• Capacitance 1

The capacitance of the transducer and that of any non-integral cable shall be stated separately. Capacitances shall be expressed as ”__ picofarads”.

Applicable for the following transducer technologies: All electrical transducers

• Excitation 2

Expressed as ” volts dc” or ”volts rms at Hz.” (Preferred values are 5, 10, 20, and 28 volts) or ” __ mA dc” or ”__mA rms at Hz.”

Applicable for the following transducer technologies: All electrical transducers with external excitation

• Maximum excitation 2

Expressed as ”__ volts dc” or ” volts rms at Hz.” or ” mA dc” or ” mA rms at __ Hz.”

Applicable for the following transducer technologies: All electrical transducers with external excitation

• Grounding 1

It shall be stated whether or not one of the transducer signal leads is internally connected to case ground electrically.

Applicable for the following transducer technologies: All electrical transducers

• Load impedance 1

The impedance presented by the immediately associated measuring system

(cable if not integral, amplifier, etc.) to the transducer’s output terminals shall be specified either as a minimum value, a range of values, or a nominal value with tolerances. All specified performance characteristics are intended to be applicable under this specified load impedance condition. Applicable for the following transducer technologies: All electrical

• Input impedance 2

Expressed as ” ± __ ohms at ± __ Hz.” If impedance is resistive, indicate this.

Applicable for the following transducer technologies: Where applicable

• Output Impedance 2

Expressed as ” ± __ ohms at ± __ Hz.” If impedance is resistive, indicate this.

Applicable for the following transducer technologies: Where applicable

• Resistance, shunting 1

Expressed as ”not less than __ megaohms at __ volts dc” as applied for two minutes between the two output terminals, unless a different time is specified.

Applicable for the following transducer technologies: Capacitive and piezoelectric

• Resistance, insulation

Insulation resistance shall be expressed as ”not less than __ megaohms at __ volts dc” as applied for two minutes between both output terminals connected in parallel and the transducer case at the mounting point. Note that this requirement is not applicable for those transducers that are internally grounded [20]. The value shall be given at room conditions and at the maximum operating temperature.

Applicable for the following transducer technologies: All electrical

• Capacitance vs. temperature 1

This may be given as a graph of transducer temperature. A corresponding curve of cable capacitance vs. cable temperature may also be provided. Applicable for the following transducer technologies: All electrical

• Cable noise 1

The noise produced by the transducer cable when mechanically excited in some specified way may be stated.

Applicable for the following transducer technologies: All electrical

• Insulation resistance vs. temperature 1

This may be given as a curve of the transducer insulation resistance vs. temperature.

Applicable for the following transducer technologies: All electrical

• Shunting resistance vs. temperature 1

This may be given as a curve of the shunting resistance of the transducer vs. transducer temperature.

Applicable for the following transducer technologies: Capacitive and piezo-

electric

• Polarity 1

The positive-going output terminal for an applied increase in pressure may be specified.

Applicable for the following transducer technologies: All electrical

• Vibration cancellation (electrical) 1

Any built-in electrical method for reducing the vibration sensitivity of the transducer may be specified.

Applicable for the following transducer technologies: All

• Range 1

The range, usually expressed as ”±__ Pa (bar/psi)” or ”from __ to __Pa (bar/psi).”

Applicable for the following transducer technologies: All

• Sensitivity, transducer output

The output sensitivity is expressed as ”__ unit of output (mV, pC, ...) per Pa (bar, psi) ± __ %,” or as ”± __ unit of output (mV, pC, ...) per Pa (bar, psi).” For optical transducers the output after the signal processing is used.

Applicable for the following transducer technologies: All

• Sensitivity shift 2

Expressed as ”± __ % over a period of minutes (hours, days, etc.)”
Applicable for the following transducer technologies: All

• Frequency response 1

This is expressed as ”within ± __ % of the sensitivity at __ Hz from __to __ Hz.” The method for determining this frequency response should be described. A graph with sensitivity deviation over frequency can also be included.

Applicable for the following transducer technologies: All

• Resonant frequency

Expressed in ”__ hertz” or ”__ kilohertz.” At least the lowest resonance frequency shall be stated.

