What counts as a remote or small sprinkler tank
There is no single size cutoff on this page, and NFPA 25 does not set the interior interval by tank size. What these tanks share is that they sit somewhere a drained inspection is hard to arrange, or they are the only fire protection water supply on the site.
Typical examples
Rural sites where the tank is the fire protection water supply for the property. Campuses with a dedicated sprinkler supply tank. Industrial yards with a tank that feeds the sprinkler system. Smaller sprinkler-supply tanks at sites where taking the tank out of service is hard to plan around.
Why taking the tank out of service is the hard part
Emptying a sprinkler tank for an interior look takes the property’s fire protection water supply out of service until the tank is full again. At a remote site, the water lost and the time spent bringing the tank back are both harder to manage, and the property is impaired the whole time. An in-service ROV tank inspection avoids that: the tank keeps protecting the property while the rover works.
How the in-service ROV tank inspection works
The tank stays full
The tank is not emptied for the inspection. The pilot puts the ROV into the water through an access point and flies it from outside the tank. The fire protection water supply stays in service during the visit.
What the rover records
The pilot flies the rover over the interior surfaces and records video of the visible coating or liner condition, corrosion, debris, and silt and sediment levels. These are observations from the video. The rover inspection does not measure steel thickness and does not repair anything it finds.
What you receive
FLOW produces the inspection video and its own findings report and sends them to the owner, and to the owner’s qualified firm when the owner asks. Keep the record with the rest of the property’s NFPA 25 records; the AHJ will want the date and the findings.
More on the method: underwater rover (ROV) tank inspection, in service.
What FLOW does not do on tank work
Draining, emptying, or refilling — FLOW does not take tanks out of service. Drained, out-of-service inspections are referred to a licensed partner firm.
Silt and sediment removal — done by others. The rover records the conditions so the owner can plan that work.
Coating or liner repair — not FLOW. The rover records visible condition only.
Thickness testing — FLOW does not run ultrasonic or other steel thickness testing.
Certification and stamps — FLOW does not hold AMPP CCI certification, does not do API 653 work, and does not issue engineering stamps. FLOW is not the AHJ.
Sprinkler system inspection — FLOW inspects the tank interior only. It does not perform sprinkler system inspections.
NFPA 25 and sprinkler tank inspection intervals
NFPA 25 Chapter 9 covers water storage tanks and sets the interior inspection interval by tank type. As our overview page explains, steel tanks without corrosion protection are on a 3-year interior interval and all other tanks on a 5-year interval. The interval is set by tank material and corrosion protection, not by how small or remote the tank is.
Virginia enforces NFPA 25-2020 through its Statewide Fire Prevention Code. Other states and localities may adopt a different edition. Confirm the adopted edition, and the interval for your tank, with your AHJ before you schedule.
The full table by tank type and edition is on our NFPA 25 tank interior requirements page. The short-cycle checks are on the tank inspection overview, and the wider standard is on What is NFPA 25?.
Is an in-service ROV inspection accepted?
The authority having jurisdiction (AHJ), usually the local fire marshal, enforces the adopted edition and decides whether an in-service rover inspection meets the interior inspection for a particular tank. Ask before you schedule. Tell the AHJ the tank material, whether it has interior corrosion protection, the date of the last interior inspection, and that you plan an in-service underwater inspection. If the AHJ wants a drained inspection instead, FLOW refers that to a licensed partner firm.
Service area for remote tank inspections
FLOW is based in Richmond, Virginia, and serves Virginia, Maryland, Washington DC, North Carolina and South Carolina, including remote sites. When you request a quote, tell us where the tank is, what it is made of, and how the rover can get into the water, so we can plan the visit.
