Vacuum to hold an object How can i check and calculate if a certain vacuum pump can hold an object that weights X kg? By "hold" I mean not let that object fall to the floor due to gravity
 A: A tiny vacuum pump that you can cary in your pocket can lift a train.
Any vacuum pump can lift anything(assuming a perfect seal). It all depends on the area with vacuum. It is not really the vacuum that is doing the lifting, but the atmosphere. 1 atm can lift 1 kg per cm^2.
A: Technically, little vacuume can carry huge wight even with little air flow. For example typical vacuum cleaner can lift column of water 2 m high other dimensions will go together with the vacuum surface. This means that it can carry some 80 cm column high of concrete or 25 cm column high of steel, assuming it is perfectly sealed. If not perfictly sealed such as  porous materal you need a bit higher air flow to compensate for the air leak and maintain sufficient vacuum to hold the product. Based on the above you select the type of machine to generate the vacuum. If fully sealed (non porous) vacuum pump with or without vacuum tank will work fine and quit and it will generate vacuum 5 times the vacuum cleaner hence 5 time the column. If  porous material you should choose fan type vacuum pump like the one in household vacuum cleaner, but noisy. 