Applicable for the following transducer technologies: All

• Full-scale output

Expressed as ” ± __ units of output”. For electrical transducers this value applies when connected to the specified load impedance.

Applicable for the following transducer technologies: All

• Zero measurand output

Expressed as ” __ ± __units of output”

Applicable for the following transducer technologies: Where applicable

• Zero shift 1

Expressed as ”±__ % of full scale output over a period of __ minutes

(hours, days, etc.)”

Applicable for the following transducer technologies: Where applicable

• Linearity 1

Linearity is normally expressed as ” __ linearity within ± __ % of full (or a specified partial) scale output.” The type of linearity to be entered in the first blank above shall be one of the straight line types defined in ISA-S37.1; namely: end point, independent, least squares, terminal, or theoretical slope.

Applicable for the following transducer technologies: All

• Hysteresis 2

Expressed as ” % of full scale output.”

Applicable for the following transducer technologies: All

• Repeatability

Expressed as ”within % of full scale output”

Applicable for the following transducer technologies: All

• Proof pressure 1

Proof Pressure shall be expressed as (application of) ”__ Pa (bar, psi) for __ minutes” (will not cause changes in transducer performance that exceed its specified error limits).

Applicable for the following transducer technologies: All

• Burst pressure rating 1

Burst Pressure Rating is stated as ” Pa (bar, psi) applied times for a period of minutes each” (will not result in mechanical failure of the transducer housing).

Applicable for the following transducer technologies: All

• Thermal sensitivity shift 1

Thermal Sensitivity Shift is expressed in terms of a maximum change from the (actual) room-temperature sensitivity level over the specified operating temperature range as ” % maximum, from °C(°F) to °C(°F).” A graph containing the sensitivity shift over temperature can be given additionally.

Applicable for the following transducer technologies: All

• Thermal zero shift 2

Expressed as ” % of full scale output per °C(°F) temperature change over a temperature range from °C(°F) to °C(°F).”

Applicable for the following transducer technologies: Where applicable

• Temperature gradient error 1

Expressed as ”less than ± __ units of output when subjected to a step-function temperature change from °C(°F) to °C(°F), applied to

(specify particular part) of the transducer” (at constant ambient pressure). It may also be expressed as equivalent Pa (bar, psi) input. The procedure of verification shall be referred to.

Applicable for the following transducer technologies: All

• Maximum and minimum ambient temperature, continuous 1

Expressed as (the transducer can be operated indefinitely at any temperature within the range from) ”__ °C(°F) to °C(°F)” (without incurring a permanent calibration shift).

Applicable for the following transducer technologies: All

• Acceleration error 2

Expressed as ”less than ± % of full scale output per g along axis at steady acceleration level of g.” The error should be listed for each of the three axes or for the axis with the largest error.
Applicable for the following transducer technologies: All

• Vibration error 1

Vibration error limits are expressed as ”less than (unit of output) RMS output due to __ g RMS acceleration along any axis over a frequency range from Hz to __ Hz.” The errors shall be listed for each of three mutually perpendicular axes, or for that axis expected to have the largest vibration error. State whether a swept sinusoidal or broad-band random vibration input is to be employed. In the latter case it is preferable to show a graphical representation of the vibration program.

Applicable for the following transducer technologies: All

• Other environmental conditions 1

Other pertinent operating or non-operating environmental conditions that shall not affect the transducer performance beyond the specified limits shall be listed. Examples are as follows: Mechanical Shock, Humidity, Salt Spray, Nuclear Radiation, Electromagnetic Interference, Ambient Pressure. The test conditions for determining such properties shall be identified.

Applicable for the following transducer technologies: All

• Sensitivity stability 1

Sensitivity stability shall be stated as, ”The sensitivity shall not vary more than ± % of its room-temperature value when subjected to temperature cycles between °C(°F) and °C(°F) and to pressure cycles up to Pa (bar, psi).”

Applicable for the following transducer technologies: All

• Resonant frequency amplification factor 1

Resonant frequency amplification factor at the lowest resonant frequency shall be expressed as ”the amplification factor at resonant frequency Hz shall not exceed .”

