14-10 PRV installation

Question: 14-10Code Section: 7Date: 10 September 2014OBC 2012 Reference:

Question Submitted: We recently had a backflow inspection for a 2” DCVA for an apartments premise protection. The pressure coming into the building exceeds 100psi and because the expansion tank is only rated for a maximum pressure of 80psi we had to install a pressure reducing valve on the line coming in. The inspector had an issue with the installation because the PRV was installed before the backflow  preventer. The inspector told us that there can be no devices before the backflow preventer. We asked if that applied to WYE strainers as well and he told us that was not a “device”. From our understanding of backflow installations was that there cannot be any connection points between the main and the backflow preventer. Since there is no connection point on the PRV then there is no risk of cross contamination, it would be the equivalent to a straight piece of pipe. The inspector told us that it was code, but we could not find such code. Would it be possible to get clarification on this?

Interpretation: The OBC only requires the installer to conform to CAN/CSA B64.10, as per Article (1). There are no requirements found in that standard that would prohibit this PRV from being installed upstream of the 2” DCVA. Manufacturer installation recommendations should always be considered as the Code Technical Committee (CTC) has found most Double Check Valve Assemblies (DCVA’s) have a maximum working pressure from the manufacturer of 175psi and a temperature operating range of 33°F – 180°F (0.5°C – 82°C). This being the case, the PRV could have been installed downstream of the DCVA, if the water pressure was less than 175psi from the water purveyor. The CTC suggests checking with all authorities having jurisdiction (i.e. water purveyor) as they may be separate from the city or town building department, for any cross connection control By-Laws that are enacted governing installation requirements.