Abu Dhabi Gas Liquefaction Company Ltd Job Training Mechanical Technician Course Module 9 Compressors

4.1.3 Cylinder 
Arrangements 
The simplest reciprocating pump has a single cylinder. This may have its axis 
horizontal, as shown in Figures 4.3 and 4.4 or vertical, as shown in Figure 4.6. 
Figure 4.5: Suction and Discharge Snubbers—Two Cylinders in Parallel 
Figure 4.6: Small Vertical Compressor
Suction 
snubber 
Discharge 
snubber 
Two 
reciprocating 
cylinder ends 
Compressor 
suction
Compressor 
discharge

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Personnel & Training Division
Job Training—Mechanical Technician 
Compressors/Rev. 0.0 
Page 19 of 90
Multi-cylinder compressors have more than one cylinder. Each cylinder has its own 
piston, piston rod, crosshead, connecting rod and valves, just like a single-cylinder 
compressor. These moving parts are operated by the same crankshaft. The cylinders 
may be arranged in a number of different ways: 
• in-line (vertical or horizontal) 
• balanced-opposed 
• L-type (or angle-type) 
• V-type 
• W-type 
In-line compressors have two or more cylinders mounted side-by-side. All cylinders 
are located on the same side of the crankshaft. These can be designed to operate 
vertically or horizontally. Figure 4.7 shows a small two-cylinder, in-line compressor 
with pistons driven directly from the connecting rods (without crossheads). 
Figure 4.7: Two-cylinder, In-line Vertical Compressor 
Cylinders 
Crankshaft 
Suction 
filter 

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Personnel & Training Division
Job Training—Mechanical Technician 
Compressors/Rev. 0.0 
Page 20 of 90
Balanced-opposed compressors have horizontal cylinders located on opposite sides of 
the crankshaft as shown in Figure 4.8. 
With pistons moving in opposite directions there is less vibration and the compressor 
is better balanced. There are always an equal number of cylinders on each side of the 
crankshaft. Most ADGAS reciprocating compressors are balanced-opposed.