These flanges are available in sizes ranging from 10mm ID to 160mm and come with mating knuckle clamps and teflon centered orings (which are required for coupling these flanges in any situation). They are essentially the glass equivalent to stainless steel KF flanges, and can be used to interface with the metal KF series. We stock 10/16, 25, 40, 50 and 69 mm ID glass flanges and their corresponding clamp assemblies and teflon seal sets. They are designed for high vacuum use,  with a leak rate of  <1x 10-9 mtorr / sec.

These flat flanges have proven to be useful in the fabrication of electrochemical cells and microbial fuel cells; basically any cells requiring sealing a membrane, such as Nafion®, between sides. See a  sketch here of how they connect, and hold membranes. 
Note - the thickness of your intended membrane affects the clamping distance between flanges, as does the senario of glass-to-metal coupling. A membrane thicker than ~ .020" (0.5 mm) will require some accommodations in order for the clamp to hold correctly. Please let us know if you intend to mount a membrane thicker than ~ .020", or clamp to a metal flange.

They are useful for mounting windows as well. We offer borosilicate plates to close off the flange and provide a clear window, as well as quartz plates to allow for UV transmission, often for photoelectrochemical uses. The diameter of the plate is the same as the outside diameter of the associated flange.

We also offer teflon blank lids for the NW series of flanges. These closures provide you with the opportunity to create your own porting configurations. They seal well using the standard NW knuckle clamps and sealing rings as shown below

Flange dimensions below;
The OD is accurate, but note tubing OD's and ID's are approximate.

	Flange OD		Nominal Tube OD		Nominal Inside Dia.
	inches	mm	inches	mm	inches	mm
NW10	1.18	30	5/8"	16	.5"	12
NW16	1.18	30	3/4"	20	.6"	15
NW25	1.58	40	1 1/4"	32	1"	26
NW40	2.17	55	1 3/4"	45	1.5"	39
NW50	2.95	75	2 1/4"	56	2"	50
NW63	3.43	87	3"	75	2.7"	68

The seal ring is the same for both NW10 and NW16 with a 16 mm inside diameter, so there will be a larger contact area on one side of the membrane when using the smaller NW10 to hold a membrane.

It is possible to overtighten the clamps. Please see a PDF of our notes about their use.

There are two flavors of clamp; the white knuckled clamps are rated to 100°C, and the autoclavable black "high temp" knuckles, rated to 150°C.

Below, these flanges provide flexibility and versatility in an elaborated vacuum manifold.

You can find many examples of these flanges in context by a general search of this site.
And the galleries below contain a lot of specific configurations for
 Microbial Fuel Cells
Electrochemical cells
Photoelectrochemical Cells

Shown below is the largest version of this flange, an NW160. It has an ID of 150mm, just under 6", for easy access to the interior.

Below is a large 2-part cyclone assembly utilizing NW flanges, both for access to the interior of the cyclone itself, through NW160 flanges, as well as for porting through the NW50 flanges.