Frequently Asked Questions
Whether you’re selecting your first oxygen analyzer, troubleshooting sampling methods, or optimizing your modified atmosphere packaging process, our comprehensive FAQ provides technical guidance from Quantek’s engineering team. Find answers about product selection, calibration, sampling techniques, and application-specific considerations for O₂ and CO₂ measurement across food packaging, pharmaceutical, industrial, and research applications. Can’t find what you’re looking for? Contact our technical support team at sales@quantekinstruments.com or (508) 839-3940.
Company & Service
Where are your products manufactured?
We manufacture all of our products in the U.S.A. – none of our processes are outsourced, which reduces lead time, and allows for superior quality control.
Where are your products serviced, repaired, and calibrated?
U.S. customers should follow the steps on the Support Page – for customers outside the U.S., we are are rapidly expanding our service partners, so please drop us a note.
What is your warranty policy?
All of our analyzers carry a two year warranty, parts and labor. You can view our policy here: Refunds, Returns, and Warranty
What is the typical turnaround time on repairs, calibrations, and service?
We know our customers rely on their analyzers, so we keep the turnaround time as short as possible. We will typically evaluate an instrument within 24 hours of receipt, and complete calibration and repair items within 48 hours of approval.
What is the HS Code for your products?
Analyzers ship with a harmonized tariff code of 9027.100000 – parts ship using the code 9027.900000.
Do your products qualify under USMCA?
Yes – since they are wholly manufactured in the U.S., we include a certificate of origin for all analyzer shipments within North America.
Product Selection & Specifications
What are the differences between the Q20, Q30, and Q40 Series analyzers?
The Q20, Q30, and Q40 Series use the same internal components—including the pump, O₂ and CO₂ sensors, and circuitry—but differ in their enclosures to serve different applications.
The Q20 series is designed to be handheld, lightweight, and portable, excelling at spot checks and mobile testing on production floors. The Q30 series features a more rugged benchtop design with solid metal mounting plates for stability, making it the preferred choice for stationary laboratory or quality control applications. The Q40 series is engineered for rack mounting with a convenient 2U size and mounting ears for seamless process integration.
All three series are designed with modularity in mind, accommodating almost any combination of sensors and options to meet diverse application needs. Contact sales@quantekinstruments.com to discuss which analyzer best fits your project requirements.
How is oxygen measured in Quantek analyzers?
Quantek oxygen analyzers utilize a proprietary electrochemical oxygen sensor that functions like a long-life battery, generating a millivolt (mV) signal that’s amplified and converted to display readings on the LCD and analog output.
Our sensors offer exceptional longevity—typically 4-5 years even under heavy usage conditions, with some customers achieving 7 years of service life. This extended sensor lifetime minimizes downtime and keeps total cost of ownership low compared to alternatives like frequent-replacement electrochemical sensors or expensive zirconia sensors requiring 400°C warm-up times.
Our oxygen sensors are accurate within ±1% of reading, require no warm-up time, and can be user-replaced by international customers or those preferring onsite maintenance, though we recommend factory service for optimal calibration and sensor condition testing.
Sampling & Testing Methods
How much headspace do I need to test a package?
We recommend a minimum of 15cc of available headspace for optimal results. This allows the internal sample pump (which draws 5cc/sec) to run for several seconds and obtain accurate readings.
However, many packages have less available headspace and require alternative sampling methods. The approach depends on whether your package is rigid or flexible:
Rigid containers (like bottles): Removing gas creates a vacuum proportional to the volume extracted. For example, removing 15cc from a 100cc rigid container will decrease internal pressure by 15%, resulting in artificially low oxygen readings. Drawing on a vacuum can also degrade the sensor and pump over time.
Flexible packages: These can typically be analyzed directly even with limited headspace, as the package can compress slightly without creating significant vacuum conditions.
For small or rigid containers, we recommend using a syringe with a stopcock mechanism to extract sample, allow it to equilibrate to atmospheric pressure, then inject into the analyzer. Alternatively, semi-rigid containers (like 2L bottles) can be gently squeezed while connected to the analyzer. For ultra-small volumes (0.5-5 mL), consider our Model 905V specifically engineered for minimum headspace applications.
How do I sample from a small package or rigid bottle?
For small-volume or rigid containers, manual syringe sampling prevents vacuum conditions and provides accurate measurements without stressing the analyzer’s pump or sensor.
The Challenge: Drawing 15cc of sample from a rigid bottle with 50cc of headspace creates vacuum conditions that can artificially lower readings and degrade components over thousands of samples.
The Solution: Use an airtight syringe with an on/off stopcock:
- Draw sample from the package and close the stopcock while the needle remains inserted
- Remove the needle and release the plunger, allowing the syringe to collapse to atmospheric pressure
- Connect the syringe to the analyzer’s sample probe and slowly inject the sample
Generally, 10cc of sample provides best results. Sample can be manually injected into our analyzers without activating the pump—the analyzer responds to whatever gas reaches the sensor.
When to use syringe sampling:
- Sample is under partial vacuum
- Container volume is so small that withdrawing sample would create vacuum
- Container is rigid with minimal flexibility (like nearly-full 2L bottles)
This method has been successfully used for O₂ and CO₂ analysis in hummus packages, salsa containers, olive oil bottles, and wine bottles with metal caps. For vials with 0.5-5 mL headspace, consider our Model 905V engineered specifically for ultra-minimum headspace applications.
