Flow & Custody Measurement Glossary
Flow meters, custody transfer, orifice and Coriolis metering, AGA/API MPMS, and gas quality. 209 terms in this topic - each defined in plain English on its own page.
When measurement determines money, it becomes custody transfer - and the vocabulary gets precise. This topic covers flow metering technologies (orifice, turbine, Coriolis, ultrasonic), the correction chain from raw pulses to standard volumes (meter factors, compressibility, base conditions), gas quality measurement, and the AGA and API MPMS framework that governs fiscal measurement. Plain process flow measurement lives here as well; the custody terms simply hold it to a higher standard.
209 Terms
What Is a Meter Proving Report?
The contractual custody-transfer record of a proving - factors, runs, corrections, and sign-offs.
Read → GlossaryWhat Is Absolute Open Flow Potential (AOF)?
The theoretical maximum gas rate at zero flowing pressure, established by backpressure and isochronal deliverability tests.
Read → GlossaryHow Do You Convert Actual Volume to Standard Volume?
The pressure-temperature-compressibility correction a flow computer applies to reduce gas volume to base conditions.
Read → GlossaryWhat is AGA 3 (Orifice Metering)?
The AGA 3 / API 14.3 standard defining the orifice plate, meter tube, and flow equation for gas.
Read → GlossaryWhat is AGA 7 (Turbine Metering)?
The AGA 7 standard governing how gas turbine meters are installed, pulse-counted, and calibrated.
Read → GlossaryWhat is AGA 8 (Compressibility)?
The AGA 8 method that computes compressibility Z and gas density from composition, behind Fpv.
Read → GlossaryAGA 8 Detail vs Gross Method
Full molar composition versus bulk properties for computing Z, when each fits, and how the wrong choice biases volume.
Read → GlossaryWhat is AGA 9 (Ultrasonic Metering)?
The AGA 9 standard for multipath ultrasonic gas meters used in custody transfer measurement.
Read → GlossaryWhat is AGA report 11 for Coriolis gas measurement?
AGA 11, also API 14.9, governs Coriolis meters in gas custody, inferring base volume from mass and composition density.
Read → GlossaryWhat is AGA report 5 for fuel gas energy measurement?
AGA 5 determines fuel gas heat value and total energy, tying heating value to volume to produce delivered MMBtu.
Read → GlossaryAGA Gas Measurement Standards
The American Gas Association reports (AGA 3, 7, 8, 9) that define how natural gas flow is measured and calculated for custody transfer.
Read → GlossaryWhat Is an Annubar?
The averaging pitot tube - a low-loss DP flow probe - and how it stacks up against an orifice plate.
Read → GlossaryWhat Is API Gravity?
The degrees-API scale that rates crude as light or heavy - the formula, the water line at 10, and how it is measured.
Read → GlossaryWhat Is API MPMS?
The Manual of Petroleum Measurement Standards: its chapter structure and how proving, sampling, and correction connect.
Read → GlossaryWhat is API MPMS chapter 11.1 volume correction and its tables?
Chapter 11.1 gives the equations behind the 6A/54B tables that correct observed liquid volume to net at 60 degF.
Read → GlossaryWhat is an as-found meter factor?
Capturing the meter's performance before adjustment, and why it drives bias and prior-period decisions.
Read → GlossaryWhat Is an Averaging Pitot Tube?
A multi-port insertion DP probe that averages the velocity profile with very low pressure loss.
Read → GlossaryWhat Is Base Pressure in Gas Measurement?
The contractual reference conditions gas volumes are corrected to, and why a wrong base silently mis-measures.
Read → GlossaryWhat is base prover volume correction?
Correcting the certified prover volume for thermal and pressure expansion of the steel and the liquid.
Read → GlossaryWhat Is a Base Volume?
The prover's certified waterdraw volume and the steel and liquid corrections that anchor every meter factor.
Read → GlossaryWhat Is a Basic Orifice Factor?
The Fb geometry term in the AGA 3 orifice equation and the corrections a flow computer layers on top.
Read → GlossaryWhat Is the Beta Ratio (Orifice Meter)?
The bore to pipe diameter ratio that sets orifice meter accuracy and is a commonly misconfigured constant.
Read → GlossaryWhat Is a Bidirectional Prover?
The U-shaped ball prover with two detector switches that runs both directions to prove custody meters with self-cancelling accuracy.
