A valve closure algorithm is presented for inclusion within a slow transien
t (rigid water column) pipe network model. The algorithm is specifically fo
rmulated for (but not limited to) node-based, graph-theoretical models and
is both direct and accurate. It is distinguished from conventional approach
es by its direct assignment of the final discharge at closure to zero and s
ubsequent use of the head loss at the closing valve to compute the flow rat
e in pipes incident to the closing valve. As a result, redistribution of re
sidual flow prior to closure to these incident pipes is not required, leadi
ng to a less computationally demanding and more robust algorithm than previ
ously published valve closure procedures. Application of the valve closure
algorithm is illustrated in a pipe network, which also nicely demonstrates
again the relation between rigid water column and water hammer models.