TM 75053
ML330/FM
Figure 55. Barometer ML330/FM.
6. TECHNICAL CHARACTERISTICS:
1. NOMENCLATURE: Barometer ML330/FM.
Range of scale:
2. TYPE CLASSIFICATION: Standard A.
Actual:
In. of mercury _ _ _ 23.5 to 32.8 (9.3 in.);
3. SECURITY REQUIREMENTS: Unclassified.
21.2 to 32.8 (11.6 in.).
4. PRIMARY USE OR CONCEPT OF EMPLOYMENT:
Millibar _ _ _ _ 800 to 1,110 (310 mb);
Used as a reference standard for checking barometers.
717 to 1,110 (393 mb).
Effective:
5. BRIEF FUNCTIONAL DESCRIPTION:
In. of mercury _ _ _ 23.7 to 31.3 (7.6 in.);
Barometer ML330/FM is a precision mercurial barom-
21.5 to 31.3 (9.8 in.).
eter which is used with two precision aneroid barometers
as a set of reference standard barometers for weather
Millibar _ _ _ _ 805 to 1,060 (225 mb);
region control offices of the Army Air Forces. All baro-
725 to 1,060 (335 mb).
metric instruments in the region are to be compared with
Graduation:
two aneroid barometers for the purpose of bringing field
In. scale _ _ _ _ _ _ In 20th of an in. each
station instruments into agreement with the standard.
integral-in. is num-
Barometer ML330/FM is of such precision that each one
bered.
is individually calibrated with the U.S. Army primary-
Millibar scale _ _ _ In whole mb.
standard barometers at the U.S. Army Signal Research
Vernier, Measurement _ Permits reading to 0.002
T h e ML330/FM is
and Development Laboratory.
(1/500) in.
available in two ranges: for general use and for high alti-
Permits reading to 0.05
tude use. Barometer ML330/FM remains in the regional
(1/20) mb.
control office as the standard for the region.
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