Process Analyzers & Gas Detection Glossary
Online process analyzers, sample systems, gas detection, and emissions monitoring instrumentation. 98 terms in this topic - each defined in plain English on its own page.
Analyzers measure what a transmitter cannot: composition, quality, and the presence of dangerous gas. This topic covers online process analyzers and their sample systems, fixed gas detection (combustible and toxic), and the emissions-monitoring instrumentation behind environmental compliance. Analyzer terms have their own reliability vocabulary - validation, response time, sample conditioning - because an analyzer that lies is worse than no analyzer at all.
98 Terms
What is an acoustic gas leak detector?
A detector that hears the ultrasound of a pressurized leak, alarming early and regardless of wind direction.
Read → GlossaryWhat is airborne ultrasound leak detection?
Hearing the broadband ultrasound a pressurized leak makes and shifting 40 kHz signals down to audible sound to locate it.
Read → GlossaryHow do you align an open-path gas detector?
Mount on rigid structures, aim each unit for peak received signal and lock it, then prove a gas response with the manufacturer's test cell.
Read → GlossaryWhat is an ammonium ion-selective electrode (ISE)?
In-basin probe that reads ammonium as a voltage for aeration control, with a potassium electrode compensating for interference.
Read → GlossaryWhat is analyzer availability and uptime?
The percentage of time an analyzer produces valid data, a reliability metric CEMS and custody units must meet.
Read → GlossaryIs my analyzer drifting or is the process changing?
Cross-check independent tags, apply a validation gas to settle it, and read the drift signature to separate a bad sensor from a real change.
Read → GlossaryWhat Is an Analyzer House?
The climate-controlled, purged shelter that groups a facility's process analyzers in the field.
Read → GlossaryWhat Is Analyzer Response Time and Lag?
The total delay from a process change to the reading, sample transport lag plus detector T90, which limits closed-loop control.
Read → GlossaryWhat Is an Analyzer Validation Check?
A routine run measuring a known reference to confirm accuracy without recalibrating; results log and alarm in SCADA.
Read → GlossaryAPI RP 1130 Program Requirements
The program elements API RP 1130 expects behind a liquids leak-detection system.
Read → GlossaryWhat is dissolved oxygen control in aquaculture ponds?
Staging paddlewheel and diffused aerators to hold minimum DO through the overnight sag, with auto-start and alarms.
Read → GlossaryWhat Is a BTU Analyzer?
The instrument that measures gas heating value and Wobbe index for custody and energy billing - calorimeter vs GC.
Read → GlossaryWhat Is a Bump Test?
Stepping the output and reading the reaction curve to extract gain, time constant, and dead time.
Read → GlossaryHow do you bump-test and calibrate a gas detector?
Bump test confirms response and alarm; full calibration zeroes on clean air then spans on certified gas at the right flow.
Read → GlossaryHow do you calibrate an ORP analyzer?
Check the millivolt reading against a certified redox standard, read the offset as an electrode-health signal, clean if needed, and verify the value to control.
Read → GlossaryHow do you calibrate a DO probe to air saturation?
Clean the sensor, settle it in water-vapor-saturated air at a stable temperature, confirm compensation, then set the span to the saturation DO.
Read → GlossaryHow Does a Chemiluminescence NOx Analyzer Work?
Reacts nitric oxide with ozone and reads the light emitted to quantify NOx; a converter captures NO2 for CEMS reporting.
Read → GlossaryWhat Is a Chilled Mirror Dew Point Analyzer?
The reference instrument that cools a mirror until condensate forms and reads the dew point optically.
Read → GlossaryCombustible vs toxic gas detection: which does a site need?
A selection guide: when an area needs combustible detection, toxic detection, or both, with placement differences and cross-sensitivity traps.
Read → GlossaryHow Does Conductivity-Based CIP Phase Control Work?
How an inline probe tells water, caustic, acid, and product apart to sequence phases and recover chemicals.
Read → GlossaryWhat Is CIP Return Conductivity Verification?
How the return probe proves chemical strength and rinse endpoint, generating the auditable electronic cleaning record.
Read → GlossaryWhy is my analyzer sample line plugged?
Read the falling flow and rising lag, check filters and low points first, locate the restriction along the line, and clear it safely at the cause.
