Leak Testing The Epc Module Only; Forward Pressure Valve Leaks - Agilent Technologies 6890 Series Service Manual

Gas chromatograph

Hide thumbs Also See for 6890 Series:

Table of Contents

Leak testing the EPC module only

Occasionally, to track down small leaks, you will need to isolate the EPC

module from the inlet weldment and leak test the EPC module separately.

On the keyboard, turn off pressure to the inlet being tested.

Use a Torx T-10 screwdriver to remove the screw in the plumbing block

on the front of the module. Remove the plumbing block from the EPC

module, being careful not to lose the O-rings between the block and the

Replace the inlet's plumbing block with the leak test block (part no.

G1530-20660) from the leak test kit (part no. G1530-60960). Make sure

you install O-rings between the block and the EPC module to create a seal.

The leak test block is a special fitting that plumbs the carrier gas

coming out of the module directly back into the septum purge flow

path on the module. It allows the carrier gas and septum purge to

function normally as if an inlet were present.

Perform the normal leak test for the EPC inlet as described previously in

this section. With the inlet removed, the internal volume is smaller and

a pressure loss of 1.0 psi in 10 minutes is considered leak-free.

Occasionally an increase in pressure, rather than a decrease may be observed.

This is usually due to slight leakage into the module across the forward

pressure control proportional valve. Although slight leaks of this nature do

not create chromatographic problems, they may obscure other small leaks

that do cause problems by allowing air into the system.

To check for internal valve leakage:

Remove the supply pressure at the carrier inlet fitting, and quickly cap

the fitting with a Solid 1/8-inch Vespel plug and a Swagelok nut.

Agilent 6890 Gas Chromatograph Service Manual

Cool On-Column Inlet

Leak testing EPC and manual inlets

, scroll to the Pressure field

6890a 6890 plus