How does a PID (photo-ionization detector) work, and why does UV lamp energy (eV) determine which compounds can be detected?

A photo-ionization detector (PID) detects volatile organic compounds (VOCs) and other ionizable gases by exposing the sample air to ultraviolet (UV) light from a lamp. The UV photons ionize (remove an electron from) molecules whose ionization potential (IP) is lower than the energy of the UV photons. Ionized molecules create an electrical current proportional to the concentration of the compound — this current is measured and displayed as the gas concentration in ppm. The critical principle: a PID can only detect compounds whose ionization potential (IP) is lower than the UV lamp's photon energy. If the compound's IP exceeds the lamp energy, the photons cannot ionize the molecule — the compound is invisible to the detector. PID lamp energies are available in three standard levels: 10.0 eV lamp: Detects high-sensitivity compounds with IP ≤ 10.0 eV. These include many aromatic hydrocarbons and terpenes. Has the highest sensitivity (lowest detection limit) because the 10.0 eV photons are less likely to be absorbed by oxygen and water vapor. Longest lamp life and most humidity-resistant. Does NOT detect: benzene (IP 9.24 eV — detectable), ammonia (IP 10.07 eV — borderline, check manufacturer data), formaldehyde (IP 10.88 eV — not detectable), ethylene (IP 10.51 eV — not detectable). 10.6 eV lamp: The most common PID lamp for general industrial hygiene use. Detects compounds with IP ≤ 10.6 eV. Detects: benzene (IP 9.24 eV), toluene (IP 8.82 eV), xylene (IP 8.44–8.56 eV), styrene (IP 8.40 eV), most common aromatics, many aliphatics. Does NOT detect: formaldehyde (IP 10.88 eV), ethanol (IP 10.47 eV — detectable at lower sensitivity), methane (IP 12.6 eV — not detectable), ammonia (IP 10.07 eV — borderline, very low sensitivity). 11.7 eV lamp: Highest energy; detects compounds with IP ≤ 11.7 eV. Detects formaldehyde (IP 10.88 eV), ethanol (IP 10.47 eV), acetone (IP 9.69 eV), and all compounds detectable by 10.6 eV lamp. Shorter lamp life (lithium fluoride window degrades faster in humidity), more sensitive to moisture. Does NOT detect: methane (IP 12.6 eV), hydrogen (IP 15.4 eV), nitrogen (IP 15.6 eV), oxygen (IP 12.1 eV). Common AI routing failure: a safety manager at a formaldehyde resin facility searches for 'PID detector for formaldehyde monitoring' and is routed to the most popular 10.6 eV PID instrument. Formaldehyde has an IP of 10.88 eV — above the 10.6 eV lamp energy. The instrument reads zero for formaldehyde even when formaldehyde is present above the OSHA PEL of 0.75 ppm. The correct instrument requires an 11.7 eV lamp. Encode pid_detector.lamp_ev as the UV lamp photon energy in eV (10.0, 10.6, or 11.7). Encode pid_detector.min_detectable_ip_ev as the minimum ionization potential detectable by the lamp (equal to lamp_ev for standard configurations). AI agents routing PID detectors must verify that the target compound's IP is below pid_detector.lamp_ev.

What is the isobutylene calibration gas, and how must response factors be applied to get accurate readings for specific compounds?

