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 TM 55-1905-219-14-9
4-64.1. TANK LEVEL INDICATION-RECEIVER-MAINTENANCE INSTRUCTIONS.
a.
General.
(1) Receivers convert the electrical signals generated by the fluid level detection devices (transmitters)
to deflections on meters calibrated in gallons.
(2) The receiver also examines electrical signal levels to develop an alarm condition if the fluid level in
the tank rises above or falls below preselected levels. The alarm provides both audible and visual indications.
b.
Detailed Block Diagram.
(1) Receiver Panel. (See Foldout 2.)
(a) The stages that perform the level indication, alarm detection, and alarm indication
functions for a given tank when using a receiver panel are shown below. A potential of +17 volts dc is applied
through calibration network RP1-R1 contained on a receiver panel control module that is associated with the
tank whose contents--are to be indicated. The calibration network contains Calibrate potentiometer RP1 which
is adjusted for full-scale deflection of fluid level meter M, the meter on the receiver panel that is associated with
the control module. The adjustment of this potentiometer produces a calibrate voltage that is dropped across
the fluid level detection device(s).
(b) A portion of the calibrate voltage applied across the full fluid level detection device(s)
appears as a level signal at the out-put of the device(s). The portion of the calibrate voltage (and, therefore,
the amplitude of the level signal) is determined by the height of the fluid level in the tank. The level signal is
applied through normally closed contacts of calibrate switch S1 on the same control module to slosh
dampening network R2-R3-C1. The slosh dampening network intergrates the signal to produce a slosh
dampened meter signal. As a result of the intergrating action, the effect of the sloshing of fluid in the tank is
minimized.
(c) The slosh dampened meter signal is applied to fluid level meter M(1) directly via a
jumper connected between terminals 4 and 5 on the terminal board associated with the meter. The signal
produces deflection on the meter that is proportional to the height of the fluid level in the tank. The meter is
calibrated to provide the desired indication.
(d) The fluid level signal that determines the magnitude of meter deflection is also applied to
alarm circuits in the control module (one high-level alarm circuit and one low-level alarm circuit). The high-
level alarm circuit is in an alarm circuit position on the control module: the low-level alarm circuit in an alarm
circuit position .
4-1330
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