Class 4 chemical indicator
The sterilization process in healthcare facilities, including hospitals, clinics, and laboratories, is a critical part of infection control. Accurate and reliable monitoring methods must be used to ensure that instruments and equipment are truly sterilized. Class 4 chemical indicators are among the tools that play an important role in this field. In this article, we will fully review these indicators, how they work, their advantages, uses, and their differences from other classes.
Class 4 indicators are sensitive to two or more parameters that affect the sterilization process. For example, in steam autoclaves, these indicators respond to a combination of temperature, time, and pressure. They change color, usually from orange to black, to indicate that sterilization conditions have been met.
What is a chemical indicator?
A chemical indicator is a non-microbial test device used to monitor the effectiveness of a sterilization process. These indicators are usually paper strips or labels that contain chemicals that are sensitive to one or more process parameters (such as temperature, pressure, time, or steam). When exposed to the appropriate sterilization conditions, the indicator changes color, indicating that the process is proceeding correctly.
Standards such as ISO 11140 and EN 867 address the design, manufacture, and use of chemical indicators and recommend their use in sterilization processes. Organizations such as AAMI also recommend the use of chemical indicators to monitor the correct operation of sterilizers.
Classification of chemical indicators (based on ISO 11140-1)
The International Organization for Standardization (ISO 11140-1) has divided chemical indicators into 6 classes:
.Class 1: Process Indicator
Class 2: Specialized indicators for specific tests such as Bowie-Dick
Class 3: Single-parameter indicator
Class 4: Multi-parameter indicator
Class 5: Biologically equivalent indicators (Integrators)
Class 6: Indicators with precise response to all parameters within a specified range
What is a Class 4 chemical indicator?
Class 4 indicators, or Multi-parameter Chemical Indicators, use two or more parameters of the sterilization process to indicate proper operation. These parameters typically include:
(Temperature)
(Exposure time)
(Saturated Steam Presence)
If any of these parameters are not provided correctly, the indicator will not show the appropriate color change, thus warning that the sterilization process was incomplete.
Class 4 Indicator Applications
Class 4 indicators are widely used in the following areas:
In healthcare facilities, Class 4 chemical indicators are commonly used to monitor the sterilization of small packages, such as dressing sets. These indicators change color to indicate whether the sterilization process has been completed correctly.
Inside sterilization packages to verify that the correct steam, time, and temperature have reached the package
Surgical and Dental Centers
Medical Laboratories
Specialty Clinics
Central Hospital Sterilization Unit CSSD
These indicators are used for internal monitoring of packs, not for overall verification of the machine process (for which Class 5 or 6 is used).
How Class 4 Indicators Work
Class 4 indicators contain a sensitive chemical that reacts to the sterilization conditions. If the temperature, time, and steam are present in sufficient quantity, the indicator changes color, indicating that the process is complete.
For example, some indicators change color from purple to green or yellow to brown. This change should be uniform, distinct, and irreversible.
Main features of the Class 4 indicator
Multi-parameter monitoring
Visible and clear color change
Irreversible color change
Easy installation into any sterile pack or tray
Compatible with saturated steam and standard autoclaves
Economical price compared to class 5 and 6
Benefits of using Class 4 Indicators
More assurance of sterilization than Class 1 and 3
Reduced risk of contamination of surgical and medical instruments
Improved internal quality control
More accurate monitoring of CSSD personnel performance
Prevents use of incompletely sterilized instruments
Limitations of using a Class 4 chemical indicator
A Class 4 indicator is not a substitute for biological testing and cannot detect the presence of microorganisms.
To monitor the overall autoclave process and verify the complete accuracy of the process, Class 5 or biological indicators should be used.
The indicator should be placed at a point in the pack that is most difficult for steam to reach (the center of the pack).
Important points in using chemical indicators:
- Placement: The indicator should be placed in a place on the pack where there is the greatest likelihood of the sterilant not penetrating, usually the center and near the pack lid.
- Interpretation of results: After the sterilization process, the color of the indicator is checked. A change in color to the desired state indicates the success of the sterilization process.
- Combination with other indicators: For greater certainty, the use of chemical indicators in combination with biological and physical indicators is recommended.
The correct and informed use of chemical indicators, especially in class 4, can help improve the quality of healthcare and ensure patient safety
How to use the Class 4 indicator
Place the indicator in the center of the sterile pack: The indicator should be placed in a place where steam is more difficult to reach so that its performance is more realistic.
Perform the autoclave process according to the instructions.
