SRS common mistakes
SRS · Understand the traps and how to avoid them.
Selects a Hazen-Williams C-factor from memory (e.g., C=120 for all steel) and applies it to existing galvanized, unlined cast iron, or aged steel pipe in the hydraulic calculation.
Candidates memorize the new-black-steel value because it appears in most practice calculations and then apply it uniformly without checking the pipe material and condition shown on the as-builts or in the field.
What to do instead
Before calculating, identify each pipe segment's material and condition, then select C from the NFPA 13 friction-loss table for that material; document the basis for every C-factor used in the calculation narrative.
Assigns a design density to a space by matching the occupancy name to a familiar example (e.g., 'warehouse = Ordinary Hazard Group 2') without confirming commodity class, storage height, and aisle configuration.
Candidates rely on occupancy labels learned from common buildings and skip the classification decision tree, especially when the space is mixed-use.
What to do instead
Classify every area using the applicable NFPA 13 hazard/commodity chapters and record the classification, commodity class, storage height, and chapter/table reference before selecting density.
Confuses design density (gpm/ft²) with discharge pressure (psi) or total flow (gpm), producing a calculation where units are silently dropped.
The three quantities are used together in the same formulas and candidates under time pressure skip unit tracking.
What to do instead
Carry units through every step and perform a dimensional check at the end (gpm/ft² × ft² = gpm; psi = psi/ft × ft); write units on every line of the calculation.
Applies the design density over the entire floor area or the entire building rather than over the remote design area (typically 1,500 ft² before adjustments).
Candidates read 'design area' as the protected floor area because the same word is used for both in ordinary speech.
What to do instead
State explicitly at the top of the calculation: remote area = base area × slope/combustible/ceiling adjustments, and show the adjusted square footage before multiplying by density.
Uses 'inspection,' 'test,' and 'maintenance' interchangeably on ITM forms and assigns the wrong frequency to gauges, alarm devices, and control valves.
The three activities appear on the same form and candidates match tasks to frequency by memory rather than by the NFPA 25 task table.
What to do instead
Build a one-page frequency matrix from NFPA 25 Chapter 4 and 5 tables and check each task against it; define inspection as visual, test as operational verification, and maintenance as corrective action.
Accepts a water supply flow test that is older than the AHJ-accepted age or that was not adjusted for seasonal/temperature differences from the design condition.
Candidates treat any flow test report as current and do not check the test date, hydrant configuration, or seasonal adjustment.
What to do instead
Verify test date, static/residual readings, hydrant and hose configuration, and apply the required adjustment factor; document the source, date, and adjustment on the hydraulic calculation cover sheet.
Omits or incorrectly completes the hydraulic design placard at the riser, leaving off the remote area, density, and supply information required for future ITM and modifications.
Candidates treat the placard as paperwork rather than a code-required design record and fill it in from memory after the calculation is finished.
What to do instead
Generate the placard directly from the final hydraulic calculation, include all required fields (density, remote area, pressures, flow, hose allowance), and verify it is mounted at the riser before close-out.
Assigns one hazard classification to an entire mixed-occupancy building instead of classifying each space separately and protecting to the most demanding applicable criteria.
Candidates simplify to save time and because the building has a single name or address.
What to do instead
Draw a hazard classification plan showing each room/area's class and the boundary conditions; size the system to the most demanding area served and document the rationale for any separation.
Records ITM results without the technician name, date, time, gauge readings, and the AHJ-required retention period, or discards records before the retention period expires.
Candidates view the record as a formality and complete it after the fact, losing traceability.
What to do instead
Use a record template with mandatory fields for date/time, technician, readings, and deficiencies; file records in a retention system that matches the AHJ period and cross-reference deficiencies to work orders.
Assumes any antifreeze concentration is acceptable and fills a wet system without confirming the listed concentration limit and the required backflow/containment provisions.
Candidates treat antifreeze as a simple freeze-protection choice and do not connect concentration to listing limitations and system design requirements.
What to do instead
Confirm the listed antifreeze type and maximum concentration for the specific system, verify the required backflow prevention and signage, and document the concentration test result at acceptance and during ITM.