Maintaining The Auxiliary Epc Module - Agilent Technologies 6850 Series II User Information

Maintaining the auxiliary EPC module

The optional auxiliary EPC module provides three additional auxiliary
pressure control channels. To work properly, there must be adequate flow
resistance downstream of each channel's pressure sensor. The auxiliary EPC
module provides this restriction for each channel via 3 frit-type restrictors
located in the manifold block on the EPC module exterior.
Four frits are available. A colored dot distinguishes the different types from
each other.
Frit marking
Blue Dot
Red Dot
Brown Dot
None (brass tube)
Agilent ships the Red Dot frit in all three channels of a new auxiliary EPC
module.
Select and install frits based on the gas type and flow requirements for the
application.
relationships for the three Dot frits, assuming there is no significant additional
resistance downstream of the frits. After changing the type of gas used with the
auxiliary EPC module, check these tables to verify the installed frit types.
Change the frits if needed.
If using a Zero resistance frit, the user must provide flow resistance
downstream and generate the pressure/flow relationships.
Warning When hydrogen is used, dangerously high flows are possible if insufficient flow
resistance is provided downstream of the supply tube. Always use either the
High (Blue Dot) or Medium (Red Dot) frit with hydrogen.
Released: March 2004
Flow resistance
High
Medium
Low
Zero
Figure 23 and Figure 24
6850 Series II GC User Information
Maintaining the auxiliary EPC module
Part no.
19234-60660
19231-60770
19231-60610
G1570-20540
show approximate pressure/flow
Routine Maintenance: General
page 116 of 256