Issue of comprehensive piston force and nominal piston force in reciprocating compressors (solved)
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This post was last edited by sunnyyulu on 2015-8-20 at 15:48. Today I came across a document regarding the maximum allowable load on piston rods, which states that \"the combined piston force under design conditions (including gas forces) should not exceed 80% of the nominal piston force of the selected model.\" Where can I find this source? In that standard?
You can check the standards. . . . . . . . . .
It should be introduced in API618; you can check that out
It was not found in API 618; Section 6.6, which deals with piston force and gas force, only provides calculations
Excuse me, is that included in that standard? It was not found in neither API 618 nor SH 3143
Stop looking into it – there’s no such rule. Piston force is divided into gas force and combined piston force; stationary components are subjected to gas force, while moving components are subjected to combined piston force. Generally, the value of the combined piston force is 80% of that of the gas force. Over time, it evolved so that the actual maximum combined piston force is 80% of the allowable value. In other words, more margin is left in this calculation, but actually there’s no need for that, as manufacturers already include a design margin when creating their designs.
One more question: does nominal piston force refer to the gas force? Or the combined piston force? In the manual, gas force is referred to as piston force in our country, while piston rod force is called comprehensive piston force in our country.
Help take a look at this: http://bbs.hcbbs.com/thread-1429491-1-1.html
Now, the machine models of various manufacturers are such as 6M25; here, the 25 denotes a gas force of 25 tons, and it does not refer to the overall force
Yes, this is gas force. The serialization and grading of compressors are based on gas dynamics. Which nominal piston force is being referred to?
For safety reasons, compressor manufacturers choose 80% when designing their products