wstf supports an extensive number of test programs
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WSTF supports an extensive number of test programs, most of which are instrumented for temperature, pressure,
load, acceleration, and other measurements. The WSTF Measurement Standards and Calibration Laboratory
ensures that the instruments used to make these measurements are accurate by calibrating them against recognized
standards. A two-level tier of standards is used. The first level contains high-accuracy reference standards. These
standards are traceable to the National Institute of Standards and Technology (NIST), and their accuracy is known in
terms of national standards. Reference standards are highly stable and repeatable; for example, measurement
uncertainty of the voltage standard is less than 0.5 ppm. The second level of standards is a group of 80+ working
standards. These standards are calibrated by the reference standards and used to calibrate customer instruments in
25 major measurement disciplines.
The Measurement Standards and Calibration Laboratory has experience in providing support to NASA, other
government agencies, and private industry. Current customers include NASA, U.S. Air Force, and U.S. Army. The
Measurement Standards and Calibration Laboratory is certified to meet the ISO 9001 Standard.
Mechanical Laboratory
Mechanical calibration is primarily based on mass and length, both of which exist in the form of artifacts. The other
mechanical measurements are derived from these basic units. Temperature is defined by the ITS-90 (International
Temperature Scale of 1990) in terms of the melting and freezing points of pure materials as measured by a
standardized platinum resistance thermometer.
Physical Standards: WSTF can calibrate mass within the range of 0.5 micrograms to 30 kilograms, and length in a
range from 50 microinches to 120 inches (1.3 m to 3 m).
Pressure Calibration Laboratory:WSTF has two deadweight pressure systems: 1000 psi (7 MPa) and 10,000 psig
(70 MPa). They operate using the basic definition of pressure-force per unit area. In this case, weights are placed on
a piston giving pounds per square inch (psi). Using very small area pistons, it is possible to generate 10,000 psi (70
MPa) without placing 10,000 lb (4 Mg) of weight on the piston. The 1000 psi system can be operated in absolute
(vacuum reference) or gauge (atmosphere reference) mode.
Straight Pressure Calibration Stations: WSTF has five stations with four different pressure ranges: 0 to 30 in. of
water (7 kPa), 0 to 1000 psia (7 MPa) (one manually operated and one fully automated), 0 to 10,000 psia (70 MPa),
and 0 to 30,000 psig (21 MPa).
Differential Pressure Station: WSTF has the capability of holding a base pressure of up to 250 psig (1.7 MPa) while
measuring differentials in the range of 0 to 100 psi (700 kPa), or we can do differentials vs. atmospheric pressure up
to 1,000 psig (7 MPa).
Flow Calibration Laboratory
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Liquid (Incompressible):The liquid used is water, and WSTF can measure flows from 0.4 to 400 gal/min (1.5 to
1,500 L/min).
Gas (Compressible): WSTF has the capability of flowing nitrogen, helium, compressed air, or anything
nontoxic/nonflammable that can be supplied in a standard DOT pressure bottle in the lower flow ranges: 0.0008 to 12
SCFM (0.37 to 5,400 cm3/s). In the higher flow ranges up to 200 SCFM (90,000 cm3/s) only nitrogen is available, but
WSTF can test with any nontoxic/nonflammable gas the customer can supply in sufficient quantity/pressure. One
customer supplied a helium tube bank semitrailer for high flow calibrations.
Temperature and Humidity Laboratory
Temperature: WSTF's temperature lab uses Standard Platinum Resistance Thermometers (SPRT) calibrated to ITS-
90 as the primary standard, and can calibrate in the range from -197 C (liquid nitrogen) to 500 C.
Humidity: WSTF's humidity standard and chamber can calibrate in the range of 1 to 98 percent relative humidity,
within a temperature range of 15 to 30 C (normally 20 to 23 C).
Force and Tool Calibration: We can calibrate force measuring devices in tension or compression up to 50,000 lbf
(220 kN). We can also calibrate cable tensiometers vs. weights.
Torque Wrenches: WSTF can calibrate torque wrenches in the range of 3 in-oz to 1,000 ft-lb (0.02 to 1,400 N-m).
Crimpers and Strippers: WSTF can gauge, inspect, and conduct pull tests for a wide range of these tools.
Vacuum Calibration Laboratory: WSTF has a vacuum calibration system, with a range from 1000 torr (100 kPa)
(760 torr is atmospheric pressure) down to 10-7 torr (10 Pa).
Software Engineering: Computer-aided calibration systems are used extensively at WSTF. Both off-the-shelf and
custom designed, written by in-house staff programmers, are utilized. Electronic data can be provided upon customer
request.
Electrical Laboratory
The Electrical Calibration Laboratory provides calibration and repair services for a wide variety of equipment types
including:
Resistance and capacitance decade boxes
Digital and analog multimeters
Power supplies
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Electronic loads
Thermocouple simulators and readouts
Current shunts
Digitizing and analog oscilloscopes
Microwave signal generators Spectrum analyzers
Power sensors
Equipment outside of WSTF capabilities are outsourced to the manufacturer or other government laboratories,
allowing customers to use WSTF's laboratory as a single source for all of their calibration support requirements.
Expense statements are provided quarterly to all non-WSTF customers.
Microwave Station
Electrical Laboratory: This station is used to calibrate microwave signal generators, spectrum analyzers,
attenuators, frequency counters, amplifiers and other associated equipment. The system consists of measuring
receiver, mixer, local oscillator, microwave signal generator, and spectrum analyzer. The system uses automated
calibration software for most of the microwave signal generators calibrated by WSTF. Software is also used for most
attenuator and spectrum analyzer calibrations.
Scope Station:All of the oscilloscopes calibrated by WSTF are done at this station. The standard is a calibration
generator for timing and amplitude accuracy, and a signal generator for bandwidth measurements. This system is
controlled by MET/CALsoftware procedures. Seventy percent of the oscilloscopes are calibrated using
MET/CAL
procedures.
Digital MultiMeter (DMM) Station: There are two calibration standards at the DMM station: a multifunction calibrator
and a multiproduct calibrator. A custom subroutine was written by WSTF to allow MET/CALto control the
multifunction calibrator, which is used to calibrate all of the benchtop multimeters of 5-1/2 digit or greater resolution.
Seventy-five percent of these meters can be calibrated in a fully automated fashion using MET/CALprocedures
written by WSTF. The multi-product calibrator is used for the rest of our DMM workload, along with some
thermocouple readouts and simulators. Ninety percent of the handheld DMMs are calibrated using
MET/CALprocedures.
Reference Standards: WSTF Measurement Standards and Calibration Laboratory reference standards are
maintained in the shield room. The volt is represented by a bank of three voltage cells. They are calibrated by the
NASA Portable Josephson Array Voltage Standard (PJAVS). The PJAVS returns to WSTF approximately every 6 to 9
months. The ohm is represented by an Thomas-type1-ohm standard resistor. This resistor was originally acquired in
1964, and since then has been the WSTF ohm standard. The value of this resistor is maintained by annual
calibrations by higher laboratories, primarily NIST and the Primary Standards Laboratory at Sandia National
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Laboratories. Additionally, WSTF is participating in the NASA Ohm Measurement Assurance Program administered
by Kennedy Space Center.