Vent and Drain Pipe Dimensions
When vents are terminated with lengths of straight PVC pipe, it can be troubling in some applications. While it is common and industry practice to terminate drains with straight pipe, for HVAC applications it is not desired. Regardless of the application, straight PVC pipes exiting a home or sump pit are an open invitation for wildlife to enter. In fact, straight intake and exhaust vents are more prone to infiltration events that are easily corrected with standard vent termination hubs.
It is important to note that straight pipe is advertised and sold by it’s inside nominal diameter. For example, straight 2″ PVC pipe has an inside usable diameter of roughly 2″ while the outside diameter is 2-3/8″. In the vent and drain pipe size table below, we have specified both the inside diameter (ID) and outside diameter (OD) of each pipe size for accurate identification. Also included in the table are the adapters or hubs that are needed to terminate non-standard PVC pipe sizes to accommodate our PVS series vent screens.
ASTM D1785/D2665 Schedule 40 DWV Pipe Dimensions
| SIZE | ID | OD | HUB/ADAPTER NEEDED | USE | OUR SKU |
| 3/4″ | .824″ | 1.050″ | None – Direct Fit | Drain/Vent | SVC-IS075 |
| 1″ | 1.049″ | 1.315″ | None – Direct Fit | Drain/Vent | SVC-IS1 |
| 1-1/4″ | 1.380″ | 1.660″ | 1-1/4″ to 2″ Adapter | Vent | PVS-IS2, PVS-RS2 |
| 1-1/2″ | 1.610″ | 1.900″ | None – Direct Fit | Drain/Vent | SVC-IS15, SVC-RS15 |
| 2″ | 2.067″ | 2.375″ | None – Direct Fit | Drain/Vent | SVC-IS2, SVC-RS2 |
| 2″ | 2.067″ | 2.375″ | 2″ Hub | Vent | PVS-IS2, PVS-RS2 |
| 2-1/2″ | 2.469″ | 2.875″ | 2-1/2″ to 3″ Adapter | Vent | PVS-IS3, PVS-RS3 |
| 3″ | 3.068″ | 3.500″ | 3″ Hub | Vent | PVS-IS3, PVS-RS3 |
| 4″ | 4.026″ | 4.500″ | 4″ Hub | Vent | PVS-IS4, PVS-RS4 |
Please note the PVS-IS2, PVS-RS2, PVS-IS3, PVS-RS3, PVS-IS4 and PVS-RS4 vent screen models are designed specifically for ventilation applications where maintaining seasonal airflow is extremely important. SVC-IS075, SVC-IS1, SVC-IS15, SVC-RS-15, SVC-IS2 and SVC-RS2 caps are best suited for drainage and general ventilation applications. Those with a small 2-3″ section of pipe extending out of a cone/saucer shaped vent should view our concentric vent cap sizing page for additional information.
Whenever adapting a vent or drain termination, it is extremely important to adapt to the next larger size. Adapting to a smaller termination may cause system lockouts in HVAC applications and introduce airflow related safety concerns for the occupants of the dwelling. More detailed information regarding adapting existing terminations for ventilation and plumbing applications is available here.
We encourage those that may have additional questions about utilizing adapter couplings and hubs to contact us. For HVAC applications, most vent termination modifications cost less than $5 and require no special skills.
