Waltron FAQ

The Waltron 3141 Silica Analyzer uses a colorimetric method based on the Lambert-Beer Law.

The recommended frequency for operational calibration is every 7 days. A manual factor (slope) calibration is specifically required during initial start-up, after replacing reagents, and following any period of extended shutdown. The analyzer can be configured to perform these calibrations automatically. Users can program a “Cycles ratio” in the Settings Menu, determining how many analysis cycles run before a calibration (extra) cycle is automatically triggered.

Annual maintenance includes cleaning the 3-way valve, replacing the colorimetric cell o-ring, and replacing reagent straw and sample tubing. A yearly consumables kit (W3140-101) is available.

The measurement range of the 9135, 9131C and 9033X Sodium Analyzers spans from 0.01 ppb to 10 ppm.

The analyzer requires a buffer solution. Two alternative reagent solutions may be used, depending on the required lower limit of measurement. Concentrated ammonia solution, which provides adjustment of sample pH to 10.7 is suitable for measurements of sodium ion to approximately 0.5ppb. At concentrations below 0.5ppb, hydrogen ion interference becomes significant and a reagent of Diisopropylamine solution should be used. This adjusts the sample pH to 11.2 – 11.5 and enables measurements to be made to concentrations below 0.5ppb.

For the reference electrode, a 3.0 M Potassium Chloride (KCl) solution is required for refilling at extended intervals.

For more details, you can see the Reagents and Standards FAQ below.

Waltron Sodium Analyzers utilize a microcontroller to control calibration via Single Point, Two Point, or Process calibration methods.

• Two-Point Calibration (Recommended): This is the standard method used to establish the slope of the calibration curve. It requires two fresh sodium standard solutions: a Low Standard (100 ppb) and a High Standard (1000 ppb / 1 ppm). It is recommended to perform a 2-Point calibration at least once a week to eliminate drift caused by changing electrode response.
• Single Point (1-Pt) Calibration: This method is performed only if the analyzer has already successfully passed a 2-Point calibration. If the monitor runs continuously at high concentrations (>100 ppb), a weekly Single Point calibration is recommended.
• Automatic Calibration: The analyzer can be configured to perform 1-Pt or 2-Pt calibrations automatically at user-defined intervals.

The Waltron Dissolved Oxygen Analyzers and Sensors utilize luminescent technology, which provides high accuracy with excellent long-term stability compared to traditional dissolved oxygen sensing technologies because it requires no membranes, no electrolyte, and no polarization time. Unlike older electrochemical sensors, LDO sensors do not consume oxygen, making them accurate even in low-flow conditions, and they require significantly less maintenance (typically a sensor cap change every 1-2 years).

For the Luminescent sensor, calibration is recommended yearly via a sensor exchange program where a fully refurbished and calibrated sensor is shipped to the customer.

The 9165 Luminescent Dissolved Oxygen Analyzer user outputs are as follows:

• Analog Outputs: The analyzer offers four analog outputs that are independent of each other. These can be configured as 0-20 mA, 4-20 mA, or 0-10 V. The Outputs can be assigned to either Oxygen or Temperature readings. The outputs support “Hold” (freeze output) and “Simulate” (force output to 0%, 50%, or 100%) functions for testing and maintenance.
• Relay Outputs: The analyzer includes four available relay outputs.

Note: If referring specifically to the 9165S Smart Sensor (standalone operation), it provides a single 4-20 mA current output. The 4000DO monitor offers 0/4-20 mA outputs. It also features relay connections and setpoints that can be configured for High, Low, Band, Latch High, Latch Low, Cleaning, and Alarm modes.

Waltron 9096 Degassed Cation Conductivity Analyzer measures specific, cation, and degassed cation conductivities. It utilizes a degassing column where a small amount of sample flow discharges constantly to provide the degassed measurement.

4000DC Degassed Cation Conductivity Analyzer measures cation conductivity through a multi-stage process designed to isolate corrosive species from other chemical masking agents..

The 9096 analyzer uses Cationic Exchange technology and measures specific and cation conductivities in high purity process water.

The 4000EC monitor utilizes electrodeless conductivity technology.

The 4000DC monitor uses dynamic degassing technology.

The 4000SC Monitor users contacting electrode technology.

The 9096 Degas Cation Conductivity supports multiple ranges: 0-9.999 µS/cm, 0-99.99 µS/cm.

The 4000EC monitor’s range is 0-1000mS/cm.The 4000DC monitor’s range is 0-9.999 µS/cm.

The 4000SC monitor offers auto-ranging or selectable ranges such – 0-9.999µS/cm to 0-999.9mS/cm depending on the cell constant selected.

For the 9096 Degassed Cation Conductivity Analyzer and 4000DC require the periodic replacement of the cation resin bottle and the soda lime cartridge.

The 4000EC is electrodeless and requires no reagents. Standard Solutions such as KCI are required for calibration.

The 4000SC utilizes contacting conductivity sensors and requires no chemical reagents for the measurement process. Standard Solutions such as KCI are required for calibration.

For more details, you can see the Reagents and Standards FAQ below.

The 4000PH is a microprocessor-controlled instrument compatible with separate glass and reference electrode pairs or combination electrodes. It supports both pH and Redox (ORP) measurement.

The 4000PH supports “Auto calibration” which is preconfigured for Waltron buffers (4pH and 9pH). It also allows for manual temperature input if the temperature compensation mode is set to manual.

The 4000PH features an “Input Filtering” (Averaging) function, allowing the user to filter sensor readings by taking a running average over a selected time period (from 10 seconds to 5 minutes) to manage very noisy environments.

The Waltron 3154 Analyzer uses a colorimetric method with a glass flowcell and LED source to measure Filming Amine concentrations,

The measurement range for the 3154 Analyzer is 0 – 500 ppb.

Analog: The analyzer provides 4-20 mA outputs (with an optional galvanic isolator module) or 0-5V outputs. 

Digital: A serial data output RS-232 is standard, while RS-485 is available as an option.