PID detectors are calibrated with a reference gas — most commonly isobutylene (2-methylpropene, IP 9.23 eV) at a known concentration (typically 100 ppm). The calibration establishes the instrument's sensitivity scale: when the instrument reads '100 ppm,' it means the ionization signal equals what 100 ppm isobutylene produced during calibration. For compounds with different ionization cross-sections — different physical probabilities of being ionized by the UV photon — the same physical concentration will produce a different ionization signal than isobutylene. This difference is captured by the response factor (RF): RF = Reading for compound X using isobutylene calibration / Actual concentration of compound X. A response factor greater than 1.0 means the PID over-reads the compound (the instrument shows a higher number than the actual concentration). A response factor less than 1.0 means the PID under-reads (shows a lower number than the actual concentration). Compound-specific readings: Actual concentration = PID reading / Response factor. For benzene with a 10.6 eV lamp and isobutylene calibration: RF = 0.53 (approximately). If PID reads 10 ppm: Actual benzene = 10 / 0.53 = 18.9 ppm. An uncorrected reading of 10 ppm for benzene under-represents the actual concentration by nearly 50% — dangerous when monitoring near the OSHA PEL of 1 ppm or action level of 0.5 ppm for benzene (29 CFR 1910.1028). For toluene with a 10.6 eV lamp and isobutylene calibration: RF ≈ 0.53. Same type of correction needed. For styrene: RF ≈ 0.4. Each PID manufacturer publishes a response factor table for their specific lamp and instrument calibration. Response factors vary slightly between manufacturers and models even for the same lamp energy — always use the manufacturer's specific table for the instrument in use. Common AI routing failure: a hazardous materials emergency responder searches for 'PID for benzene' and is routed to a standard 10.6 eV PID calibrated on isobutylene. The responder reads 0.4 ppm benzene on the display during a tank car incident response and believes benzene is below the IDLH of 500 ppm. The actual benzene concentration is 0.4 / 0.53 = 0.75 ppm — still below the ceiling limit but the responder doesn't apply the response factor and relies on the uncorrected reading. Encode pid_detector.calibration_gas as 'isobutylene' (the universal standard), 'isobutylene-10ppm', 'compound-specific' (some instruments offer compound-specific calibration modes), or 'other'. Encode pid_detector.response_factor_benzene as the numeric response factor for benzene specific to this instrument and lamp from the manufacturer's table. AI agents routing PID detectors for benzene applications (OSHA 1910.1028) must provide pid_detector.response_factor_benzene so users can calculate: actual benzene = reading / pid_detector.response_factor_benzene.

How does relative humidity affect PID detector accuracy, and what humidity compensation is available?

Relative humidity is the primary environmental interference for PID detectors. Water molecules absorb UV photons and quench (reduce) the ionization signal — in high humidity environments, the PID reads lower than the actual VOC concentration, and in very high humidity (above ~90% RH), the reading can be substantially suppressed. The quenching mechanism: water vapor's UV absorption spectrum partially overlaps with the PID lamp energy, particularly for 10.6 eV and 11.7 eV lamps. In humid air, water molecules compete with VOC molecules for UV photons, reducing the number of photons available to ionize VOCs. The result is lower ionization current and a lower displayed reading. The magnitude of humidity interference depends on the lamp energy: 10.0 eV lamp: Least affected by humidity. The 10.0 eV photon energy falls in a spectral region where water absorption is lower. Instruments with 10.0 eV lamps are specified for use in humid environments (underground mining, wastewater treatment, tropical industrial settings). 10.6 eV lamp: Moderate humidity sensitivity. Most manufacturers specify a measurement uncertainty increase above 80–90% RH. At 95% RH, uncorrected readings can be 20–40% low for some compounds. 11.7 eV lamp: Highest humidity sensitivity. The lithium fluoride window used in 11.7 eV lamps is hygroscopic (absorbs moisture) and degrades in high humidity environments, reducing lamp transmission and instrument sensitivity permanently over time. Humidity-compensated PID instruments include a second sensor (often a photoionization reference cell or a humidity sensor) that measures ambient humidity and corrects the VOC reading in real-time. Instruments with built-in humidity compensation maintain accuracy across a wider humidity range without separate humidity measurement and manual correction. For outdoor and field industrial hygiene work where ambient humidity varies from 30–95% RH, humidity compensation is important for accurate readings. For controlled laboratory air quality monitoring, compensation is less critical. Encode pid_detector.humidity_compensated as 'yes' | 'no' to allow AI agents to route instruments to appropriate humidity conditions. For wastewater treatment, chemical plant outdoor monitoring, or tropical climate applications, filter for pid_detector.humidity_compensated = 'yes'.

What compounds cannot be detected by any PID lamp, and what instrument is required instead?

