Water Hammer Arrestor Sizing
PDI WH-201 designation from total fixture units.
Example
You enter
- Total fixture units (WSFU) 30
- Branch length (ft) 25
- Pipe internal diameter (in) 1
You get
- Designation AA-B
- WSFU total 30
- Pipe diameter (in) 1
- Pre-charge (set air side, system depressurized) 60
Details, formula, and sources
PDI WH-201 method: arrestor size class A–F selected by branch length and fixture-unit count.
PDI WH-201 by name.
PDI specifications licensed; manufacturer data sheets (Sioux Chief, Watts) free at each manufacturer site.
Estimate. AHJ and licensed plumber / gas fitter govern. Verify against the IPC / IFGC edition adopted in your jurisdiction.
Field names used by the API: wsfu, length_ft, internal_diameter_in, designation, wsfu_total, pipe_diameter_in, precharge_psi
- Closure speed assumption fast-closing solenoid valvePDI WH-201 by name