and tested to 4m) |
IWA |
International Water Association |
NDF |
Night Day Factor used used to convert night leakage (in m3/hour) into average daily leakage, using the Average Zone Pressure (P4). |
P1 |
Pressure at PRV inlet |
P2 |
Pressure at PRV outlet |
P3 |
Pressure at Critical Point |
P3 Sensor |
Sensor measuring and transmitting pressure at Critical Point |
P3ref |
Minimum pressure at Critical Point specified by the water company. Normally between 15m and 20m |
P4 |
Average Zone Pressure |
PRV |
Pressure reducing valve |
Safe Mode |
P2 remains at a pre-determined, safe value |
Watchdog |
Independent circuit monitoring the correct operation of the system. |
Water Loss Task Force |
Set up by the IWA to develop and promote best practice in water loss management |