FM Global DS 2-81: Inspection, Testing and Maintenance (ITM) Field Guide

A data centre came out of a five-year insurance survey with a list of major recommendations: the dry pipe valve trip test had not been done for three years, fire pump run records were incomplete, and gauge status was unknown. The site had been working to an annual flow test regime, but FM Global DS 2-81 (Fire Protection System Inspection, Testing and Maintenance, April 2019, Interim Revision April 2026) sets out tasks in Tables 2.4.2.1–2.12.3.1 at frequencies from weekly to 15 years. Under 2.4.1 some activities may be modified for site conditions in discussion with an FM field engineer. This article summarises the frequencies period by period.

Weekly

• Control valves: visual inspection for full-open, secured (dedicated lock and chain) and accessible conditions, including valves in waterflow alarm sensing lines (Table 2.4.2.1, items 1a–1b).
• Diesel fire pumps: started in automatic mode by pressure drop and run at churn for at least 30 minutes; the pump is not isolated by closing a valve; suction and discharge pressures and engine rpm, oil pressure and coolant temperature are recorded (Table 2.9.1.1 item 2; 2.9.3.1.2).
• Pump room: controller in automatic with no trouble alarms, room above 4°C, all valves locked fully open, no leaks, no combustible storage (2.9.4).
• Dry, preaction and deluge systems: system valve air and water pressures, quick-opening device (QOD) in service, valve enclosure above 4°C (Table 2.5.3.3 items 1–3).
• Tanks: atmospheric tanks confirmed full; weekly without a supervised level alarm, monthly with one that is tested annually (Table 2.10.1.1-2 item 2).

Monthly

• Electric fire pumps: started in automatic mode by pressure drop and run at churn for at least 10 minutes, without isolating the pump (Table 2.9.1.1 item 2; 2.9.2.1.2).
• Valves without position indication: physical test for full-open position of PIVs, wall PIVs, NRS valves, non-FM Approved indicating butterfly valves, curb-box valves and non-indicating butterfly valves (Table 2.4.2.1 item 2).
• Dry systems: automatic drain valve, priming water level, compressed air supply and indicating desiccant (Table 2.5.3.3 items 4–7).
• Other: hydrants and standpipes for accessibility, leakage and damage (Table 2.6.1.1 item 2); diesel engine batteries by cold-cranking amps (Table 2.9.1.1 item 11); tank exteriors and break tank automatic fill systems (Table 2.10.1.1-2).

Quarterly and Semiannually

• Waterflow alarms: quarterly by flowing water through a system test connection (annually for antifreeze systems); the alarm should be received in less than 60 seconds (Table 2.5.1.1 item 2).
• Hose houses, standpipe valves and monitors: quarterly availability and accessibility check (Table 2.6.1.1 item 3).
• Valve supervisory (tamper) alarms and enhanced security valves are tested semiannually (Table 2.4.2.1 items 1c and 3).

Annually

• Control valve exercise: full travel of all valves, recording turns to close and to reopen (Table 2.4.2.1 item 4).
• Main drain flow test: checks for significant obstruction in the supply to each riser, discharging outside; ideally after the annual valve exercise (Table 2.5.1.1 item 4).
• Sprinklers, piping, supports and seismic protection: annually or more often depending on conditions (Table 2.5.1.1 item 7); for sealed concealed sprinklers at least 10% per room physically inspected (item 13).
• Pump performance: at least three points (churn, rated capacity, maximum capacity) recording suction and discharge pressure, flow and rpm, compared with the manufacturer’s curve or previous tests; flow meters calibrated every 3 years; diesel speed within 10% of rated at 100% flow (2.9.5).
• Pump checks: controller set for manual stop only, pressure maintenance pump set points, remote alarms and driver alignment (Table 2.9.1.1 items 5–9).
• Backflow preventers and single check valves: full-flow test above the greatest sprinkler demand, recording the flow (Table 2.7.3.1 item 1).
• Dry systems: FM Approved QOD test (quarterly for non-approved devices), air leakage rate, low air and low temperature alarms, valve internals and a partial-flow trip test (Table 2.5.3.3 items 9–13).
• Hydrants are inspected and flow tested (Table 2.6.1.1 item 4), and tank level indicators and alarms tested (Table 2.10.1.1-2 item 3).