Read → GlossaryWhat is a BTU meter for thermal energy?
A flow meter, a matched temperature pair, and a calculator that turns flow and delta-T into delivered chilled or hot water energy.
Read → GlossaryWhat is C6+ splitting in a custody gas chromatograph?
Dividing a lumped heavy-end peak into fixed hexane, heptane, and octane fractions that shift heating value and density.
Read → GlossaryWhat is canal turnout flow measurement?
Measure delivery with a flume or meter, or by rating the gate on opening and head, then totalize the volume to bill.
Read → GlossaryWhy monitor carrier gas consumption on a custody GC?
The carrier bottle depletes and a falling pressure shifts retention times before runout, so trend it to schedule changeouts.
Read → GlossaryWhat is carrier gas purity and why does it matter in a custody GC?
How clean the helium or hydrogen carrier is; contamination raises baseline noise and skews custody composition and BTU.
Read → GlossaryHow do you check flow computer inputs against transmitters?
Compare live values side by side, reconcile ranges, units, and absolute-pressure handling, then prove each channel by injection.
Read → GlossaryWhat Is a Clamp-On Flow Meter?
External ultrasonic transducers that read flow through the pipe wall with no cut and no shutdown.
Read → GlossaryHow does a clamp-on ultrasonic flow meter work?
Firing pulses through the pipe wall and timing the upstream-downstream difference, plus V, W, and Z beam paths.
Read → GlossaryWhat is column backflush in a custody gas chromatograph?
How reversing flow through a precolumn lumps the heavies as C6+ and shortens cycle time, and how mistimed valves corrupt BTU.
Read → GlossaryWhat is a combustion reference temperature in heating value calculation?
The two separate reference temperatures baked into every BTU number and how a basis mismatch causes systematic disputes.
Read → GlossaryHow do you commission a gas chromatograph stream?
Prove the sample and carrier gas, run the calibration standard, check peak separation and the unnormalized total, and confirm the composition to SCADA.
Read → GlossaryHow do you commission a vortex flow meter?
Verify straight run and gaskets, configure real pipe and fluid data, check minimum Reynolds at low flow, and prove zero under vibration.
Read → GlossaryWhat Is a Compact Prover?
How an optically switched piston and pulse interpolation prove a meter in a fraction of a pipe prover's volume.
Read → GlossaryWhat Is a Composite Sampler?
The flow-proportional device that blends a representative crude sample for BS&W and API testing at custody transfer.
Read → GlossaryWhat is a composite sampler grab volume?
How grab size and grabs-per-unit-volume are set so a composite sampler fills its receiver correctly over a batch.
Read → GlossaryWhat is a conditioning orifice plate?
A multi-bore orifice plate that conditions the flow itself, cutting the upstream straight-run needed in tight piping.
Read → GlossaryWhat Is the Coriolis Effect in Flow Measurement?
Why fluid through a vibrating tube twists it, and how the phase shift yields true mass flow directly.
Read → GlossaryCoriolis Meter
A mass flow meter that reads flow directly from a vibrating tube and also measures fluid density - ideal for custody transfer.
Read → GlossaryWhat is Coriolis meter zero drift?
A shift in the no-flow reference so the meter reads flow at zero flow or biases totals; trend no-flow windows to catch it.
Read → GlossaryWhat is Coriolis two-phase flow error?
Entrained gas or flashing decouples the tube vibration, spiking drive gain and collapsing mass and density accuracy.
Read → GlossaryCoriolis vs nuclear density measurement
A selection guide on fluid abrasiveness, pipe intrusion, and licensing for choosing Coriolis or nuclear density measurement.
Read → GlossaryCoriolis vs turbine meter for custody transfer
A selection guide on mass vs volume, proving, and fluid conditions for choosing a Coriolis or turbine custody meter.
Read → GlossaryWhat is a corner tap orifice meter?
Pressure sensed right at the plate faces, often via annular chambers, common in ISO 5167 and small-bore lines.
Read → GlossaryWhat Is a Counter Rollover in a Totalizer?
How a 16- or 32-bit register wrapping to zero produces a false negative flow delta, and how rollover handling corrects it.
Read → GlossaryHow do you cross-check a flow meter with a clamp-on?
Mount on a full straight run, enter measured pipe data, demand strong signal, and compare totals over a stable window.
Read → GlossaryCustody Transfer
The fiscal metering point where ownership of oil or gas passes between parties, held to strict accuracy and audit standards.