Technical & Calibration
Do different inert background gases affect CO₂ concentration measurements?
Yes, background gas composition significantly affects CO₂ measurement accuracy. We’ve found that customers in process control, research, and especially welding applications prefer analyzers pre-calibrated for their specific background gas.
An analyzer calibrated with 20% CO₂ / 80% Nitrogen will read differently with other background gases:
- 20% CO₂ / 80% Argon reads approximately 18% CO₂
- 20% CO₂ / 80% Helium reads approximately 22% CO₂
Quantek can factory-calibrate your CO₂ analyzer for your specific background gas composition and issue a NIST traceable calibration certificate documenting performance across the entire concentration range. This ensures accurate measurements regardless of whether you’re using nitrogen, argon, helium, or other inert atmospheres in your process.
What is the effect of elevation on oxygen readings?
Elevation significantly affects oxygen readings due to changes in atmospheric pressure. Our analyzers are calibrated at 500 feet elevation, so customers at substantially different altitudes may notice variations in ambient air readings.
Oxygen readings at different elevations:
A few hundred feet of elevation change makes minimal difference, especially when testing nitrogen-flushed packages with less than 1% oxygen. However, at 2,000 feet elevation, ambient air reads approximately 5% lower than at our factory elevation.
The effect is proportional: a package with 10.0% O₂ will read 9.5% at 2,000 feet; a package with 0.5% O₂ shows negligible difference. For testing nitrogen-flushed packages where the goal is maximum oxygen removal, this may not be significant. However, we recommend calibrating your analyzer upon receipt—simply draw in room air, let the reading stabilize, and adjust to 20.9% O₂.
What are your flow conditioning recommendations for process analyzers?
Proper sample conditioning preserves sensor life and prevents measurement errors in process applications. Here are our recommendations:
Flow Rate:
- Analyzers with bypass (default configuration): No pressure effect on readings until 500 cc/min. At 1,000 cc/min, readings increase by approximately +1% of measured concentration (e.g., 85% CO₂ reads 85.8%)
- Analyzers without bypass: Pressure effect of approximately +3% at 1,000 cc/min (e.g., 85% CO₂ reads 88%)
- Best practice: Use a flow meter before introduction to the analyzer. Use a T-splitter to vent excess flow if needed
Particulates: While our internal 0.45-micron filter handles most applications, pre-filtering your sample is recommended. External filters are inexpensive and easier to replace than contaminated sensors.
Moisture: Sample should be <95% RH, non-condensing. Quantek offers drierite tubes for small amounts of moisture. High-humidity applications should use condensing systems before sample introduction.
Temperature: Less than 50°C
Contaminants: Sample should be free of solvents and dioxides that form acidic compounds with water (such as NO₂ and SO₂)
Process analyzers include the Q30 and Q40 series, as well as Model 902P, Model 905P, Model 906, and Model 201.
Applications & Industry Knowledge
What gas mix is right for our modified atmosphere package?
While we cannot provide specific product advice, we can outline key variables to consider when selecting MAP gas mixtures.
Gas mix selection depends on: 1) the product type, 2) whether packaging is for bulk shipment/storage or retail sale, and 3) whether the product is raw or cooked.
General principles: With exceptions for raw red meat, raw offal, cooked poultry, and many fresh/whole fruits, the goal is typically removing as much oxygen as possible.
CO₂ applications: Cheese, dairy, pasta, and bakery products often use CO₂ percentages to prevent staleness and inhibit bacterial growth, as bacteria struggle in CO₂-rich environments.
Fruit packaging: Typically contains low oxygen (1-10%) and CO₂ levels between 0-20%. Since fruits continue respiring after packaging, membrane permeability allowing consistent O₂ and CO₂ passage is often a design factor.
Why testing matters: MAP equipment can introduce incorrect gas mixes, packages can leak (admitting ambient air), and understanding product respiration over days, weeks, or months is crucial for appealing appearance, extended shelf life, and food safety.
No matter which gas mix you choose, accurate package testing both immediately after packaging and during shelf-life studies is essential.
Why is quality control testing important for modified atmosphere packaging?
Even with significant investment in packaging equipment, packages can leak, gas mixes can be incorrect, and different product textures may require adjusted flushing parameters. Additionally, any biological processes occurring after packaging (such as respiration or CO₂ emission) need monitoring for shelf-life and freshness management.
Quality control testing ensures:
- Packaging equipment is functioning correctly
- Target oxygen levels are achieved
- Package integrity is maintained
- Product freshness is preserved throughout shelf life
Quantek offers several solutions for residual oxygen analysis including the Model 901 and Model 905 oxygen analyzers. Both feature built-in pumps, leak-tight seals, and deliver results in approximately 15 seconds. With oxygen sensors lasting 4-5 years, these analyzers provide the lowest total cost of ownership in the industry by minimizing sensor replacement, downtime, and service interruptions.
Where can I find a MAP gas selection guide?
For additional information on modified atmosphere packaging gas selection, Air Products provides a helpful MAP Gas Selector tool that can help determine optimal gas environments for various products. However, accurate testing of your actual package atmosphere remains essential regardless of target gas mix.