When ordering lots of smaller items (e.g. 50 x 40mm PVC ball valves) it is a good idea to order 5 to 10 percent more than required.
- This allows for breakages.
- This is especially important if the project is not well planned (e.g. the design is not complete at the time of order) .
- Ordering extras saves money because you get them at the bulk price instead of buying small numbers of extras later at a higher per item price.