Multi-Year Tasks

• 2 years: diesel engine batteries replaced; biodiesel in diesel tanks replaced at least every 2 years (Table 2.9.1.1 items 16–17).
• 3 years: full-flow trip test of dry and preaction systems, or videoscope or ultrasonic localized guided wave evaluation (every 10 years with nitrogen); water must reach the hydraulically remote area within the specified time, 60 seconds unless stated otherwise (Table 2.5.3.3 item 14). Deluge system strainers are dismantled and inspected (item 22). Sprinklers with fusible elements of 180°C or more under prolonged exposure to 150°C are sample tested (Table 2.5.1.1 item 8).
• 5 years: obstruction checks on wet systems fed by an open water supply and mineral deposit checks in hard water areas (Table 2.5.2.1); sample tests of recalled O-ring sprinklers (Table 2.5.1.1 item 9); standpipe flow tests at design flow and hose valve pressure (Table 2.6.1.1 item 8); inspection of backflow preventer internals (Table 2.7.3.1 item 2).
• At 10 and 20 years, then every 5 years: obstruction checks on dry systems with black steel pipe, excluding systems originally installed with nitrogen and refrigerated-area systems (Table 2.5.3.3 item 15).
• 15 years: sample test of dry-type (dry pendent) sprinklers; dry-type sprinklers made before 2003 are replaced when found (Table 2.5.1.1 items 10–11).

Comparison With NFPA 25 (DS 2-81 Appendix C, Table C-1)

Appendix C of DS 2-81 compares FM frequencies with the 2026 edition of NFPA 25 (the table was updated in the April 2026 interim revision of DS 2-81). Some examples:

Task	FM DS 2-81	NFPA 25-2026 (per Table C-1)
Visual inspection of indicating control valves	Weekly	Monthly / weekly
Physical test of non-indicating valves	Monthly	Annually
Dry system valve air and water pressures	Weekly	Monthly / quarterly
Full-flow trip test	3 years (10 years with nitrogen)	3 years
Dry-type sprinkler sample test	15 years	10 years
Electric pump churn test	Monthly	Weekly / monthly
Diesel pump churn test	Weekly	Weekly
Diesel battery check	Monthly	Annually

The current edition of NFPA 25 is not among the sources for this article; the comparison reproduces only the table in DS 2-81.

Quick Checklist

• Weekly: visual valve checks, diesel pump 30 minutes, pump room, dry system pressures
• Monthly: electric pump 10 minutes, physical test of non-indicating valves, diesel batteries
• Quarterly: waterflow alarm test; semiannually: valve supervisory alarms
• Annually: valve exercise, main drain test, pump performance test, backflow full-flow test, partial-flow trip test
• Every 3 years: full-flow trip test (10 years with nitrogen)
• 5 years and beyond: obstruction checks, O-ring and dry-type sprinkler samples
• Records cover system, activity, results and corrective actions and are kept at least one year (2.2.2)

Frequently Asked Questions

What does the main drain test actually tell you?

Under DS 2-81 Table 2.5.1.1 item 4, the annual main drain flow test checks for significant obstructions in the water supply upstream of each riser, discharging to an outside location. Where several risers are manifolded on a common lead-in, one test covers them all. It is ideally done after the annual valve exercise, since it is often the final step in restoring impairments such as valve closures.

How often is a full dry pipe trip test required?

Under DS 2-81 Table 2.5.3.3 item 14, every 3 years, or every 10 years for systems with nitrogen; a videoscope or ultrasonic localized guided wave evaluation is an accepted alternative. The system must deliver water to the hydraulically remote area within the specified time, 60 seconds unless an occupancy data sheet states otherwise. A partial-flow trip test is also done annually (item 13).

Which sprinklers are sample tested?

Per DS 2-81 Table 2.5.1.1: dry-type (dry pendent) sprinklers every 15 years, recalled O-ring sprinklers every 5 years, and sprinklers with fusible elements of 180 °C or more under prolonged exposure to 150 °C every 3 years. Dry-type sprinklers made before 2003 are replaced when found, and after a fire all non-operated sprinklers within 6 m of operated ones are replaced.

How do FM expectations differ from NFPA 25 in practice?

DS 2-81 Appendix C Table C-1 compares FM with NFPA 25-2026. FM is more frequent for some tasks, such as the monthly physical test of non-indicating valves (NFPA annually), weekly dry system pressure checks and monthly diesel battery checks (NFPA annually), and less frequent for others, such as the 15-year dry sprinkler sample test (NFPA 10 years).

Can the weekly pump test be automated?

Under the October 2025 revision of DS 2-81, yes: an FM Approved automated fire pump test system can conduct the weekly (diesel) and monthly (electric) churn tests without personnel present (2.9.2.2, 2.9.3.2). Such systems monitor alignment, vibration, cooling water flow, room temperature and leakage and send an alert if limits are exceeded (3.1.11.3). DS 3-7 2.4.9.1 separately warns against relying on a controller's own weekly test timer without supervision.

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