A fire sprinkler hydrostatic test before handover means filling the piping with water and holding it at 200 psi for two hours with no drop on the gauge and no visible leakage. Where the normal working pressure is above 150 psi, the test pressure becomes 50 psi above working pressure. This is the reference value in NFPA 13, NFPA 14 and NFPA 24, and the result is recorded on a signed test certificate.
This guide covers test values for each part of the system, the site procedure, underground flushing, the dry system air test and the records needed for handover.
Key takeaways
- NFPA 13 (2025 edition) requires aboveground sprinkler piping to be tested at 200 psi for 2 hours without loss of pressure.
- Where working pressure is above 150 psi, which is common with a fire pump, the test pressure is 50 psi above working pressure.
- Test pressure is read from a gauge at the lowest point of the section under test.
- Underground mains are flushed before they are connected to the building piping, and tested under NFPA 24 with a calculated limit on makeup water.
- Dry pipe and double interlock preaction systems also need an air test at 40 psi for 24 hours, in addition to the water test.
- The test pressure must not exceed the test rating on the datasheet of any installed component.
In this article
- Why is the hydrostatic test done before handover?
- What test pressure and duration apply?
- How is the hydrostatic test carried out on site?
- Underground mains: flushing and the allowable leakage
- What about dry pipe and preaction systems?
- Can the installed components take the test pressure?
- How is the pressure test documented?
- Is a retest needed after a modification or extension?
- Common mistakes in pressure testing
- Frequently asked questions
- Conclusion
Why is the hydrostatic test done before handover?
The hydrostatic test, the “hydro test” on site, is the first practical proof that pipes, grooved couplings, joints and valves were installed tight. It is done before ceilings are closed and before underground lines are finally backfilled, because a leak found later means stripping finishes or digging again.
In Saudi Arabia, the Saudi Fire Protection Code SBC 801 applies (the 2024 edition of the Saudi Building Code, mandatory since 30 June 2025). The General Directorate of Civil Defense oversees fire protection requirements during construction and operation, and facilities are licensed through the Salamah platform. The test values come from the NFPA standards adopted in the specification. They are technical references, not standalone law.
AZEIDK’s team carries out pressure tests as part of its testing, commissioning and handover service, alongside hydrant flow tests and room integrity tests.
What test pressure and duration apply?
The base value is the same in all three standards: 200 psi (about 14 bar) for two hours. The pass criterion and the rule for higher pressures vary by system part.
| System part | Reference standard | Test pressure | Duration | Pass criterion |
|---|---|---|---|---|
| Aboveground sprinkler piping | NFPA 13 (2025), Chapter 29 | 200 psi, or 50 psi above working pressure where it exceeds 150 psi | 2 hours | No drop on the gauge and no visible leakage |
| Standpipes and hose cabinets | NFPA 14, acceptance tests chapter | 200 psi, or 50 psi above system working pressure, whichever is greater, including yard and FDC piping | 2 hours | No leakage, with pressure read at the low point of the system or zone |
| Fire department connection (FDC) piping | NFPA 13 and NFPA 14 | Tested with the rest of the system at the same pressure | 2 hours | As for the system |
| Underground mains (hydrant and supply lines) | NFPA 24 | 200 psi, or 50 psi above working pressure, whichever is greater, held within ±5 psi | 2 hours | Drop of less than 5 psi or no visible leakage, and makeup water within the calculated limit |
| Dry pipe and double interlock preaction systems | NFPA 13 (2025) | Water test as above, then an air test at 40 psi | 24 hours for air | Loss not more than 1.5 psi |
When does the test pressure go above 200 psi?
Where normal working pressure exceeds 150 psi, for example in high-rise buildings or systems fed by a fire pump with a high churn (zero-flow) pressure, that section is tested at 50 psi above working pressure. The designer should show the maximum working pressure for each zone on the drawings.
Where is the pressure read?
NFPA 13 requires the test pressure to be read from a gauge at the lowest elevation of the system or the section under test. The water column adds pressure at the bottom, so a reading taken on an upper floor is lower than the real pressure at the base.
How is the hydrostatic test carried out on site?
- Written procedure: sections, test pressure for each, gauge location and witnesses.
- Isolate what cannot take the pressure: disconnect or isolate any equipment rated below the test pressure. Fit test blanks where needed and record their number and locations.
- Fill and vent: fill slowly from the lowest point and bleed air from high points and branch ends.
- Pressurise: use a manual or electric test pump with a calibrated gauge of suitable range and raise pressure gradually.
- Stabilise and monitor: once at pressure, close the pump valve, record the reading and start time, and watch the gauge for two hours while checking joints visually.
- Record and release: record the final reading, release the pressure safely, remove the test blanks and check that the number removed matches the number fitted.
NFPA 13 prohibits additives and corrosive chemicals such as sodium silicate or brine during the test or to stop leaks, and the test certificate asks the contractor to confirm this.
