The meaning of \"switched\" in a sentence
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The ethylene double block and bleed valves are first switched on in order to open the ethylene supply line, while the seven ethylene feed flow control valves remain closed. Last edited by beileim1 on 2009-2-20 15:33]
Switch refers to a switch; it should be turned on here
It implies a direction, so it’s translated as “open” here; there’s a “close” afterwards
The ethylene double block and bleed valves are first switched on in order to open the ethylene supply line, while the seven ethylene feed flow control valves remain closed. It should be noted that double block and bleed is a safety-approved method of isolation: it involves using two valves for isolation along with a bleed valve, with the valves before and after the bleed valve being closed while the bleed valve itself is opened. \"Switched\" here refers to the transition from an isolated state to an operational state, including actions such as opening the isolation valves, closing the backflow valves, and purging the system. The overall meaning of this sentence is that it is necessary to put the ethylene feed line into operation; therefore, I translate it as: First, remove the isolation from the ethylene valves and backflow valves so that the ethylene feed line can be activated, at which point the seventh ethylene flow control valve on this line is closed
It is more appropriate to translate this as “open” here
Here, switch means to turn on, corresponding to close later on
Double Block and Bleed can be translated as “double shut-off bleed valve.” Its structure consists of two block valves (shut-off valves, usually ball valves) along with a bleed valve (a release valve, usually a needle valve); in other words, two ball valves and one needle valve are combined to form a single unit. Its main purpose is to be used in high-pressure applications within the natural gas industry, for connecting instruments such as pressure gauges, pressure sensors, level gauges, etc., or for sampling natural gas pipelines and injecting chemical agents. The selection principle is as follows: a Single Block and Bleed Valve (i.e., a ball valve combined with a needle valve) is used when the pressure is below 900 cl, while a Double Block and Bleed Valve is used when the pressure is above 900 cl. When the valve is fully closed or fully open, and when there is pressure in the pipeline, the pressure in the hollow part of the valve body can be reduced to zero ； The drain port provided on the valve body can be used to remove water, dirt, sediment, and other substances that have accumulated in the hollow part of the valve body.