German term (edited): Öffner fallend

Normally Closed (NC) valves or contacts. These are designed to be normally closed and to open on input. In this case the valve or contact opens to 280 mm. Hope this helps :)

The term standardized by IEC is "break contact", but other designations as NC contact, N/C contact, normally closed contact are also common.

Area Elementary relays / Output circuits
IEV ref 444-04-18
en break contact (for elementary relays)
contact which is open when the relay is in its operate condition and which is closed when the relay is in its release condition
de Öffner (eines Elementarrelais), m
Ausschaltkontakt (eines Elementarrelais), m
http://www.electropedia.org/iev/iev.nsf/display?openform&iev...

opener der Öffner Pl.: die Öffner
break contact [TECH.] der Öffner Pl.: die Öffner
"b" contact [ELEKT.] der Öffner Pl.: die Öffner
normally closed contact [Abk.: NCC] [TECH.] der Öffner Pl.: die Öffner
https://dict.leo.org/englisch-deutsch/Öffner

break contact contact which is open when the relay operated and closed when the relay is released.
https://books.google.de/books?id=aN0gBQAAQBAJ&pg=SA16-PA8&lp...
(Electronics Engineer's Reference Book)

A normally closed (NC) contact pair is closed (in a conductive state) when it, or the device operating it, is in a deenergized state or relaxed state.[citation needed]
A normally open (NO) contact pair is open (in a non-conductive state) when it, or the device operating it, is in a deenergized state or relaxed state.[
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The National Association of Relay Manufacturers and its successor, the Relay and Switch Industry Association define 23 distinct forms of electrical contact found in relays and switches.[5] Of these contact forms, the following are particularly common:
Form A contacts ("make contacts") are normally open contacts. The contacts are open when the energizing force (magnet or relay solenoid) is not present. When the energizing force is present, the contact will close. An alternate notation for Form A is SPST-NO.[5]
Form B contacts ("break contacts") are normally closed contacts. Its operation is logically inverted from Form A. An alternate notation for Form B is SPST-NC.[
https://en.wikipedia.org/wiki/Electrical_contacts

What is the most common designation?

"break contact"
About 317.000 results (0,35 seconds)
https://www.google.de/search?biw=1054&bih=690&ei=qyuKXMH8HsG...

"normally closed contact" About 313.000 results (0,31 seconds)
https://www.google.de/search?biw=1054&bih=690&ei=miyKXL3oMsP...

"NC contact" About 567.000 results (0,37 seconds)
https://www.google.de/search?biw=1054&bih=690&ei=1yyKXPLzAom...

and with "closes":

"normally closed contact closes" About 9.280 results (0,35 seconds), e.g.:

A normally-open contact closes at "1" and opens at "0". A normally-closed contact closes at "0" and opens at "1".
https://www.google.de/search?biw=1054&bih=690&ei=Cy6KXL-PDIv...

"NC contact closes" About 7.430 results (0,55 seconds), e.g.:

The temperature setting minus switch temperature difference (and tolerances) equals to the lower switch point, which means that the NC contact closes.
https://www.stego.de/en/products/regulating/regulators/fzk-0...

"N/C contact closes" About 1.200 results (0,98 seconds), e.g.:

When normal power drops out, the relay coil is deactivated, and N/C contact closes, creating the pathway for the emergency backup power to flow.
https://www.google.de/search?biw=1054&bih=690&ei=qS-KXN6hPMn...

"break contact closes" About 2.490 results (0,25 seconds), e.g.:

The relay also de-energizes (break contact closes) if no radio signal is received for at least 270s.
https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd...

I do add (at 280 mm), even this specification is not very clear. It may refer to any liquid level or distance.

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Note added at 3 days 19 hrs (2019-03-17 11:03:01 GMT) Post-grading
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Even the question has been closed I think it being useful to focus on the differences between the terms N/C and break. As seen below, the terms "normally open contact" and "break contact" are used interchangeably. There is only one slight difference: "normally open/closed contacts" are attributed regularly to contacts not regarding electrical loads as for relay contact configuration, and "break/make contacts" are related frequently to devices switching circuits.

An electrical contact is an electrical circuit component found in electrical switches, relays, connectors and circuit breakers.
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When the contacts touch, the switch is "closed"; when the contacts are separated, the switch is "open".
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Schematic for an electromechanical relay showing a coil, four pair of normally open and one pair of normally closed contacts
:
Form A contacts ("make contacts") are normally open contacts. The contacts are open when the energizing force (magnet or relay solenoid) is not present. An alternate notation for Form A is SPST-NO.
Form B contacts ("break contacts") are normally closed contacts. Its operation is logically inverted from Form A. An alternate notation for Form B is SPST-NC
Form C contacts ("change over" or "transfer" contacts) are composed of a normally closed contact pair and a normally open contact pair that are operated by the same device; there is a common electrical connection between a contact of each pair that results in only three connection terminals. These terminals are usually labelled as normally open, common, and normally closed (NO-C-NC). An alternate notation for Form C is SPDT.
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Form Z or double-make double-break contacts are comparable to Form C contacts, but they almost always have four external connections, two for the normally open path and two for the normally closed path. As with forms X and Y, both current paths involve two contacts in series, mechanically linked and operated by a single actuator. Again, this is also described as an SPDT contact.
https://en.wikipedia.org/wiki/Electrical_contacts

A float switch is a type of level sensor, a device used to detect the level of liquid within a tank. The switch may be used to control a pump, as an indicator, an alarm, or to control other devices.
One type of float switch uses a mercury switch inside a hinged float. Another common type is a float that raises a rod to actuates a microswitch. One pattern uses a reed switch mounted in a tube; a float, containing a magnet, surrounds the tube and is guided by it. When the float raises the magnet to the reed switch, it closes.
https://en.wikipedia.org/wiki/Float_switch

A miniature snap-action switch, also trademarked and frequently known as a micro switch, is an electric switch that is actuated by very little physical force, through the use of a tipping-point mechanism, sometimes called an "over-center" mechanism.
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The internals of a micro switch. Contacts, from left to right, are common, normally open, and normally closed.
https://en.wikipedia.org/wiki/Miniature_snap-action_switch

liquid level switch - break contact
https://gallery.proficad.eu/Symbols/house-electrical-symbols...

9.1.2 Operating mode selector switch
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The device completes the circuit in the dry state (empty state) so that a fault at the device in the wiring results in a voltage drop that causes an alarm to be triggered (break circuit). Conversely, if the switch is to WET-ON, the device operates as n N/O contact (lower limiter) in fail-safe mode, in which case the fork is normally immersed in liquid.
https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd...

Contact “Normal” State and Make/Break Sequence
Chapter 4 – Switches
Any kind of switch contact can be designed so that the contacts “close” (establish continuity) when actuated, or “open” (interrupt continuity) when actuated. For switches that have a spring-return mechanism in them, the direction that the spring returns it to with no applied force is called the normal position. Therefore, contacts that are open in this position are called normally open and contacts that are closed in this position are called normally closed.
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Multiposition switches can be either break-before-make (most common) or make-before-break.
https://www.allaboutcircuits.com/textbook/digital/chpt-4/con...