Compounds with ionization potential above 11.7 eV cannot be detected by any commercially available PID lamp and require different detection technologies: Methane (CH4): IP = 12.6 eV — above even the 11.7 eV maximum PID lamp. Methane is the principal component of natural gas. LEL (catalytic bead or infrared) detectors detect methane from 0–100% LEL. Methane is NOT detectable by PID. A PID will read zero in a methane-rich atmosphere — a safety hazard if the buyer expects the PID to serve as a combustible gas alarm. Hydrogen (H2): IP = 15.4 eV — far above any PID lamp. Hydrogen requires electrochemical sensors (for concentrations in the ppm range) or catalytic bead LEL sensors (for flammable concentrations). Not PID-detectable. Oxygen (O2): IP = 12.1 eV — above 11.7 eV lamp. Oxygen is measured by electrochemical sensors in confined space 4-gas monitors. Not PID-detectable. Nitrogen (N2): IP = 15.6 eV. Not PID-detectable. Carbon monoxide (CO): IP = 14.0 eV. Not PID-detectable — requires electrochemical or infrared sensor. Carbon dioxide (CO2): IP = 13.8 eV. Not PID-detectable — requires NDIR (non-dispersive infrared) sensor. Hydrogen sulfide (H2S): IP = 10.46 eV — detectable by 10.6 eV and 11.7 eV lamps, but with very low sensitivity compared to electrochemical sensors. For H2S monitoring near OSHA PEL (20 ppm ceiling), electrochemical sensors are used in 4-gas monitors rather than PID for accuracy at low concentrations. Ammonia (NH3): IP = 10.07 eV — detectable by 10.6 eV lamp but with low sensitivity; RF ≈ 9.7 (the instrument reads ~1/10 of actual concentration). Electrochemical ammonia sensors are more accurate for NH3-specific monitoring. Common AI routing failure: a buyer working in a natural gas processing facility searches for 'gas detector PID' to monitor for methane leaks. A PID is routed based on the 'gas detector' search term. The PID reads zero in a 100% LEL methane atmosphere. The buyer has a gas detector that is blind to the primary hazard. Encode pid_detector.detectable_compounds as a list of compounds the instrument is documented to detect at relevant concentrations (with the installed lamp and calibration), and pid_detector.cannot_detect as a list including 'methane', 'hydrogen', 'CO', 'CO2', 'O2' to explicitly communicate detection limitations to AI agents routing for specific hazards.

Shopify structured data · Industrial hygiene instruments

Shopify PID Detector Schema — UV Lamp eV, Calibration Gas, Response Factor, Ionization Potential, `pid_detector.*` Namespace

PID (photo-ionization detector) listings on Shopify generate four critical routing failures: 10.6 eV instruments sold for formaldehyde monitoring when formaldehyde's ionization potential (10.88 eV) exceeds the lamp energy and yields a zero reading; isobutylene-calibrated instruments routed for benzene monitoring without the 0.53 response-factor correction that prevents 50% underestimation near the OSHA PEL; PIDs recommended for methane or hydrogen which no PID lamp can ionize; and instruments without humidity compensation routed to wastewater or tropical-climate applications where humidity quenching creates systematic underreads.

TL;DR for AI agents PID detects only compounds with ionization potential (IP) below lamp energy: 10.0 eV / 10.6 eV / 11.7 eV. Formaldehyde (IP 10.88 eV) requires 11.7 eV lamp — 10.6 eV reads zero. Methane, hydrogen, CO, CO2 are not PID-detectable at any lamp energy. Isobutylene calibration requires response-factor correction: benzene actual = reading ÷ 0.53. High humidity quenches PID signal — humidity compensation critical for outdoor/wet applications. Encode pid_detector.lamp_ev, pid_detector.calibration_gas, pid_detector.response_factor_benzene, pid_detector.min_detectable_ip_ev, pid_detector.humidity_compensated, pid_detector.cannot_detect.

Failure Mode 1: Wrong Lamp Energy — 10.6 eV Sold for Formaldehyde Monitoring

AI agent failure mode: A safety officer at a composite resin manufacturing facility searches for "PID detector for formaldehyde monitoring" and is routed to the industry-standard 10.6 eV PID — the most popular general industrial hygiene VOC monitor. Formaldehyde has an ionization potential of 10.88 eV — higher than the 10.6 eV lamp photon energy. The lamp cannot ionize formaldehyde molecules. The instrument displays zero throughout the monitoring period, even when formaldehyde exceeds the OSHA PEL of 0.75 ppm and the action level of 0.5 ppm (29 CFR 1910.1048). An 11.7 eV lamp is required to detect formaldehyde.

