Page 33 - Lehrbuch Neigungsmessung deutsch 2018.indd

COMPENDIUM INCLINATION MEASUREMENT
WYLER AG, WINTERTHUR / SWITZERLAND

5 PRECISION SPIRIT LEVELS

With the advent of the electronic age, the classic spirit level was expected to be outdated. Despite this,
the spirit level is still widely used and prized as a precision measuring instrument. Specialists in the measu-
ring field expect a measuring instrument to be easily understandable, simple to use and reliable. All these
expectations as well as excellent cost effectiveness are fulfilled by the spirit level. The heart of the spirit
level is the vial.
The precision of the spirit level is heavily influenced by the quality and the sensitivity of the vial. If a spirit
level with a sensitivity of 0.020 mm/m is inclined in such a manner that the bubble of the vial travels from
one line to the next (the standard distance from one line to the next line is 2 mm), then the spirit level was
inclined by 20 μm in relation to 1000 mm.
The vials of medium and high sen-
Ground vial for
sitivity are ground on the inside like precision spirit levels,
a barrel. The radius of this barrel radius = 5 ... 200 Meter
side conforms to the desired sen- Hight arc based on
sitivity and comes to about 200 m 80 mm = 160 ... 4 μm
when the vial has a sensitivity of
0.020 mm/m. The radius is about
5 m when the sensitivity is 0.500
mm/m.
The vials of WYLER precision levels are additionally mounted in a
steel tube. These tubes can be adjusted in the body of the spirit le-
vel by fine thread setting screws. This patented system allows exact
assembly and makes it possible for the necessary adjustments to be
effected.
Besides the precision of a vial, it is
quite clear that the body of the spi- Bent vial (low cost version),
radius = 0.5 ... 1 Meter
rit level has a great influence on the
performance. The material, mostly
cast iron or special steel must be free of tension. The treatment of the
material before and during the manufacturing process is of utmost
importance. The bases of a spirit level usually have two surfaces for
secure positioning on a measuring object. Prismatic bases are used
for measurements on shafts and
spindles. In addition, the bases can be equipped with magnetic inserts.

Of greatest importance is the fact that the axis of the vial must be ad-
justed parallel to the base’s contact surfaces. This is be done by grinding
and/ or manual scraping. Only by this process can it be guaranteed that
the instruments measure correctly even when the level is slightly placed
offset on a surface (no twist error).

Here a WYLER AG specialist
scrapes the base of a spirit
level

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