Application |
Description |
The closed bladder expansion tank consists of a cylindrical casing made by carbon steel with a rubber bladder inside. System fluid is connected with the bladder inner chamber via the flange at the casing bottom. The chamber between the casing and bladder is pre-charged with Nitrogen as air cushion. Fluid is contained inside the bladder without contacting casing. The air cushion accommodates the fluid volume changing inside bladder during expansion and contraction as system fluid temperature changes. The bladder expansion tanks are designed to absorb the expansion forces resulting from the changes in temperature of the heating/cooling fluid in hydronic heating/cooling systems, to maintain the proper system pressurization. As the system fluid expands, it is forced into the rubber bladder of the pre-pressurized tank to the higher system pressure. The pre-charged air cushion then forces the fluid back from the bladder into the system as it contracts. The rubber bladder is fixed within the casing by flanges at top and/or bottom. It is replaceable easily by removing the flange(s). A pressure gauge is installed on the casing for monitoring working pressure. A charging port is provided on the casing for easier adding air into tank whenever necessary. | ![]() |
Working Principle |

Original status:
The bladder is filled with liquid at same pressure as nitrogen inside casing, not deformed.
Contraction status:
Liquid inside bladder is under less pressure when system total liquid volume is less as temperature lower. The bladder is compressed by nitrogen to feed liquid back to system.
Expansion status:
The bladder is expanded when liquid pressure inside is higher than nitrogen, when system total liquid volume is more as temperature higher. The bladder is expanded by liquid and absorb the extra liquid volume from the system.
★However, bladder expansion will be avoided by selecting models with sufficient capacity, even bladder allows deforming at a certain level. Over-expansion is the main reason for bladder broken.
Features |
◇ Replaceable rubber bladder.
◇ Pre-pressurized by Nitrogen.
◇ Pressure gauge on casing.
◇ Air charging port on casing.
◇ Complete separation of air from water.
◇ Standard: GB 150-1998 (Steel Pressure Vessels), 2014/68/EU
◇ Permissible operating temperature: 70 °C
◇ Max. permissible system temperature 120 °C
Specification |
Model | Total Capacity (L) | Adjustable Capacity (L) | Dimension (mm) | ||
Diameter | Total Height | Connection Size | |||
G110 | 100 | 54 | 400 | 1260 | DN50 |
G350 | 350 | 125 | 600 | 2000 | DN50 |
G800 | 800 | 350 | 800 | 2340 | DN50 |
G1300 | 1300 | 500 | 1000 | 2420 | DN50 |
G2200 | 2200 | 750 | 1200 | 2800 | DN50 |
G3100 | 3100 | 1000 | 1400 | 2970 | DN50 |
G4200 | 4200 | 1950 | 1600 | 3050 | DN80 |
G5500 | 5500 | 2120 | 1800 | 3170 | DN80 |
G7000 | 7000 | 3650 | 2000 | 3320 | DN80 |
Detailed Images |


DOWNLOAD
Data sheet: Bladder Expansion Tank
ORDERING INFO
Particular information: |
General information for ordering: |
1. Quantity of each size.
2. Delivery location, and price term: EXW, FOB, CIF, DDU, DDP, etc.
3. Detailed information of the contact person and buyer's company, which is helpful to prioritize your inquiry with faster response and better price.
SHIPPING
Delivery Options:
Delivery Method | Incoterms Term | Applicable Countries |
LCL, FCL by sea | EXW, FOB, CFR, CIF | General for all countries. |
Air courier to door | DDU, DDP | General for all countries. |
Air cargo to airport | CIF | General for all countries. |
Door to door by road | DDP | Cambodia, Laos, Myanmar, Thailand, Vietnam. (keep expanding to more countries) |
Door to door by sea | DDU, DDP | Cambodia, Indonesia, Malaysia, New Zealand, Philippines, Singapore, Thailand, United Arab Emirates, United Kingdom, United States. (keep expanding to more countries) |
LCL=Less than Container Load. FCL =Full Container Load
DDU = Delivery Duty Unpaid DDP = Delivery Duty Paid
The above shipping information is general, and changing from time to time. Confirmation with us is necessary for each order.