Check the color change after the end of the cycle: If the color changes completely, the pack is ready for use.
Record the result on the sterilization monitoring form (if required by health organizations)
Comparing Class 4 with other classes
Feature / Class Class 1 Class 3 Class 4 Class 5
Measured parameter Only one parameter Only one parameter Two or more parameters All parameters (biologically similar)
Main application Autoclave entry detection Simple in-pack testing More accurate in-pack monitoring Overall process validation
Accuracy and sensitivity Low low Medium to High Very high
price Cheap Cheap average More expensive
Recommendations for buying and choosing the right indicator
Use reputable brands with international approvals (ISO 11140-1), (CE, (FDA).
The color change of the indicator should be clear and uniform.
Check the product expiration date
Buy from official sellers approved by the Ministry of Health.
Documenting and tracking results
In many countries, including Iran, it is essential to document the results of chemical tests. For this purpose, you can:
Stick the used part of the indicator to the patient’s file.
Record the result on the CSSD report form.
Analyze and review the tests performed on a weekly or monthly basis.
Class 4 chemical indicators are a key tool for internal quality control of sterile packs. By simultaneously monitoring several important parameters, such as temperature, time, and steam, these indicators allow sterilization personnel and infection control teams to ensure that the autoclave process is working properly.
Although Class 4 indicators cannot completely replace biological tests, they are an essential and economical tool for routine monitoring of sterile packages. Proper selection, regular use, careful review of results, and proper documentation are the keys to effective use of these indicators.
ATS brand class 4 chemical indicator
Ensuring Accurate Monitoring of Sterilization Packs with Reliable Quality
The ATS Class 4 Chemical Indicator is a precise, professional and economical instrument for monitoring the integrity of the steam sterilization process inside sterile packs. This indicator is multi-parameter and responds simultaneously to three critical process parameters:
(Temperature)
(Exposure Time)
(Steam Saturation)
If the minimum standard conditions are not met, the indicator will not show the appropriate color change, so its use provides greater assurance of complete sterilization of instruments.
Key Features of ATS Indicator
Feature Description
Types Class 4 (Multi-parameter) Chemical Indicator
Compliant with ISO 11140-1
Reaction Parameters Temperature, Time, Saturated Steam
Internal Use of Sterile Packs in Steam Autoclaves (Steam Sterilizers)
Visible Color Change from Purple to Dark Green or Gray (in Some Models)
Irreversible Permanent and Stable Color Change
Recording and Tracking Possibility of Cutting and Pasting the Indicator Section to Patient Documents
Made in Iran (with Imported and Licensed Raw Materials)
Benefits of using the ATS Class 4 indicator
✅ High precision in internal quality control
✅ Suitable for all standard steam autoclaves
✅ Full compatibility with 121 and 134 ° C cycles
✅ Economical and affordable price compared to class 5 and 6
✅ Approved by the Ministry of Health and leading medical centers
How to use the ATS Class 4 Indicator
Place the indicator inside the sterile pack
Place it in the center of the package or in areas where steam is difficult to penetrate.
Perform a steam autoclave cycle
Set the temperature to 121 or 134 degrees Celsius according to the device’s instructions.
Check the indicator color change
After the cycle is complete, the indicator color should have changed completely. No color change or incomplete change indicates a defect in the sterilization process.
Documentation and record keeping
File the detachable part of the indicator in the patient file or sterilization logbook.
Maintenance and storage recommendations
Keep away from direct sunlight, high humidity and high temperatures.
Store at 15-25°C and 30-60% relative humidity.
Do not use after the expiration date (production and expiration dates are listed on the package).
ATS Indicator Uses
Hospital Surgical Packs
Dental and Dermatology Clinics
Sterilization of Laboratory Equipment
Beauty and Skin Care Centers
Infertility and IVF Centers
Clinics, Outpatient and Veterinary Centers
The difference between the ATS indicator and other market examples
Feature ATS (Original) Unreliable Brands
Color stability after sterilization is very stable and traceable, no fading or instability
Response to all parameters is complete and accurate, only to temperature or time
100% autoclave compatible with standard models may be incompatible
Does it have quality certification (ISO 11140-1) or is it fake
Fair price with misleading and cheap-looking guarantee
?Conclusion: Why is ATS a good choice
If you are looking for an accurate, economical and reliable solution to ensure the proper sterilization of medical devices, the ATS Class 4 Indicator is a smart choice. With its multi-parameter performance, clear color change, affordable price and full compliance with global standards, this product is among the best options for monitoring the internal process of sterile packs.
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