Relay: The unit features 2 or 4 configurable alarm relays.

The 3151 Hardness (Calcium) uses a colorimetric method with matching reagents to measure hardness.

The Aqualert 6051 uses automatic titrimetric technology to detect hardness levels in water as total or carbonate hardness.

The 3151 Analyzer offers wide ranges including 0-250ppb, 0-1ppm for measuring Calcium Harndness.

The Aqualert 6051 measures total hardness in the range of 0.02-30 °dH (3.6 – 5349 µmol/l). Specific ranges depend on the reagent used; for example, reagent type 500S/500 covers 0.22-2.14 ppm, while type 600/500 covers 53.40-534.0 ppm.

Our Hardness Analyzers use a Hydrochloric Acid Reagent, A Buffer Solution Reagent, and a Calibration Standard which can be purchased individually or as a kit at https://shop.waltron.net/collections/hardness-analyzer-consumables.

For more details, you can see the Reagents and Standards FAQ below.

Maintenance kits including peristaltic pump cartridges and gaskets are also available.

The 2410 Oil in Water Analyzer uses light scatter and transmission signals to detect oil.

The analyzer monitors for specific errors such as “Error SH” which indicates excessive solids content, or “Error BC” for bad clean water calibration.

Maintenance includes performing flush and cleaning procedures if errors regarding solids content or signal faults occur.

The Waltron 3142 Analyzer uses a colorimetric determination method based on the Lambert-Beer Law, measuring absorbance at a specific wavelength using a glass colorimetric reaction cell,

The Waltron 3142 Analyzer uses multi-point calibration (zero and mid-range) and includes matrix corrections for sample blank correction. It is critically important to use DI water with the lowest possible Phosphate concentration for blank calibration.

The analyzer uses chemical reagents including a Phosphate Blue Reagent #1, Molybdate/Sulfuric Acid Reagent, a Phosphate Blue Reagent #2, Reducing Reagent, and Calibration standards for multiple ranges. A yearly consumables kit (part number W3040-101) is available which includes tubing and fittings for scheduled maintenance.

You can purchase these consumables at our online store at https://shop.waltron.net/collections/phosphate

For more details, you can see the Reagents and Standards FAQ below.

The Waltron 3144 Hydrazine Analyzer uses a colorimetric method to measure Hydrazine concentrations.

The Waltron 9072 Hydrazine Analyzer measurement is based on a highly-accurate potentiostatic electro-chemical principle.

The 3144 Analyzer ranges are 0-100ppb, 0-500ppb.

The 9072 Analyzer offers a wide range of 0-1000ppb.

The Waltron 3148 Iron Analyzer is an on-line analyzer for batch analysis using a colorimetric method.

The Waltron 3148 Iron Analyzer uses three reagents: Sulfuric Acid and Molybdate Reagent, Oxalic Acid Reagent, and a Reducing Reagent. These are available for purchase at our online store at https://shop.waltron.net/collections/iron-analyzer-consumables

For more details, you can see the Reagents and Standards FAQ below.

The Waltron 3149 Ethylene Glycol Analyzer has a range of 0 – 15 ppm and 0 – 150ppm with an accuracy of +/- .1ppm or +/- 2% of full scale, whichever is greater.

The analyzer utilizes four reagents: Periodic Acid, Potassium Hydroxide, Potassium Persulfate, and Purpald Color Reagent. These reagents, and calibration standards, are available for purchase at our online store at https://shop.waltron.net/collections/ethylene-glycol-analyzer-consumables

For more details, you can see the Reagents and Standards FAQ below.

As a guideline, analyzer equipment is delivered between 2 – 6 weeks from the date of order depending on the product. Consumables are delivered between 1 – 2 weeks from the date of order.

The 3141 uses a colorimetric method requiring three distinct chemical reagents.

Reagents:

Reagent 1: Sulfuric Acid and Molybdate Reagent.

Reagent 2: Oxalic Acid Reagent.

Reagent 3: Reducing Reagent.

Standards:

Silica Calibration Standard: Options include 200 ppb, 1.5 ppm, or 75 ppm, depending on the measurement range.

These analyzers require a base-raising reagent to buffer the sample pH, calibration standards, and electrode maintenance solutions.

Reagents (Buffer Solutions):

Ammonium Hydroxide (29%): Used for standard applications,

Diisopropylamine (DIPA) (99%): Used for low-level sodium measurement applications (<0.5 ppb) to eliminate hydrogen ion interference,

Standards:

Low Standard: 100 ppb Sodium Standard

High Standard: 1000 ppb (1 ppm) Sodium Standard (Note: This is often red in color to distinguish it from the low standard)

Maintenance Consumables:

Etching/Regeneration Solution: Sodium Fluoride solution used to reactivate the glass sodium electrode

Reference Electrolyte: 3.0 M or 3.5 M Potassium Chloride (KCl) solution for refilling the reference electrode

The luminescent technology LDO analyzers does not require chemical reagents for measurement, but calibration consumables are needed.

Reagents: None required for operation.

Calibration Standards:

Zero Point: Certified Nitrogen (N2) or CO2 gas (99.999% purity), or Waltron Zero Oxygen Water

High Point: Air (water-saturated air) or certified gas with 1-2% O2 content.

Reagents:

Cation Resin: Required for Cation and Degassed Cation Conductivity analyzers (9095, 9096, 4000DC). The resin bottles (Waltron Part W1234-609) must be replaced monthly

Soda Lime: Required for the 9096 Degassed Cation Conductivity Analyzer to scrub CO2 from the air.

Standards:

KCl Standards: Potassium Chloride solutions are used for sensor calibration (e.g., 147 µS/cm or 12.88 mS/cm)

This 3142 Analyzer uses a single reagent for colorimetric detection.

Reagents:

Reagent 1: Phosphate Reagent.

Standards:

Phosphate Calibration Standard: 50 ppb (for 0-100 ppb range) or 200 ppb (for 0-500 ppb range).

Model 3144 (Colorimetric)

Reagents:

Reagent 1: Hydrazine Reagent.

