Glass Capillary Array0 pages

Glass Capillary Arrays

Applications

Features

Collimation
Gas flows
X-rays
Calibrated leaks
Controlled air flow
Differential pressure barrier
In-line filtration
Optical beam splitters
Laser entrance windows

Precise pore sizes
High heat tolerance (to
450 °C)
Mechanical strength
Optical quality finishes
Custom shapes and
materials
Applications support

Glass Capillary Arrays (GCAs) consist of millions of precision glass capillary tubes fused together to produce
a uniform and mechanically rigid structure. They can be supplied as circular or rectangular thin plates and
offer sieve-like filtration with a positive particle size cut-off. GCAs are strong, self-supporting devices with
exceptional thermal and chemical stability; they can be manufactured to withstand temperatures greater than
450 °C for applications in severe environments.
Pore Size

Bias Angles

Standard pore sizes for GCAs range from 2 to 50
microns. Other pore sizes can be special ordered.
Stringent process controls ensure that pore size
variations are less than 1% within a single GCA. There
is a 6% maximum pore size variation between GCAs.

The capillaries within an array may be offset from
perpendicular to the input surface. Angular
displacements from 0° to 19° may be ordered.

Pore Density
Typically, GCAs are manufactured to have an open
area ratio of 45% or greater, depending on pore
diameter. This provides the ideal combination of a high
flow rate and high mechanical strength. As a special
order, as few as one pore in a 25 mm disc can be used
as a calibrated leak.

Flow Rate
The flow rate for a 25 micron pore, 0.5 mm thick GCA
is approximately 2.5 ml/sec/cm2 with a differential
pressure of 1 cm of mercury, and 16 ml/sec/cm2 with a
differential of 6 cm of mercury, measured using distilled
water at 23° C. Actual flow rates for any capillary array
depend on fluid characteristics, aspect ratio, and flow
characteristics of the holding apparatus.
Mounting

Regardless of the thickness, the aspect ratio (pore
length to diameter) should be ≤100.The standard GCA
thickness is 0.5 mm. GCAs can be manufactured to
order with a thickness from 0.25 mm to 6 mm.

Solid border GCAs are compatible with most existing
Millipore or Nuclepore equipment, requiring little or no
hardware modification. For high temperature or high
pressure applications, GCAs may be fritted in a metal
flange and mounted on metal or glass tubing. In many
other applications epoxies can be used for mounting.

Standard Materials

Special Requirements

Lead glass is used as the basic standard matrix due to
its mechanical strength and chemical stability. The
density is 4.44 g/cc and the nominal refractive index is
1.70. It has a thermal expansion coefficient of 77 x 107

Whenever possible, standard dimensions should be
used. The following options can be supplied on a
special order basis. When requesting a quotation
specify all characteristics listed below plus any special
requirements. For special shape or pore size please
specify the following:
• Diameter or Length and Width
• Thickness
• Pore Size
• Bias Angle (0-19°)
Unless otherwise specified, surface finish will be matte,
open area ratio will be nominally 45% and material will
be lead glass.

Thickness

per °C.
Surface Finish
GCAs can be supplied with a ground matte finish (9
micron abrasive) on both faces; a polished surface on
both faces is also available. In either case, the pore
surfaces have a smooth finish. The input surface can
be blackened to minimize light scattering.

19/05/2010