Lighthouse ApexZ Series Compatibility with Hydrogen Peroxide

What Is Vaporized Hydrogen Peroxide?

VHP (Vaporized Hydrogen Peroxide) is a vapor derived from H2O2 and is used with the help of a generator for decontamination in cleanrooms.

Oxidizing effects of VHP

VHP is a strong oxidizer, as it will chemically react with most materials it comes into contact with.

Some grades of stainless steel have been shown to oxidize with H2O2, turning a light brownish color, and the same can be seen on aluminum air sampler heads, which turn a greenish color. For this reason, material compatibility is very important, especially when bringing equipment into the cleanroom.

How can VHP affect a particle counter?

Because VHP disperses very effectively as a vapor, and that vapor is designed to adhere to surfaces, it can reach almost anywhere. At Lighthouse Worldwide Solutions, particle counters are tested and designed to be resistant to VHP both externally and internally. Our Apex series comes standard with VHP resistance and a 3-year warranty based on a non-condensing VHP process.

Particle counter exterior

The ApexZ portable particle counter has a polycarbonate exterior designed specifically to meet the cleaning requirements of the pharmaceutical industry. The ApexZ design, with its sealed enclosure and sealed communication ports and power connectors, makes for an easy wipe-down process. The ApexZ series is one of the most cleanroom-friendly particle counters on the market, with no open areas where particles and contamination could collect.

Particle counter interior

Thanks to the high-grade sealing technology used in Lighthouse particle counter designs, the likelihood of VHP entering the internal components of the particle counter is extremely low. VHP ultimately degrades many of the surfaces it touches, and our seals can easily be tested and replaced during routine servicing of the instruments. Protecting the internals of a particle counter is very important and needs careful consideration in the design. Circuit boards and other sensitive electronics are all susceptible to corrosion. Fortunately, Apex particle counters have been designed with these conditions in mind, and with this additional protection, built to prevent any ingress into the main exterior housing, they still feature the latest generation of particle counter technology on the market.

Test summary and overview of chemical compatibility and H2O2 exposure

Meeting the requirements for portable monitoring in cleanrooms, the ApexZ is made of a polycarbonate material, and its other housing materials have all been immersed in the following cleaning solutions:

• Sodium Hypochlorite (Bleach) 8.25%
• Isopropyl Alcohol 70%
• Hydrogen Peroxide 35%
• Spore Klenz (from Steris) 1% H2O2 and 0.08% peroxyacetic acid

The tests were carried out over a 1-week period in which samples of the ApexZ exterior housing materials were fully immersed in each solution. These are accelerated tests, keeping the materials in contact with the chemicals for 1 week. In reality, however, depending on use, the instrument will be subjected to a wipe-down for disinfection control several times a day or week in accordance with user guidelines.

Each sample material was visually inspected every day, and the thickness of each material was checked against its starting thickness. There was no significant effect on material thickness over the week, and no discoloration or any other sign of degradation was observed on the material. Summaries of the tests completed on the ApexZ housing parts are below.

Polycarbonate Enclosure (the body of the ApexZ)

Bleach 8.25% Sodium Hypochlorite

Starting Thickness: 0.112

After 7 days: 0.115

% Deviation: 2.6%

Hydrogen Peroxide 35%

Starting Thickness: 0.113

After 7 days: 0.113

% Deviation: 0%

Isopropanol 70%

Starting Thickness: 0.122

After 7 days: 0.124

% Deviation: 1.6%

Spor-Klenz® Ready-to-use

Starting Thickness: 0.113

After 7 days: 0.116

% Deviation: 2.6%

Thermoplastic Olefin (Covers power jack, I/O cover and sample inlet)

Bleach 8.25% Sodium Hypochlorite

Starting Thickness: 0.067

After 7 days: 0.066

% Deviation: 1.5%

Hydrogen Peroxide 35%

Starting Thickness: 0.067

After 7 days: 0.066

% Deviation: 1.5%

Isopropanol 70%

Starting Thickness: 0.066

After 7 days: 0.065

% Deviation: 1.5%

Spor-Klenz® Ready-to-use

Starting Thickness: 0.067

After 7 days: 0.067

% Deviation: 0%

Steralloy (ApexZ handle)

Bleach 8.25% Sodium Hypochlorite

Starting Thickness: 1.028

After 7 days: 1.026

% Deviation: 0.2%

Hydrogen Peroxide 35%

Starting Thickness: 1.027

After 7 days: 1.022

% Deviation: 0.5%

Isopropanol 70%

Starting Thickness: 1.032

After 7 days: 1.032

% Deviation: 0%

Spor-Klenz® Ready-to-use

Starting Thickness: 1.028

After 7 days: 1.023

% Deviation: 0.5%

* The test criterion for each material was set as a 3% deviation. The ApexZ handle was wiped with isopropanol every day and showed no signs of swelling or discoloration during the wipe test week.

Conclusion

The ApexZ housing materials and flow path have been tested with cleaning solutions, and the flow path has been exposed to VHP. Tests performed on the housing confirm that the materials are not affected by any oxidation or swelling. With its lightweight, durable housing and tight sealing, the ApexZ is very well suited to pharmaceutical cleanroom operations and sterile wipe-down procedures using the most common cleaning solutions found in cleanrooms.

Because of the unknown nature of the VHP process and environment, we recommend caution when running a particle counter during VHP exposure. Although the sensor can withstand VHP in some cases when this vapor condenses, it may contaminate the sensor, leading to bad data and calibration failure. For this reason, unless the process has been fully validated by the customer, we advise the end user to close off the sample inlet and, when using a remote particle counter, to switch off the internal pump or vacuum.