The rule of thumb for suction piping to a centrifugal pump is 5 to 10 diameters of an uninterrupted straight run of pipe to the suction nozzle. The 10 times the diameter is the safe extreme and is required on small diameters. When you start getting up to about 6 inch diameter or more, you can start cutting it back towards 5 diameters.

You mention that you are installing the system on a small footprint and don't have much room. I would question whose decision that is? If it is the customer's decision, he should be made aware that it is inconsistent to the requirement for 10 diameters. If it is someone else's requirement, this should be discussed with the end user.

The problem is simple. Anything less than 5 - 10 diameters has the possibility of creating turbulence in the suction line with the resulting effect of air entrainment becoming an ongoing problem with the pump operation for years to come.

On my website, there is a complete article on this topic you may wish to review at www.practicalpumping.com.