It is the key study how to make sure the pressure distribution of liquid in the pump barrel and to study the pump valve-ball's movement to improve the systematic efficiency.

对有杆抽油泵泵阀运动规律的研究和确定抽油泵泵阀筒内液体压力的分布是提高抽油机井系统效率研究的关键性课题。

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The pump barrel of the hand-press pump is arranged in a liquid medicine box, and the pressure storage barrel is usually arranged at the outer side of the liquid medicine box.

手压泵的泵筒设置在药液箱里，手压泵的储压筒一般设置在药液箱外。

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Members of Opec, made up of the world's major oil producers, have come under pressure to do something to stop the recent sharp rises in the cost of a barrel.

BBC: Opec agrees output boost