Standards:

Hydrazine Calibration Standard: 50 ppb or 200 ppb.

Model 9072 (Electrochemical)

Consumables:

Electrolyte: 3M Potassium Chloride (KCl) solution.

Buffer: Granular Marble (used to maintain sample pH).

The 3148 uses a colorimetric method requiring three distinct chemical reagents.

Reagents:

Reagent 1: Sulfuric Acid and Molybdate Reagent.

Reagent 2: Oxalic Acid Reagent.

Reagent 3: Reducing Reagent.

Standards:

Iron Calibration Standard: Options include 200 ppb, 1.5 ppm, or 75 ppm, depending on the measurement range.

The 3149 uses a colorimetric method requiring four distinct chemical reagents.

Reagents:

Reagent 1: Periodic Acid Reagent.

Reagent 2: Potassium Hydroxide Reagent.

Reagent 3: Potassium Persulfate Reagent.

Reagent 4: Purpald Color Reagent.

Standards:

Ethylene Glycol Standard: 8ppm (for 0 – 15 ppm range).

The 3154 uses a colorimetric method requiring three distinct chemical reagents.

Reagents:

Reagent 1: Buffer Solution – Call 908-534-5100 or send an email to sales@waltron.net for details..

Reagent 2: Indicator Solution – Call 908-534-5100 or send an email to sales@waltron.net for details..

Reagent 3: Cleaning Solution – Call 908-534-5100 or send an email to sales@waltron.net for details.

Standards:

Filming Amine Calibration Standard: Call 908-534-5100 or send an email to sales@waltron.net for details.

The 3151 uses a colorimetric method requiring two distinct chemical reagents.

Reagents:

Reagent 1: Hardness Reagent #1, Hydrochloric Acid

Reagent 2: Hardness Reagent #2, Buffer Solution

Standards:

Calcium Hardness Calibration Standard: 50 ppb

The 6051 analyzer uses specific reagents that determine the measurement range. In all, the analyzer covers the measurement range of 3.6 – 5349 µmol/l.

Total Hardness Reagents:

0.22-2.14ppm / 0,02-0,12°dH / 0,04-0,21°f

0.36-3.56ppm / 0,02-0,2 °dH / 0,04 – 0,36°f

0.53-5.34ppm / 0,03-0,3°dH / 0,05-0,54°f

1.07-10.68ppm / 0,06-0,6°dH / 0,11-1,07°f

1.60-16.02ppm / 0,09-0,9°dH / 0,16-1,61°f

2.67-26.70ppm / 0,15-1,5°dH / 0,27-2,68°f

5.34-53.40ppm / 0,3-3,0°dH / 0,54-5,36°f

10.68-106.8ppm / 0,6-6,0°dH / 1,07-10,71 °f

16.02-160.2ppm / 0,9 – 9,0°dH / 1,61-16,07°f

26.70-267.0ppm / 1,5-15°dH / 2,68-26,79°f

53.40-534.0ppm / 3,0-30°dH / 5,36-53,57°f

Carbonate Hardness Reagents:

5.34-53.4ppm / 0,3-3,0°dH / 0,54-5,36°f

8.01-80.10ppm / 0,45-4,5°dH / 0,80-8,04°f

10.68-106.8ppm / 0,6-6,0°dH / 1,07-10,71°f

16.02-160.2ppm / 0,9-9,0°dH / 1,61-16,07°f

Analyzer chemicals must be kept away from heat and extreme temperatures. Reagent powders must be kept dry.

Liquid waste from analyzers contains small amounts of reagent chemicals and must be disposed of in accordance with appropriate regulations,. Users should follow all regulations and warning labels.

Individual Safety Data Sheets (SDS) can be obtained by contacting Waltron at sales@waltron.net.

The shelf life of the Hydrazine Standard is 30 Days. Hydrazine is a highly reactive oxygen scavenger, and its concentration can degrade over time due to its inherent chemical instability when exposed to oxygen and other environmental factors. As a result, the material’s accuracy and reliability cannot be assured beyond the one-month stability period. For this reason, Waltron specifies a maximum shelf life of 30 days to ensure that all analytical measurements performed with the standard remain valid and compliant with quality assurance requirements.

We recommend that users store the Hydrazine Standard Solution tightly sealed, in a dark and cold place. Any material remaining beyond the stated shelf life should be discarded and replaced with a freshly manufactured standard.

Consumables are delivered between 1 – 2 weeks from  the date of order.

 Flow rate requirements vary by analyzer technology.

Colorimetric Analyzers (3140 Series): Typically require a sample flow between 100 – 500 ml/min,,.

Luminescent Dissolved Oxygen Suite Requires 10 – 500 ml/min.

Sodium Analyzers (9135/9033X): During a 2-point calibration, the sample must be delivered at a rate of 150 – 400 ml/min to avoid calibration failure.

Degassed Cation Conductivity (9096): Requires a flow rate of 0.031 – 0.044 GPM (7-10 L/h).

Yes, if your sample temperature exceeds the analyzer’s operational limits. Most Waltron analyzers, such as the 3140 series and 9096 Degassed Cation Conductivity units, are rated for sample temperatures between 5°C and 50°C or 55°C (41°F – 131°F). Samples from high-temperature sources must be cooled to within this range before entering the instrument.

Most Waltron Analyzers can be wall or panel mounted. For example.

Colormetirc Analyzers (3140 series): Supplied with brackets for wall mounting or stainless steel support rack installation. Panel mounting kits are available as an option

4000 Series Transmitters: Support surface, panel, and pipe mounting configurations.

9096 Degassed Cation Conductivity: Designed for wall or panel mounting with dimensions of 29 x 37 x 10”.

To confirm configurations for a specific analyzer, you may consult the user guide or email us at sales@waltron.net

Waltron analyzers generally support multiple output formats for integration with DCS:

Analog: Galvanically isolated 0/4-20mA outputs are standard on most units, including the 9131, 3141, and 4000 series

Digital: RS-232 is standard on many models (e.g., 3141 Silica), while RS-485 using Modbus RTU protocol is available as an option or standard depending on the model (e.g., 9135 Sodium)

Relays: Configurable relays for High, Low, and General Alarms are standard

To confirm outputs for a specific analyzer, you may consult the user guide or email us at sales@waltron.net

To ensure sample integrity, particularly for trace analysis, Stainless Steel (AISI 316) is the standard material for wetted parts and connections in analyzers like the 3140 series. Sample inlet connections are typically ¼” Swagelok fittings.

