Page 252 - Reciprocating Compressors Operation Maintenance

Overhaul and Repair of Reciprocating Compressors 2 37

knowledgeable enough to correctly interpret the information.
Choosing one instrument over another becomes a matter of skill
level and personal preference.
Regardless of the instrument used in taking web deflection read-
ings, a well-trained technician or mechanic holds the key to accurate
web deflection measurements. The more accurate the measurements
taken and the more precise the reading, the greater the amount of
information that will be available to determine the condition of a
compressor crankshaft. Combining this information with all other
factors and comparing it with previous records can be the difference
between a budget-depleting crankshaft failure or an online profit-
producing machine.

ELECTRONIC WEB DEFLECTION INDICATOR

A well-designed electronic web deflection system gives at least the
same degree of accuracy as the dial indicator, and sometimes more.
It can provide measurement readings of deflection to within one hun-
dredth of a thousandth of an inch (10 microinches). Being a digital
instrument, the system eliminates all guesswork as to measurement read-
ings, while also providing movement indication of either positive (+) or
negative (-) changes. The system provides up to a 15-foot cable between
the measuring instrument and the receiving digital unit. This means that
all readings can be taken outside the crankcase. For safety reasons and
just plain ease and comfort, this is a marked advantage. Remember, "hot"
web deflection occurs when unit temperature is 120°F and above. The
monitoring of web deflection readings during rotation of the crankshaft is
greatly facilitated with the digital readouts.
A major attraction of any well-designed electronic unit is ease of
placement in the webs. The preloading monitor lamps, digital angle and
deflection readouts, and being able to stay outside of the crankcase all
make the unit easy to train on and operate with confidence. An experi-
enced technician or mechanic using the electronic unit can take a series
of web deflection readings on several units in approximately half the
time than if using a conventional dial indicator approach.
For the system operator, accurate, unambiguous readings and indepen-
dence of operator technique are additional advantages. System-wide, his-
torical records allow the operator to monitor the performance of a single
machine over a period of time as well as to compare similar machines