Slip resistance reports and product information often use terms such as BPN, SRV and P rating, and may also refer to SCV or TCV.

Because these terms all appear in discussions about pendulum testing, they are sometimes treated as interchangeable.

They are not.

One term may describe a reading, another may describe a reported numerical result, and another may describe a classification assigned under a particular Standard.

Understanding the difference helps prevent an existing floor result from being mistaken for a new-product classification, or a technical number from being given more meaning than it can support.

What is BPN?

BPN commonly stands for British Pendulum Number.

It is associated with the numerical response produced by a pendulum friction tester. The term reflects the historical development and use of the British pendulum instrument.

BPN is still widely used in technical discussions, product literature and older documentation.

It may also be used informally as a general description of a pendulum reading.

However, seeing a number described as BPN does not tell you everything needed to interpret it.

You still need to know:

• which Standard or test method was used;
• whether the surface was tested wet or dry;
• which slider was used;
• whether the number is an individual reading or a reported mean;
• whether the test involved a laboratory sample or an installed surface;
• how the surface and test location were prepared;
• what purpose the result is being used for.

The number does not carry its entire meaning by itself.

The test context gives it meaning.

What is SRV?

SRV means slip resistance value.

In slip resistance reporting, it is used to describe a numerical test result derived from the relevant pendulum readings for the surface or sample.

An SRV is therefore a numerical value rather than a P classification.

The distinction between an individual instrument reading and the reported result is important.

A compliant test uses a prescribed procedure and a series of readings. The report should make clear what result has been calculated and how it relates to the location or sample tested.

When an existing pedestrian surface is tested under AS 4663:2013, the reported SRV describes the measured performance of that installed surface under the recorded test conditions.

It should not automatically be converted into a product classification.

What is SCV?

SCV means slope correction value.

Walking on a sloping surface generally requires greater slip resistance than walking on an equivalent level surface. For this reason, a pendulum result obtained on a slope may need to be adjusted to account for the gradient.

Under AS 4663:2013, the SCV is the adjusted SRV that expresses the result as an equivalent value for a level surface. The correction allows the measured performance of a ramp or sloping walkway to be considered in the context of the additional friction required by the slope.

The steeper the surface, the greater the potential difference between the measured SRV and the SCV.

An SCV is therefore not a separate test or classification. It is a slope-corrected numerical result calculated from the SRV and the measured gradient.

What is TCV?

TCV means temperature corrected value.

The performance of Slider 55 rubber can vary with temperature. When Slider 55 is used for wet pendulum testing, AS 4663:2013 requires the reported SRV to be adjusted according to the recorded air temperature.

The resulting temperature-corrected figure may be described as the TCV. The adjustment standardises the result so that testing conducted in colder or warmer conditions can be assessed on a consistent basis.

Temperature correction applies specifically when Slider 55 is used. It should not be assumed that every pendulum result requires a TCV.

Like an SCV, a TCV remains a numerical test result. It is not a P classification.

What is a P rating?

A P rating is a classification used for new pedestrian surface materials tested by the wet pendulum method under AS 4586:2013.

The P classification communicates a range of performance rather than presenting only the underlying numerical result.

Depending on the outcome of the applicable test procedure, the new surface material is classified within the P scale.

The important words are new surface material and classification.

A P rating generally relates to a product or sample tested under controlled conditions before, or independently of, its performance as an installed and used floor.

Once a surface is installed, its actual condition may be influenced by workmanship, wear, traffic, cleaning, coatings, contamination and maintenance.

Its original laboratory classification does not necessarily describe its current performance indefinitely.

Why do people confuse SRV and P ratings?

The confusion arises because P classifications are based on wet pendulum testing and are connected to numerical slip resistance results.

This can make it appear that every pendulum number has a corresponding P rating.

That overlooks the role of the applicable Standard and the purpose of the test.

AS 4586:2013 classifies new pedestrian surface materials.

AS 4663:2013 measures existing pedestrian surfaces.

The testing contexts are related, but they are not identical.

A classification produced under one Standard should not be attached retrospectively to a result reported under another.

A simple way to remember the difference

BPN: the instrument language

BPN is terminology associated with the numerical response of the British pendulum tester.

SRV: the reported numerical result

SRV is the slip resistance value derived and reported for the tested surface or sample in accordance with the applicable procedure.

P rating: the classification

A P rating is a classification assigned to a new pedestrian surface material tested under the wet pendulum method in AS 4586.

This is deliberately simplified, but it provides a useful starting point:

BPN and SRV concern the measured numbers. SCV and TCV are corrected numerical values. A P rating is a classification.

The Standard, method and testing context must still be checked before interpreting any of them.

What should you look for in a slip test report?

Before relying on a result, check that the report identifies:

• the applicable Standard;
• the test method;
• the test date;
• the exact surface or sample tested;
• the location of each in-situ test;
• wet or dry test conditions;
• the slider used;
• the individual readings where required;
• the calculated or reported result;
• any classification that the Standard permits;
• relevant observations and limitations.

A number copied into a specification, email or product data sheet can lose essential context.

Where possible, obtain the complete test report rather than relying on a result quoted in isolation.

Why terminology matters

Using the wrong term can change the apparent meaning of a result.

For example, describing an existing-surface SRV as a P rating may suggest that the surface received a formal AS 4586:2013 product classification when it did not.

That can affect:

• product selection;
• compliance decisions;
• maintenance planning;
• incident investigations;
• tender documentation;
• risk assessments;
• communication with building owners, designers and contractors.

Clear terminology is therefore not merely technical tidiness.

It protects the chain of evidence from the test to the decision made from it.