---
kind: "range"
citation: "43 C.F.R. §§ 3175.131–3175.135"
title: "43"
from: "3175.131"
to: "3175.135"
count: 5
url: "https://uscodex.org/cfr/43/3175.131..3175.135"
---

# §3175.131. General requirements for transducer testing.

- (a) All testing must be performed by a qualified test facility.
- (b) **Number and selection of transducers tested.**
  - (1) A minimum of five transducers of the same make, model, and URL, selected at random from the stock used to supply normal field operations, must be type-tested.
  - (2) The serial number of each transducer selected must be documented. The date, location, and batch identifier, if applicable, of manufacture must be ascertainable from the serial number.
  - (3) For the purpose of this section, the term “model” refers to the base model number on which the BLM determines the transducer performance. For example: A manufacturer makes a transmitter with a model number 1234-XYZ, where “1234” identifies the transmitter cell, “X” identifies the output type, “Y” identifies the mounting type, and “Z” identifies where the static pressure is taken. The testing under this section would only be required on the base model number (“1234”), assuming that “X”, “Y”, or “Z” does not affect the performance of the transmitter.
  - (4) For multi-variable transducers, each cell URL must be tested only once under this section. For example: A manufacturer of a transducer measuring both differential and static pressure makes a model with available differential-pressure URLs of 100 inches, 500 inches, and 1,000 inches, and static-pressure URLs of 250 psia, 1,000 psia, and 2,500 psia. Although there are nine possible combinations of differential-pressure and static-pressure URLs, only six tests are required to cover each cell URL.
- (c) **Test conditions—general.** The electrical supply must meet the following minimum tolerances:
  - (1) **Rated voltage—** ±1 percent uncertainty;
  - (2) **Rated frequency—** ±1 percent uncertainty;
  - (3) **Alternating current harmonic distortion—** Less than 5 percent; and
  - (4) **Direct current ripple—** Less than 0.10 percent uncertainty.
- (d) The input and output (if the output is analog) of each transducer must be measured with equipment that has a published reference uncertainty less than or equal to 25 percent of the published reference uncertainty of the transducer under test across the measurement range common to both the transducer under test and the test instrument. Reference uncertainty for both the test instrument and the transducer under test must be expressed in the units the transducer measures to determine acceptable uncertainty. For example, if the transducer under test has a published reference uncertainty of ±0.05 percent of span, and a span of 0 to 500 psia, then this transducer has a reference accuracy of ±0.25 psia (0.05 percent of 500 psia). To meet the requirements of this [paragraph (d)](#d), the test instrument in this example must have an uncertainty of ±0.0625 psia or less (25 percent of ±0.25 psia).
- (e) If the manufacturer's performance specifications for the transducer under test include corrections made by an external device (such as linearization), then the external device must be tested along with the transducer and be connected to the transducer in the same way as in normal field operations.
- (f) If the manufacturer specifies the extent to which the measurement range of the transducer under test may be adjusted downward (i.e., spanned down), then each test required in §§ [3175.132](/cfr/43/3175.132.md) and [3175.133](/cfr/43/3175.133.md) must be carried out at least at both the URL and the minimum upper calibrated limit specified by the manufacturer. For upper calibrated limits between the maximum and the minimum span that are not tested, the BLM will use the greater of the uncertainties measured at the maximum and minimum spans in determining compliance with the requirements of [§ 3175.31(a)](/cfr/43/3175.31.md?p=a).
- (g) After initial calibration, no calibration adjustments to the transducer may be made until all required tests in §§ [3175.132](/cfr/43/3175.132.md) and [3175.133](/cfr/43/3175.133.md) are completed.
- (h) For all of the testing required in §§ [3175.132](/cfr/43/3175.132.md) and [3175.133](/cfr/43/3175.133.md), the term “tested for accuracy” means a comparison between the output of the transducer under test and the test equipment taken as follows:
  - (1) The following values must be tested in the order shown, expressed as a percent of the transducer span:
    - (i) (Ascending values) 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100; and
    - (ii) (Descending values) 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, and 0.
  - (2) If the device under test is an absolute-pressure transducer, the “0” values listed in paragraphs [(h)(1)(i)](#h-1-i) and [(ii)](#h-1-ii) of this section must be replaced with “atmospheric pressure at the test facility;”
  - (3) Input approaching each required test point must be applied asymptotically without overshooting the test point;
  - (4) The comparison of the transducer and the test equipment measurements must be recorded at each required point; and
  - (5) For static-pressure transducers, the following test point must be included for all tests:
    - (i) For gauge-pressure transducers, a gauge pressure of −5 psig; and
    - (ii) **For absolute-pressure transducers, an absolute pressure of 5 psia.**

