Engineering FAQ Center

Start from design flow and allowable velocity/head loss. Convert DN/NPS to inside diameter using wall/SDR data, then iterate with HW or Darcy tools.

SDR = OD / minimum wall. Same SDR implies the same geometric pressure class relationship across sizes for a given design stress model.

Educational Barlow form: P = 2S/(SDR−1). Catalogue PN also depends on standard design coefficients, temperature, and compound — confirm with ALFA.

Common for water distribution friction with an agreed C-factor. Not automatically best for all fluids.

When Re-based analysis, roughness, or non-water viscosity matters, or the consultant requires it.

Smaller actual ID than assumed, higher flow, closed valves, air, fouling, or optimistic C/ε.

Primarily soil-structure interaction: poor bedding/haunching, soft foundation, insufficient cover/compaction, early traffic loads.

Follow the underground center sequence and ASTM D2321-oriented practice adapted to the project specification.

CPVC is chlorinated for higher temperature capability. Do not use uPVC pressure ratings for hot CPVC duties.

When the specification requires elevated temperature service that exceeds practical uPVC limits — confirm P/T with ALFA.

Use the Consultant/MAR checklists: spec extract, product match, document requests, installation references, compliance matrix.

Datasheets, certificates as available, drawings if required, standards mapping, ITP/test expectations — request anything not online.

Material, standard, diameter system, class/SDR/Schedule/SN, joint type, fittings, testing, documentation — see BOQ center.

No. It is vendor registration. Product approval follows project/SAMSS processes as applicable.

No. They are engineering-reference defaults unless a specific ALFA document states otherwise.