A Comprehensive Guide to Expansion Bladder/Diaphragm Tanks

What is a bladder tank?

An expansion tank which contains a bladder is known as a bladder tank. A bladder expansion tank is a system which is used for heating and cooling purposes by absorbing the expansion force. It uses compressed air to adjust with the pressure changes by eliminating or accepting the water volume changes as it expands or contracts due to heating and cooling. A pre-charged bladder tank is an expansion tank which is already charged with air. Bladder expansion tanks offer the benefit of replacing the bladder as and when required.

The bladder separates the expanded water from air. This way, the water does not come into contact with tank and it prevents corrosion by oxygen and rusting. It also increases the pump life by reducing the number of pump cycles. This system prevents water clogging by using an air wall between the interior of the tank and the exterior of the bladder.

An Overview of Diaphragm Tanks

Diaphragm tanks are water vessels which are subject to a high amount of pressure. These tanks

The diaphragm keeps the water and air separate inside the vessel. Diaphragm tanks work in a similar manner as bladder tanks. The key difference lies in the fact that one system uses bladders and the other uses diaphragms. Diaphragms cannot be replaced from a tank.

It keeps the system from being waterlogged and prevents absorption of air. This way, it protects water heating and cooling systems.

●What is the difference between a bladder tank and a diaphragm tank?

A bladder tank contains a vinyl tank inside it. A bladder tank can be replaced as and when required.

On the other hand, a diaphragm tank contains a rubber flat diaphragm, a butyl tank or a vinyl tank that is mounted on it. The diaphragm is kept attached in the internal area of the tank. Therefore, it cannot be replaced.

Both the tanks, bladder and diaphragm, have the same functionality.

Pre-charged expansion tanks

Pre-charged expansion tanks contain a bladder or a diaphragm. They serve the purpose of separating the air from the water inside the tank. Tanks are used as reservoirs to store water and also to decrease the daily cycle of pumps to enhance its life. When the pump fills the tank with water, the bladder or diaphragm gets compressed. This leads to an increase in the pressure and it continues until the pressure switches of the pump shuts off.

The feature of a pre-charged expansion tank is that it charged with air. It holds the charge and it can be extended in the field when used. Pre-charged tanks have a connection of a single pipe. As the size of the tank increases, the amount of usable water will increase and there will be lesser pump cycles. This can extend the pump life and enhance its durability.

The expansion tanks offered by Bell & Gossett

Bell & Gossett offers pre-charged expansion tanks with a diaphragm or a bladder in three different series. Learn about the specifications of the three series below. All the  Bell & Gossett Expansion Tanks, heating and cooling systems meet the standards of ASME Section VIII, Division 1.

1. Bell & Gossett Series B Expansion Tanks

This series is available in sizes 53 - 3,63 gallons. It has a heavy duty replaceable butyl bladder. It is available in California-code sight glass and high pressure models up to 250 PSI are also available. This model is pre-charged to 12 PSI but it can be adjusted in the field as per requirements. You can also get seismic restraints if needed.

2. Bell & Gossett Series Series D Expansion Tanks

This model has a fixed butyl diaphragm which cannot be replaced. It is economical in usage. You can go for a vertical shape or a horizontal one. It is available in sizes 8- 211 gallons. Seismic restraints and California-code sight glass are available. Its charge can be adjusted and its factory pre-charge is up to 12 PSI.

The shell of this model is made from carbon steel. It decreases waterlogging issues, prevents oxygen corrosion and thus, keeps the tank from being rusted.

It maintains a proper pressurization system at several operating conditions which helps it to absorb the expansion forces of cooling and heating systems.

3. Bell & Gossett Series B-LA Expansion Tanks

This model is one of the best as it contains an economical heavy duty replaceable butyl bladder. It comes in sizes 10-158 gallons. Like the other series, seismic restraints and California-code sight glass are also available with this model.

The models of this series are designed specifically to absorb expansion forces of cooling or heating water systems. It maintains the pressurization excellently under varying conditions of operation.

Furthermore, Series B-LA bladder tanks reduce the chances of tank corrosion and maintain its quality. It also eliminates water-logging problems and oxygen corrosion. Check out  Bell & Gossett Expansion Tanks page for more information.