Read → GlossaryWhat is a custody transfer meter skid?
Packaged metering system: parallel runs, flow computers, densitometer, sampler, and prover connections reporting to SCADA.
Read → GlossaryWhat is a Dall tube flow meter?
A short, high-recovery DP element giving a strong signal for low permanent pressure loss, saving pumping energy.
Read → GlossaryHow do you diagnose a flow meter that reads low?
Quantify the shortfall, audit configuration first, then hunt bypass leakage, fouling, entrained gas, and wear, escalating to proving.
Read → GlossaryHow do you diagnose a flow meter reading zero?
Prove flow exists, split meter from signal path at the local display, then check cutoffs, impulse lines, diagnostics, and wiring in order.
Read → GlossaryHow do you diagnose pulsating flow readings?
Match the oscillation to machinery, a hunting loop, slugging, or signal settings, and mind the square-root averaging bias on DP meters.
Read → GlossaryWhat Is a Diaphragm Gas Meter?
Alternating diaphragm chambers displace fixed gas volumes; the standard low-pressure fuel-gas PD meter.
Read → GlossaryWhat is diluent adjustment for nitrogen and CO2 in heating value?
Inert N2 and CO2 lower gross heating value and shift compressibility; GPA 2172 and the AGA 8 gross method treat them explicitly.
Read → GlossaryWhat Is the Doppler Effect in Flow Measurement?
How a frequency shift off suspended particles reveals velocity, and why Doppler needs dirty fluid, not clean.
Read → GlossaryWhat Is a Doppler Ultrasonic Flow Meter?
Reads the frequency shift off bubbles and particles; built for slurries and aerated produced water.
Read → GlossaryHow Does the Differential-Pressure Flow Principle Work?
The Bernoulli square-root law shared by orifice, venturi, and pitot meters, and why it limits turndown.
Read → GlossaryWhat Is Dry vs Saturated Heating Value Basis?
How the water-content assumption shifts Btu per cubic foot across the dry, saturated, and as-delivered bases.
Read → GlossaryWhat is an eccentric orifice plate?
An offset-bore orifice plate that lets sediment, condensate, or gas pass without fouling the plate in dirty service.
Read → GlossaryWhat is an elbow flow meter?
An existing pipe bend becomes a rough flow meter by tapping the inner and outer radius for centrifugal DP.
Read → GlossaryWhat Is Empty Pipe Detection?
The magmeter safeguard that forces flow to zero and alarms when the pipe is not full.
Read → GlossaryWhat is an energy flow computer and how does it integrate BTU?
A flow computer that ingests live GC composition, computes heating value, and integrates BTU against corrected volume every period.
Read → GlossaryWhat is energy summation in a gas flow computer?
The per-interval multiply of corrected volume by heating value into MMBtu; store the volume, HV, and energy triplet to audit it.
Read → GlossaryWhat Is Faraday's Law in Magnetic Flow Measurement?
How a conductive fluid moving through a magnetic field induces a velocity-proportional voltage - the magmeter principle.
Read → GlossaryFlange Taps vs Pipe Taps
Where orifice DP is sensed, why tap location changes the Cd equation, and why the flow computer must match the taps.
Read → GlossaryWhat is a flow computer configuration and event log?
The logs that record every constant value and parameter change so a flow computer's volumes stay auditable.
Read → GlossaryWhat Is a Flow Conditioner?
The tube-bundle or perforated-plate insert that removes swirl and flattens the velocity profile to shorten meter runs and hold accuracy.
Read → GlossaryWhat Is a Flow Nozzle?
A contoured-throat DP element between an orifice and a venturi, built for high-velocity steam service.
Read → GlossaryWhat Is a Flow-Proportional Composite Sample?
A composite of grabs paced by metered flow so tested water and gravity match the batch that crossed the meter.
Read → GlossaryWhat is a flow-weighted average heating value?
A daily heating value weighted by flow volume, accumulated interval by interval, avoiding the error of naive time-averaging.
Read → GlossaryWhat is flow-weighted vs time-weighted averaging in a flow computer?
Flow-weighting weights each sample by flow so idle periods do not skew the average; API 21.1 requires it for volume variables.
Read → GlossaryWhat Is a Frequency Input (Turbine)?
How turbine blade-passage pulses and the K-factor become custody volume in a flow computer.
Read → GlossaryWhat is a fully developed flow profile?
