Maintenance and repair of the expansion vessel

Service of the expansion vessel:

• Monthly check of the pump switch-on and switch-off pressure, to ensure compliance with the values set during installation.
• Semi-annual check of external damage to the expansion vessel, for corrosion, dents and leaks. If any external damage is found, it is necessary to determine and eliminate the cause.
• Semi-annual check of the initial pressure of the gas space Pг, to ensure compliance with the calculated value. The initial pressure of the gas space can be calculated in the Calculations section of the website.
• Semi-annual check of the integrity of the membrane, and replacement if any damage is found.
• If the expansion vessel is not used for a long time, it should be stored in a dry place, after draining all water.

Checking the initial pressure of the gas space in the expansion vessel. To check the initial pressure of the gas space, it is necessary to disconnect the vessel from the water supply system, drain the water and connect a pressure gauge to the gas space nipple. If the pressure is lower than the set value during installation, the vessel needs to be inflated through the same nipple using a compressor (e.g. an automotive compressor).

Checking the pump switch-on and switch-off pressure. The switch-on and switch-off pressure of the pump is measured using a pressure gauge installed on the expansion vessel. To do this, open any water supply valve and record the pressure value at the moment the pump switches on. The switch-off pressure is recorded after closing the valve and switching off the pump.

Possible malfunctions of the expansion vessel

Repair of an expansion vessel in case of a membrane rupture. To detect a torn membrane, it is necessary to disconnect the vessel from the water supply system and drain the water. If air comes out of the drain valve, it means that the integrity of the membrane is compromised.

It is better to replace the torn membrane if it is replaceable. Gluing the membrane is not recommended since most adhesives are not allowed for use with drinking water, and the cyclic stretching-compression of the membrane, which occurs several times per hour, is destructive for glued joints.

Procedure for replacing the membrane

• Disconnect the expansion vessel from the water supply system and drain it.
• Release the pressure from the gas chamber through the nipple at the top of the vessel.
• Remove the flange of the membrane, which is located near the pipe connection. Unscrew the nut at the top of the housing (if present) to free the membrane holder.
• Remove the membrane from the hole at the bottom of the housing.
• Check the internal surface of the housing for contaminants and corrosion. If present, remove them and rinse the surface with water. Then, dry the expansion vessel housing.
• Remember that the membrane is not oil-resistant, so oil-containing substances should not be used for anti-corrosion protection of the internal surface of the housing.
• Insert the membrane holder into the hole at the top of the installed membrane (if the attachment is provided by the vessel design). Screw the bolt into the membrane holder, insert the membrane into the housing, and insert the holder into the hole at the bottom of the housing. Secure the membrane holder with a nut.
• Mount the flange of the membrane on the housing.
• Set the initial air pressure in the expansion vessel. Check for leaks and connect the vessel to the system.

Attention!

Replacement of parts is allowed only with original spare parts from the vessel manufacturer.

It is best to fill the air chamber with an inert gas, such as nitrogen.

Before removing the gas from the air chamber, it is necessary to drain the water from the vessel.

The service life of the expansion vessel decreases at maximum values and overloads, as well as outside the range of specified temperatures.

question : comment : feedback