Sapel Blog
How to Seal Jerrycan and Bottle Caps
Correct packaging and sealing of containers and bottles is one of the most critical stages in producing, storing and supplying food, pharmaceutical, cosmetic and chemical products. When packaging liquids and chemical compounds, poor sealing can cause product spills, safety hazards, financial losses and serious damage to a brand’s reputation. A completely airtight seal keeps oxygen, moisture and environmental contaminants out of the container and preserves the product’s quality, taste, aroma and shelf life throughout storage and transport. Sealing methods such as induction seal foils also prove the product’s authenticity to consumers and rule out deliberate or accidental tampering or contamination before it reaches the end customer.
Sealing Polyethylene Containers
High-density polyethylene (HDPE) is one of the most widely used thermoplastics in the packaging industry and in the production of bottles and jerrycans of all kinds, including 20-liter jerrycans. HDPE containers are rigid and strong, with excellent impact resistance and good heat stability. They also offer outstanding resistance to aggressive chemicals and detergents, and thanks to their reasonable production cost and easy recyclability they are an ideal choice for the pharmaceutical, food and chemical industries. Below we look at how these containers are sealed, along with other related points.
How to Make Caps Liquid-Tight and Gas-Tight
Induction Sealing
In this method a composite liner or foil (an aluminum layer combined with a foam or plastic layer) is placed inside the cap. Once the cap is tightened, the container passes under the head of an induction sealer: electromagnetic induction heats the aluminum layer without direct contact and melts the plastic layer, which bonds to the container neck and forms a completely tight, impermeable seal.
The advantages of induction sealing are that it completely prevents liquid leaks, preserves product quality and freshness, extends shelf life (up to two years or more) and assures that the product has not been tampered with before use.
Direct Heat Sealing
In this method heat and pressure are applied directly to the thermoplastic material so that the layers melt and fuse together. The quality of this type of seal depends on precise control of three factors, temperature, pressure and dwell time, to avoid over-melting or an incomplete seal.
Heat/band sealers: These machines create an airtight seal by applying a heat impulse or continuous heat together with pressure.
Using Vented (Degassing) Caps
Some chemical products, agricultural pesticides and detergents release gas, so simply tightening the cap is not enough; they need a venting system.
How it works: These caps are fitted with a porous membrane or a special valve (vented caps) that lets gases built up inside the container escape without any liquid leaking out.
Preventing deformation: Venting stops polyethylene containers from bulging, collapsing or deforming as ambient temperature and pressure change.
Cap Sealing Methods and Equipment for Home and Small-Scale Use
- Handheld and tabletop induction sealers: Portable (handheld) induction sealers and small tabletop models are practical equipment for small workshops, laboratories and sealing caps at home. Without the need for complex packaging lines, they let you induction-seal containers one at a time with full control.
- Manual heat sealers: With manual equipment the operator handles every step: placing the container, applying pressure and controlling the heat dwell time. This offers great flexibility for different package sizes and shapes, but it is time-consuming because every package has to be handled by hand.
Home sealing methods require very little upfront investment, and they are simple to use and take up little space. However, their speed and capacity are low, running costs are higher over time because they need more labor, and the quality and consistency of the seal depend directly on the operator’s skill, care and technique.
Industrial Sealing Methods and Equipment
- Continuous automatic machines: On mass-production lines, automatic cap sealing systems for jerrycans are mounted directly over the conveyor. Containers pass continuously under the machine head, and sealing is carried out at high speed with no manual intervention.
- Precise control of operating parameters: Automatic machines offer precise digital control over critical parameters such as temperature, pressure and dwell time or line speed. This prevents common problems such as containers stopping on the line, caps melting or foils burning, and produces perfectly uniform seals.
- Benefits of industrial scale: Automatic equipment greatly increases production speed and capacity and removes packaging bottlenecks. By eliminating human error it also guarantees consistent seal quality, reduces raw material waste and keeps product hygiene and safety standards at the highest level.
