CD vs VHP

Chlorine Dioxide (CD) and formaldehyde are the only effective decontaminating agents for the decontamination of buildings, rooms, isolators, and bio-safety cabinets that are "true" gases.  Hydrogen peroxide is a liquid at room temperature and requires boiling or vaporization to generate the vapor.  The boiling point for 35% hydrogen peroxide is 109 C while room temperature is only 21-22 C. A vapor is basically a superheated fluid that, when introduced into a room, wants to return to its original form, a liquid, as condensation. If the target chamber is a long distance from the generator (more than a few feet), heat tracing or insulation of hosing is required to REDUCE condensation in the hoses.
Chlorine dioxide on the other hand does not require condensation or lack of condensation for an efficacious process.  Gaseous CD does not require tight control of Dew Point temperatures (ie. difficult to obtain uniform condensation or lack of condensation in a real world application).  Gaseous CD has Quicker Aeration due to minimal absorption and lack of condensation.   Additionally, CD systems from CSI can include integrated, accurate, and repeatable CD concentration measurement and control.  This means that while only an injection rate is selected with VHP and the chamber concentration assumed, an actual chamber concentration is chosen and attained with CD.   This greatly simplifies validation efforts and assures efficacy and repeatability. 
Scalability: One single ClorDiSys CD generator can decontaminate spaces from 1 to over 60,000 cubic feet as compared to multiple Hydrogen Peroxide generators. Injection rates also do not need adjustment based on volume.
Material Compatibility: Hydrogen Peroxide is 1.9 times more corrosive than CD based on its higher oxidation potential. 1
Efficacy: CD is 250% more efficient than Hydrogen Peroxide due to CD’s higher oxidation capacity based on CD seeking 5 free electrons vs. 2. 1
Quicker Cycles: To further highlight the benefits of CD, the following documents example cycle times for both CD and VHP.

 

Equipment required:

Room size cu ft (area in sq ft)

Amount of ClorDiSys CD Generators required

Amount of VHP generators required

500 cu ft (50sq ft)

1

1

1000 cu ft (100 sq ft)

1

1

1500 cu ft (150 sq ft)

1

1

2000 cu ft (200 sq ft)

1

1-2*

5000 cu ft (500 sq ft)

1

2-3*

10000 cu ft (1000 sq ft)

1

6-7*

15000 cu ft (1500 sq ft)

1

10

20000 cu ft (2000 sq ft)

1

13-14*

30000 cu ft (3000 sq ft)

1

20
* lower number generator used if room is empty room geometry is simple (no closets or lab benches which block the flow of vapors).

 

Isolator Decontamination Volume Cycle Time
Steris VHP ~25 ft3 3-6 hours2
Bioquell Clarus ~25 ft3 3-3.5 hours2
ClorDiSys CD systems 31 ft3 1.3 hours3

 

Room Decontamination

Volume

Cycle Time

Steris VHP

300 ft3

7.5 hours4

Steris VHP

760 ft3

4.25 hours+overnight aeration5

Bioquell Clarus

2500 ft3

10-11 hours6

ClorDiSys CD systems

2700 ft3

3.5 hours7

References:

1.  Wintner, Barry, Contino, Anthony, and O’Neill, Gary. Chlorine Dioxide, Part 1: A Versatile, High-Value Sterilant for the Biopharmaceutical Industry. Bioprocess International, Dec’ 2005

2. Caputo, Ross A. and Fisher, Jim.  Comparing and Contrasting Barrier Isolator Decontamination Systems. Pharmaceutical Technology, November 2004.

3. Czarneski, Mark A. and Lorcheim, Paul. Isolator Decontamination Using Chlorine Dioxide Gas.  Pharmaceutical Technology, Volume 29, No 4, April, 2005

4. Steris Case Study M1456, VHP Case Study #1 – Hydrogen Peroxide Gas Decontamination of A Material Pass-Through (MPT) Room, Publication ID #M1456(8/99), Steris, August, 1999.

5. Steris Case Study M1455, Case Study #3 - VHP 1000 Decontamination of a 760 ft3 room Containing Blood and Urine Analyzers, Publicaiton ID#M1455/990810 (8/99), Steris August 1999.

