Materials Compatibility Benefit of MB-10 Tablets

The study aimed to compare the room temperature materials compatibility of type 304 stainless steel with three chemicals: 200 PPM of free chlorine dioxide from Quip MB-10™ tablets, 600 PPM of sodium chlorite solution acid-activated to 2.5 pH, and a 0.525% (5250 PPM) solution of sodium hypochlorite (chlorine bleach diluted 1:9 with water).

Discussion of Results: Six 304 stainless steel test coupons were weighed and measured. For each test solution, two coupons were immersed vertically to about 30% of their height in the solution in a capped glass jar at room temperature. The solution was changed daily for 14 days. After the test, the coupons were rinsed, dried, weighed, and measured.

The coupons subjected to the two chlorine dioxide solutions experienced superficial surface staining at the air-liquid interface but no dimensional changes. In contrast, the diluted bleach solution caused significant corrosion, resulting in weight loss and increased coupon thickness due to scale formation.

Key Findings:

• Weight Change Due to Chemical Corrosion:
  • 0.525% Sodium Hypochlorite: Significant weight loss
  • 600 PPM Acid-Activated Sodium Chlorite: Moderate weight loss
  • 200 PPM MB-10 Chlorine Dioxide: Minimal weight loss
• Thickness Change Due to Chemical Corrosion:
  • 0.525% Sodium Hypochlorite: Increase in thickness
  • 600 PPM Acid-Activated Sodium Chlorite: No significant change
  • 200 PPM MB-10 Chlorine Dioxide: No significant change

Corrosion due to acid-activated sodium chlorite was more subtle but statistically significant compared to the more neutral pH of the MB-10 solution.

Conclusion:

1. Chlorine dioxide solutions made from either Quip MB-10 tablets or acid-activated sodium chlorite are substantially more compatible with 304 stainless steel compared to a 5250 PPM solution of sodium hypochlorite. The reduction in corrosion ranges from 85%-90% (weight) to 100% (thickness).
2. The MB-10 tablet solution resulted in a slightly, but statistically significantly, lower level of weight loss than the acid-activated sodium chlorite solution.

Preparation of Test Solutions and Procedure:

1. Prepare a 200 PPM solution of chlorine dioxide by adding two Quip MB-10 tablets to one liter of tap water. Store in a tightly capped amber glass jar in the refrigerator.
2. Prepare a 600 PPM solution of acid-activated sodium chlorite using a specific activation and dilution procedure.
3. Prepare a 0.525% sodium hypochlorite solution by diluting laundry bleach with tap water.
4. Clean, weigh, and measure six corrosion test coupons of 304 stainless steel.
5. Place two coupons in each of three labeled glass jars with the respective test solutions.
6. Cap tightly and store at room temperature, changing the solution daily for 14 days.
7. After the test period, rinse, dry, weigh, measure, and photograph the coupons.

This study provides valuable insights into the materials compatibility of disinfectants with 304 stainless steel, highlighting the benefits of using chlorine dioxide solutions over sodium hypochlorite.