Cut-Off Filters

Point of use Filters with a precise flow
at a specified inlet pressure

Universal Microsystems

Phone: 408-727-1313

Cut-off Filters combine high quality media filter with a precision flow orifice to create a point-of-use filter that can never
exceed a designated over-flow resulting from a line break of component failure downstream

Applications > Limiting catastrophic gas flow

> Backfill a chamber with a particle free gas in a precise time
Industry standard lengths (3.31" & 2.80") for ease of retrofit
Custom lengths available

Ultraclean, 1 in. dia. filters

Various inlet/outlet fittings (photo)

CAD Drawing, 2.8"MF

CAD Drawing, 3.31

No more than 1 particle/ft3
Less than 10 ppb THC
Less than 10 ppb moisture
He leak check to 10-9atm sccm/sec
99.9999999 percent removal rating at rated flow
To order, you will need to determine the Flow Model Number
based on the gas species involved, the inlet pressure and the desired flow rate.


The flow model# specifies the orifice ID used. To determine choose the maximum flow Qmax to be larger than the process flow Q,
for example Qmax = 2Q. Then find the nitrogen flow at 20 psig for that orifice with QN2 = Qmax/K x 34.7/Pi with Pi
the inlet pressure in psia units, and K a constant for gases other than nitrogen.
With the closest QN2 from the table below, the matching Orifice ID is the Flow Model Number.

There is a pressure drop through the restrictor from Pi to Po
For example with Qmax=2Q, P o = 0.933Pi
If Po is insufficient increase Qmax