Welch Vacuum 2028 Self-Cleaning Dry Vacuum System - Manual (Page 21)

21
Problem Possible Cause Solution
Mechanical Failures
Insuf
fi cient
V
acuum
External connection leak
•
Check and tighten all external tubing connections;
•
check tubing for cracks; tighten connections in
PTFE heads
Gas Ballast is On
•
Switch Gas Ballast to OFF position
•
Vacuum Control is not Closed
•
Closed Vacuum control (CW)
•
Jar “Intake Side” is not tightened in
•
place
Use Rubber Wrench to tighten jar
•
Check vacuum pump pressure with
•
external vacuum gauge, attached to
pump inlet fi tting
If external vacuum gauge pressure is the same
•
as unit’s display, problem is with faulty pump or
external connection leaks (mechanical problems)
Solenoid valve is not operating properly
•
Valve is always in closed position except purge
•
cycle. Remove valve silencer and plug valve inlet
with rubber stopper. If pressure drops it indicates
leaky valve.
Internal leak
•
Bad valve or bad diaphragm; both bad parts also
•
effect noise; if there is no vacuum, intake stage is
problem.
Vacuum level around 30-40 Torr indicates bad
•
exhaust stage, valve or diaphragm.
High noise
Bad valve or diaphragm
•
Change Valve / Diaphragm
•
Loose eccentric or counterweight
•
Tighten Loose Parts. Use Loctite
•
Broken diaphragm threaded insert
•
Change Diaphragm
•
Bad Con-Rod bearing or motor bearing
•
Change Con-Rod
•
Broken motor shaft
•
Change Shaft
•
Loose housing cover
•
Tighten housing screws on back of unit Slide rail
•
loose, remove housing cover and slightly crimp
slide rails on inner top of housing cover. Do not
over crimp
Loose inlet/outlet jars
•
Tighten jars
•
Damaged diaphragm
•
Check vacuum performance - See Poor Vacuum
•
section below If vacuum is still poor, contact
Welch Technical Support*
Excessive
vibration
Loose motor mounting screws
•
Tighten screws
•
Incorrectly installed counterweight or
•
wrong Counterweight
Failures described above also
•
contribute to excessive noise
Adjust/reinstall/change Counterweight
•
Slow
pump-
down
Indicates partially plugged passage,
•
usually in exhaust stage
Clean/Unplug Stage
•
Plugged silencer
•
Unplug /change silencer
•