Level floater

[AG]

Фраза:
The clutch that will hold from below the liquid level should be blocked neither by feeding or emptying pipes of the container, nor the boiler. Otherwise, the counter current that might come out within the boiler or the container may cause an impact on the internal level of the regulator.

Подскажите, pls, что могут означать:
1) The clutch that will hold from below the liquid level...
2) internal level

Спасибо.

[Фифа]

2) внутренний уровень (жидкости)

[AG]

Спасибо.