The Pendulum Test Value — PTV — is the single number produced by a pendulum test. For pool operators, interpreting PTV correctly is the difference between meaningful and misleading slip-resistance evidence. Pool environments use the test slightly differently to dry retail and commercial floors, because pool users are barefoot, the contamination is persistent, and the slider used (Slider 55 rather than the standard Slider 96) reflects that.
The pendulum tester releases a weighted arm from a fixed height, swinging it through an arc. As the rubber slider on the arm strikes the floor, friction reduces the swing's onward travel. The reduction is read off the calibrated scale as the PTV — a value from 0 (frictionless) to about 80 (very high friction).
The slider strikes the floor at a known velocity, simulating the heel-strike phase of walking. The result is a measure of the dynamic coefficient of friction at that point.
| PTV (wet) | Slip potential | Pool interpretation |
|---|---|---|
| 0–24 | High | Foreseeable claim risk; remediation indicated |
| 25–35 | Moderate | Borderline; depends on contamination, supervision and user vulnerability |
| 36+ | Low | Acceptable for general pool surround use |
The bands derive from HSE and TRL forensic and laboratory work over four decades correlating pendulum results with reported slip incidents.
For most floor environments the relevant slider is Slider 96 — the harder Four-S rubber compound that simulates a standard shoe heel. Pools are different. Pool users on the surround are barefoot, which means the friction characteristics that matter are not the rubber-on-tile of a shoe heel but the wet-skin-on-tile of a barefoot user.
For pool surrounds we use Slider 55 (simulating bare wet skin) as the principal slider, with Slider 57 for sock environments such as some changing-room transitions. Slider 96 is used additionally only at the few zones where shod use is foreseeable (poolside reception, lifeguard station carpets, dry wet-room thresholds).
Detailed guidance in our slider selection guide.
HSE 36+ wet is the baseline for general pool surrounds, but best practice for vulnerable user populations is higher:
| Pool zone | Best-practice PTV (wet, Slider 55) |
|---|---|
| General adult surround (hotel, leisure) | 36+ |
| School and learner pool surround | 40+ |
| Pool steps and ladder approaches | 40+ |
| Hydrotherapy and rehab pool surround | 40+ |
| Sloped wet zones (pool ramps, beach entries) | 45+ |
| Care home or retirement pool surround | 45+ |
These thresholds reflect the elevated fall consequence in vulnerable populations, the geometry of sloped surfaces, and the hand-grip recovery available at steps versus open surround.
Pool surrounds are wet by definition. Dry PTV is therefore not the relevant value — almost no pool surround test would meaningfully be reported on the dry value. Wet testing is delivered with clean tap water at ambient temperature as the standard contaminant. In specific forensic contexts, additional contaminants (sun cream, body oil, soap) may be tested as supplementary evidence; the report states the contaminant explicitly in such cases.
A PTV of 38 wet on a pool surround does not guarantee that no one will slip. It means the friction at that test point, under standard test conditions, places the surface in the low-slip-potential band per HSE guidance. In service, contamination, footfall, plant chemistry and user behaviour interact in ways the standardised test cannot fully capture. Pendulum data is therefore best understood as one component of a broader slip-risk management framework — alongside surround cleaning, lifeguard supervision, signage, and pool plant chemistry control.
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