To confirm sample line requirements for a specific analyzer, you may consult the user guide or email us at sales@waltron.net

Colorimetric (3140 series): It is recommended to perform a multi-point calibration (zero and mid-range) every 7 days.

Sodium (9135): A 2-Point calibration should be performed at least once a week to eliminate drift.

Luminescent Dissolved Oxygen: These sensors are highly stable; however, annual calibration is recommended, often handled via a sensor exchange program.

For additional calibration requirements for specific equipment, consult the user guide or email us at sales@waltron.net

 You can consult the user guide or reach out to us at sales@waltron.net for specific maintenance timelines. Here are some standards for Waltron equipment.

Monthly:

Colorimetric Analyzers: Refill reagent containers, clean the colorimetric cell, and perform a visual check for leaks,,.

Degassed Cation Conductivity (9096/4000DC): Replace the cation resin bottle and the soda lime cartridge (for the 9096),

Sodium (9135/9131C): Replenish the buffer solution (DIPA or Ammonia).

Quarterly:

Replace pump tubing for reagents and samples on wet-chemistry units

 Electrodes: The warranty covers reusable electrodes (such as pH and Sodium) for six months after shipment.

Luminescent Optical Sensor Spots : Waltron sensor spots used in our LDO equipment are replaced only when photobleaching has rendered them inaccurate. This is based on the number of pulses and generally comes into play every 2-4 years based on the settings of the sensor. This means Waltron sensor spots have to be replaced far less frequently than those from typical optical DO instruments.

Drift: In sodium analysis, drift is often caused by changing electrode response, which is mitigated by weekly 2-point calibration.

Fouling/Interference: In colorimetric analysis), turbidity or sample color can interfere with readings. Waltron analyzers utilize a reference measurement step to eliminate these interfering factors,

Resin Issues: For conductivity analyzers, failure to use pre-rinsed resin can cause reading delays or inaccuracies lasting from hours to days.

Colorimetric Cells: The glass optical cell should be cleaned monthly using a soft, non-aggressive cleaner to remove deposits.

4000 Series (pH/DO): These transmitters support automated cleaning cycles, such as operating a jet spray wash on a timed cycle with adjustable duration and recovery times.

1. Safety First: Always wear protective clothing and safety glasses when handling reagents.
2. Empty Tubing: Before removing the tubing, put the analyzer in standby mode. Pull the reagent straw from the bottle and perform a manual “add reagent” command for 60 seconds to empty the tube of chemicals.
3. Rinse: Always label and rinse all connected tubing with water prior to removal.
4. Replace: Remove the pump head screws, disconnect the old tubing, and install the new assembly, ensuring the head aligns with the motor shaft.

IAPWS specifies a particular chemical analysis method for the online determination of silica to ensure accuracy and consistency across the industry.

IAPWS Guideline: Instrumentation guidance delineates “colorimetric technique in which the sample is mixed with ammonium molybdate at a controlled low pH to form yellow molybdosilicic acid which is subsequently reduced to a heteropoly blue complex that can be detected spectrophotometrically”.¹

Waltron 3141 Conformity: The 3141 utilizes Colorimetric technology. Its operation requires a three-reagent system consisting of Sulfuric Acid and Molybdate Reagent, Oxalic Acid Reagent, and a Reducing Reagent to form the blue color complex for photometric analysis. This is the exact chemical methodology prescribed by IAPWS.

IAPWS sets strict limits for silica in steam to prevent deposition on turbine blades, which causes efficiency loss and potential mechanical imbalance.

IAPWS Guideline: Steam Purity guidance establishes a silica limit for superheated steam of “< 10 µg/kg” (ppb).² To prevent deposits, the concentration should be kept below this solubility limit. Instrumentation Guidance includes Silica as a “Key Instrument” for Superheated and Reheated Steam to ensure this target concentration is met.³

Waltron 3141 Conformity: The 3141 exceeds the sensitivity required to monitor this limit:
o Range: 0-1000 ppb (low range)
o Accuracy: ±1 ppb or ±2% of reading
This ±1 ppb accuracy is critical for reliably distinguishing between 8, 9, and 10 ppb, allowing operators to take action before the IAPWS limit is violated.

IAPWS recommends monitoring silica at the source (Makeup) and in the boiler drum to control the concentration upstream of the steam turbine.

IAPWS Guideline: Volatile Treatments Guidance sets a strict silica limit for makeup water of “< 10 µg/kg”.⁴ Instrumentation Guidance notes that silica may be measured in the boiler water to control levels in steam, provided the distribution relationship is known.⁵

Waltron 3141 Conformity: The 3141 is explicitly designed for make-up water, condensate, boiler feedwater, and steam applications. Its wide range (up to 150 ppm or 300 ppm) accommodates the higher concentrations found in drum boilers, while its low-range accuracy (0 – 1000 ppb) handles the strict makeup water limits.

IAPWS guidelines note that silica analyzers historically require a high level of maintenance, which often restricts their use to only the most vulnerable plants.

IAPWS Guideline: Instrumentation Guidance cautions that “Appropriate maintenance schedules are required to ensure replenishment of reagents, to check operation of pumping and mixing systems, and to recalibrate”.⁶

Waltron 3141 Conformity: The 3141 addresses these specific IAPWS concerns to make continuous monitoring more feasible:
o Low Maintenance: Features a 100% tooless wet section and Pre-assembled pump/sample heads for quick changeout.
o Calibration: Offers Automatic calibration and validation to reduce operator workload.
o Reagent Consumption: Designed for Monthly replenish reagents (approx. 2L per month), aligning maintenance intervals with standard plant rounds rather than requiring frequent intervention.

