Hydrotrol Water Hammer Arresters
SIZING OF HYDROTROLS
All Sizing and Placement Data is in Accordance with Plumbing and Drainage Institute Standard P.D.I. WH-201
SIZING - Single and Multiple Fixture Branch Lines

Most engineers employ the fixture unit method of sizing water piping systems. Smith uses the P.D.I. simplified method of sizing HYDROTROLS based on fixture unit weight. The correct size HYDROTROL can therefore be specified and located at the same time that the pipe sizes are determined.

Table 1 indicates the fixture unit weights for most popular plumbing fixtures and is based upon information offered in the National Plumbing Code. Certain local codes may vary and should be reviewed prior to using Table 1.
 Hydrotrol Sizing
Find fixture unit weight of each fixture using Table 1. Total the fixture units weights for both hot and cold branches.

Sizing Calculation

Sizing Example

Find fixture unit weight of each fixture using Table 1. Total the fixture unit weights for both hot and cold water branches.

Sizing Calculation 2
SIZING
Table 1
Table 2 indicates fixture unit ratings for P.D.I. certified water hammer arrester categories and the corresponding Smith HYDROTROL for each category. Where several fixtures are installed in a branch usually only one fixture valve at a time will be closed. Table 2 takes into consideration other design factors including the simultaneous usage of one or more fixtures, pipe size, length, flow pressure and velocity. Therefore, this method offers a simple fast determination of the proper size water hammer arrester for a given battery of plumbing fixtures.
Hydrotrol Sizing Table
Hydrotrol Sizing Table
Table 2

Plumbing and Drainage Institute established these size symbols to correspond to those units covered by the Certification and Testing Program described in P.D.I. Standard Manual WH-201.