Read → GlossaryCombustible & Toxic Gas Detector
The fixed sensor that watches for flammable (LEL) and toxic (H2S) gas releases and feeds the fire and gas system that alarms and shuts down.
Read → GlossaryHow do you commission a fixed LEL gas detector?
Verify placement against the hazard, apply the first zero and span, and prove the low alarm, high alarm, and executive action end to end.
Read → GlossaryHow do you commission an H2S gas detector?
Verify breathing-zone placement, run the manufacturer's first bump and calibration with certified H2S gas, and prove the toxic alarm chain.
Read → GlossaryHow do you commission a chlorine residual analyzer loop?
Prove the sample path, confirm the free-or-total method, scale the signal end to end, then set and test the alarm and control setpoints.
Read → GlossaryHow do you commission a dissolved-oxygen analyzer loop?
Place the probe in a representative spot, confirm the sensor method, scale the 4-20 mA to SCADA, and set meaningful DO alarms.
Read → GlossaryWhat Is a Conductivity Analyzer?
The measurement of water's ionic content and salinity, and how it relates to TDS.
Read → GlossaryContinuous Emissions Monitoring (CEMS)
Real-time measurement of stack pollutants for compliance, the analyzers and data system involved, and the regulatory role they play.
Read → GlossaryWhat is the difference between coulometric and volumetric Karl Fischer?
Coulometric suits ppm-level trace water, volumetric suits percent-level water; the sample's water level picks the mode.
Read → GlossaryCPM Evaluation Attributes (RP 1130)
Test a leak-detection system against the four API 1130 attributes in order.
Read → GlossaryWhat Is CPM Leak Detection?
The API 1130 software approach that infers leaks from SCADA flow, pressure, and temperature.
Read → GlossaryWhat is a copper-copper sulfate reference electrode?
The standard soil half-cell behind buried-pipeline CP potentials and the -850 mV protection criterion.
Read → GlossaryWhat Is Dew Point Control?
Keeping natural gas dry of water and heavy hydrocarbons so it will not condense liquids in the pipeline.
Read → GlossaryWhat is a Dissolved Oxygen Analyzer?
The online ppb-level instrument that verifies scavenger performance and detects air ingress in water.
Read → GlossaryWhat is a dissolved oxygen control loop?
A feedback loop that modulates blowers or air valves to hold basin DO at setpoint and cut aeration energy.
Read → GlossaryWhat is a DPD colorimetric chlorine analyzer?
Online instrument that doses DPD reagent, develops a pink color, and reads its absorbance to report chlorine residual each cycle.
Read → GlossaryWhat is a toxic gas monitoring system in a semiconductor fab?
Sensor network that catches silane, arsine, and hydride leaks in gas cabinets and subfabs, interlocking to shutoff and abatement.
Read → GlossaryWhat Is a Fast Loop Sample System?
A high-flow bypass that keeps fresh sample at the analyzer to slash lag time.
Read → GlossaryHow do you bump test a fixed gas detector?
Apply certified challenge gas through the cap, confirm a timely response into the pass window and the alarm activating, and log a pass without adjusting.
Read → GlossaryWhat Is a Flame Ionization Detector?
The hydrogen-flame detector that quantifies hydrocarbons in GCs and THC/VOC analyzers.
Read → GlossaryWhat is the difference between frost point and dew point in natural gas?
Below freezing, moisture frosts rather than condenses, so frost point runs several degrees warmer than the dew point.
Read → GlossaryGas Detection
Continuously sensing combustible, toxic, and oxygen hazards, the sensor technologies involved, and how detection drives site safety.
Read → GlossaryWhat Is a Gas Detector?
Fixed detection for combustible gas, H2S, and oxygen - sensor types, percent LEL vs ppm, and the safety role.
Read → GlossaryWhat is gas detector voting or coincidence detection?
Requiring two or more detectors in a zone to confirm gas before ESD or deluge, so one faulty detector cannot trip a plant.
Read → GlossaryWhat Is an H2S Analyzer?
The continuous ppm hydrogen sulfide analyzer that verifies sour-gas treating and sales spec - not a safety detector.
Read → GlossaryWhat is a hydrocarbon dew point margin alarm?
Watching the gap between operating temperature and the calculated dew point at line pressure to warn of liquid dropout.
Read → GlossaryHow does HVAC gas detection trigger a damper shutdown?