IAPWS suggests monitoring silica at multiple points (Makeup, Steam) to fully diagnose ingress and transport.

IAPWS Guideline: Instrumentation Guidance suggests silica monitoring can be justified at the Steam and Make-up Water.”⁷

Waltron 3141 Conformity: The 3141 supports “1 to 2” sample streams .This allows a single analyzer to monitor two critical points (e.g., Main Steam and Reheat Steam) simultaneously, offering a cost-effective way to meet the multi-point monitoring recommendations of the TGDs.

1. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 13.
2. International Association for the Properties of Water and Steam, IAPWS TGD5-13, Technical Guidance Document: Steam Purity for Turbine Operation, https://iapws.org/public/documents/II9hN/Purity.pdf. pg. 11.
3. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 26.
4. International Association for the Properties of Water and Steam, Technical Guidance Document: Volatile treatments for the steam-water circuits of fossil and combined cycle/HRSG power plants (2015), https://iapws.org/public/documents/QKsnz/Volatile-2015.pdf pg. 12-18,28.
5. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 18.
6. Ibid., pg. 13.
7. Ibid. pg. 26..

IAPWS provides guidance on acceptable monitoring technologies for dissolved oxygen.

IAPWS Guideline: Instrumentation guidance identifies two distinct technologies for online dissolved oxygen (DO) monitoring: membrane diffusion/amperometric and luminescence-based measurement. “Both technologies can be highly reliable and provide accurate readings in typical power system applications.”¹

Waltron 9165 Conformity: The Waltron 9165 analyzer operates on the principle of dynamic luminescence quenching. A blue LED excites a luminescent dye (Luminophore) on a sensor spot, causing it to emit red light. Dissolved Oxygen molecules collide with the excited luminophore and “quench” this fluorescence. This means no membranes, no toxic chemicals and no relentless recalibrations eliminating the maintenance burdens of traditional membrane diffusion/amperometric galvanic sensors presenting a near-zero maintenance solution.

IAPWS sets strict limits for dissolved oxygen in various chemistry regimes, requiring instrumentation capable of high accuracy in the low ppb range.

IAPWS Guideline:

• Instrumentation: The guidance emphasizes the need for accuracy in the “low µg/kg (ppb) range”²
• Volatile Treatments: For plants operating on AVT (Reducing), oxygen levels must be maintained at “~10 µg/kg [ppb] or less,”3 For Oxygenated Treatment (OT), dosing levels are typically between “30 and 150 µg/kg.”⁴

• Air In-Leakage: Air in-leakage contributes to increased concentrations of dissolved oxygen, requiring strict monitoring at the Condensate Pump Discharge to maintain <10 ppb levels ^5,6

Waltron 9165 Conformity: The 9165 meets and exceeds these requirements:
o Range: 0–2,000 ppb (low range) and 0–20 ppm (high range)
o Accuracy: ±0.5 ppb.
This sub-ppb accuracy ensures operators can reliably monitor the <10 ppb limits required for AVT(R) and early detection of air in-leakage, while the wide dynamic range covers OT applications.

IAPWS identifies sample flow variations as a potential source of error in dissolved oxygen measurements, particularly for traditional sensors.

IAPWS Guideline: Instrumentation guidance warns of measurement errors derived from “changing redox conditions” and suggests minimizing difficulties by “ensuring that sample flow rate is properly maintained.”⁷

Waltron 9165 Conformity: The 9165 addresses this directly with its optical sensor design:
o Flow Independence: The analyzer provides excellent results independent of the sample flow rate because it uses optical technology. The sample delivery operating conditions specify a maximum pressure of 145 psig (10 bar).
o Response Time: t90 < 30 is an extremely fast response time with minimal flow requirements.
This capability allows for reliable data collection even during startups or load changes where sample line pressure and flow may fluctuate.

IAPWS highlights the importance of maintenance and calibration to maintain reliability and accuracy.

IAPWS Guideline: Instrumentation Guidance advises that “calibration and maintenance of all types of dissolved oxygen instruments requires extremely careful processes and procedures to achieve accuracy in the low μg/kg (ppb) range typically specified in power cycle operations.”⁸

Waltron 9165 Conformity: The 9165 luminescent technology drastically reduces the maintenance burden compared to traditional galvanic/amperometric sensor methods:
o No Membranes that can tear and are difficult to replace
o Two year calibration cadence
o Extended Sensor Life with replacement dependent on pulse count, often lasting two years, ensuring long-term stability without frequent operator intervention.

IAPWS recommends monitoring dissolved oxygen at multiple points in the cycle to fully understand corrosion risks and air in-leakage.

IAPWS Guideline: Instrumentation Guidance lists Dissolved Oxygen sampling as part “Minimum Key Instrumentation” at:
o The Condensate Pump Discharge (CPD)
o The Economizer Inlet (EI),
o The Boiler Drum/Downcomer for plant on OT.⁹

Waltron 9165 Conformity: The 9165 supports up to four sample streams on one electronics platform. This allows a single analyzer to monitor the Condensate, Feedwater, and other key points simultaneously, providing a cost-effective solution to meet comprehensive monitoring requirements.

1. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 10
2. Ibid., pg. 10
3. International Association for the Properties of Water and Steam, Technical Guidance Document: Volatile treatments for the steam-water circuits of fossil and combined cycle/HRSG power plants (2015), https://iapws.org/public/documents/QKsnz/Volatile-2015.pdf,  pg. 8
4. Ibid., pg. 9
5. International Association for the Properties of Water and Steam, IAPWS TGD9-18, Technical Guidance Document: Air In-leakage in Steam–Water Cycles, https://iapws.org/public/documents/KuswX/AIL.pdf,  pg. 7
6. Ibid., pg. 25.
7. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 10
8. Ibid., pg. 10,
9. Ibid., pg. 25.

IAPWS specifies the use of ion-selective electrodes for sodium monitoring but mandates specific chemical conditioning (pH adjustment) to eliminate interference, particularly for low-level measurements.

