Conduit Seal Effectiveness

1 CCoonndduuiitt SSeeaall EEffffeeccttiivveenneessss 659 Van Meter Street Cincinnati OH 45202-1568 T: 513 241 1230 F: 513 241 1287 Email: Website: By Scott T. McGlamery, ; and Bret T. Heckman, Department of Electrical Engineering, Hixson, Cincinnati, OH Abstract - When there is a significant temperature difference between two adjacent spaces, maintaining an effective vapor barrier between the spaces is essential to prevent vapor infiltration and condensation in the cold space. Conduit penetrations through walls and ceilings can compromise the vapor barrier if not done properly.

2 This paper reports the results of testing four different Conduit vapor seals. I. Introduction GMP (Good Manufacturing Practice) facilities often contain spaces that are conditioned to low temperatures for product / ingredient storage and to maintain product temperature during processing and packaging. Typical temperature requirements range from 60 F to 0 F or lower. At these temperatures, the dew point in the room is often below the temperature in the adjacent spaces. This makes an effective vapor barrier essential for preventing vapor infiltration and condensation.

3 Vapor and condensation control is particularly critical in any penetration that could provide a niche where microbial growth could occur out of sight and in an area that is difficult to clean. Conduit penetrations are of particular concern, because they are a closed system capable of transferring vapor between spaces, and capable of holding water in a niche that could go unnoticed for a long time. Condensation occurs when a Conduit system is open to a space with warm, humid air, and a space with a dew point below the temperature of the adjacent space.

4 Vapor pressure pushes the water vapor towards the cool, dry end of the Conduit , where the lower temperature causes the vapor to condense inside the Conduit . Over time, the condensation can fill the Conduit and the enclosures they serve with water, creating a dark wet niche that represents a food safety concern. Conduit drains are sometimes used to allow any condensation to drain out of the Conduit system, but the first line of defense should be to prevent the condensation from occurring in the first place.

5 After observing the failure of several types of Conduit seals in the field, either due to workmanship, Effectiveness of the type of seal employed, or other issues, we tested four types of Conduit seals to determine which seal was most effective. The four seal types were: neutral cure silicone, expanding polyurethane foam sealant, duct seal compound, and hazardous location sealing compound. The tests evaluated ease of installation, vapor infiltration, and pressure resistance.

6 II. Test Setup and Procedure Before testing could begin, an apparatus was built to emulate facility conditions. This arrangement consisted of 3/4" Schedule 80 PVC conduits mounted vertically and horizontally. Conductors were cut at 20 long to project out of the top and bottom of the conduits. A Conduit fill of four Thermoplastic High Heat-resistant Nylon-coated (THHN) conductors and a Conduit fill of 12 THHN conductors were used for the experiment. A Conduit body was affixed to one end of the Conduit to replicate a junction point in the Conduit system.

7 In the case of the hazardous location sealing compound, a Class I Div 2 Conduit seal was used. See Figure 1 for the apparatus set up. Figure 1: From left to right Silicone, Expanding Foam, Duct seal , and Hazardous Location Compound Sealant CCoonndduuiitt SSeeaall EEffffeeccttiivveenneessss 659 Van Meter Street Cincinnati OH 45202-1568 T: 513 241 1230 F: 513 241 1287 Email: Website: A. Ease of Installation Each one of the sealants was placed in the vertical and horizontal conduits. Workmanship of installation for each was conducted as good as or better than observed in the field.

8 The sealants were then allowed to cure for at least eight hours or per manufacturer s requirements. The ease of installation and level of workman-ship required was recorded. After testing was completed, the conductors were removed from the seal to test the ability to remove conductors for renovation or replacement. B. Vapor Infiltration The vapor infiltration test assessed the sealant s ability to prevent vapor from passing through the Conduit . The horizontal conduits were mounted vertically for testing.

9 Water was used to simulate vapor infiltration due to the logistical complexities of testing with water vapor. The measured amount of 25mL of water ( 3/4 of water in a 3/4" Conduit ) was poured into the top of each Conduit . The bottom of the Conduit was then observed for any leakage. The vapor infiltration test with 25mL of water was the equivalent to approximately psig of differential pressure on either side of the Conduit seal . C. Pressure Testing Pressure testing was conducted to find the failure point of each sealant.

10 The pressures employed significantly exceed those that would normally be found in a facility. To pressure test, the remaining space at the top of the Conduit was filled with water. Then compressed air was applied to the top of the Conduit to force water through the sealant. Increments of 1, 5, 10, and 15 psig were used to test the product s resilience. In some cases, the pressure was increased beyond 15 psig to find its failure point. III. Analysis A. Ease of Installation Neutral Cure Silicon: The silicone was applied using a standard caulking gun.