Applicable for the following transducer technologies: All

• Life, cycling

Expressed as ”__ full scale output pressure cycles (applied at a rate of

Hz) and __ temperature cycles over which the transducer shall operate without change in characteristics beyond their specified tolerances.” The temperature cycles shall range from room temperature to specified maximum ambient temperature where each condition is held for 1 hour. (proposal, needs to be adjusted to accelerated lifetime testing procedure)

Applicable for the following transducer technologies: All

• Storage life 2

Expressed as ”Transducer can be exposed to Specified Environmental Storage Condition for days (months, years) without changing the performance characteristics beyond their specified tolerances.” Environmental storage conditions shall be described in detail. Pertinent performance characteristics (examples: sensitivity, zero shift) shall be specified.

Applicable for the following transducer technologies: All

• Combined linearity, repeatability, hysteresis

The root sum RSS of linearity, repeatability and hysteresis given in ”__ % full scale output max.”

Applicable for the following transducer technologies: All

• Creep 2

Expressed as ”__minutes for subsequent shifts in output not to exceed __

% of full scale output.”

Applicable for the following transducer technologies: Where applicable

• Phase shift 2

Expressed as either ”phase shift linear within ±__ % from zero to __ Hz, reaching __ degrees at__ Hz” or ”phase shift less than __ degrees between zero and Hz.”

Applicable for the following transducer technologies: All

• Damping ratio 2

Expressed as ” __ % of critical damping.” Only defined for second order

single-degree-of-freedom system. For other cases use ringing period, rise time, and overshoot.

Applicable for the following transducer technologies: All

• Overshoot 2

Expressed as ”__ % of applied pressure.”

Applicable for the following transducer technologies: All

• Ringing period 2

Expressed as ” __ milliseconds.”

Applicable for the following transducer technologies: All

• Rise time 2

Expressed as ” milliseconds (microseconds) for response to rise from 10% to 90% for an applied pressure step function of Pa (bar, psi).”

Applicable for the following transducer technologies: All

• Mounting error 2

Expressed as ”within ± % of full scale output,” or, ”within the static error band,” under specified conditions of mounting force or torque.

Applicable for the following transducer technologies: All

• Maximum and minimum ambient temperature, intermittent Expressed as (the transducer can be operated at a maximum or minimum temperature) ” °C(°F) for minutes (hours)” (without incurring a permanent calibration shift). The type maximum/minimum temperature needs to be indicated.

Applicable for the following transducer technologies: All

• Maximum and minimum operating temperature, transducer sections Continuous or intermittent rating to be specified for transducer sections expressed as ” __ °C(°F) to °C(°F) at ” (insert the transducer section at the last blank space: transducer tip, connector, ...) without incurring a permanent calibration shift. If an intermittent value is mentioned, then the maximum duration needs to be specified. The limits may also be given in a schematic or drawing of the transducer.

Applicable for the following transducer technologies: All

• Temperature error 2

Expressed as ” __ % full scale output at __ Pa (bar, psi) for a temperature change from __ °C(°F) to __ °C(°F).”

Applicable for the following transducer technologies: All

• Warm-up period 2

Expressed as ” __ minutes for subsequent shifts in sensitivity and zero balance not to exceed __ % of full scale output.”

Applicable for the following transducer technologies: Where applicable

Outline:

This chapter is intended to provide exemplary calibration and compliance testing procedures for dynamic pressure transducers. Procedures for all specifications mentioned listed in the previous chapter shall be developed. ISA-S37.10-1982 [2] and ISA-S37.3-1982 [3] feature exemplary procedures that can be adapted for this purpose. The developed procedures shall be applicable for the different transducer technologies available and can be referenced by transducer manufacturers

Outline:

This chapter shall introduce standardized transducer shapes that can be produced by transducer manufacturers. The goal is to generate shapes which can then be employed in standardized measuring ports. This should increase the interchangeability between different products. The following example shapes can be used as a basis for further developments, however, common tolerances for the shapes need to be established.