Resource Hub · Slip Testing, Explained
DCOF, SCOF, PTV —
what the numbers mean.
Slip resistance is measured, not guessed. Here’s what each measurement tells you, which instrument produces it, and which one your floor needs.
In this guide
What is PTV (Pendulum Test Value)? The method we lead with.
PTV is produced by the Pendulum Slip Tester under ASTM E303-22, and it is the measurement we recommend first for real-world wet slip risk. A weighted arm with a rubber slider swings across the wet surface at roughly walking speed, and the energy it loses to friction is read as a Pendulum Test Value. Decades of research tie PTV closely to slip probability, one of the few cases where a test result maps to real-world risk. PTV is the method of choice outdoors, on ramps, and on textured surfaces where a tribometer’s flat sensor can’t sit properly.
Widely referenced as the wet Pendulum Test Value indicating a low slip potential under worst-case in-service conditions.
What is coefficient of friction?
Coefficient of friction (CoF) is the ratio of the force needed to slide an object across a surface to the weight pressing them together. On a floor, it’s a plain-English measure of grip: the higher the number, the more traction underfoot. Slip resistance testing puts a number on that grip so it can be compared to a standard, tracked over time, and defended in a claim. There are two kinds that matter for walkways, and confusing them is the single most common mistake we see.
What is DCOF (dynamic coefficient of friction)?
DCOF measures friction while a surface is already in motion, the condition that exists as a heel is sliding on a wet floor. It is more meaningful than a static reading, though for judging real-world wet slip risk the pendulum (PTV, above) is our reference. In the U.S., wet DCOF is measured with the BOT-3000E tribometer under ANSI A326.3 to document compliance, and its values are referenced by tile manufacturers, insurers and courts.
What is SCOF, and why did the industry move on from it?
SCOF, or static coefficient of friction, measures the friction needed to start an object moving from a standstill. It was the historical basis of older test methods, but static measurements poorly predict real-world slips, which happen dynamically. Standards development moved toward dynamic measurement for exactly this reason, which is why a modern report leads with DCOF rather than SCOF. We can still measure SCOF when a manufacturer spec requires it. We’re just honest about its limits.
SCOF vs DCOF: which one matters?
For predicting slips on walking surfaces, DCOF is the more meaningful number because it reflects a foot in motion. SCOF still appears in some product literature and legacy reports, so knowing the difference protects you when a manufacturer quotes a reassuring static value that tells you little about wet, in-motion performance. When someone hands you a friction number, the first question is always: static or dynamic, wet or dry?
Threshold quick-reference
The numbers below are the values most often referenced by each standard. Thresholds vary by product-use category and standard edition — treat this as an orientation, not a compliance ruling, and see Standards Decoded for the detail.
| Measure | Standard | Referenced threshold |
|---|---|---|
| Wet DCOF | ANSI A326.3 | ≥ 0.42 interior wet; ≥ 0.55 exterior/wet work areas |
| Wet DCOF | ANSI/NFSI B101.3 | High ≥ 0.45; Acceptable 0.30–0.44; Low < 0.29 |
| Wet SCOF | ANSI/NFSI B101.1 | High ≥ 0.60; Moderate 0.40–0.59; Low < 0.40 |
| Dry SCOF | ASTM D2047 (lab) | ≥ 0.50 (polish-coated floors) |
| Wet PTV | ASTM E303-22 | ≥ 36 for low slip potential |
Which test does your floor need?
For real-world wet slip risk we lead with Pendulum (PTV) testing, the reference method outdoors, on pool decks, ramps and heavily textured floors. Interior hard flooring under U.S. specifications also calls for DCOF testing to document ANSI A326.3 compliance. Many situations, especially litigation, benefit from both, which closes the “wrong instrument” argument before it starts. For greasy environments, add surface roughness testing, because texture is what defeats grease. We field every method, so the measurement fits the surface.
Slip resistance glossary
| Term | Meaning |
|---|---|
| CoF | Coefficient of friction — the ratio that describes grip |
| DCOF | Dynamic CoF — friction in motion; the U.S. walkway benchmark |
| SCOF | Static CoF — friction from a standstill; largely superseded |
| PTV / BPN | Pendulum Test Value — the pendulum result (BPN is the older abbreviation) |
| Tribometer | An instrument that measures floor friction (e.g., the BOT-3000E) |
| Asperities | The microscopic peaks that pierce a fluid film and provide wet traction |
| Wet vs dry | Testing condition — wet numbers are what protect you, because that’s when people fall |