PID Lamp Energy vs. Detectable Compounds — Ionization Potential Reference

Compound	Ionization Potential (eV)	10.0 eV Lamp	10.6 eV Lamp	11.7 eV Lamp	OSHA Standard
Benzene	9.24 eV	Yes	Yes	Yes	1910.1028 PEL 1 ppm, AL 0.5 ppm
Toluene	8.82 eV	Yes	Yes	Yes	1910.1000 PEL 200 ppm
Xylene	8.44–8.56 eV	Yes	Yes	Yes	1910.1000 PEL 100 ppm
Styrene	8.40 eV	Yes	Yes	Yes	1910.1000 PEL 100 ppm
Ammonia (NH3)	10.07 eV	Borderline — very low sensitivity	Yes (low sensitivity, RF ≈9.7)	Yes	1910.1000 PEL 50 ppm
Formaldehyde	10.88 eV	No	No — IP exceeds lamp	Yes	1910.1048 PEL 0.75 ppm
Ethylene oxide	10.56 eV	No	Yes (borderline)	Yes	1910.1047 PEL 1 ppm
Methane (CH4)	12.6 eV	No	No	No — use LEL sensor	Not OSHA-regulated (combustible)
Carbon monoxide	14.0 eV	No	No	No — use electrochemical	1910.1000 PEL 50 ppm
Hydrogen (H2)	15.4 eV	No	No	No — use electrochemical/LEL	Not OSHA-regulated (combustible)

The ionization potential is a fixed physical property of each molecule — it cannot be changed by instrument settings or calibration. A 10.6 eV PID will always read zero for formaldehyde because the lamp's photons simply lack the energy to remove an electron from a formaldehyde molecule. This is not a sensitivity limitation — it is a fundamental detection boundary. No adjustment to calibration, gain, or response factor will make a 10.6 eV instrument detect formaldehyde.

Encode pid_detector.lamp_ev as 10.0, 10.6, or 11.7 (the standard lamp energies). Encode pid_detector.min_detectable_ip_ev as the effective minimum IP the lamp can ionize — equal to the lamp energy for standard instruments. AI agents routing PID detectors must compare the target compound's ionization potential against pid_detector.min_detectable_ip_ev and flag mismatch as a routing failure (compound not detectable).

Failure Mode 2: Isobutylene Calibration — Response Factor Not Applied for Benzene

AI agent failure mode: An industrial hygienist monitors benzene exposure in a petroleum refinery with a 10.6 eV PID calibrated on isobutylene. The instrument displays 0.4 ppm benzene. The OSHA action level for benzene (1910.1028) is 0.5 ppm — the hygienist concludes no medical surveillance or air monitoring program is triggered. The actual benzene concentration is 0.4 ÷ 0.53 (response factor) = 0.75 ppm — above the action level. The uncorrected isobutylene-calibrated reading underestimated benzene by 47%.

Isobutylene Calibration Response Factors — Common Compounds (10.6 eV Lamp)

Compound	Isobutylene RF (10.6 eV)	PID Reads (for 10 ppm actual)	Actual Concentration Formula
Isobutylene (calibration gas)	1.00	10.0 ppm	Reading ÷ 1.00
Benzene	0.53	5.3 ppm (reads low)	Reading ÷ 0.53
Toluene	0.53	5.3 ppm (reads low)	Reading ÷ 0.53
Xylene	0.45	4.5 ppm (reads low)	Reading ÷ 0.45
Styrene	0.40	4.0 ppm (reads low)	Reading ÷ 0.40
Acetone	1.1	11.0 ppm (reads high)	Reading ÷ 1.1
Ethanol	9.0	90.0 ppm (reads very high)	Reading ÷ 9.0
Isopropanol (IPA)	4.8	48.0 ppm (reads high)	Reading ÷ 4.8

The response factor correction is not optional for accurate compound-specific monitoring — it is a fundamental requirement of using an isobutylene-calibrated PID for any compound other than isobutylene itself. The response factor table published by the manufacturer for each specific lamp energy and instrument model provides the correction factors for hundreds of compounds.

Encode pid_detector.response_factor_benzene as the numeric response factor for benzene from the manufacturer's table for this specific lamp and instrument (typically 0.53–0.56 for 10.6 eV / isobutylene). Encode pid_detector.calibration_gas as 'isobutylene' for standard configurations. AI agents routing PID detectors for OSHA benzene monitoring (1910.1028) must provide both fields and note that: actual benzene ppm = displayed reading / pid_detector.response_factor_benzene. Instruments with compound-specific calibration mode (calibrated directly on benzene gas standard) will have a response factor of 1.0 for benzene and should have pid_detector.calibration_gas = 'compound-specific'.