Underground mains: flushing and the allowable leakage
NFPA 24 requires underground lines feeding hydrants and the building system to be completely flushed before they are connected to downstream piping, so that stones and debris do not end up in valves and sprinklers. Flushing continues until the water runs clear of debris. The standard sets minimum flushing flows in a table based on a velocity of 10 ft/s in the pipe; where those flows cannot be reached, the maximum flow available to the system is acceptable.
| Nominal pipe size | Minimum flushing flow (10 ft/s) |
|---|---|
| 4 in | 390 gpm |
| 6 in | 880 gpm |
| 8 in | 1,560 gpm |
| 10 in | 2,440 gpm |
| 12 in | 3,520 gpm |
The underground main is tested at the set pressure for two hours. According to the NFPA 24 text quoted by QRFS, a pass is a drop of less than 5 psi or no visible leakage. Because gasketed underground pipe can lose a small amount of water, NFPA 24 sets an allowable makeup water limit: L = S × D × √P ÷ 148,000, where L is makeup water in gallons per hour, S is the length tested in feet, D is the nominal diameter in inches and P is the average test pressure in psi. Exposed joints are checked visually during the test.
A pressure test does not replace a hydrant flow test. The first proves the piping is tight. The second measures the flow and pressure the water supply can actually deliver. Once the pressure test passes, the remaining sprinkler system acceptance tests, such as the main drain and inspector test, are covered in a separate guide.
What about dry pipe and preaction systems?
These systems are water-tested at the same values. For dry pipe and double interlock preaction systems, NFPA 13 then adds an air test at 40 psi for 24 hours, and any loss above 1.5 psi in that period must be corrected. Drain the system fully after the water test, because water left in a dry system causes corrosion and can freeze in cold areas.
Can the installed components take the test pressure?
Before pressurising, check the datasheet of every installed component and compare the required test pressure with the model’s working pressure and test rating. Examples from products AZEIDK offers in Saudi Arabia:
- KDI pipe: Schedule 10 to ASTM A795 and Schedule 40 to ASTM A53, with a hydrostatic test as part of the mill’s production inspection. Ask for Mill Test Certificates for each batch. See the KDI sprinkler pipe article.
- AFC A-3000 and AG-3000 OS&Y gate valves: maximum working pressure 300 psi and maximum test pressure 600 psi per the datasheet, as covered in the AFC gate valve guide.
- TYCO and Victaulic sprinklers: each model has a rated working pressure on its datasheet. Check it before the test, especially in high-pressure zones.
Devices not designed for the test pressure, such as some pressure switches or meters, are isolated in line with the manufacturer’s instructions. See also the fire protection piping and fittings guide.
How is the pressure test documented?
The test is recorded on the Contractor’s Material and Test Certificate, with forms in NFPA 13 for aboveground piping and in NFPA 24 for underground piping. It typically covers:
- Hydrostatic test pressure and duration, plus the air test pressure and duration for dry systems.
- Flushing results for underground mains.
- A statement that no additives or chemicals were used.
- The number and locations of test blanks used, and the number removed.
- Valve details and the alarm valve or dry pipe valve test, where fitted.
- Signatures and dates from the contractor and the owner’s representative.
Attach photos of the gauge at the start and end of the test, the gauge calibration certificate, and a drawing marking the sections tested. These records belong in the fire systems handover documents and make the consultant’s and authority’s review easier.
Is a retest needed after a modification or extension?
NFPA 13 (Chapter 30 in the 2025 edition) requires modifications to existing systems to be tested at system working pressure. Where a modification affects more than 20 sprinklers, the new section is isolated and tested at not less than 200 psi for two hours; modifications affecting 20 or fewer sprinklers do not need testing above working pressure. After handover, the system moves to periodic inspection and testing under NFPA 25.
Common mistakes in pressure testing
- Reading the gauge on an upper floor instead of at the lowest point.
- Using an uncalibrated gauge or one with the wrong range.
- Leaving trapped air, so the pressure swings and is mistaken for a leak.
- Testing after the suspended ceilings are closed.
- Leaving a test blank inside the system after the test.
- Using 200 psi in a zone whose working pressure is above 150 psi.
- Using sealants or chemicals to stop a leak instead of repairing the joint.
- Flushing the underground main only after it has been connected to the system.
Frequently asked questions
What is the hydrostatic test pressure for a fire sprinkler system?
200 psi (about 14 bar) for two hours under NFPA 13, NFPA 14 and NFPA 24, or 50 psi above working pressure where it exceeds 150 psi.
Is any pressure drop acceptable?
For aboveground piping, no loss of pressure or visible leakage is accepted. For underground mains, NFPA 24 allows a drop of less than 5 psi and makeup water within the calculated limit.
Is the fire department connection tested with the system?
Yes. The piping between the FDC and the check valve in its inlet pipe is tested in the same way as the rest of the system.
Is an air test enough for a dry pipe system?
No. For dry pipe and double interlock systems, the 40 psi, 24-hour air test is added to the water test. It does not replace it.
Who should witness the test?
The contractor or testing company runs it. The consultant or owner’s representative should attend so the result can be approved on the spot.
Conclusion
The base value of a fire sprinkler hydrostatic test is simple: 200 psi for two hours. Acceptance depends on the details: correct working pressure per zone, the gauge at the lowest point, flushing underground mains before connection, an air test for dry systems and a signed certificate.
Getting ready to test the sprinkler and hydrant network on your project? Send us the drawings and working pressures, and we will prepare the test procedure with you and document the results for handover. Talk to the AZEIDK team
