CST NIST Handbook 44 Standards 2 — Questions and Answers
Question 1: According to NIST HB 44, what is the maximum allowable difference between the zero-load reference value and the zero reading after a weighing operation?
- One-fourth the value of the smallest division (Correct answer)
- One-half the value of the smallest division
- One full scale division
- Two scale divisions
Correct answer: One-fourth the value of the smallest division
NIST HB 44 requires that zero-load balance be maintained within one-fourth of a scale division for most commercial weighing devices.
Question 2: Under NIST HB 44, which of the following is classified as a 'Type III' weighing system?
- A railroad track scale
- A vehicle scale
- A crane scale or hanging scale (Correct answer)
- A retail computing scale
Correct answer: A crane scale or hanging scale
NIST HB 44 classifies crane (hanging) scales as Type III devices, which have specific tolerance and performance requirements.
Question 3: What does the abbreviation 'MWC' stand for in NIST HB 44 scale specifications?
- Maximum Weight Capacity
- Minimum Weight Certification
- Maximum Weighing Capacity (Correct answer)
- Measured Weight Coefficient
Correct answer: Maximum Weighing Capacity
MWC stands for Maximum Weighing Capacity, the greatest load a device is designed to measure under normal operating conditions.
Question 4: Which NIST HB 44 requirement applies to the 'shift test' performed on a platform scale?
- Place the test load in the center only
- Place the load sequentially in each quadrant and record variations (Correct answer)
- Apply two separate loads simultaneously
- Test only at maximum capacity
Correct answer: Place the load sequentially in each quadrant and record variations
The shift test requires placing the test load sequentially in each quadrant (or section) of the platform to verify that off-center loads produce readings within tolerance.
Question 5: NIST HB 44 defines 'maintenance tolerance' as:
- The tolerance applied during initial type approval testing
- The tolerance that in-service devices must not exceed during field inspection (Correct answer)
- The tolerance used only when calibrating laboratory standards
- The tolerance for devices manufactured before 1970
Correct answer: The tolerance that in-service devices must not exceed during field inspection
Maintenance tolerances in NIST HB 44 are the wider tolerances applied to devices already in commercial service during routine weights and measures inspections.
Question 6: According to NIST HB 44, a device found to underweigh by more than the applicable tolerance during an official inspection should be:
- Adjusted and retested immediately without notifying the owner
- Condemned and removed from service or adjusted before further use (Correct answer)
- Allowed to remain in service if the error is less than 2%
- Sealed in its current condition pending annual reinspection
Correct answer: Condemned and removed from service or adjusted before further use
Devices exceeding maintenance tolerances must be condemned (placed out-of-service) or adjusted and brought within tolerance before continued commercial use.
Question 7: What is the purpose of the 'sensitivity requirement' specified in NIST HB 44 for nonautomatic weighing instruments?
- To ensure the device can detect small changes in load near any point in its range (Correct answer)
- To establish the maximum load the device can sustain without damage
- To define the minimum environmental temperature for operation
- To set the required number of decimal places on the display
Correct answer: To ensure the device can detect small changes in load near any point in its range
The sensitivity requirement ensures that a small additional test load causes a noticeable and consistent change in the indicator, verifying adequate resolution throughout the scale's range.
CST NIST Handbook 44 Standards 2
According to NIST HB 44, what is the maximum allowable difference between the zero-load reference value and the zero reading after a weighing operation?