6. Room Decontamination Presentation to Council on Private Sector Initiatives, Washington, DC, by Henry Vance PE of Alpha Engineering, February 11, 2002

7. Lorcheim, Paul. Decontamination using Gaseous Chlorine Dioxide, A case study of automatic decontamination of an animal room explores the effectiveness of this sterilization system.  Animal Lab News, Vol. 3, No. 4 , p25-28, July/August 2004.

 

Additional benefits can be seen in the following table:

  "Vapor" Hydrogen Peroxide Chlorine Dioxide
Safety
  • Not Carcinogenic
  • Mucus Membrane Irritant
  • No decontamination needed upon exiting facility
  • People entering area need to be in self contained breathing apparatus
  • Not Carcinogenic
  • Mucus Membrane Irritant
  • No decontamination needed upon exiting facility
  • People entering area need to be in self contained breathing apparatus
Current Uses
  • Pharmaceutical and Medical Device Equipment and Components
  • Medical Device Sterilization
  • Hospital
  • Bio-remediation (Anthrax- Hart Building, Trenton Post Office, AMI Building
  • Pharmaceutical and Medical Device Equipment and Components
  • Medical Device Sterilization
  • Hospital
  • Removal of biofilms
  • Water Treatment
  • Food Sanitization (Meats and Produce)
  • Drinking Water
Regulatory Status
  • Steris Vaprox is EPA registered for sterilization/decontamination (including rooms)
  • ClorDiSys Solutions, Inc. is EPA registered for sterilization/decontamination (including rooms)
Biocidal Activity
  • Broad Spectrum

    -Requires low humidity

  • Good sporicidal activity
  • Broad Spectrum

    -Higher humidity (>65%)

  • Good sporicidal activity
Mode of Action
  • Oxidation (oxidation potential of 1.78)
  • Oxidation capacity of only 2e-
  • Oxidation (oxidation potential of 0.95)
  • Oxidation capacity of 5e-
  • Free radical monomer
  • Does not chlorinate
Functional Conditions
  • Use concentrations > 2.0 - 5 mg/L
  • Need very low humidity levels prior to starting cycle
  • Concentration based on loss in mass
  • Ideal temp > 35 C (to reduce condensation)
  • Boiling/Vaporization of liquid
  • Typical cycle time 3 hours (25ft3 chamber)
  • Use concentration used typically 0.2 - 5 mg/L
  • Need > 65% RH (hydration critical to sporicidal properties)
  • Effective at ambient temperatures (15 - 40 C)
  • In situ generation
  • Typical cycle time 1.3 hours (25ft3 chamber)
Advantages / Disadvantages
  • Broad Spectrum
  • Good sporicidal activity
  • Vapors have poor penetrating ability
  • Cannot monitor hydrogen peroxide concentration in real time
  • Oxidation Capacity of only 2e-
  • More corrosive effects due to higher oxidation potential
  • Need higher operating temperatures in chamber to reduce hydrogen peroxide condensation
  • Cannot take into account loss of vapor concentration due to condensation
  • Long cycle times
  • If generator is long distance from chamber (>5 ft) insulation and heat tracing of hoses is required to reduce condensation
  • Can be corrosive to uncoated ferrous metals at higher concentrations
  • Broad Spectrum
  • Good sporicidal activity
  • Chlorine Dioxide is a true gas (Boiling point 11ºC)
  • Gas concentration is continuously monitored during process
  • More efficient due to oxidation capacity of 5e-
  • No neutralization of the gas is needed
  • Can vent to atmosphere or scrub
  • Gas penetrates dead legs and hard to reach places
  • Broad spectrum biocidal properties
  • Used to sanitize equipment in food industry
  • EPA approved sterilant
  • Novartis validated filling line using Chlorine Dioxide
  • Does not chlorinate environment and equipment
  • Does not have effect on wide range of plastics
  • Does not have effect on stainless steel surfaces
  • Does not have effect on anodized aluminum
  • Can be corrosive to uncoated ferrous metals at higher concentrations

 

Additional References:  

       

Download CD vs. VHP Comparison Brochure

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