PETpla.net Insider 10 / 2016

CAPPING / CLOSURES 47 PET planet Insider Vol. 17 4.8.8 Carbonation Retention Non-top Load Capped and filled bottles are condi- tioned at 22°C (72°F). The carbonation level is checked after 24 hours and 1, 3, 6, 9, and 12 weeks. These intervals may vary by container size and beverage company. If one or more samples show significantly larger carbonation loss than the group average, the cause must be found. This is important because both closure and bottle contribute to the loss. Acceptable carbonation loss during the test period also varies greatly, but 10–15% is used by many companies. 4.8.9 Carbonation Retention at Ele- vated Temperature Capped and filled bot- tles are conditioned at 42°C (108°F) for 16 hours. They are then removed from the chamber and stabilized at room tempera- ture for 24 hours, and the carbonation is measured. Carbonation loss must not be significantly different from the carbonation reten- tion non-top load test. 4.8.10 Carbonation Retention withTop Load Capped and filled bottles are conditioned at 42°C (104°F) for 24 hours. They are removed from the chamber and left to stabilize at ambient conditions for another 24 hours. Then the top load of 45.5kg (100lb) is applied for 5 days. After another 24 hours and 1, 3, 6, 9, and 12 weeks at ambient conditions without top load, the carbonation is checked again and must be within the agreed specification. 4.8.11 Plastic Ball Impact Test Both at ambient and “cold” conditions, a 286g (10oz.) heavy steel ball is dropped against the closure at various angles from a height of 762mm (30in). None of the closures may release or chip under both conditions. 4.8.12 Drop Test Both at ambient and cold condi- tions, capped and filled bottles are dropped from a height of 1.5m (5ft). Bottles are dropped in the vertical and horizontal directions. None of the clo- sures may come off during the test. Of course, all these tests are in addition to cap measurements and visual checks. The cost of setting up a quality control laboratory and the manpower required to run it should not be underestimated. Failing to con- stantly monitor cap quality, however, can result in shipment rejections and additional audits and must therefore be avoided.