Impingement rods are commonly used in high velocity applications for vacuum services when protecting tubes from erosive effects. Impingement rods are ideal as they can be made of material that is cost effective, like carbon steel. In addition, the rods are made of solid material, which will last longer. Another nice part about impingement rods is they can be placed in the support plates in the same tube pattern, which allows for full cover protection as it is typically two rows of rods. It also allows for steam to enter the condenser evenly without being deflected or generating additional pressure drop.

Impingement tubes are also used for high velocity applications for vacuum services to protect tubes. The main difference with impingement tubes versus the rods is they are typically a thicker gauge tube with a similar metal as the condenser tubes or a stainless steel tube. Again the advantage is the impingement tubes allow the vapor entering the vapor inlet to evenly enter the bundle while minimizing the additional pressure drop.

Perforated plate protects the bundle from the majority of the high velocity vapors from directly impacting the condenser tubes. The issue with perforated plate is there may still be some impingement on the tubes where there are holes. Typically, the holes are small, so it is a minimally impact. Perforated plate tends to be the most cost effective for material as it is typically steel and installation in most cases. The perforated plate will deflect most of the vapor inlet from going straight into the bundle. If installed correctly the deflection of the vapor is small to not impact performance. Perforated plate is also fairly thin compared to multiple layers of rods allowing it to be installed in units with minimal room.

Solid plate is sometimes used for impingement at vapor inlets, however it needs to be installed correctly. If the solid impingement plate is not installed correctly, then it can negatively impact the performance of the vacuum condenser as it will restrict the vapor from entering the tube bundle correctly. The material is typically steel. Another reason solid plate is used is for connections with steam or water enter that should not enter the condenser directly and should be deflected. For example, a high temperature drain in a hotwell or a startup recycle connection on the condenser shell for turbine exhaust condensers. These connections would be protected with v-baffle type connections. Solid plate is not traditionally used in a vacuum service for the process inlet as it creates additional pressure drop and creates a dead condensing zone on its opposite side.