The stable, symmetric velocity shape flow meters assume; elbows and valves distort it with swirl and asymmetry.
Read → GlossaryWhat Is a Gas Chromatograph?
The instrument that measures natural gas composition to set BTU and correct custody-transfer flow - how a GC works.
Read → GlossaryWhat Is Gas Compressibility (Z-Factor)?
The real-gas correction to the ideal gas law that feeds flow-computer supercompressibility and gas volume calculations.
Read → GlossaryWhat Is Gas Energy Measurement?
How gas is sold on energy (MMBtu, dekatherms) by tying chromatograph heating value to metered volume.
Read → GlossaryWhat Is the Gas Expansion Factor (Y)?
The AGA 3 term that corrects for gas thinning across the orifice plate, and why a wrong Y biases custody volumes.
Read → GlossaryWhat is gas interchangeability and how is it controlled?
Whether a gas burns acceptably in equipment tuned for a reference gas, held online by Wobbe bands and flame indices.
Read → GlossaryWhat Is a Gas Odorizer?
The system that injects mercaptan or THT odorant into natural gas for leak-detection safety, proportional to gas flow.
Read → GlossaryWhat Is GC Analysis Cycle Time?
How often an online chromatograph produces a fresh composition, how it feeds the flow computer, and GC fault behavior.
Read → GlossaryWhat is a GC validation run in custody gas measurement?
A non-adjusting check that injects a known gas, compares, and logs pass or fail without changing the operating calibration.
Read → GlossaryWhat is GC carryover and a ghosting peak in a custody chromatograph?
Residual heavy components carried into the next cycle create ghost peaks that inflate composition and bias heating value between streams.
Read → GlossaryWhat is GC oven temperature stability and how does it affect custody analysis?
How tightly a chromatograph holds column temperature; drift shifts retention times and can misidentify custody peaks.
Read → GlossaryWhat is a GC response factor in a custody gas chromatograph?
The per-component factor turning peak area into mole percent, why it drifts, and how SCADA should trend and alarm on it.
Read → GlossaryWhat is GC stream switching in a multi-stream analyzer?
Sharing one custody GC across several meter runs through a selector, with a stabilization purge to prevent carryover.
Read → GlossaryWhat is a GC unnormalized total and why is it a quality check?
The raw pre-normalization mole percent sum is the best real-time GC health check; alarm on its drift from one hundred.
Read → GlossaryWhat Are GOV, GSV, and NSV?
The TOV to GOV to GSV to NSV volume chain in tank custody transfer and where VCF and S&W deductions apply.
Read → GlossaryWhat Is Gross Heating Value (BTU)?
The BTU-per-cubic-foot figure that converts measured gas volume into the MMBTU energy that gets billed.
Read → GlossaryGross vs Net Volume
How observed liquid becomes gross standard volume and then net oil after water and sediment - and why the split matters.
Read → GlossaryWhat is heating value substitution during analyzer downtime?
Holding last good composition, a contractual default, or a nearby analyzer to keep energy computing while the GC is offline.
Read → GlossaryWhat Is a High-Flow Sampler?
An instrument that quantifies a component leak in scfh, feeding emissions inventories and repair prioritization.
Read → GlossaryWhat is inferential BTU measurement of natural gas?
Estimating heating value from physical properties instead of a full GC, cheaper and continuous but checked against periodic analysis.
Read → GlossaryHow is heating value inferred without a full GC?
Correlative methods estimate gas energy from a few properties like speed of sound and CO2 instead of a full component GC.
Read → GlossaryWhat Is an Insertion Flow Meter?
A single-point velocity probe that infers average flow, with a hot-tap install advantage on large lines.
Read → GlossaryWhat is the integral multiplier value (IMV) in orifice measurement?
The integral value is the square root of hw times Pf that a flow computer integrates each second to build orifice volume.
Read → GlossaryWhat is an integral orifice meter?
A small precision orifice close-coupled to a DP transmitter for low flows in small-bore lines.
Read → GlossaryWhat are the ISO 5167 orifice installation requirements?
Minimum upstream and downstream straight lengths, keyed to fitting and beta, so an orifice plate meets its stated uncertainty.
Read → GlossaryWhat is ISO 6976 heating value calculation?
The international method computing calorific value, density, and Wobbe index from composition, where reference bases decide the result.
Read → GlossaryWhat Is a K-Factor?
