Reciprocating compressor
Reciprocating compressor
(OP)
Hi All
How can I estimate the cylinder pressure and "rod load" (force on the crosshead pin, in compressor terminology) in a double-acting reciprocating compressor ?
How the volume of liquid present inside the cylinder can effect in the piston, piston rod bending?
Thanks for help
How can I estimate the cylinder pressure and "rod load" (force on the crosshead pin, in compressor terminology) in a double-acting reciprocating compressor ?
How the volume of liquid present inside the cylinder can effect in the piston, piston rod bending?
Thanks for help





RE: Reciprocating compressor
In many systems where we use reciprocating compressors, the discharge pressure is constant and we must be very careful that we never allow the suction pressure to become too low which would exceed our rod loading limit. It is good idea to have automated alarms to alert you if you are getting a high rod load.
The volume of gas present in the cylinder is not important. The pressure is the key.
The method I refer to does not take into account the pressure drop across the suction and discharge valves. I am assuming that the pressure drop is the same for both. If that is true, the affects cancel each other out, approximately. That is to say, the pressure in the outer end is slightly higher than discharge pressure and the pressure in the frame end is slightly lower than suction pressure. The net force is approximately the same.
RE: Reciprocating compressor
RE: Reciprocating compressor
Visit thread135-76261.
Besides, as JJPellin explained, discharge gas temperatures are often used as alarms or cutouts to protect the rods rather than the lubricant, since high temperatures may indirectly serve to indicate high pressure ratios with possible overstressing of the rod.
RE: Reciprocating compressor
Liquid in a cylinder and pressure! The pressure will go to infinty because the liquid won't pass through the valves quick enongh and it won't compress. You will se broken, bent, distroyed rod, crossheads... I even saw a fly wheel weld it itself to the crank when the cylinder was had some water in it and it stopped the compressor cold.
RE: Reciprocating compressor
For an 8-inch cylinder with 3.5 inches of stroke and 6% built-in clearance, you can ingest 5.84 fluid oz (not quite 2/3 cup, 173 mL) without a problem, but 5.9 oz would probably break something.
David