Humboldt FD-4A, Product Manual

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Overview
The FD-4A force measuring adapter is engineered for accurate measurement of the force
in tensile stress testing in a ductility machine. The unit features a platform for test sample
placement and a stationery body which houses a linear variable differential transformer
(LVDT). The LVDT detects movement of the platform and displays force to hundredths of
a pound through the electronic digital transducer readout unit.
The FD-4A adapter is an improved version of the FD-4 apparatus. The FD-4A
incorporates design changes which improve performance and offer a wider range of force
measurements-up to 30 pounds. The unit is complete with a digital readout for the LVDT
mounted in the adapter, a calibration stand and weight holder.
Standard Features
• The FD-4A adapter is universal. It does not require any specific material, preparation,
procedure or type of test. It simply measures and displays the force applied to the
platform.
• No modifications to the ductilometer are necessary. The adapter can easily be
positioned without tools between the ductilometer stand and the sample to be
tested.
• The FD-4A is compact in size. The narrow width allows two units to be operated
simultaneously on one ductilometer stand. Its short length does not significantly
reduce overall ductilometer travel.
• Exclusive parallel spring design cancels out the width of the sample-only the tensile
force of the test is measured. The design also provides for frictionless movement and
there are no parts to wear.
• All electronic components are safely located out of the water bath. The digital
transducer readout unit incorporates an analog output for connection to a strip chart
recorder or data acquisition unit. Once started, tests can be monitored unattended
so technicians are free for other work.
• The stainless steel construction eliminates rust and corrosion.
• Each FD-4 unit is serially numbered and individually calibrated before shipment.
• Copies of the calibration results are sent with each apparatus.
New Features
• Two specially heat treated 0.091" thick stainless steel spring plates replace the two
pair of 0.031" shim material. Travel distance per pound of force is ten times less
and maximum tensile stress measurement capacity is doubled to 30 pounds without
danger of spring deformation.
• Improved display stability for “English”, “Metric”, “Span” and zero adjustments.
The miniature circuit board trimmers in the readout unit have been replaced with
ten turn wire round precision potentiometers. Additionally, the range of the “Zero”
adjustments has been reduced to increase ease of setting.
• A ground wire from the FD-4A directly to the digital readout unit prevents drifting of
the display due to partial grounding or other interference.
• The analog output is calibrated lower to 0.1 VDC/pound of force with a maximum
output of 3.0 VDC. This range is more compatible with strip chart recorders and data
acquisition equipment.
• The metric display is changed from three decimal places to two that is closer to the
sensitivity of the English scale.
• Since a calibration stand is now included, the FD-4A can be checked for accuracy at
anytime. This ensures consistent results from test to test as well as from one lab to
another.