The pulses-per-unit-volume constant that turns a turbine or PD meter's pulses into volume - and how it differs from meter factor.
Read → GlossaryLACT Unit
The automated skid that meters, samples, and quality-checks crude oil at the point ownership transfers from lease to pipeline.
Read → GlossaryWhat is a laminar flow element?
Many small passages keep flow laminar so DP is linear with flow, giving wide-turndown low-flow gas measurement.
Read → GlossaryWhat Is a Low-Flow Cutoff?
The DP threshold below which a flow computer calls flow zero, killing square-root noise that creates phantom volume.
Read → GlossaryWhat Is a Magmeter Electrode?
The Faraday-induced voltage pickup in a magnetic flow meter, plus wetted vs capacitive types and fouling.
Read → GlossaryMagmeter vs Coriolis for liquid flow
A selection guide on mass vs volume, conductivity, cost, and accuracy for choosing a magnetic or Coriolis meter on liquid.
Read → GlossaryMagmeter vs DP orifice flow: how to choose
A selection guide on conductivity, pressure loss, and turndown for choosing a magnetic or DP orifice flow meter.
Read → GlossaryWhat Is a Magnetic Flow Meter?
The obstructionless mag meter behind produced-water and disposal-well flow - Faraday's law and its conductivity limit.
Read → GlossaryWhat is a magnetic flow meter for sewage?
No-moving-parts meter for full-pipe force-main sewage, needing the right liner, electrodes, coating control, and empty-pipe detection.
Read → GlossaryWhat Is a Master Meter?
A certified reference meter run in series to prove a working meter - a third proving method beyond pipe and volumetric provers.
Read → GlossaryWhat Is the Master Meter Proving Method?
Proving a meter with a proven reference meter in series - no dedicated prover, and its accuracy limits.
Read → GlossaryWhat Is a Master Meter Station?
A reference-meter skid that verifies field meters in series where a pipe prover is impractical.
Read → GlossaryHow do two water agencies reconcile a master meter?
Compare both meters over the same window, accept a stable gap, and run down a growing one before recalibrating.
Read → GlossaryWhat Is a Custody Transfer Measurement Uncertainty Budget?
How the uncertainty on custody net volume is built up from level, temperature, density, and water-cut errors - and where to tighten it.
Read → GlossaryWhat Is a Meter Factor?
The correction multiplier from a prove that aligns a flow meter's output with a reference - and how it differs from K-factor.
Read → GlossaryWhat is a meter factor control chart?
Applying SPC limits to successive factors to separate normal scatter from a real meter shift.
Read → GlossaryWhat is meter factor drift?
Gradual wear-driven factor creep versus an abrupt step, and how trending catches it before OOT.
Read → GlossaryWhat is meter factor uncertainty?
The prover volume, temperature, pressure, density, and pulse-count contributions and how they roll up.
Read → GlossaryWhat Is Meter Proving?
Verifying a flow meter against a known-volume prover to produce its meter factor - the basis of trusted custody transfer.
Read → GlossaryHow does a meter run switching station work?
How a flow computer stages parallel runs by total rate to keep each in its accurate band.
Read → GlossaryWhat Is Meter Slippage?
Fluid leaking past a PD meter's clearances that grows at low flow and low viscosity and shifts the factor.
Read → GlossaryWhat Is a Meter Tube?
The precision-machined pipe run around an orifice or ultrasonic meter, with controlled bore and straight-length requirements.
Read → GlossaryWhat is the difference between methane number and Wobbe index for interchangeability?
Wobbe governs burner heat release and methane number governs engine knock, so a gas can pass one and fail the other.
Read → GlossaryWhat Is Minimum Night Flow Analysis?
Estimating leakage from a DMA's lowest overnight inflow after subtracting legitimate night use.
Read → GlossaryMPMS Chapter 21 Scope
Electronic gas and liquid measurement and the audit trail they require.
Read → GlossaryMPMS Chapter 4 Proving
Proving systems, prover types, and how a meter factor is established.
Read → GlossaryMPMS Chapter-to-Task Map
Which MPMS chapter to open for proving, sampling, correction, and more.
Read → GlossaryMPMS Chapters for a LACT Unit
Which MPMS chapter governs each function on a LACT skid.
Read → GlossaryWhat Is a Multiphase Flow Meter?
The MPFM that meters oil, gas, and water together without separation - how it works and why it replaces test separators.
