Single Step Analysis

Run a single step analysis.

Icon	Command	Shortcut Key	Toolbar
	WATERSINGLESTEP

The Single Step analysis is normally used before running the time simulation of the water supply network, in order to determine the state of the network in typical cases of demand (usually the times of minimum and maximum water use). It is also used when controlling accidental and other infrequent states that are not normally addressed during normal simulation. It is usual, though not always the best, to combine the analysis of maximum water use with minimum water levels in the reservoir, and minimum water use with maximum water levels.

Error checking is done automatically every time calculations are started. If an error is detected, the error list displays and the analysis does not proceed.

Modelling Accidents

It is useful to note that while analysing accident related conditions, sections of the system which are out of order are simulated by assigning a very high local resistance value e.g. 1e8. The state caused by a pipe burst is simulated either by placing an outflow on the desired node (if a break in the middle of the section is desired, then it is necessary to insert an internode), or by assigning a predetermined value for outflow. If the simulation is achieved by an inserted outflow, the pressure coefficient is given on the basis of the size of the imagined opening in the pipe wall.

Procedure

There are four possibilities for single step analysis. Choose the appropriate option:

- Specific Time
- Average Demand
- Maximum Demand
- Minimum Demand

Option	Description
Parameters
Specific Time	The hour and minute for the analysis can be specified. The demand pattern factors for the chosen time are used for the analysis and it is therefore wise to check the shape of the selected water use diagrams by viewing the corresponding Demand pattern.
Average Demand	Average water use is understood to denote a state in which all hourly water use coefficients are equal to one i.e. demand patterns are ignored but seasonal factor may still be applied. During calculations, all given algorithms for controlling pump stations and regulating valves are active, except, for obvious reasons, those controlled by time.
Maximum Demand	The maximum demand simulation gives the maximum demand at each node, irrespective of time.
Minimum Demand	The minimum demand simulation gives the minimum demand at each node, irrespective of time.
Apply Seasonal Peak Factor	Select this checkbox to take the seasonal peak factor into account during analysis.
Advanced
Link discharge to pressure	This option links the discharge to the pressure at that point.
Calculate water losses	This option calculates the water losses.

Click Start to begin the analysis.
The following progress window displays.

The analysis is terminated if the number of iterations exceeds 200. The number of iterations normally does not exceed 15, except if pressure control valves are used.

On completion of the analysis, you have the option to save the results or view the messages.