Instrument Percent of Span Error

An important part of performing instrument calibration is determining the extent of an instrument’s error. Error is usually measured in percent of span.

Calculate the percent of span error for each of the following examples, and be sure to note the sign of the error (positive or negative):

Question 1:

Calculate the percent of span error for Pressure gauge as per the below details.

LRV = 0 PSI
URV = 100 PSI
Test pressure = 65 PSI
Instrument indication = 67 PSI

Question 2:

Calculate the percent of span error for weigh scale as per the below details.

LRV = 0 pounds
URV = 40,000 pounds
Test weight = 10,000 pounds
Instrument indication = 9,995 pounds

Question 3:

Calculate the percent of span error for thermometer as per the below details.

LRV = -40 ^o F
URV = 250 ^o F
Test temperature = 70 ^o F
Instrument indication = 68 ^o F

Question 4:

Calculate the percent of span error for Ph analyzer as per the below details.

LRV = 4 pH
URV = 10 pH
Test buﬀer solution = 7.04 pH
Instrument indication = 7.13 pH

Percent of Span Error Formula

Answer 1

Error = +2 % of span

Answer 2

Error = -0.0125 % of span

Answer 3

Error = -0.69 % of span

Answer 4

Error = +1.5 % of span

Credits: Tony R. Kuphaldt

Instrument Percent of Span Error