The drain screw of fuel oil sludge tank to be changed with valve or cock .

燃油沉淀柜的排放螺杆应改为 阀或 旋塞。

Open upstream slowly fill the valve and bleed the air through Test cock 2 3 and 4 .

慢慢开启上游，注满 阀门，通过测试 旋塞2，3和4号排放空气。

Connect bypass hose between vent needle valve and loosely connect to test cock No.1 .

在排气针形 阀上连接旁路软管，并将其松散连接到测试 旋塞1号上。

The shutoff valve with the test cock is to be mounted on the inlet side of the backflow preventer .

带测试 旋塞的关闭 阀安装在防回流阀的进口一侧。

This is a gate valve ( check valve butterfly valve cut-off valve magnetic valve remote valve relief valve throttle valve cock ) .

这是一个闸阀（止回阀、蝶阀、切断阀、电磁阀、遥控阀、安全阀、节流 阀、 旋塞）。

The characteristics and application of the cock valves were introduced in detail in view of the fact that oil seal cock valve and pressure equilibrium conical oil seal cock valve were in use worldwide in oil and gas transportation piping .

并根据世界各国的输油及输气管线广泛采用油封式旋塞 阀和压力平衡式倒锥油密封 旋塞阀的情况，重点介绍其特点和应用。