qǐng guān fámén.

请 makes the sentence polite. In front of a verb, it often works like please in English.

So:

• 关阀门 = close the valve
• 请关阀门 = please close the valve

A small nuance: 请 can sound a bit formal or direct depending on context. It is common in instructions, workplace speech, signs, and polite requests.

In Mandarin, the subject is often omitted when it is obvious from context.

So instead of saying:

• 请你关阀门

people often simply say:

• 请关阀门

This is very natural. In commands and requests, leaving out the subject is especially common.

Yes. 关 is the basic everyday verb meaning to close or to shut.

Examples:

• 关门 = close the door
• 关窗 = close the window
• 关灯 = turn off the light
• 关阀门 = close the valve

For a valve, 关 means to shut it so that flow stops.

阀门 means valve.

It is a two-character noun:

• 阀 = valve
• 门 = gate/door

But in modern Mandarin, 阀门 is the standard full word for valve. You should usually learn and use it as one vocabulary item.

Usually, 关阀门 is the safer and more standard way for learners.

In technical contexts, native speakers may shorten things and say 关阀 if the meaning is clear, but 阀门 is the normal full noun. If you are not sure, use 阀门.

The pinyin is:

• 请 = qǐng (3rd tone)
• 关 = guān (1st tone)
• 阀门 = fámén (2nd tone + 2nd tone)

A careful pronunciation would be:

qǐng guān fámén

A few tips:

• q in qǐng sounds somewhat like ch in English, but with the tongue placed more forward.
• guān rhymes roughly with gwan.
• fá and mén are both rising tones.

In normal speech, the 3rd tone in 请 is often not pronounced as a full deep dip; it may sound lower and shorter before the 1st tone.

Mandarin usually follows verb + object order here:

• 关 = verb
• 阀门 = object

So:

• 关阀门 = close the valve

With 请, the structure becomes:

• 请 + verb + object

This is a very common pattern:

• 请坐 = please sit
• 请进 = please come in
• 请开门 = please open the door
• 请关阀门 = please close the valve

Yes, 请关闭阀门 is correct.

The difference is mainly style:

• 关 = more common, everyday, direct
• 关闭 = a bit more formal or written

So:

• 请关阀门 sounds natural and straightforward
• 请关闭阀门 sounds slightly more formal, like workplace instructions, manuals, or signage

Yes, absolutely. That is also natural.

Compare:

• 请关阀门
  simple, direct: please close the valve

• 请把阀门关上
  also natural; the 把 structure emphasizes handling the object and completing the action

• 请关上阀门
  also fine; 上 suggests the action is fully completed

These are all possible, but 请关阀门 is the simplest pattern.

In 关上阀门, 上 is a result complement. It suggests that the valve gets fully shut.

So:

• 关阀门 = close the valve
• 关上阀门 = close the valve fully / shut the valve

In many situations, the difference is small, and both are natural.

It depends on context.

With 请, it is polite enough for many practical situations, especially:

• workplace instructions
• safety instructions
• technical communication
• notices or labels

However, it is still a fairly direct request. If you want to sound softer in conversation, you could say things like:

• 请你关一下阀门。
• 麻烦你关一下阀门。

Adding 一下 often makes the request sound lighter and less abrupt.

Mandarin does not use articles like a or the the way English does.

So 阀门 can mean:

• a valve
• the valve

The exact meaning depends on context.

If the speaker and listener both know which valve is meant, then English would often translate it as the valve, even though Mandarin does not need a separate word for the.

Not in this sentence.

Measure words are used mainly with numbers or demonstratives, for example:

• 一个阀门 = one valve
• 这个阀门 = this valve
• 那个阀门 = that valve

But after a verb like 关, you can just say the noun directly:

• 关阀门

That is completely normal.

Yes, it is the same character 门, whose basic meaning is door or gate.

But in 阀门, the whole word means valve. You should not try to translate it literally character by character in normal use. Just learn 阀门 as one complete noun.

This sentence fits practical, physical situations, such as:

• a factory
• a lab
• a gas or water system
• equipment maintenance
• emergency or safety instructions

It sounds like a real-world instruction rather than casual everyday conversation. That is why the vocabulary feels a bit technical.