Intake-mounted detectors close dampers and stop fans so a gas cloud is not pulled into a control room or analyzer house.
Read → GlossaryWhat Is a Hydrocarbon Dew Point Analyzer?
The analyzer that finds the temperature at which heavy hydrocarbons condense, driving pipeline HCDP limits.
Read → GlossaryWhat is a hydrogen leak detection system?
Sensor network that catches H2 leaks at %LEL thresholds and interlocks to ventilation and shutdown at hydrogen sites.
Read → GlossaryHydrogen Sulfide (H2S)
The colorless, deadly gas found in sour oil and gas, its properties, exposure limits, and how it is detected and controlled.
Read → GlossaryWhat is Karl Fischer titration?
The iodine-based reference lab method for measuring trace water in crude, glycol, and transformer oil.
Read → GlossaryWhat Is an LDAR Program?
The survey, monitor, tag, repair, and reverify cycle that finds and fixes fugitive emissions leaks.
Read → GlossaryWhat is a lead acetate tape H2S analyzer?
Measures H2S by how fast a stain forms on impregnated tape, reaching the low ppm to ppb pipeline-quality gas needs.
Read → GlossaryWhat Is a Leak Detection System?
The methods and software that catch pipeline releases early.
Read → GlossaryLiquid Pipeline Leak Program
Instrumentation, controller procedures, testing, and records around the algorithm.
Read → GlossaryLower Explosive Limit (LEL)
The leanest flammable gas-air mixture, how percent-LEL is measured, and the alarm levels that keep atmospheres below the explosive range.
Read → GlossaryHow do you maintain an O2 analyzer sample conditioning path?
Leak-check for air ingress that reads as a false high, service filters and dryers, set flow, and prove the path with a known gas.
Read → GlossaryWhat Is a Mercaptan Analyzer?
Measures odorant thiols separately from H2S, supporting gas odorization control and product-spec monitoring.
Read → GlossaryWhat is a mercury analyzer in natural gas?
A gold-amalgamation atomic fluorescence instrument that measures trace mercury to protect aluminum exchangers and catalysts.
Read → GlossaryWhat is a methane number and why does an engine control system watch it?
A knock-resistance rating for fuel gas, like octane, that an engine layer uses to derate or blend as heavy ends rise.
Read → GlossaryWhat Is a Moisture Analyzer?
The online instrument that measures water in gas in lb/MMscf to verify dehydration and meet pipeline specs.
Read → GlossaryHow do you calibrate a moisture analyzer with a permeation tube?
Stabilize the tube temperature and carrier flow, calculate the concentration as emission rate over flow, and verify the analyzer once everything has settled.
Read → GlossaryHow Does an NDIR Gas Analyzer Work?
Reads CO2, CO and hydrocarbons by how much infrared light a filtered band the gas absorbs, no reagents needed.
Read → GlossaryWhat Is Negative Pressure Wave Detection?
How a rupture launches a rarefaction wave, and how arrival timing pinpoints the leak.
Read → GlossaryWhat Is an Oil-in-Water Analyzer?
The online instrument that measures residual oil in treated water and guards discharge limits.
Read → GlossaryWhat Is Opacity Monitoring?
Measuring how much light a stack or flare plume blocks as a proxy for smoke - via Method 9 and COMS.
Read → GlossaryWhat Is an Open Path Gas Detector?
A beam of IR or laser light across an open span that catches any gas cloud crossing the line.
Read → GlossaryWhat Is an ORP Analyzer?
The millivolt measurement of water's oxidizing state that controls biocide and chemical dosing.
Read → GlossaryWhat Is a Paramagnetic Oxygen Analyzer?
The magnetic, non-consuming sensor that gives a highly accurate O2 measurement.
Read → GlossaryWhat is a potential hydrocarbon dew point calculation?
HCDP computed from GC composition through an equation of state, highly sensitive to the C6+ characterization.
Read → GlossaryWhat Is a PEMS?
How a model predicts emissions from process parameters as a CEMS alternative, its inputs, and how it is validated.
Read → GlossaryHow do you purge and leak-check an analyzer sample line?
Pressure or vacuum test the line for integrity, inert-purge to displace air, then slowly introduce process sample and confirm a clean first reading.
Read → GlossaryWhat is a quartz crystal microbalance moisture analyzer?
