• How to seal plastic bottle caps tightly?

How to seal plastic bottle caps tightly?

Bottle caps: can be divided into single-piece caps and double-piece caps;

Single-piece cap: There is no gasket inside the bottle cap. The entire cap is made of the same material and relies on folding edges or inner plugs for sealing.

Double-piece cap: There is a gasket inside the bottle cap. The gasket material is relatively soft and relies on the rebound force of the compression gasket to maintain the seal.

Single-piece lids are not padded and do not require a padding machine, so the equipment investment is less than that of two-piece lids. Moreover, the price of the gasket material is more than twice that of the cover material, and the cost of a single-piece cover is lower than that of a double-piece cover.

The single-piece cap has high requirements on the size and shape of the bottle mouth; the fold-type single-piece cap seals by pressing the outer edge and cross section of the bottle mouth with the elastic force of the folding deformation; the inner-plug type single-piece cap seals by the outer diameter of the inner plug and the The interference fit of the inner diameter of the bottle mouth plays a sealing role. The gasket of the double-piece cap is softer and has greater tolerance for defects in the bottle mouth.

The sealing performance of the bottle cap refers to the sealing ability of the bottle cap and the bottle mouth to prevent or slow down the leakage of liquid and gas inside the bottle. For all plastic anti-theft bottle caps, sealing is one of the most important functions. Many outsiders may think that the sealing ability of bottle caps is provided by threads, but they are totally wrong. Ordinary bottle cap threads and bottle mouth threads are flat threads with clearance fit and have no sealing ability.

Only vertebral threads can be used for thread sealing, which are American standard NPT and national standard RT threads, and these two types of thread sealing require the use of magic rope, raw material tape or thread sealant. Without thread fillers, threads alone cannot be sealed. The beverage bottle has a flat thread, and secondly, we didn’t see filler on the thread, so it’s definitely not a thread seal. This is usually a sealing gasket or O-ring. When I was young, there was a soft diaphragm on the beverage bottle cap, which was a gasket seal. Nowadays, there is no such gasket, and it is replaced by an O-ring. As for what many people say, tightening the threads hard will prevent leakage, so the threads are the ones that seal. In this case, the vertebral threads are indeed OK. For our ordinary civilians, the gasket or o is actually squeezed by tightening the threads. The ring strengthens the seal. Without a sealing gasket or O-ring, it will be useless even if you twist the flat thread.
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Post time: Mar-12-2024