How to avoid damages and malfunctions in expansion vessels and guarantee longevity to the installed product.

To avoid breakages and malfunctions, first consult the special label affixed to the expansion vessel and the instruction manual supplied by the manufacturer. Furthermore, it is necessary to: Perform a correct and periodic maintenance of the system in which the expansion vessel is installed Periodically check the pre-charge pressure of the vessel and if necessary restore it to the value indicated on the label Check the correct grounding of the system, in order to avoid galvanic currents Check the correct sizing of the expansion vessel Pay attention to excessive overpressure and water hammering phenomena in the system Avoid to install the expansion vessel in unsuitable environments or areas subjected to particularly aggressive climatic conditions Avoid the formation of condensation that leads to the development of corrosive phenomena (see question 13) Monitor the pH value of solutions containing glycols or other substances Avoid mixing different antifreeze products

What information is required and how do you size CIMM expansion vessels?

Depending on the type of use (for boilers, heating systems, domestic hot water systems, hot and cold water systems, solar energy systems) it is possible to size the expansion vessel by consulting the CIMM CALCULATOR SOFTWARE FOR DIMENSIONING OF CIMM PRODUCTS at this link. For more information, contact our technical department.

What is the advantage of stainless steel vessels?

The expansion vessels in the Inox line are ideal for installations in particular and hostile environmental and climatic conditions, as they are made entirely of AISI 304 stainless steel, a material with greater resistance to oxidation.

What are anti-water hammer tanks used for?

Anti-water hammer membrane tanks are tanks built for civil and industrial water systems where high operating pressures are required. They are particularly suitable for preventing the serious consequences of water hammer, i.e. the pressure wave that is created inside a pipe when an incompressible liquid, such as water, is stopped abruptly or instantaneously (for example: the rapid closing of a valve or the stopping of a pump).

What is the purpose of the anti-legionella valve?

The anti-legionella valve ensures a continuous flow of water, thus preventing the proliferation of bacteria such as Legionella, which thrive in stagnant fluids. The CIMM anti-legionella valve has been designed and developed to operate at a maximum working pressure of 10 bar and a maximum water temperature of 65°C. It converts a standard single-connection expansion tank into a flow-through expansion tank, thus preventing water stagnation that could lead to bacterial growth.

Why does corrosion occur in expansion vessels in heating systems?

In heating systems expansion vessels corrosion is a known and widespread phenomenon, due essentially to the combined action of water and oxygen. Under correct operating conditions, in a closed heating system, oxygen is quickly eliminated during the first operating periods (vents) and should not lead to the formation of corrosive phenomena. Nevertheless, other external factors such as condensation, the presence of galvanic currents, high temperatures and undersized expansion vessels can cause or accelerate corrosion phenomena.

What are the CIMM expansion vessels suitable for use with drinking water?

The CIMM expansion vessels suitable for use with drinking water are the ones with the interchangeable membrane that show the drinking water eligibility sign on the vessel label. In these vessels, the water is contained entirely inside a special bag shaped rubber membrane and never coming in contact with the metal body of the vessel.

Are CIMM fixed membrane expansion vessels suitable for use with drinking water?

NO, CIMM fixed membrane vessels, as indicated on the vessels label, CAN NOT be used in a sanitary water circuit and CAN NOT come in contact with drinking water.

Which CIMM expansion vessels are suitable for use with water and glycol? And in what percentage?

All the expansion vessels of the SOLAR range, manufactured by CIMM, can be utilized with water and glycol mixtures with a maximum glycol concentration of 49%.

What is the recommended volume for a CIMM Intermediate Solar Tank in solar systems?

Approximatively, the volume of a CIMM Intermediate Solar Tank should be at least 1/3 of the volume of the CIMM Solar expansion vessel to which it is combined.

When and why should you add a CIMM Intermediate Solar Tank to a CIMM Solar expansion vessel?

In solar energy systems, it is useful to provide a CIMM Intermediate Solar Tank – which is an additional tank without membrane – in order to protect the Solar expansion vessel from overheating in case of stagnant water. According to the VDI 6002 Directive, the use of an additional tank, such as CIMM Intermediate Solar Tank, is recommended when the fluid of the pipes placed between the solar collector battery and the expansion vessel is less than 50% of the correctly measured reception capacity of the expansion vessel.

