Enter and view data for tanks

Use the tank tool to create a Tank object representing any storage vessel with an inventory.

Tanks can store material from one event time to the next. You can enter the volume for tanks directly, as a volume or mass value.

Tanks are different from streams because they do not explicitly contain information about a flow, but rather only a snapshot of the tank’s inventory at a given time. Using this information from two neighboring periods, of course, one can infer that a flow into or out of the tank must have taken place. (In fact, as described below, it is possible to intentionally configure a stream to capture tank level changes as a number which may represent tank loss due to evaporation or other causes.)

The balance equation of a tank is of the form:

The starting inventory quantity is usually the measured end of period inventory quantity from the previous event.

If the tank’s tolerance is set to a nonzero value, then the reconciled value will be used, but using a nonzero tolerance with a tank is unusual.

Display properties for a tank object

• Double-click a Tank object to display the dialog box for a tank.

The tank object dialog looks like the combination of stream and process object since tank object have both measurement and balance point. The aspect in which a tank event’s data differs from other objects’ event data is that each tank object event is a point in time, not a period.

This means the measured inventory is the inventory value for a point in time, not from start time to end time as it would be for a stream, process or node.

If you compare the events frame between stream and tank object, you can understand why there is a difference. The stream event has both a start time and an end time but the tank event has only a start time.

Stream Events window

Tank Events window

Tank objects have two main types of tabs in the dialog for entering and displaying data. The tabs are a combination of the tabs for stream and process (or node) objects.

Legends:

• 1: Status Detail tabs

• 2: Event Detail tabs

• 3: Event Detail frame