I am designing a hail gun for my senior design project. I am needing about 70 psi of pressure for my maximum pressure. I am going to use various diameters of Schedule 40 PVC. The max pressure rating for this diameter is 220 psi at 73 degrees F. However this is for water. I've seen articles where it says not to use PVC for compressed air because it has other energies that water doesnt. However, I am not going to be approaching anywhere near 220 psi. Will I be ok to use this PVC with my max air pressure being 70 psi? I don't see it being a problem but want to make sure. Also I was going to use heavy duty cement and primer. Will this cement and primer withstand 70 psi? I can't find anywhere saying otherwise. I just want to prevent serious injury if possible. Oh, also, the reason I am choosing PVC is because I'm on a tight and small budget. Please let me know opinions.