IAPWS Guideline: Instrumentation guidance states that glass electrodes sensitive to sodium ions are used at a controlled high pH. While ammonia hydroxide can be used as an alkalizing agent to control pH, it notes that “if high accuracy below 1.0 µg/kg (1 ppb) is required, then the use of DIPA [Diisopropylamine] is required” to suppress hydrogen ion interference.¹

Waltron 9135 Conformity: The 9135 utilizes Ion-Select Electrode technology. User guidance explicitly addresses the IAPWS requirement for buffering, stating that while ammonia is suitable for measurements down to 0.5 ppb, at concentrations below 0.5ppb, hydrogen ion interference becomes significant and a reagent of Diisopropylamine needs to be used. This directly aligns with the rigorous IAPWS requirement for sub-ppb accuracy.

IAPWS sets strict limits for sodium in steam to prevent stress corrosion cracking and deposition in the phase transition zone of the turbine.

IAPWS Guideline: Steam Purity guidance sets a sodium limit for superheated steam at “< 2 µg/kg” (ppb).² At Start-up, Steam should not be sent to the turbine if sodium exceeds “20 µg/kg”³

Waltron 9135 Conformity: The 9135 exceeds these sensitivity requirements:
o Range: “0.10ppb – 10ppm”
o Accuracy: “±5% of reading or ±0.1ppb”
This capability allows the analyzer to reliably monitor the strict <2 ppb limit during normal operation and the higher 20 ppb limit during startup events.

IAPWS identifies sodium is a primary tracer used to determine total carryover from boiler drums a critical performance metric for steam purity.

IAPWS Guideline: Guidance for the Measurement of Carryover of Boiler Water into Steam states that “aodium salts… have good solubility in boiler water and a low volatility in steam, which makes them suitable tracers for determining the total carryover,”⁴ It notes that on-line sodium analyzers have “proven to be successful” for this application which requires testing “for a sodium concentration in the boiler water on the order of 1 to 5 mg/kg (ppm), and a sodium concentration in the steam . . . on the order of 2 to 10 µg/kg (ppb). In some cases, the sodium concentration in steam is as low as 0.4 to 2.0 µg/kg (ppb).”⁵

Waltron 9135 Conformity: The 9135 includes boiler drum and steam as specific sampling streams. Its wide dynamic range (up to 10 ppm) accommodates the higher concentrations found in boiler water (typically 1–5 ppm) while simultaneously measuring the trace levels (ppb) in the steam, making it ideal for the carryover calculations required by IAPWS.

IAPWS identifies sodium monitoring as a critical tool for detecting cooling water ingress, particularly in seawater-cooled plants.

IAPWS Guideline: Instrumentation Guidance lists Sodium at the Condensate Pump Discharge (CPD) as Key Instrumentation especially at salt-water cooled plants. It notes that sodium monitoring “offers higher sensitivity than conductivity after cation exchange” for detecting small leaks and suggests sampling close to extraction points for early detection. ⁶

Waltron 9135 Conformity: The 9135 is designed for extraction pump discharge applications. Its sub-ppb sensitivity allows for the early detection of condenser leaks well before they would be visible via cation conductivity, aligning with the early warning philosophy of the IAPWS guidelines.

IAPWS warns that sodium electrodes can lose sensitivity over time when exposed to high-purity water and require specific maintenance protocols.

IAPWS Guideline: Instrumentation Guidance states that “sensitivity of sodium electrodes may tend to reduce if they are persistently exposed to very high purity water… maintenance schedule must include sodium sensor reactivation and calibration.”⁷

Waltron 9135 Conformity: The 9135 addresses this specific degradation issue with built-in protocols:
o Automatic Calibration: The unit features Automatic 2-point or single point calibration reducing labor hours and eliminating manual errors.
o Reactivation: The 9135 provides specific Sodium Measuring Electrode Etching/Regeneration procedure using a sodium fluoride solution to recover electrode response, directly addressing the IAPWS concern regarding electrode aging in high-purity water.

1. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 11.
2. International Association for the Properties of Water and Steam, IAPWS TGD5-13, Technical Guidance Document: Steam Purity for Turbine Operation, https://iapws.org/public/documents/II9hN/Purity.pdf. pg. 19.
3. Ibid., pg. 20.
4. International Association for the Properties of Water and Steam, IAPWS TGD1-08, Technical Guidance Document: Procedures for the Measurement of Carryover of Boiler Water into Steam, https://iapws.org/public/documents/0is-8/Carryover.pdf , pg. 5.
5. Ibid., pg. 6.
6. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 15.
7. Ibid., pg. 11.

IAPWS recommends specific spectrophotometric methods to accurately determine Film Forming Amine (FFA) concentration, noting that standard pH or conductivity measurements are insufficient for dosage control.

IAPWS Guideline: The guidance recommends determining FFA residual using spectrophotometric tests. It specifically highlights the xanthene dye reaction (using dyes like Rose Bengal) as a preferred method because it does not require toxic organic solvents and measures the formation of a water-soluble colored complex. ¹ The guidance explicitly states that “Control of the cycle chemistry using pH, conductivity, or TOC… is not accurate enough for monitoring dosing of FFA”.²

Waltron 3154 Conformity: The 3154 analyzer utilizes a colorimetric (spectrophotometric) method using an LED source at 572 nm. It uses a three-reagent system (Buffer, Indicator, and Cleaning Solution) to develop a colored complex for measurement]. This aligns with the IAPWS preference for photometric determination of amine residuals over surrogate indicators like pH.

IAPWS emphasizes that monitoring systems must be sensitive enough to detect trace levels of free FFA to ensure a protective film is maintained without overdosing.

IAPWS Guideline: A suitable test method or online measuring system should feature a detection limit preferably lower than 0.1 mg/kg (100 ppb) to measure traces of free FFA effectively.³

Waltron 3154 Conformity: The 3154 exceeds this requirement:
o Range: 0 – 500 ppb (0 – 0.5 mg/kg)
o Accuracy: +/- 10 ppb (0.01 mg/kg)
This high sensitivity allows operators to control dosage at the “low mg/L (ppm) level” required during initial measuring and continuous operation as suggested by IAPWS.

