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How to use a Membrane Filter

Tisch Scientific offers a large array of membrane filter materials, diameters and pore sizes. All of this information can be a bit overwhelming if you are new to your filtration application, or you are just unsure of what filter you should be using.

First make sure you have chosen the appropriate membrane filter material, diameter and pore size. A few of the resources listed below will help you to do this:

Basic Filtration Concepts
Membrane Filter Selection Guide
Membrane Quick Pick Guide
Membrane Filter Chemical Compatibility Chart

What is a Membrane Filter?

A semi permeable membrane is utilized in separating suspended solids and other substances from various solvents, gases or liquids depending on the user’s application and choice of membrane. Some membrane materials are hydrophobic and do not allow aqueous solutions to pass, while some are hydrophilic and designed to let these solutions pass with optimal flow rates. There are a wide array of laboratory applications that use membrane filtration processes and for various reasons. Some of the common applications include:

  • Gas, oil, alcohol or bacteria filtration
  • Ground water and waste water filtration
  • Industrial water filtration
  • Chemical filtration
  • Beverage filtration
  • Tissue culture media filtration
  • Vapor filtration
  • Medicine filtration
  • Food filtration
  • Strong acid filtration
  • Organic solvent filtration
  • Alkali solvent filtration
  • and much more..

Devices used with Membrane Filtration

Below is a list of commonly used devices with membrane filtration.

Inline Reusable Filter Holders

There are several different kinds of configurations for reusable filter holders, Tisch Scientific sells them in stainless steel housings as well as polypropylene. You can purchase them with standard female luer/male slip configurations like a typical syringe filter, or you can purchase them with tubing connections. Reusable inline filter holders are autoclavable and can be used many times by simply cleaning and replacing the membrane filter after use.

View Tisch Reusable Filter Holders here

Vacuum System Filter Holders, Flasks and Funnels

If you are using a vacuum system to filter your solvent, you may be using a filter holder or filter funnel with your system. Vacuum filter holders typically attach to a vacuum manifold which is then directly connected to a vacuum pump.

View Tisch Vacuum filter holders here
View Tisch Manifolds here
View Tisch Vacuum Pumps here

Vacuum funnel sets can come in either disposable form, autoclavable polypropylene, or glass. They will have a funnel top, with a frit that connects to a receiving flask. The membrane is placed in the frit and the set is connected directly to a vacuum pump with tubing to allow for the solvent to drain through the membrane and frit into the receiving. Sometimes disposable funnel sets commonly referred to as, “Bottle Top Vacuum Assemblies,” will come with a membrane pre-installed in the frit.

View Tisch Vacuum Funnel Sets here

Inlet side of a Membrane Filter

Sometimes the user may have difficulty locating the inlet side of a membrane filter when installing their filter into their devices. This typically is the case with membranes that come with a substrate layer. Substrate layers are used to improve the durability along with ease-of-use of a membrane. First, you need to determine if the membrane you purchased has a substrate. You can determine this by either analyzing both sides to see if there is a different texture and appearance on one side, or by contacting the manufacturer to be sure. If the membrane does not have a substrate, it is bio-directional and either side can be used as the inlet. If it has a substrate, the substrate layer will be more coarse and ridged than the membrane side. The membrane side would be the inlet and the coarse substrate side the outlet.  The solvent should enter the inlet side of the membrane first.

Requesting Samples

Would you like to try out some of our membrane filters?  If you are still struggling to find the appropriate membrane filters for your application Tisch Scientific offers free product samples for testing prior to purchase. In order to request samples simply click the green, “Request a Sample,” button on any product page. Or click here. We will promptly send you samples within a business day.