Humboldt FD-4A, Product Manual

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• If you have an FD-4 adapter, it can be upgraded and the readout recalibrated to
FD-4A specifications. The FD-4 does not become obsolete since you can build on
your current investment.
Apparatus
FD-4A Adapter:
The body of the FD-4A adapter is drilled on the bottom such that it can be placed
directly on the pin of either the ductilometer stand or carriage. It is constructed of
stainless steel for corrosion resistance and stability while it functions to protect the LVDT
and keep it out of the water bath. Attached to the top of the body are two parallel
stainless steel spring plates which project down into the water and hold a movable
platform onto which the test specimen is placed. An arm, fastened behind the spring
plates, rises up and positions the core in the LVDT coil in exact relationship to the
movement of the platform so that a force measurement can be determined.
Transducer:
The AC operated LVDT features a stainless steel housing to provide electrostatic and
electromagnetic shielding. It has a high density, glass filled polymer inner sleeve, which
has low moisture absorption and excellent thermal stability. The coils are vacuum
impregnated with varnish and epoxy encapsulated. The core is hydrogen-annealed
nickel-iron for low harmonics, low null voltage and high sensitivity.
Digital Transducer Readout:
The DTR-451 is a self contained, power line operated, high stability LVDT signal
conditioner with a 4-½ digit readout. It supplies a high frequency AC voltage for the
LVDT and a 0 to 3.0 VDC analog output for data acquisition interfacing. A switch on the
front panel can change the display from pre-scaled English units to pre-scaled metric
units.
Calibration Stand:
This one piece phenolic block has a ledge and stainless pin to hold the FD-4A for
calibration checks. It is lightweight and not susceptible to rust or corrosion. Other
components which might come in contact with water or brine or stainless steel. An
acrylic level vial is built into the stand for convenient leveling during set-up. Two
countersunk screw holes are provided for permanent mounting or as an alternative,
the back end has a 1 ½" long extension where a clamping device maybe located. The
aluminum cable wheel is fitted with a ground ball bearing for low friction movement.
Besides its calibrating function, the stand provides a safe resting place for the adapter
when it is not in use.
Weight Holder (weights not included):
The weight holder will accommodate a maximum load of 30 pounds and itself is
calibrated to weigh one pound (less cable and platform block). The nickel plated steel
bottom has a ¼" diameter stainless shaft which allows for 9 ½" of combined weight
height. The replaceable stainless steel cable has been selected for flexibility and
strength. It has a drilled brass pull block attached on the other end to fit on the platform
pin of the FD-4A adapter during calibration.