Read → GlossaryWhat Is Net vs Gross Heating Value?
Gross counts the heat from condensing combustion water, net does not, and confusing them misstates energy.
Read → GlossaryWhat Is Net Versus Gross Flow Totalization?
Accumulating gross measured volume versus net volume after per-interval water, shrinkage, and temperature correction.
Read → GlossaryWhat Is Net Heating Value in the Combustion Zone (NHVcz)?
The heating value of gas at a flare's flame after assist dilution, kept above a floor and computed live for compliance.
Read → GlossaryHow does a no-flow cutoff timer work in a flow computer?
The timer that stops flow-time accrual and declares a run idle after DP stays below cutoff.
Read → GlossaryWhat Is a Nutating Disc Meter?
A wobbling-disc PD meter that displaces a fixed volume per cycle; the classic low-cost water meter.
Read → GlossaryWhat Is an Observed API Gravity Reading?
The raw hydrometer reading at sample temperature, corrected to 60F before it lands on a custody ticket.
Read → GlossaryWhat is an open channel flow meter?
Meter that derives gravity flow from the water depth over a flume or weir using a head-to-flow equation.
Read → GlossaryWhat is an orifice plate drain or vent hole?
A small drain hole at the bottom or vent hole at the top of an orifice plate that passes a nuisance second phase.
Read → GlossaryWhat is orifice plate edge sharpness and why it matters?
A dulled upstream bore edge raises the discharge coefficient and biases orifice flow high, threatening custody accuracy.
Read → GlossaryHow is the orifice flow rate calculated in AGA 3?
A walk through the AGA 3 mass flow equation and its iterative discharge-coefficient solution.
Read → GlossaryOrifice Meter
A differential-pressure flow meter that infers flow from the pressure drop across a plate - the AGA 3 standard for gas.
Read → GlossaryWhat Is Orifice Plate Bore Condition?
Why the upstream edge must stay sharp and square, how nicks and warping skew flow, and how inspection protects volumes.
Read → GlossaryWhat Is an Orifice Plate Inspection?
Pulling and checking a plate for edge sharpness, bore size, and cleanliness per AGA 3 to keep gas measurement accurate.
Read → GlossaryWhat causes orifice plate wear measurement error?
A rounded edge or worn bore shifts the discharge coefficient and silently biases AGA-3 flow; trending against a check meter reveals it.
Read → GlossaryHow do you build an orifice meter uncertainty budget under AGA 3?
Combine Cd, expansibility, diameters, DP, pressure, temperature, and density via sensitivity coefficients by root-sum-square.
Read → GlossaryWhat Is an Oval Gear Flow Meter?
Meshing oval gears count fixed volumes as pulses for accurate viscous-fluid and chemical-dosing metering.
Read → GlossaryWhat is permanent pressure loss in a DP flow meter?
The unrecovered head across a flow element; orifices lose most of the DP, venturis and cone meters recover it.
Read → GlossaryWhat Is a Piston Prover?
The compact small-volume prover with optical detectors and double-chronometry interpolation that resolves fractions of a meter pulse.
Read → GlossaryWhat Is a Pitot Tube?
Velocity flow from stagnation pressure - the single-point insertion probe for flare and large-duct gas, and its limits.
Read → GlossaryWhat is a pitot-static tube?
A Prandtl probe combining total and static ports so one differential gives spot flow velocity.
Read → GlossaryWhat Is a Positive Displacement Meter?
The PD meter that counts trapped fluid pockets - why it beats velocity meters on viscous, low-flow service.
Read → GlossaryWhat Is Process Flow Animation on an HMI?
Moving dashes or arrows on a pipe graphic that show fluid is flowing and in which direction.
Read → GlossaryWhat is a profile factor in an ultrasonic meter?
The diagnostic ratio built from path velocities that reveals an abnormal flow profile.
Read → GlossaryHow Does Proportional-to-Flow Chemical Injection Work?
Pacing a dosing pump to production so concentration stays constant as rate swings, closed by the RTU.
Read → GlossaryHow do you prove a liquid turbine flow meter?
Run repeat prover passes at operating flow, count pulses against certified volume, and accept a meter factor only when it repeats.
Read → GlossaryWhat is a prover detector switch?
The switches that mark a prover's calibrated volume and define the counted pulses, and how wear corrupts a prove.
Read → GlossaryWhat Is a Prover Loop?