A coated quartz crystal weighs water by frequency shift over a wet-dry cycle; contrast it with chilled mirror and TDLAS.
Read → GlossaryWhat Is a Sample Conditioning System?
The filtration, pressure, and phase-control plumbing that makes an analyzer reading valid.
Read → GlossaryWhat Is a Sample Probe?
The insertion probe and upstream mixing that pull a representative grab from a well-mixed crude stream.
Read → GlossaryHow do you set up a fast-loop sample system?
Route a high-flow loop past the analyzer, tap a small conditioned slip stream to the cell, set both flows, and verify the reduced lag by step test.
Read → GlossaryHow do you set up an analyzer stream switching sequence?
Map the shared volume, size the purge time to clear carryover, sequence the selector to sample after purging, and prove each stream reads its own gas.
Read → GlossaryWhat Is a Soil Moisture Sensor?
The probe that measures root-zone water, plus capacitance vs TDR, volumetric content, calibration, and trending.
Read → GlossaryWhat Is a Stream Selector Valve?
A switching valve that lets one GC or analyzer serve many sample streams in sequence.
Read → GlossaryWhat is T90 response time for a gas detector?
The time to reach 90% of the final reading after exposure, and what slows a detector down over time.
Read → GlossaryWhat is a TDLAS H2S analyzer for custody gas?
A laser-absorption H2S analyzer with no consumable tape, giving fast, low-maintenance custody measurement and real-time SCADA spec enforcement.
Read → GlossaryWhat Is a Thermal Conductivity Detector?
The universal, non-destructive GC detector that measures inerts and enables BTU analysis.
Read → GlossaryWhat Is a Total Acid Number (TAN) Analyzer?
Measures crude and oil acidity by titration; TAN flags naphthenic-acid corrosion risk and guides crude selection.
Read → GlossaryWhat is a total sulfur analyzer for custody gas?
Measures all sulfur species, H2S plus mercaptans and COS, against a contract limit, unlike an H2S-only analyzer.
Read → GlossaryWhat Is a Trace Oxygen Analyzer?
The ppm-level analyzer that catches oxygen ingress in pipelines and blanketing systems.
Read → GlossaryWhat Is a Transmissometer?
A double-pass opacity monitor that reads stack particulate by light attenuation, with path correction and daily checks.
Read → GlossaryWhat Is a TDLAS Analyzer?
A laser tuned to a gas's absorption line to measure H2S, moisture, or CO2 fast and without consumables.
Read → GlossaryWhat is the Tutwiler method for measuring H2S?
A manual iodine titration for H2S used as a spot check and referee to validate online analyzers against the SCADA trend.
Read → GlossaryHow do you calibrate a pH analyzer with two buffers?
Pick buffers that bracket the process, set offset in the first and slope in the second, and confirm the slope is healthy before trusting it.
Read → GlossaryHow Does a UV Fluorescence Total Sulfur Analyzer Work?
Burns the sample to SO2, then measures the fluorescence it emits under UV to report total sulfur at trace levels.
Read → GlossaryHow does sample pressure affect a dew-point analyzer?
Confirm the pressure at measurement, decide whether the analyzer reads at line or reduced pressure, and reference the reported dew point correctly.
Read → GlossaryHow do you verify analyzer sample-system lag time?
Calculate transport lag as tubing volume over flow, then confirm it with a gas-switch step test timing the analyzer response.
Read → GlossaryWhat is the difference between water dew point and hydrocarbon dew point specs?
Water dew point guards against corrosion and hydrates; hydrocarbon dew point guards against liquid dropout, tracked as two separate margins.
Read → GlossaryWhat is a wet-chemistry ammonia analyzer?
Reagent analyzer that reacts a conditioned sample to measure ammonia with compliance-grade accuracy for permit reporting.
Read → GlossaryHow do you zero and span an NDIR gas analyzer?
Purge and zero on gas free of the target, span on a certified bracketing gas, treat a low span as optical fouling, and confirm the value to SCADA.
Read → GlossaryHow do you zero and span calibrate a gas detector?
Apply zero gas to set the baseline, then certified span gas to set the gain, correcting drift at both ends.
Read → GlossaryWhat Is a Zirconia Oxygen Analyzer?
The heated ceramic cell that measures flue-gas oxygen for combustion and excess-air control.
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