How much greater is the working pressure of a PVC pipe labeled PVC 1220 compared to one labeled PVC 1210?

The correct answer arises from understanding the labeling of PVC pipes, specifically the significance of the numbers within the labels. The first two digits signify the type of pipe and its intended use, while the last two digits typically indicate the pressure rating.

For PVC 1220 and PVC 1210, the last digit '2' in PVC 1220 indicates that it has a higher pressure rating than that of PVC 1210, where the last digit is '1'. This means that PVC 1220 can withstand twice the pressure of PVC 1210. In practical terms, if PVC 1210 is rated for a certain nominal working pressure, PVC 1220 is rated for a pressure that is twice that amount.

Understanding pressure classifications is critical in landscaping projects as it ensures that the correct materials are chosen for specific applications to avoid failures leading to leaks or bursts, which could result in costly repairs or damage to the landscape. Thus, knowing the distinction in pressure ratings directly informs the decision-making process for contractors when selecting materials for irrigation, drainage, and other plumbing needs in landscaping.