latch ring closure
Ringless tin can packaging are sometimes closed with a latch ring closure. This is possible for tin cans of 1 litre up to drums of 200 litres. The intermediary range of measures of capacities (2,5 litres up to 60 litres) are conical. The packaging of 1 litre are cylindrical. The steel packaging starting at 12 litres (up to 200 litres) can also be closed with a latch ring closure. The inner of the packaging can be coated or uncoated the same applies for the lids.
Latch ring closures are often combined with an UN or RID/ADR approval, but this is not standard. After all the combination with the packaging itself determines the approval. So it is important to check if a packaging has to be closed with a certain latch ring closure combination. Often an extra compound is being put on the lid to guarantee impermeability. (liquid resistance).
An aperture in the lid is also possible. The aperture can revoke the UN approval but can also be a part of the approval.
Compound ring
The closing ring injected into the rim of the lid to aid the air-tightness of the packaging is a compound. It can come in different compositions. The most common kinds of compound are the PVC white and PVC red. The PVC white compound is the most used. PVC red is used for the more corrosive filling products. That type of compound contains a substance that makes the compound adhere better to the lid with respect to some filling products, with which the PVC white would not adhere. The rubber ring can be used with filling products that are even more highly corrosive.
Tin can packaging
| Latch ring closure Ø in mm |
Aperture (optional) |
Version | Approval |
|---|---|---|---|
| 99 mm | - | uncoated / white | unapproved |
| 118 mm | - | uncoated / white | RID/ADR / Z/S |
| 160 mm | • | uncoated or internal coated | UN Y |
| 180 mm | • | uncoated or internal coated | UN Y |
| 230 mm | • | uncoated or internal coated | UN Y of UN S |
| 286 mm | • | uncoated or internal coated | UN Y of UN S RID/ADR / Z/S |
| 328 mm | • | uncoated or internal coated | UN Y |
Steel packaging
Starting at 230mm (6 litres) up to 571mm (200 litres open head drums).