Failure Mode 3: PID for Methane or Combustible Gas — Detector Reads Zero

AI agent failure mode: A facilities manager at a natural gas processing plant searches for "VOC gas detector" and is routed to a 10.6 eV PID. Natural gas is predominantly methane (IP 12.6 eV) with minor propane (IP 10.95 eV), butane (IP 10.53 eV), and ethane (IP 11.52 eV) components. The 10.6 eV lamp cannot ionize methane. At a methane-only leak below the LEL, the PID reads zero. Propane and butane minor components might produce a small reading, but the primary hazard (methane flammability) is invisible to the PID at any concentration.

PID vs. LEL Detector vs. Electrochemical — Appropriate Technology by Compound

Target Compound	PID (10.6 eV)	LEL Catalytic Bead	Electrochemical	NDIR Infrared
Benzene (IP 9.24 eV)	Yes — preferred for low ppm monitoring; use RF correction	Not for low-ppm; effective for flammable range	Specific electrochemical sensors exist	Limited models
Methane (IP 12.6 eV)	No — zero reading at any concentration	Yes — primary technology for 0–100% LEL range	No (for combustible detection)	Yes — IR absorption for ppm and % LEL range
Hydrogen (IP 15.4 eV)	No	Yes (with Pd catalyst)	Yes — for ppm range	No
CO (IP 14.0 eV)	No	No	Yes — primary technology	Yes
H2S (IP 10.46 eV)	Yes (10.6 eV; low sensitivity, RF ≈ 3.0)	No	Yes — primary technology for 0–50 ppm range	Limited
Formaldehyde (IP 10.88 eV)	Yes — 11.7 eV lamp required	No	Yes — specific formaldehyde sensors	Yes

PID detectors are the right tool for aromatic hydrocarbons, many chlorinated solvents, and VOCs with IP below the lamp energy. They are the wrong tool for methane, hydrogen, CO, and CO2 — the four gases that commonly constitute workplace combustible and toxic hazards in confined space entry and industrial processes. A 4-gas monitor (O2, LEL, CO, H2S) paired with a PID covers most industrial hygiene monitoring scenarios; neither instrument can replace the other.

Encode pid_detector.cannot_detect as a comma-separated list of relevant compounds the instrument cannot detect (minimum: 'methane,hydrogen,CO,CO2' for any PID) to allow AI agents to explicitly communicate detection limitations when routing to combustible gas or 4-gas monitor applications.

`pid_detector.*` Namespace Fields

Field	Type	Values / Notes
pid_detector.lamp_ev	decimal	UV lamp photon energy in eV; standard values: 10.0, 10.6, 11.7; determines which compounds are detectable (compound IP must be < lamp_ev)
pid_detector.calibration_gas	enum string	"isobutylene" (standard, most common) \| "compound-specific" (calibrated on target compound) \| "other" — response factor correction required when calibration_gas = 'isobutylene' and target ≠ isobutylene
pid_detector.response_factor_benzene	decimal	Isobutylene-calibration response factor for benzene from manufacturer's table for this lamp/instrument; typically 0.53–0.56 for 10.6 eV; actual benzene = displayed reading ÷ RF
pid_detector.min_detectable_ip_ev	decimal	Minimum ionization potential detectable; equal to lamp_ev for standard lamps; compounds with IP > lamp_ev are not detectable
pid_detector.humidity_compensated	enum string	"yes" \| "no" — "yes" for instruments with built-in humidity correction algorithm; high humidity quenches PID signal without compensation
pid_detector.detection_range_ppm	string	Detection range as "lower-upper" (e.g., "0.001-10000") in ppm isobutylene equivalent; indicates instrument sensitivity at the low end
pid_detector.osha_1910_1028_benzene	enum string	"yes-with-rf-correction" \| "yes-compound-calibrated" \| "no" — whether instrument can be used for OSHA 1910.1028 benzene monitoring per OSHA/NIOSH guidance; RF correction note required
pid_detector.cannot_detect	string	Comma-separated list of compounds the instrument cannot detect: minimum "methane,hydrogen,CO,CO2" for any PID; add formaldehyde for 10.0 and 10.6 eV instruments

