Many large cooling systems use ammonia refrigerant and water-cooled condenser units. These systems are efficient and dependable. However, they must be properly maintained, and this takes maintenance staff with experience and training. One of the most common refrigeration system troubleshooting issues is high condensing pressure. Let’s look at this problem and explore the best ways to correct it.
What Causes Excessive Pressure?
In order to correct a problem, you have to understand what’s causing it. That’s why the best maintenance people keep detailed pressure records. This gives them important information to use, as they can study fluctuations at various times. This makes refrigeration system troubleshooting easier and more effective.
Air in the System
Because air cannot condense, it can greatly add to condenser pressure. But why does air make the pressure rise? This can happen when you have more than one gas under pressure. For example, refrigerant condenses at a specific pressure, and it is affected by volume. When air takes up some of that volume, it adds to the total condensing pressure. Once you bleed air from the system, the pressure will lower.
Bleeding an Ammonia Refrigeration System
The first step is to shut down the system, but water flow to the condensing unit is still maintained. This lets the ammonia return to liquid form, making it heavier than the air in the system and air and ammonia gas separate. When bleeding the receiver, use a hose and a large container of water. Pressure must be monitored while bleeding. Open the valve and let the air bleed into the water. You can see the air form bubbles and ammonia will mix with the water. During the purging process, the pressure should lower. If you are not sure what to do, contact your refrigeration system troubleshooting specialists. They have years of experience with industrial refrigeration.
