A neutralization tank is a treatment device that protects plumbing, pipes, and the environment by reducing the pH of condensate produced by condensing boilers and similar systems to an acceptable level before discharge. Acidic condensate can cause corrosion and erosion of cast iron, copper, and concrete pipe joints; furthermore, discharging condensate with a pH below local regulatory limits presents legal and operational risks. The neutralization tank typically reduces the effluent to a pH between 5.5 and 8.5, extending the life of pipes and facilitating compliance.

The most common method involves bringing the condensate into contact with high-purity limestone granules (calcium carbonate) contained within the tank. In these units, baffles integrated into the PP or HDPE body increase the contact time; neutralization occurs as the acidic water passes through the bed of granules, resulting in a more neutral flow at the top outlet. The tank contents consist primarily of CaCO₃; to optimize performance under high loads, magnesium oxide or special neutralizing granules can be added, depending on the application. The lid bolts are made of stainless steel, and the body design facilitates maintenance.

The first step is to determine the maximum condensate flow rate, based on the thermal load, equipment type, and manufacturer's specifications. Next, the contact time and the mass of granules required to reach the target pH at this flow rate are calculated. In practice, a hydraulic retention time of a few minutes and an appropriate bed height are targeted for optimal contact, with a safety margin built in for critical processes. Granule consumption depends on the acid load of the condensate; autonomy is calculated based on the planned maintenance interval for your installation, and, if necessary, a modular capacity is provided with tanks in parallel or series. Finally, commissioning tests are performed to verify the outlet pH.

The tank must be installed on level ground, as close as possible to the condensate source, and protected from frost and direct sunlight. Gravity drainage is the safest solution; in areas with insufficient elevation, it is preferable to install a condensate pump after neutralization. Valves at the inlet and outlet, along with a bypass line for maintenance, ensure continuous operation; a sludge drain at the bottom and a vent at the top are recommended. Until the pH is verified, suitable plastic pipes should be used rather than metal ones, and an easily accessible sampling point should be provided at the outlet.

After initial commissioning, system stability is monitored by regular pH measurements for several weeks; monthly checks, based on the system's load profile, are then sufficient. If the outlet pH falls below the target value, the pellet bed is replenished; if its depth drops too low, it is completely replaced. As the calcium carbonate is depleted, the resulting salt and fine sediment can form sludge at the bottom, necessitating periodic draining and regular cleaning of the flow channels and internal filters. These simple maintenance operations ensure consistent long-term operation.