The Difference Between Gravity and Vacuum Filtration

As a technique widely used in the lab, filtration is the best way to remove solid impurities from an organic solution and isolate an organic solid. We can find two types of filtration: gravity filtration vs vacuum filtration. Hawach provided Stainless Steel Triple-Branches Vacuum Filtration Units, Glass Triple-Branches Vacuum Filtration System, and Stainless Steel 6-Branches Buchner Funnel Vacuum Filtration for your choice.


Gravity Filtration:

  1. Principle:
    • Process: Gravity filtration relies on the force of gravity to pull the liquid through the filter medium.
    • Setup: The setup includes a filter paper or a glass funnel with a filter medium, placed in a funnel holder. The liquid passes through the filter due to gravitational force.
  2. Speed:
    • Filtration Speed: Gravity filtration is generally slower compared to vacuum filtration because it relies solely on the force of gravity to move the liquid through the filter.
  3. Pressure:
    • Pressure Source: The pressure driving the filtration process comes from the weight of the liquid itself.
    • Height: The height difference between the liquid level in the container and the filter medium determines the pressure.
  4. Applications:
    • Common Use: Gravity filtration is commonly used for small-scale laboratory filtrations where a vacuum source may not be available.
    • Application Type: It is suitable for processes where the filtration rate can be relatively slow.
  5. Equipment:
    • Setup: The setup includes a filter flask, funnel, filter paper, and a funnel holder.
    • Maintenance: Generally simpler setup with fewer components.

Vacuum Filtration:

  1. Principle:
    • Process: Vacuum filtration uses an external vacuum source to create a pressure difference, pulling the liquid through the filter medium.
    • Setup: A filter flask, Buchner funnel, and a vacuum pump or water aspirator are part of the setup.
  2. Speed:
    • Filtration Speed: Vacuum filtration is typically faster than gravity filtration because an external force is applied to enhance the filtration rate.
  3. Pressure:
    • Pressure Source: The pressure driving the filtration process comes from an external vacuum source.
    • Control: The vacuum level can be adjusted to control the filtration rate.
  4. Applications:
    • Common Use: Vacuum filtration is widely used in laboratories for various applications, especially when rapid filtration is required.
    • Application Type: Suitable for processes where a higher filtration rate is necessary.
  5. Equipment:
    • Setup: The setup includes a filter flask, Buchner funnel, vacuum pump or water aspirator, and additional tubing.
    • Maintenance: The setup may be more complex due to the inclusion of a vacuum source and additional components.

What is the difference between gravity filtration and vacuum filtration?

Gravity vs vacuum filtration
Gravity filtration is a common method to remove solid impurities from an organic liquid. The impurity that we call in the applications could be a drying agent, an undesired side product, or a leftover reactant. Gravity is used for basic filtration when you are removing solid sediment to separate the filtrate (liquid) for further work or testing. Gravity filtration can be used to collect solid products, although vacuum filtration is usually used for this purpose as it is faster.

Vacuum filtration is used to collect a desired solid too. But gravity filtration vs vacuum filtration, is much faster as the result of the solvent and air being forced through the filter paper by the application of reduced pressure. Remember, never use vacuum filtration to filter a solid from a liquid if you want to use the liquid, and the solvent boiling at about 125 degrees or lower will boil off in the vacuum flask while the pressure is reduced.
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How to Select the Vacuum Filtration or Gravity Filtration?

Difference between gravity filtration and vacuum filtration. There are two types of filtration that are widely used in organic chemistry labs, one is called gravity filtration which is the traditional form of filtration forced by gravity. It’s easy to set, but might come out with poor results at low speed sometimes, and the other one is vacuum filtration. It pushes material through the filter in the Buchner funnel by using a pump that can generate. Both of them can remove solid impurities from an organic solution or isolate an organic solid.

Selecting the right filtration method depends on the nature of the experimental situation. Here are some tips you should think about.

As the method of removing solid impurities such as a drying agent, an undesired side product, or a kind of reactant leftover, gravity filtration can be used to collect the solid from an organic liquid. Actually, you can find that vacuum filtration can do that too, but much fast than gravity filtration.

Gravity vs vacuum filtration. Difference between gravity and vacuum filtration. Although vacuum filtration is faster than gravity, there is something important you should know when you take the vacuum filter into use. First, the glass filter flask must not have any cracks on the bottom of the sides. Second, you have to make sure that the filter flask and the vacuum trap are clamped tightly, and that they will not move during the filtration.

It’s important that the clean filter flask, the vacuum trap, and the tubing are made of thick-walled glassware. The water hoses might collapse during the vacuum process if you use normal tubing.

Remember, don’t perform vacuum filtration without a vacuum trap, and always keep the trap clean. If there is something sucked in there, you will find that easier to recover it from a clean trap than from a dirty one.

If you want to collect the solid, vacuum filtration might be the best according to its high speed. If what you want to collect is the filtrate, gravity filtration methods are highly recommended.

Difference between gravity filtration and vacuum filtration. Gravity filtration will the better choice when you have a large volume to filter. Vacuum filtration is good on the one hand because it’s pretty fast, but on the other hand, the risk of spills will increase and the speed will slow down when you need to empty the flask partway through releasing the pressure and removing the funnel. Vacuum filtration is also preferred if there is only a small amount of solids to be collected or if a solid is fine.