In which CIMM expansion vessels can you directly install a manometer to check the air pressure?

On the interchangeable membrane expansion vessels with the upper tie rod, it is possible to install a manometer fixing it directly on the tie rod, after removing the cutting screw inside the tie rod itself.

How can you check if the internal membrane of an expansion vessel is broken?

All CIMM expansion vessels with membrane are pre-charged with air through an air valve. The rubber membrane inside the vessel keeps the water separated from the air. Therefore, in case of malfunction, to check if the membrane of the vessel is broken, you must act on the internal mechanism of the air valve, pressing it with a tool such as a screwdriver, and checking what comes out. If water leaks, it means the membrane is broken and the water has completely filled the vessel. Whereas, if air comes out, the membrane should still be intact and it is necessary to simply pre-charge the expansion vessel again to make it work. Download the instructions to know how to change the membrane of an expansion vessel with interchangeable membrane.

Can the air pre-charge pressure of CIMM expansion vessels be modified?

Yes, it is possible to modify the air pre-charge pressure of CIMM expansion vessels with cautions. We suggest to ask to an expert and authorized personnel to carry out the operation. Being aware of the specific features of the system or plant where the vessel has to be or is installed, the pre-charge pressure of an empty CIMM vessel can be increased up to a maximum of 3.5 bar and can be reduced to a minimum of 0.5 bar.

What are General Terms and Conditions of Sale?

Download the General Terms of Sale

Is it necessary to check the air pre-charge pressure of the expansion vessels?

Yes, as written in the instruction manual, it is necessary to periodically check – at least once a year – the air pre-charge pressure of the expansion vessels, and if necessary charge them again to the value indicated on the label, to guarantee the correct functioning of the vessels in the plant.

What documents are issued by the manufacturer?

According to the PED Directive 2014/68/EU, the pressure equipment manufacturer must issue the instruction manual and, where required, the Declaration of Conformity. Download the Operating Instruction Manual – EC Workbook

Which expansion vessels must have the CE mark?

According to the European Directive PED 2014/68/EU, the “CE” mark must be affixed to all the vessels in which the product of the maximum working pressure (PS) indicated in the vessel’s label, and the volume (V) is more than 50 liters per bar. Vessels for which the product PSxV is equal to or less than 50 liters per bar are included in the category of vessels ruled by Article 4 par.3 of the Directive, which does not need the “CE” mark.

Are CIMM expansion vessels marked “CE”?

Yes, CIMM expansion vessels are built in compliance with the European PED Directive 2014/68 / EU (Pressure Equipment Directive) and according to EN 13831, therefore where required, they are provided with the “CE” mark.

Frequently asked questions about expansion vessels

General questions

Yes, CIMM expansion vessels are built in compliance with the European PED Directive 2014/68 / EU (Pressure Equipment Directive) and according to EN 13831, therefore where required, they are provided with the "CE" mark.
Download the General Terms of Sale
According to the PED Directive 2014/68/EU, the pressure equipment manufacturer must issue the instruction manual and, where required, the Declaration of Conformity. Download the Operating Instruction Manual - EC Workbook
According to the European Directive PED 2014/68/EU, the "CE" mark must be affixed to all the vessels in which the product of the maximum working pressure (PS) indicated in the vessel’s label, and the volume (V) is more than 50 liters per bar. Vessels for which the product PSxV is equal to or less than 50 liters per bar are included in the category of vessels ruled by Article 4 par.3 of the Directive, which does not need the "CE" mark.

