4.2.1 SLIV Maintenance Overview
Schedule
This section provides routine maintenance and repair procedures for the liquid injection valve.
A 6-week preventive maintenance schedule is recommended for servicing the valve; however,
the schedule you choose will depend upon the:
● Sample properties
● Vaporization temperature
● Ambient temperature
● Sample pressure
● Analysis Duty Cycle
Valve Service Life
You can expect a 1 year service life for the valve. However, the service life of the valve is also
dependent upon the properties of the sample as well as the preventive maintenance schedule.
The service life of the valve is adversely effected if the sample is injected at a high sample
pressure >20 bar (290 psi.).
● If the sample has a corrosive effect on the surface of the injection stem (also called a tappet),
the stem must be replaced with a different material type (e.g. Hastelloy).
● Over time, particles from the sample build up on the gaskets and will eventually obstruct
the sample flow. Teflon and Rulon made gaskets are less subject to build up, but are not
suitable for all applications. In addition, if the gaskets are subjected to temperatures outside
of their rating they will lose their shape and reduce the service life of the valve.
● A sample that contains non-volatile or easily polymerized components (salts, proteins,
monomers etc.) can deposit residues in the vaporizer (16), in the injection hole, on the
sample flow unit (15), and on the injection stem (6). Therefore, these parts should be
cleaned regularly if the sample contains materials which are not vaporized. See Exploded
View (Page 38).
● The sample flow unit (15) should be oriented vertically when the valve is installed. This is
so that the sample will flow vertically through the valve to prevent air bubbles from forming
in the valve. Make note of this when reinstalling the valve after service.
Part Locations
Throughout this section, the numbers located next to part names, such as “Flange (17)”, refer
to callouts listed in the Liquid Injection Valve Exploded View (Page 38).
Operational Notes
● If the sample has a corrosive effect on the surface of the injection stem (also called a tappet),
the stem must be replaced with a different material type (e.g. Hastelloy).
● Over time, particles from the sample build up on the gaskets and will eventually obstruct
the sample flow. Gaskets made of Teflon and Rulon are less subject to build up, but are
not suitable for all applications. In addition, if the gaskets are subjected to temperatures
outside of their rating they will lose their shape and reduce the service life of the valve.
Valves
4.2 Liquid Injection Valve
Maxum II Valves and Oven Components
Service Manual, 10/2018, A5E42019844001 37
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