User guide

Section 5: TROUBLESHOOTING

5.10 VACUUM PROBLEMS

Welch dry vacuum pumps are 100% oil-free. The pump employs a non-lube piston and

cylinder. Leakage, contamination and unusual outgassing are the general causes of problems

with poor vacuum. To operate at maximum efﬁ ciency a system must be thoroughly clean. If

the system is completely clean and free from leaks, and unwarranted vacuum problems still

exist, the pump should be checked. A simple criterion for the condition of the pump is the

determination of its maximum vacuum capability. This can be accomplished by blocking of the

intake and reading the vacuum level on the gauge (See Section 2.8).

5.20 TROUBLESHOOTING TABLE

Poor

Pumping

Speed

Poor

Vacuum

Loud

Unit

Possible Cause Corrective Action

X X X Damaged valves Replace ﬂ apper valves

X X X Debris in valves Remove debris and check for valve damage

X X X Damaged gasket Replace gasket

X X X Loose head screw Tighten head screw

X X X Loose ﬁ tting Tighten ﬁ tting