A major technical hurdle identified by IAPWS is the “sticky” nature of film-forming amines, which adsorb onto instrument surfaces, potentially compromising measurement accuracy.

IAPWS Guideline: FFA adsorbs onto metal oxides, glass, and plastics. This can lead to coating effects on probes and sensors, causing drifts in readings or loss of sensitivity. ^4,5

Waltron 3154 Conformity: The 3154 incorporates a specific automatic cleaning cycle into its analysis program.
o The Process: After every reading, the analyzer drains, refills, adds a specific Cleaning Solution (Reagent 3), mixes, and flushes the cell.
This feature directly mitigates the IAPWS concern regarding sensor fouling and carryover, ensuring that the glass flow cell remains clean and subsequent readings are not biased by previous samples.

IAPWS advises that online monitoring should be supplemented or verified by grab samples, provided specific handling precautions are met.

IAPWS Guideline: Monitoring should be performed at all available sample points. Grab samples require specific handling (e.g., using PTFE containers) to prevent the amine from plating out on the container walls.⁶

Waltron 3154 Conformity: The analyzer features a dedicated “Grab Sample” mode. This allows operators to analyze external samples (e.g., from different points in the cycle like the condensate pump discharge or drum) using the analyzer’s calibrated optics and chemistry, ensuring consistency between online and offline measurements.

IAPWS stresses the importance of establishing a baseline and monitoring trends over time to evaluate the success of an FFS treatment program.

IAPWS Guideline: Operators must monitor trends to determine optimum usage and verify that the FFS is providing the intended benefit. “The trend of the data is more important than the absolute value”.⁷

Waltron 3154 Conformity: he unit includes an internal data logger capable of storing the previous 500 results organized by date, which can be exported via USB . This supports the IAPWS requirement for long-term trend monitoring and baseline comparison.

1. International Association for the Properties of Water and Steam, IAPWS TGD11-19, Technical Guidance Document: Application of Film Forming Substances in Industrial Steam Generators, https://iapws.org/public/documents/Ibwav/FFS-Industrial.pdf, pg. 31)
2. Ibid., pg. 16.
3. Ibid., pg. 31
4. Ibid,, pg. 13-14.
5. Ibid, pg 22
6. Ibid., pg 30.
7. Ibid.. pg 41.

IAPWS dictates strict normal and target limits for pH in various locations around the steam-water cycle .

IAPWS Guideline: Volatility guidance recommends target pH values are narrowly defined, such as a pH of 9.2 – 9.8 at the Economizer Inlet and 9.0 – 9.8 at the Boiler Drum for AVT(O) chemistry.¹ Furthermore, IAPWS states that operators should develop “Action Levels, which define when the operators need to take some avoiding action in response to values outside the limits”²

Waltron 4000 PH Conformity: The 4000 PH analyzer has a full operating range of 1–14 pH and incorporates dedicated control relays for programmable setpoints. The software allows operators to define High, Low, and Band setpoint triggers. This allows plant personnel to map IAPWS suggested Action Levels directly into the instrument so that alarms or dosing adjustments occur immediately when target ranges are violated.

IAPWS emphasizes that because pH changes with temperature, all monitored limits must be referenced to a standard temperature of 25°C to ensure valid data interpretation.

IAPWS Guideline: Multiple Guidance documents including Phosphate Caustic and Purity  standard dictates that “All conductivities and pHs in this document refer to water samples cooled to 25 °C” ^3,4

Waltron 4000 PH Conformity: The 4000 PH intrinsically supports this requirement via its built-in temperature compensation capabilities. It accommodates Pt1000 or Pt100 resistance temperature detectors (RTDs) to apply automatic temperature compensation from -10°C to +150°C, ensuring that the displayed pH correctly references the 25°C standard regardless of minor sample cooler temperature fluctuations.

IAPWS acknowledges the challenges in obtaining a stable, direct pH reading.

IAPWS Guideline: Cooling Water Chemistry Guidance notes that “Direct pH measurement in high purity water is a delicate, error-prone procedure”. Similar challenges are common in condensate and feedwater lines where conductivity is extremely low.⁵

Waltron 4000 PH Conformity: To address the environmental instability found in high-purity samples, the 4000 PH features an adjustable Input Filter (averaging) setting. This function allows the user to filter sensor readings in noisy environments by calculating a running average over a selected time period (from 10 seconds up to 1 minute). This actively mitigates erratic readings and “chatter” enhancing reliability.

IAPWS guidelines highlight the importance of pH for demonstrating the effectiveness of solid alkali dosing treatments and the necessity of keeping instrumentation reliably calibrated.

IAPWS Guideline: Instrumentation Guidance states that “pH measurement is valuable because it demonstrates that the phosphate present in the boiler water is appropriate to provide the necessary control over the risks of both acidic and alkaline corrosion”⁶. It further emphasizes the need for well-maintained instrumentation.

Waltron 4000 PH Conformity: The 4000 PH utilizes predefined Waltron Buffer tables (accounting for temperature/pH variation curves) for precise automatic calibration. Furthermore, it addresses instrument maintenance proactively by featuring an internal Calibration Interval timer. The system will generate an alarm when a scheduled calibration is due, directly supporting the IAPWS mandate for vigilant instrumentation upkeep.

IAPWS outlines specific operational regimes that require either oxidizing or reducing environments, the latter of which requires monitoring of Oxidation-Reduction Potential (ORP).

IAPWS Guideline: For plants operating on All-Volatile Treatment (Reducing) — AVT(R) — Volatile Treatment Guidance specifies that an Oxidation/Reduction Potential of “Reducing (< 20)” mV should be maintained at the Deaerator Inlet.⁷

Waltron 4000 PH Conformity: The 4000 PH serves as a dual-purpose platform. The channel can be user-configured as either a pH or a Redox (ORP) input. Because it accommodates both separate and combination ORP electrodes, operators can deploy the exact same transmitter model to monitor high-pH dosing in the boiler drum, as well as the <20 mV ORP requirements at the Deaerator inlet.