The permanently installed proving subsystem - four-way valve, detectors, and taps - that a flow computer sequences for an auto prove.
Read → GlossaryWhat is a prover connecting piping fill check?
Confirming the prover and its piping are liquid-full and gas-free before proving, and how trapped air corrupts the factor.
Read → GlossaryWhat is prover recertification?
Why a prover must be periodically re-water-drawn, what voids a certificate, and the cost of an expired one.
Read → GlossaryWhat is proving frequency in custody transfer?
How operators decide how often to prove a meter, and how SCADA schedules and trends proves.
Read → GlossaryWhat Is a Pulse Output Meter?
Raw meter pulses, dual A/B pulse security, and the fidelity levels a flow computer verifies.
Read → GlossaryWhat is pump runout?
End-of-curve operation at high flow and low head that overloads the motor and can cavitate, and how telemetry catches it.
Read → GlossaryWhat is a quadrant-edge orifice plate?
A quarter-circle inlet orifice plate that keeps its coefficient stable at low Reynolds numbers for viscous fluids.
Read → GlossaryWhat Is a Quantity Transaction Record (QTR)?
The API 21.1 quantity, configuration, and event logs a flow computer keeps so a measurement can be audited.
Read → GlossaryWhat is a radius tap orifice meter?
Radius (D and D/2) taps sense pressure one diameter upstream and a half diameter downstream, near the vena contracta.
Read → GlossaryWhat is a recording calorimeter for heating value?
A legacy instrument that reads BTU by burning a metered slipstream, reconciled against a chromatograph in the historian.
Read → GlossaryHow is relative density used in gas flow calculations?
Where gravity enters the AGA flow math, a symbolic example of how errors propagate, and the flow computer entry mistakes to avoid.
Read → GlossaryWhat Is a Resettable Versus Non-Resettable Totalizer?
Running a resettable period total alongside a permanent grand total that never clears, with safe reset logic.
Read → GlossaryWhat is a restriction orifice?
A plate that reduces pressure or limits flow rather than measuring it, often multi-stage to avoid cavitation.
Read → GlossaryWhat Is the Reynolds Number (Flow)?
The dimensionless number that classifies laminar versus turbulent flow and shifts discharge coefficients and meter accuracy.
Read → GlossaryWhat Is a Rotameter?
The tapered-tube-and-float variable-area meter for chemical injection and purge flows - a powerless local flow indicator.
Read → GlossaryWhat is a segmental orifice plate?
A crescent-opening orifice plate that hugs the pipe wall to pass slurry, solids, or gas in the dirtiest service.
Read → GlossaryWhat Is a Senior Orifice Fitting?
The dual-chamber fitting that lets you pull and inspect an orifice plate under pressure without shutting in the meter.
Read → GlossaryWhat Is Slack Line Flow?
When a steep downhill runs partially full, why it hurts measurement, and how back pressure fixes it.
Read → GlossaryWhat is stagnation pressure in flow measurement?
The total pressure where a fluid stops, static plus dynamic, and the basis of pitot and annubar readings.
Read → GlossaryWhat Are Standard Conditions?
The base temperature and pressure that oil and gas volumes are corrected to so they can be traded and audited consistently.
Read → GlossaryWhat is pump station storm-flow mode?
An automatic wet-weather mode that raises start levels and calls all pumps, favoring capacity over efficiency.
Read → GlossaryWhat Is a Straight-Run Requirement?
The undisturbed pipe length in diameters a meter needs, why fittings distort flow, and conditioners.
Read → GlossaryWhat Is the Strouhal Number?
The dimensionless constant linking vortex-shedding frequency to velocity that makes a vortex meter linear.
Read → GlossaryWhat Is a Tank Prover?
The calibrated volumetric tank read on a neck scale as a field standard for proving meters, and the evaporation errors to manage.
Read → GlossaryWhat is a target flow meter?
A disc in the pipe senses drag force, so target meters handle dirty and viscous fluids that clog orifice plates.
Read → GlossaryHow Does Thermal Mass Flow Measurement Work?
How a heated element cooled by passing gas gives direct mass flow with no DP or moving parts.
Read → GlossaryWhat is total inerts content in custody gas?
The combined nitrogen and CO2 fraction that dilutes heating value, why tariffs cap it, and how a host trends it against the limit.
Read → GlossaryWhat Is Total Probable Error In Flow Measurement?
How root sum square combines meter, transmitter, pressure, and temperature errors into one custody figure.
