Page 48 - Reciprocating Compressors Operation Maintenance

Reciprocating Compressors and Their Applications 35

1. Discharge pressure required.
2. Capacity required.
3. Power supply characteristics.
4. Availability and cost of cooling water.
5. Space required for compressor,
6. Compressor weight.
7. Type and size of foundation required.
8. Type of control required.
9. Maintenance costs.

The initial choice is between the two basic types, positive displace-
ment and dynamic. Once this decision is made, you can make a further
study of the characteristics of various compressor types to see which one
will be best for the job. Keep in mind that the selection of a compressor
is an engineering decision in which every factor should be considered.
Remember, the average life of a compressor is usually 20 years or more,
so every decision made that affects the operating cost will be in effect for
a long time.

REVIEW OF SELECTION POSSIBILITIES

For a quick review of possibilities, it is best to consider only horse-
power and pressure. The upper limits for each type are summarized from
previous references. These columns do not usually apply simultaneously.
Figure 1-19 shows the approximate application ranges for reciprocat-
ing, centrifugal, and axial flow compressors.

Approx. Max.* Approx. Max.
Compressor Type BHP Power KW psig

Reciprocating 20,000 15,000 100,000
Vane Type Rotary 860 Twin Unit 640 400
Helical Lobe Rotary 8,000 6,000 250
Centrifugal Dynamic 60,000 45,000 10,000
Axial Flow Dynamic 100,000 74,600 500
*These maximums are subject to certain limitations imposed by other factors and under
certain conditions can be exceeded.