First acquaintance with thermos tumblers

Wednesday, Nov,9th 2022

Thermos tumblers are loved by everyone because they can continue to maintain a stable temperature. 

Now, thermos tumblers on the market function roughly the same, but look wildly different.



When choosing a thermos tumbler, should you choose appearance or quality?

How to buy a tumbler that is both safe and warm?

The appearance of a thermos tumbler is not enough. The appearance is the basic "responsibility" of 

a thermos tumbler, but when we drink water while holding it in the palm of our hand, we will find that 

the material is more important than the appearance.


Most of the thermos tumblers are made of stainless steel, which is resistant to high temperature and 

has good thermal insulation performance. Other materials such as glass, ceramics, etc., are affected 

by factors such as heat preservation and anti-fall, and are not easily favored by people in seasons 

with large temperature changes.

★Stainless steel materials are usually divided into three types, the "numbers" are 201#, 304# and 316#.


A.201 stainless steel, best at camouflage

Most of the unqualified thermos tumblers we have seen in the news use 201 stainless steel as the inner 

liner of the thermos tumbler. 201 stainless steel has high manganese content and poor corrosion 

resistance. If it is used as the inner liner of a vacuum flask, long-term storage of acidic substances 

may lead to the precipitation of manganese. Manganese metal is an essential trace element for the 

human body, but excessive intake of manganese can harm the body, especially the nervous system. 

Imagine if children were allowed to drink this water all day long, the consequences would be dire!

B.304 stainless steel, the most commonly used stainless steel

When stainless steel comes into contact with food, the potential safety hazard is mainly the migration 

of heavy metals. Therefore, stainless steel materials that come into contact with food must be food 

grade. The most commonly used food grade stainless steel is 304 stainless steel with better corrosion 

resistance. To be named 304, it needs to contain 18% chromium and 8% nickel, which is justifiable.

However, merchants will mark the word 304 on the obvious position of stainless-steel products, but 

marking 304 does not mean that it meets the requirements for food contact use. 304 stainless steel 

is relatively acid-resistant, but it is prone to pitting corrosion when encountering substances containing 

chloride ions, such as salt solutions.

C.316 stainless steel, more advanced version

Compared with 304 stainless steel, it is prone to pitting corrosion when encountering substances 

containing chloride ions. 316 stainless steel is an advanced version: it adds metal molybdenum on 

the basis of 304 stainless steel, which has better corrosion resistance and is more "carrying". 

Unfortunately, the cost of 316 stainless steel is relatively high, and it is mostly used in high-precision 

fields such as medical treatment and chemical industry. 

When buying a vacuum flask, pay attention to 3 steps

★According to the consumption tips of thermos tumblers issued by the State Administration for Market 

Regulation, when purchasing thermos tumblers, you can follow the 3 steps of "smell", "touch" and "try":

A."Smell": There is no irritating odor in the body.

B."Touch": the surface of the inner tank and the outer tank is uniformly polished, without bumps, 

scratches or burrs; the welding of the mouth is smooth and consistent.


C."Try": pour boiling water, screw the lid tightly, and the product does not heat up significantly after 

2-3 minutes, indicating that the product has good thermal insulation performance; pour boiling water, 

tighten the lid, and turn it upside down for 4-5 minutes without leakage, indicating that the product 

has no leakage. Good sealing performance (limited to screw lids).