# §3175.132. Testing of reference accuracy.

- (a) The following reference test conditions must be maintained for the duration of the testing:
  - (1) Ambient air temperature must be between 59 °F and 77 °F and must not vary over the duration of the test by more than ±2 °F;
  - (2) Relative humidity must be between 45 percent and 75 percent and must not vary over the duration of the test by more than ±5 percent;
  - (3) Atmospheric pressure must be between 12.46 psi and 15.36 psi and must not vary over the duration of the test by more than ±0.2 psi;
  - (4) The transducer must be isolated from any externally induced vibrations;
  - (5) The transducer must be mounted according to the manufacturer's specifications in the same manner as it would be mounted in normal field operations;
  - (6) The transducer must be isolated from any external electromagnetic fields; and
  - (7) For reference accuracy testing of differential-pressure transducers, the downstream side of the transducer must be vented to the atmosphere.
- (b) Before reference testing begins, the following pre-conditioning steps must be followed:
  - (1) After power is applied to the transducer, it must be allowed to stabilize for at least 30 minutes before applying any input pressure or temperature;
  - (2) The transducer must be exercised by applying three full-range traverses in each direction; and
  - (3) The transducer must be calibrated according to manufacturer specifications if a calibration is required or recommended by the manufacturer.
- (c) Immediately following preconditioning, the transducer must be tested at least three times for accuracy under [§ 3175.131(h)](/cfr/43/3175.131.md?p=h). The results of these tests must be used to determine the transducer's reference accuracy under [§ 3175.135](/cfr/43/3175.135.md).

# §3175.133. Testing of influence effects.

- (a) **General requirements.**
  - (1) Reference conditions (see [§ 3175.132](/cfr/43/3175.132.md)), with the exception of the influence effect being tested under this section, must be maintained for the duration of these tests.
  - (2) After completing the required tests for each influence effect under this section, the transducer under test must be returned to reference conditions and tested for accuracy under [§ 3175.132](/cfr/43/3175.132.md).
- (b) **Ambient temperature.**
  - (1) The transducer's accuracy must be tested at the following temperatures ( °F): +68, +104, +140, + 68, 0, −4, −40, +68.
  - (2) The ambient temperature must be held to ±4 °F from each required temperature during the accuracy test at each point.
  - (3) The rate of temperature change between tests must not exceed 2 °F per minute.
  - (4) The transducer must be allowed to stabilize at each test temperature for at least 1 hour.
  - (5) For each required temperature test point listed in this paragraph, the transducer must be tested for accuracy under [§ 3175.131(h)](/cfr/43/3175.131.md?p=h).
- (c) **Static-pressure effects (differential-pressure transducers only).**
  - (1) For single-variable transducers, the following pressures must be applied equally to both sides of the transducer, expressed in percent of maximum rated working pressure: 0, 50, 100, 75, 25, 0.
  - (2) For multivariable transducers, the following pressures must be applied equally to both sides of the transducer, expressed in percent of the URL of the static-pressure transducer: 0, 50, 100, 75, 25, 0.
  - (3) For each point required in paragraphs [(c)(1)](#c-1) and [(2)](#c-2) of this section, the transducer must be tested for accuracy under [§ 3175.131(h)](/cfr/43/3175.131.md?p=h).
- (d) **Mounting position effects.** The transducer must be tested for accuracy at four different orientations under [§ 3175.131(h)](/cfr/43/3175.131.md?p=h) as follows:
  - (1) At an angle of −10° from a vertical plane;
  - (2) At an angle of +10° from a vertical plane;
  - (3) At an angle of −10° from a vertical plane perpendicular to the vertical plane required in paragraphs [(d)(1)](#d-1) and [(2)](#d-2) of this section; and
  - (4) At an angle of +10° from a vertical plane perpendicular to the vertical plane required in paragraphs [(d)(1)](#d-1) and [(2)](#d-2) of this section.
- (e) **Over-range effects.**
  - (1) A pressure of 150 percent of the URL, or to the maximum rated working pressure of the transducer, whichever is less, must be applied for at least 1 minute.
  - (2) After removing the applied pressure, the transducer must be tested for accuracy under [§ 3175.131(h)](/cfr/43/3175.131.md?p=h).
  - (3) No more than 5 minutes must be allowed between performing the procedures described in paragraphs [(e)(1)](#e-1) and [(2)](#e-2) of this section.
- (f) **Vibration effects.**
  - (1) An initial resonance test must be conducted by applying the following test vibrations to the transducer along each of the three major axes of the transducer while measuring the output of the transducer with no pressure applied:
    - (i) The amplitude of the applied test frequency must be at least 0.35mm below 60 Hertz (Hz) and 49 meter per second squared (m/s 2) above 60 Hz; and
    - (ii) The applied frequency must be swept from 10 Hz to 2,000 Hz at a rate not greater than 0.5 octaves per minute.
  - (2) After the initial resonance search, an endurance conditioning test must be conducted as follows:
    - (i) Twenty frequency sweeps from 10 Hz to 2,000 Hz to 10 Hz must be applied to the transducer at a rate of 1 octave per minute, repeated for each of the 3 major axes; and
    - (ii) **The measurement of the transducer's output during this test is unnecessary.**
  - (3) A final resonance test must be conducted under [paragraph (f)(1)](#f-1) of this section.