Read → GlossaryTransit-Time Ultrasonic Flow Meter
Times sound with and against the flow for velocity; clean-fluid, no-pressure-drop custody metering.
Read → GlossaryTurbine Meter
A flow meter whose rotor spins in proportion to velocity, giving high accuracy and wide rangeability under AGA 7.
Read → GlossaryUltrasonic Flow Meter
A no-moving-parts meter that derives flow from the transit-time difference of sound pulses, used for gas custody under AGA 9.
Read → GlossaryWhat Is an Ultrasonic SOS Check?
Comparing measured speed of sound against the AGA 10 value as a live custody meter health check.
Read → GlossaryWhat is inline ultrasonic meter self-verification?
How a multipath meter checks gain, SNR, path velocities, and speed of sound to flag drift.
Read → GlossaryWhat causes ultrasonic flow meter signal dropout?
Bubbles, solids, attenuation, or fouled transducers drop measurement paths; alarm on per-path SNR and gain, not just flow.
Read → GlossaryWhat is the unnormalized total check on a custody GC?
Why the raw pre-normalization sum near 100 is the best early warning of carrier loss or valve leak, and how to alarm on it.
Read → GlossaryWhat Is a V-Cone Flow Meter?
A DP meter with a centered cone that conditions flow, tolerating short straight run and dirty service.
Read → GlossaryHow do you validate a gas chromatograph calibration?
Run a certified check gas without adjusting, compare each component to tolerance, check the unnormalized total, and decide pass, fail, or recalibrate.
Read → GlossaryWhat is the vena contracta in an orifice meter?
The point of minimum jet area and lowest pressure past an orifice plate that drives tap placement and Cd.
Read → GlossaryWhat Is a Venturi Meter?
The converging-diverging DP flow element that recovers most of its pressure - and where it beats an orifice plate.
Read → GlossaryHow do you verify a Coriolis flow meter?
Run the tube-stiffness diagnostic, do a proper stopped-flow zero at process temperature, and cross-check indicated density.
Read → GlossaryHow do you verify a magnetic flow meter?
Do a full-pipe no-flow zero, check coil and electrode resistance, test insulation, and prove the converter with a simulator.
Read → GlossaryHow do you verify magmeter empty-pipe detection?
Read what the trip is configured to do, prove it on a genuinely drained line, and make sure SCADA shows it as bad data, not real zero flow.
Read → GlossaryHow do you verify a flow-pacing signal to a metering pump?
Match the signal type, confirm the scaling end to end, and prove the pump stops at no-flow and tracks linearly to maximum.
Read → GlossaryHow do you verify orifice plate installation?
Match the stamped bore to the configuration, face the bevel downstream, center the plate, and inspect the edge before reinstalling.
Read → GlossaryHow do you verify turbine meter K-factor entry?
Trace the value to the calibration certificate, reconcile units, check linearization points, and prove volume equals pulses over K.
Read → GlossaryWhat Is a Virtual Flow Meter?
How a model infers flow from pressure, temperature, and choke position for allocation and well surveillance.
Read → GlossaryWhat Is a Volume Correction Factor (VCF)?
The CTL and CPL correction under API 11.1 that restates liquid volume to standard conditions on a ticket.
Read → GlossaryWhat Is a Vortex Flow Meter?
The vortex-shedding meter for steam, fuel gas, and clean liquid - the von Karman principle and its low-flow cutoff.
Read → GlossaryWhat Is Vortex Shedding in Flow Measurement?
How a bluff body sheds alternating vortices at a frequency set by velocity, and why the effect drops out at low flow.
Read → GlossaryVortex vs orifice flow for steam and gas
A selection guide on turndown, pressure loss, low-flow cutoff, and maintenance for choosing a vortex or orifice meter on steam and gas.
Read → GlossaryWhat Is a Wedge Flow Meter?
A DP meter with a V-shaped restriction for viscous, abrasive, and slurry fluids that plug an orifice.
Read → GlossaryWhat is witness proving in custody transfer?
When both parties observe a proving and jointly accept the meter factor and report.
Read → GlossaryWhat Is the Wobbe Index?
The interchangeability figure - heating value over root specific gravity - that says whether one gas can substitute at a burner.
Read → GlossaryHow do you zero a Coriolis meter?
Flood the tubes, prove no-flow between tight valves at operating temperature, run the routine, and judge the stored offset before keeping it.
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