Case Study: Compatibility Of Lighthouse Particle Counters With Vaporized Hydrogen Peroxide

Case Study: Compatibility Of Lighthouse Particle Counters With Vaporized Hydrogen Peroxide Medium Image

Executive Summary

The purpose of this case study was to evaluate the durability of Lighthouse Worldwide Solutions’ ApexZ3 and ApexR5p in a cleanroom where live microorganisms are processed and then decontaminated with Vaporized Hydrogen Peroxide (VHP). When exposed to VHP, the equipment needed to be able to deliver accurate readings while maintaining its integrity.

VHP cycles started on April 6 and ended on June 17. The equipment was checked on April 5 upon installation, May 17 in the middle of the study, and on June 20, at the end of the study. The ApexZ3 was exposed to 28 cycles of VHP.  The ApexR5p was exposed to 23 cycles of the VHP. While this study was conducted over the span of 3 months, the number of VHP cycles is indicative of the number of cycles run in 6 months.

As the world’s clean air experts, we were proud to stand by the validity, durability, and reliability of our particle counters.



In this study, two questions were primarily addressed:

  1. Is there a visual influence on the equipment (internally/externally/tubing) when exposed to a representative number of VHP cycles, and is this acceptable within that period?
  2. Is there any impact on the generated measurement results when exposed to a representative number of VHP cycles, and is this acceptable in relation to the timeframe and maintenance/calibration costs?

During the study, no abnormalities were recorded in the particle measurements. During the VHP cycles, the number was of particles detected was elevated, but that was to be expected and desired. It signified a strong exposure to the VHP.

Additionally, during the visual inspections and calibration activities, no abnormalities were recorded. No re-calibrations or re-adjustments were needed after the inspections, and no visual deviations could be detected in relation to the VHP. After the first inspection, some white residue was noted on the ApexR5p, but it did not get worse throughout the study.



This study was conducted in an operational cleanroom by the cleanroom’s staff using their VHP protocol. We did not make any modifications to the particle counters in use and were present in the capacity of examining the equipment to detect abnormalities.


VHP’s Historical Influence

Vaporized Hydrogen Peroxide is a gas used to sterilize equipment. It is a low-temperature form of sterilization. In previous studies conducted by the Environmental Protection Agency, VHP was shown to cause severe corrosion of some types of metal and discoloration of wiring. The damage caused also depended on the severity of the VHP used. Still, the precedent stands: VHP can cause deterioration of materials and equipment.


Equipment Used

The ApexZ3 is a portable airborne particle counter. It has the industry’s most complete set of self-diagnostics while being designed for ease of use. From the ergonomic design of the particle counter to the true multi-touch enabled display, the ApexZ3 is the particle counter for today’s cleanroom. It can integrate into just about any environmental monitoring program, print wirelessly, sends data wirelessly, and generate cleanroom certification reports. Its features also include 0.3 - 10.0μ Particle Size Channels, 1.0 CFM Flow Rate, 21 CFR Part 11 Compliant, Sealed VHP Compatible Enclosure, Integrated Status Lights, and Hot Swappable Smart Batteries.

The ApexR5p is a remote particle counter that is designed for the utmost data integrity, risk mitigation, and environmental capability. It is fitted with self-diagnostics and a long-life laser diode sensor. The physical design lends itself to decontamination and cleaning. Its features also include 0.5 – 10 μm Particle Size Range, 1.0 CFM Flow Rate, 3,000 Records Data Storage, Smart Bracket, Validation Mode, and Built-in Alarm Light.


How Equipment Was Inspected

Throughout the duration of the study, the particle counters were examined by our team 3 times. Before opening up the equipment, we evaluated three factors:

  1. Flow measurement
  2. Measurement sensor response
  3. Visual inspection of housing, external parts, and tubing.

We then disassembled the particle counters and conducted visual inspections of:

  1. Mirror
  2. Photodiode and aperture
  3. Light trap
  4. Flow sensor
  5. Flowpath

Upon reassembly, we examined:

  1. Flow measurement
  2. Measurement sensor response
  3. Size calibration

As mentioned in the equipment overview, both the ApexZ3 and ApexR5p are equipped with self-diagnostics. These diagnostics should cause an alarm if the readings are deemed unreliable. This could include degradation because of the VHP treatments. This possibility was considered and accounted for; however, no alarms were triggered during the study.



Using the facility’s protocols and practices for Vaporized Hydrogen Peroxide (VHP) to sanitize the cleanroom, the ApexZ3 and ApexR5p did not show any abnormalities upon regular inspection. While the use of VHP could have degraded the equipment, the materials and functionality of the particle counters showed only normal wear.


Overall, we can conclude that Lighthouse’s equipment can be compatible with VHP exposure for more than 6 months of operational exposure. In addition, these units were also sent in for routine calibration at 12 months, and no abnormalities were found.


If you use Lighthouse’s particle counters in a cleanroom that is sanitized with VHP cycles uncapped, we recommend conducting regular maintenance and checks of the equipment. Additionally, we recommend the continual operation of the particle counter during a VHP cycle ( Airflow running through the unit).


Contact us to learn more about our instruments and their VHP compatibility. 




Dec 7, 2021