Thermoplastic materials

For the purposes of requirements B2 and B4, thermoplastic materials should be classified as TP(a)
rigid, TP(a) flexible or TP(b), as follows:
a. TP(a) rigid
i. rigid solid uPVC sheet
ii. solid (as distinct from double- or multi-skinned) polycarbonate sheet a minimum of 3mm
thick
iii. multi-skinned rigid sheet made from uPVC or polycarbonate that has a class 1 rating when
tested to BS 476-7
iv. any other rigid thermoplastic product, a specimen of which (at the thickness of the
product as put on the market), when tested to BS 2782-0 Method 508A, performs so that
both:
• the test flame extinguishes before the first mark
• the duration of flaming or afterglow does not exceed 5 seconds following removal of
the burner.
b. TP(a) flexible
Flexible products a maximum of 1mm thick that comply with the Type C requirements
of BS 5867-2 when tested to BS 5438 Test 2 with the flame applied to the surface of the
specimens for 5, 15, 20 and 30 seconds respectively, but excluding the cleansing procedure; and
c. TP(b)
i. rigid solid polycarbonate sheet products a maximum of 3mm thick, or multi-skinned
polycarbonate sheet products that do not qualify as TP(a) by test
ii. other products which, when a specimen of the material between 1.5 and 3mm thick is
tested in accordance with BS 2782-0 Method 508A, have a maximum rate of burning of
50mm/minute.
NOTE: If it is not possible to cut or machine a 3mm thick specimen from the product, then a 3mm