1. International Association for the Properties of Water and Steam, Technical Guidance Document: Volatile treatments for the steam-water circuits of fossil and combined cycle/HRSG power plants (2015), https://iapws.org/public/documents/QKsnz/Volatile-2015.pdf, pg 17.
2. Ibid., pg. 10
3. International Association for the Properties of Water and Steam, Technical Guidance Document: Phosphate and NaOH treatments for the steam-water circuits of drum boilers of fossil and combined cycle/HRSG power plants (2015), https://iapws.org/public/documents/lq8bK/PhosphateCaustic-2015.pdf, pg. 7.
4. International Association for the Properties of Water and Steam, IAPWS TGD5-13, Technical Guidance Document: Steam Purity for Turbine Operation, https://iapws.org/public/documents/II9hN/Purity.pdf. pg. 7.
5. International Association for the Properties of Water and Steam, IAPWS TGD10-19,Technical Guidance Document: Chemistry Management in Generator Water Cooling during Operation and Shutdown. https://iapws.org/public/documents/TCL_i/Generator.pdf, pg. 15.
6. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 19.
7. International Association for the Properties of Water and Steam, Technical Guidance Document: Volatile treatments for the steam-water circuits of fossil and combined cycle/HRSG power plants (2015), https://iapws.org/public/documents/QKsnz/Volatile-2015.pdf, pg 13.

IAPWS mandates the continuous monitoring of conductivity and CACE at multiple locations in the cycle to ensure chemical control and detect contamination.

IAPWS Guideline: Instrumentation guidance for monitoring and control of cycle chemistry designates “Conductivity” (Specific) and “Conductivity after cation exchange” (CACE) as Minimum Key Instrumentation for Condensate Pump Discharge (CPD), Feedwater, Boiler/Evaporator Water, and Steam. ¹

Waltron 9095 Conformity: The 9095 is explicitly designed to measure specific conductivity, cation conductivity and calculated pH. By integrating both Specific and Cation Conductivity into a single transmitter, the 9095 fulfills the core IAPWS requirement for these paired measurements at critical sampling points like the Condensate Pump Discharge and Steam.

IAPWS recognizes the difficulties of maintaining glass pH electrodes in high-purity, low-conductivity water and validates the use of calculation-based pH monitoring as a reliable alternative.

IAPWS Guideline: Instrumentation guidance states that “An alternative on-line instrument for the measurement of pH… relies on a calculation from measurements of the conductivity and the conductivity after cation exchange.” It notes that this method provides an “accurate stable and reliable measurement of pH” within specific ranges (typically pH 8.0–11.5) ²

Waltron 9095 Conformity: The 9095 features highly accurate calculated pH. The analyzer uses the inputs from the Specific and Cation conductivity sensors to derive the pH value, aligning with the IAPWS preference for avoiding the drift and maintenance associated with glass electrodes in low-conductivity feedwater and steam.

IAPWS sets strictly low conductivity limits for steam turbine acceptance, requiring high-accuracy instrumentation capable of measuring trace impurities.

IAPWS Guideline: Steam Purity guidance sets the limit for CACE in superheated steam at “< 0.2 µS/cm”. To accurately monitor this limit, instrumentation must be sensitive enough to detect variations in the 0.05–0.2 µS/cm range.³

Waltron 9095 Conformity: The 9095 features a measuring range of 0 to 9.999 µS/cm with an accuracy of < 0.6% of the measuring range. This sub-microsiemens precision is essential for verifying compliance with the strict IAPWS steam purity limits and turbine warranty requirements.

IAPWS advises that cation exchange columns must be monitored to ensure the resin has not been exhausted, which would lead to erroneous data due to masking contaminants.

IAPWS Guideline: Instrumentation Guidance suggests utilizing a cation exchange resin that “changes color as it is exhausted” enabling the operator to judge when replacement is necessary to maintain valid CACE readings .⁴

Waltron 9095 Conformity: The 9095 includes specific features to address this:
o Visual Check: Users are advised to visually check status of the cation resin by monitoring color change.
o Alarm: An automated calculated resin exhausted alert ensures data integrity is maintained, preventing operation with spent resin.

IAPWS identifies CACE as the primary indicator for detecting air in-leakage (which introduces CO2) in condensate.

IAPWS Guideline: Air In-Leakage Guidance states that “CACE, especially in the condensate, is usually the most sensitive indicator of an AIL [Air In-Leakage]” because the ingress of CO2 increases the conductivity after cation exchange.⁵ Instrumentation Guidance reinforces that CACE at the Condensate Pump Discharge (CPD) is a “Minimum Key Instrument.”⁶

Waltron 9095 Conformity: As a dual-channel analyzer capable of measuring CACE, the 9095 is the correct tool for the CPD location. Its high accuracy in the low range (0–9.999 µS/cm) allows it to detect the small elevations in CACE (e.g., rising from 0.2 to 0.4 µS/cm) that signify the onset of an air leak.

1. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 25-26.
2. Ibid., pg. 10
3. International Association for the Properties of Water and Steam, IAPWS TGD5-13, Technical Guidance Document: Steam Purity for Turbine Operation, https://iapws.org/public/documents/II9hN/Purity.pdf. pg. 19.
4. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 8.
5. International Association for the Properties of Water and Steam, IAPWS TGD9-18, Technical Guidance Document: Air In-leakage in Steam–Water Cycles, https://iapws.org/public/documents/KuswX/AIL.pdf , p. 33.
6. International Association for the Properties of Water and Steam, IAPWS TGD2-09(2024), Technical Guidance Document: Instrumentation for monitoring and control of cycle chemistry for the steam/water circuits of fossil-fired, combined cycle, and industrial power plants (2024), https://iapws.org/public/documents/jl_oN/Instrumentation-2024.pdf, pg. 25