Products

Yes, it is possible to modify the air pre-charge pressure of CIMM expansion vessels with cautions. We suggest to ask to an expert and authorized personnel to carry out the operation. Being aware of the specific features of the system or plant where the vessel has to be or is installed, the pre-charge pressure of an empty CIMM vessel can be increased up to a maximum of 3.5 bar and can be reduced to a minimum of 0.5 bar.
All CIMM expansion vessels with membrane are pre-charged with air through an air valve. The rubber membrane inside the vessel keeps the water separated from the air. Therefore, in case of malfunction, to check if the membrane of the vessel is broken, you must act on the internal mechanism of the air valve, pressing it with a tool such as a screwdriver, and checking what comes out. If water leaks, it means the membrane is broken and the water has completely filled the vessel. Whereas, if air comes out, the membrane should still be intact and it is necessary to simply pre-charge the expansion vessel again to make it work. Download the instructions to know how to change the membrane of an expansion vessel with interchangeable membrane.
To avoid breakages and malfunctions, first consult the special label affixed to the expansion vessel and the instruction manual supplied by the manufacturer. Furthermore, it is necessary to:
1. Perform a correct and periodic maintenance of the system in which the expansion vessel is installed
2. Periodically check the pre-charge pressure of the vessel and if necessary restore it to the value indicated on the label
3. Check the correct grounding of the system, in order to avoid galvanic currents
4. Check the correct sizing of the expansion vessel
5. Pay attention to excessive overpressure and water hammering phenomena in the system
6. Avoid to install the expansion vessel in unsuitable environments or areas subjected to particularly aggressive climatic conditions
7. Avoid the formation of condensation that leads to the development of corrosive phenomena (see question 13)
8. Monitor the pH value of solutions containing glycols or other substances
9. Avoid mixing different antifreeze products
Yes, as written in the instruction manual, it is necessary to periodically check - at least once a year - the air pre-charge pressure of the expansion vessels, and if necessary charge them again to the value indicated on the label, to guarantee the correct functioning of the vessels in the plant.
Depending on the type of use (for boilers, heating systems, domestic hot water systems, hot and cold water systems, solar energy systems) it is possible to size the expansion vessel by consulting the CIMM CALCULATOR SOFTWARE FOR DIMENSIONING OF CIMM PRODUCTS at this link. For more information, contact our technical department.

Heating sytems

NO, CIMM fixed membrane vessels, as indicated on the vessels label, CAN NOT be used in a sanitary water circuit and CAN NOT come in contact with drinking water.
In heating systems expansion vessels corrosion is a known and widespread phenomenon, due essentially to the combined action of water and oxygen. Under correct operating conditions, in a closed heating system, oxygen is quickly eliminated during the first operating periods (vents) and should not lead to the formation of corrosive phenomena. Nevertheless, other external factors such as condensation, the presence of galvanic currents, high temperatures and undersized expansion vessels can cause or accelerate corrosion phenomena.

Sanitary water

Anti-water hammer membrane tanks are tanks built for civil and industrial water systems where high operating pressures are required. They are particularly suitable for preventing the serious consequences of water hammer, i.e. the pressure wave that is created inside a pipe when an incompressible liquid, such as water, is stopped abruptly or instantaneously (for example: the rapid closing of a valve or the stopping of a pump).
The CIMM expansion vessels suitable for use with drinking water are the ones with the interchangeable membrane that show the drinking water eligibility sign on the vessel label. In these vessels, the water is contained entirely inside a special bag shaped rubber membrane and never coming in contact with the metal body of the vessel.

Solar

Approximatively, the volume of a CIMM Intermediate Solar Tank should be at least 1/3 of the volume of the CIMM Solar expansion vessel to which it is combined.
In solar energy systems, it is useful to provide a CIMM Intermediate Solar Tank – which is an additional tank without membrane - in order to protect the Solar expansion vessel from overheating in case of stagnant water. According to the VDI 6002 Directive, the use of an additional tank, such as CIMM Intermediate Solar Tank, is recommended when the fluid of the pipes placed between the solar collector battery and the expansion vessel is less than 50% of the correctly measured reception capacity of the expansion vessel.
All the expansion vessels of the SOLAR range, manufactured by CIMM, can be utilized with water and glycol mixtures with a maximum glycol concentration of 49%.

Stainless Steel

The expansion vessels in the Inox line are ideal for installations in particular and hostile environmental and climatic conditions, as they are made entirely of AISI 304 stainless steel, a material with greater resistance to oxidation.

Accessories

On the interchangeable membrane expansion vessels with the upper tie rod, it is possible to install a manometer fixing it directly on the tie rod, after removing the cutting screw inside the tie rod itself.
The anti-legionella valve ensures a continuous flow of water, thus preventing the proliferation of bacteria such as Legionella, which thrive in stagnant fluids. The CIMM anti-legionella valve has been designed and developed to operate at a maximum working pressure of 10 bar and a maximum water temperature of 65°C. It converts a standard single-connection expansion tank into a flow-through expansion tank, thus preventing water stagnation that could lead to bacterial growth.

FAQ