# §3175.134. Transducer test reporting.

- (a) Each test required by [§§ 3175.131 through 3175.133](/cfr/43/3175.131..3175.133.md) must be fully documented by the test facility performing the tests. The report must indicate the results for each required test and include all data points recorded.
- (b) The report must be submitted to the PMT. If the PMT determines that all testing was completed as required by [§§ 3175.131 through 3175.133](/cfr/43/3175.131..3175.133.md), it will make a recommendation that the BLM approve the transducer make, model, and range, along with the reference uncertainty, influence effects, and any operating restrictions, and posts them to the BLM's website at www.blm.gov as an approved device.

# §3175.135. Uncertainty determination.

- (a) Reference uncertainty calculations for each transducer of a given make, model, URL, and turndown must be determined as follows (the result for each transducer is denoted by the subscript i):
  - (1) **Maximum error—** (Ei). The maximum error for each transducer is the maximum difference between any input value from the test device and the corresponding output from the transducer under test for any required test point, and must be expressed in percent of transducer span.
  - (2) **Hysteresis—** (Hi). The testing required in [§ 3175.132](/cfr/43/3175.132.md) requires at least three pairs of tests using both ascending test points (low to high) and descending test points (high to low) of the same value. Hysteresis is the maximum difference between the ascending value and the descending value for any single input test value of a test pair. Hysteresis must be expressed in percent of span.
  - (3) **Repeatability—** (Ri). The testing required under [§ 3175.132](/cfr/43/3175.132.md) requires at least three pairs of tests using both ascending test points (low to high) and descending test points (high to low) of the same value. Repeatability is the maximum difference between the value of any of the three ascending test points for a given input value or of the three descending test points for a given value. Repeatability must be expressed in percent of span.
- (b) **Reference uncertainty of a transducer.** The reference uncertainty of each transducer of a given make, model, URL, and turndown (Ur,i) must be determined as follows:
- (c) Reference uncertainty for the make, model, URL, and turndown of a transducer (Ur) must be determined as follows:
- (d) **Influence effects.** The uncertainty from each influence effect required to be tested under [§ 3175.133](/cfr/43/3175.133.md) must be determined as follows:
  - (1) **Zero-based errors of each transducer.** Zero-based errors from each influence test must be determined as follows:
  - (2) **Span-based errors of each transducer.** Span-based errors from each influence effect must be determined as follows:
  - (3) Zero- and span-based errors due to influence effects for a make, model, URL, and turndown of a transducer must be determined as follows: