The core component of the vacuum flask is the liner. There are 4 steps to make a glass liner:
The glass material applied in vacuum flask production is commonly used soda lime silicate glass. We take uniform high-temperature glass liquid without impurities, and separately blow it into inner and outer vessels with a wall thickness of 1~2mm in the metal mold. Check pump action vacuum flask and water dispenser flask if you have interests.
Production process: put the inner bottle into the outer; seal the mouth of the bottles together; arrange a conduit at the bottom of the outer bottle for silver plating and air extraction. Glasses in this structure is called glass liner. There are mainly three methods to make glass lined thermos flask liners: bottom-pulling sealing, shoulder-shrinking sealing and waist-jointing sealing.
(1) The bottom-pulling sealing method: cut the top of the inner vessel and both the top and the bottom of the outer vessel; put the inner one into the outer from the bottom; fix them with an asbestos pad; seal the bottom of the outer bottle; connect it with small tail pipe; and melt and seal the mouth of the two bottles at last.
(2) The shoulder-shrinking sealing method: cut the top of the two vessels; put inner bottle into the outer one from its top; fix it with an asbestos pad; shrink the upper end of the outer vessel into the shoulder; seal the two vessels; and connect the small tail pipe at last.
(3) The waist-jointing method: cut the top of the the two vessels;split the outer bottle into two sections from its waist; put the inner bottle into the outer one; re-weld the waist; and connect the small tail pipe at last.
A certain amount of silver ammine complex solution and aldehyde solution as a reducer are poured into the interlayer of the vacuum thermos flask jug through the small tail pipe; Thereafter, the silver mirror reaction is carried out. The reduced silver ions will deposit on the surface of the glass lined thermos flask, forming a mirror-like thin layer of silver. Inquiry high grade vacuum flask.
Connect the tail pipe of the silver-plated double-layer glass liner with the vacuum system, and heat it to 300~400℃, so that the glass can release gases and residual moisture clinging to it. Meanwhile, pump out air with a vacuum pump till the vacuum degree of the interlayer space reaches 10-3~10-4mmHg. Last, melt and seal the tail pipe.
The modern vacuum flask was invented in 1892 by British physicist Sir James Dewar when he was conducting a research on liquefying gas. To liquefy gas at low temperature, he first needed to design a container that could isolate the gas from the outside temperature. Therefore, he asked glass technician Berg to blow a double-layered glass for him. After painting the inner walls of the two vessels with mercury, and then pumping out the air between them, a personalised vacuum flask was built. We later call this vacuum flask Dewar bottle which can retain the temperature of the liquid contained in it for a certain period regardless of whether it is cold or hot.