Transfer lines

A transfer line, a pipe, moves material from one vessel to another at a rate. Both ends must be a vessel or a boundary. A pipe cannot start or end at an activity, because material moves on pipes and entities move on routes.

Drawing a pipe

Hover over the edge of one element until a handle appears, then drag from that handle to the element you want to connect to. Because both ends are vessels or boundaries, the product makes a transfer line rather than a route. Click the new line and fill in three boxes: the Line Name, the Material, and the Rate with its Per unit.

Figure 1. A pipe's settings. The note under Rate states the literal number rule in the product's own words.

The rate is a literal number

A freshly drawn pipe has an empty rate on purpose. A pipe that quietly moved a hundred a minute would be a figure you never chose, flowing into every number the model produces. The model refuses to run until you supply a rate, which is the behavior you want.

The rate takes a literal number only, never a variable, an attribute or a distribution. Change the number between runs, or vary it with a scenario.

Priority

When two pipes feed one vessel, they are served by priority first, and then by the order they were declared.

The pipe priority trap is silent. A return line left at the default priority, behind a busy main feed, can move nothing for an entire run while still reporting running minutes, and nothing warns you. Whenever a secondary inlet genuinely must get its material in, give it a priority.

Opening and shutting a pipe

A pipe has a Starts open setting, so a line can begin the run closed. From anywhere logic can run, OPENLINE("name") and CLOSELINE("name") open and shut a pipe by name. A pipe commanded shut stays shut until something opens it, even when its working window comes back around.

Because a pipe finds its vessels by name, and these commands take a name in quotes, renaming a pipe after wiring it orphans every reference while still looking fine. Name your lines before you wire them.