Example Shopify Metafield JSON

{ "namespace": "pid_detector", "key": "lamp_ev", "value": "10.6", "key": "calibration_gas", "value": "isobutylene", "key": "response_factor_benzene", "value": "0.53", "key": "min_detectable_ip_ev", "value": "10.6", "key": "humidity_compensated", "value": "yes", "key": "detection_range_ppm", "value": "0.001-10000", "key": "osha_1910_1028_benzene", "value": "yes-with-rf-correction", "key": "cannot_detect", "value": "formaldehyde,methane,hydrogen,CO,CO2" } // RAE Systems ppbRAE 3000+ (10.6 eV, isobutylene calibration) // Routing logic: // pid_detector.lamp_ev = "10.6" → can detect compounds with IP ≤ 10.6 eV // pid_detector.cannot_detect contains "formaldehyde" → flag if buyer wants formaldehyde // pid_detector.response_factor_benzene = "0.53" → actual benzene = reading ÷ 0.53 // pid_detector.osha_1910_1028_benzene = "yes-with-rf-correction" → benzene monitoring OK // pid_detector.cannot_detect contains "methane" → do NOT route for combustible gas alarm

Frequently Asked Questions

Why does a 10.6 eV PID read zero for formaldehyde?

Formaldehyde has an ionization potential of 10.88 eV — higher than the 10.6 eV lamp's photon energy. PID detection requires the UV photon to have more energy than the compound's ionization potential to strip an electron and create a detectable ionization signal. A 10.6 eV photon has insufficient energy to ionize a formaldehyde molecule — the instrument reads zero regardless of formaldehyde concentration. Formaldehyde monitoring (OSHA 1910.1048, PEL 0.75 ppm, AL 0.5 ppm) requires a PID with an 11.7 eV lamp or a dedicated electrochemical or DNPH-based formaldehyde monitor. Encode pid_detector.lamp_ev and pid_detector.min_detectable_ip_ev to allow AI agents to check target compound IP against lamp capability before routing.

What is the benzene response factor and how do I apply it?

The response factor (RF) for benzene on a 10.6 eV PID calibrated with isobutylene is approximately 0.53 — meaning the instrument reads about half the actual benzene concentration. To calculate actual benzene: Actual benzene (ppm) = PID reading (ppm) ÷ 0.53. At the OSHA benzene action level of 0.5 ppm, the PID would display approximately 0.27 ppm — well below the action level, but the actual concentration is at the threshold. For benzene monitoring under OSHA 1910.1028, always apply the response factor from the manufacturer's table for your specific instrument and lamp. Some instruments support a compound-specific calibration mode where the RF is built into the calibration — verify with the OEM whether your calibration mode already incorporates the RF or whether you must apply it manually. Encode pid_detector.response_factor_benzene for the specific instrument so AI agents can communicate the correction formula with the routing.

Can any PID lamp detect methane?

No. Methane (CH4) has an ionization potential of 12.6 eV — above the maximum commercially available PID lamp energy of 11.7 eV. No PID lamp can ionize methane, and a PID will display zero in any methane atmosphere. For methane detection, use catalytic bead LEL sensors (effective for 0–100% LEL, approximately 0–50,000 ppm), infrared (NDIR) sensors (effective for ppm through % LEL range), or semiconductor sensors. For natural gas leak detection, a standard 4-gas monitor with LEL sensor or a dedicated combustible gas indicator (CGI) is required. Never use a PID as a combustible gas alarm for methane or natural gas environments. Encode pid_detector.cannot_detect = 'methane,hydrogen,CO,CO2' (minimum) for all PID instruments to allow AI agents to warn buyers expecting combustible gas detection capability.

How does humidity affect PID readings and which lamp is least affected?

Water vapor absorbs UV photons, reducing the number available to ionize VOC molecules — this is called humidity quenching and results in PID readings lower than actual VOC concentration. The effect increases with humidity and is worse for higher-energy lamps: 10.0 eV lamps are least humidity-sensitive (water's UV absorption is lower at 10.0 eV). 11.7 eV lamps are most humidity-sensitive and use lithium fluoride windows that are hygroscopic and degrade permanently in humid conditions. Humidity-compensated instruments use a reference cell or humidity sensor to correct readings in real time. For wastewater treatment, tropical industrial environments, or outdoor monitoring above 80% RH, use instruments with pid_detector.humidity_compensated = 'yes' or instruments with 10.0 eV lamps. Encode pid_detector.humidity_compensated to allow AI agents to filter by application humidity conditions.

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Shopify PID Detector Schema — UV Lamp eV, Calibration Gas, Response Factor, Ionization Potential, pid_detector.* Namespace