Wessels Expansion Tanks

Wessels manufactures three expansion tank designs: Compression, Bladder & Diaphragm. Each tank style has models that are either ASME or Non-ASME coded. Tanks range in size from 2 to 10,000 gallons. Most of Wessels pressure vessels are designed using a pre-pressurized vessel with an internal bladder or diaphragm to manage fluids under pressure.

Wessels Bladder Expansion Tanks:

Wessels bladder expansion tanks are required in a closed loop heating or chilled water HVAC system to absorb the expanding fluid and limit the pressure within a heating or cooling system. A properly sized expansion or compression tank will accommodate the expansion of the system fluid during the heating or cooling cycle without allowing the system to exceed the critical pressure limits of the system.

Information:

• Wessels NLA Series (ASME) Bladder Expansion Tank Brochure
• Wessels NLA 35-800L Series (ASME) Bladder Expansion Tank Submittal Sheet
• Wessels NLA 35-800L Series (ASME) High Pressure Bladder Expansion Tank Submittal Sheet
• Wessels NLA 1000-1500L Series (ASME) Bladder Expansion Tank Submittal Sheet
• Wessels NLA 1000-1500L Series (ASME) High Pressure Bladder Expansion Tank Submittal Sheet
• Wessels NVA 85-800L Series (ASME) Bladder Expansion Tank Submittal Sheet
• Wessels NVA 1000-1500L Series (ASME) Bladder Expansion Tank Submittal Sheet
• Wessels NLAP Series (ASME) Bladder Expansion Tank Submittal Sheet
• Wessels NL Series (Non-ASME) Bladder Expansion Tank Submittal Sheet

Wessels Compression Tanks:

Compression tanks are designed to absorb expansion forces and control the pressure in heating/cooling systems. This tank is the oldest style design and works well when the air is controlled and kept in the tank, not in the system.

Information:

• Wessels NA Series (ASME) Compression Tank Submittal Sheet
• Wessels NA Series (ASME) Compression Tank Instruction Manual
• Wessels Stainless Steel NA Series Compression Tank Series Submittal Sheet
• Wessels NAG Series (ASME) Compression Tank Submittal Sheet

Wessels HVAC Expansion Tanks

The Wessels diaphragm tank has been developed to allow the systems air cushion to be separated from the systems water. No water logging of the tank can occur as the air is held between the tank wall and the outside of a bladder placed inside the tank, while the system water is contained inside the bladder. This changes the system to an air elimination system, as any air extracted from the system water is passed out of the system into the atmosphere.

Information:

• Wessels NTA Series (ASME) Expansion Tank Submittal Sheet
• Wessels N Series (Non-ASME) Expansion Tank Submittal Sheet

Expansion tanks are required in a closed loop heating or chilled water HVAC system to absorb the expanding fluid and limit the pressure within a heating or cooling system. A properly sized tank will accommodate the expansion of the system fluid during the heating or cooling cycle without allowing the system to exceed critical pressure limits. The expansion tank uses compressed air to maintain system pressures by accepting and expelling the changing volume of water as it heats and cools. Some tank designs incorporate a diaphragm or bladder to isolate the expanded water from the pressure controlling air cushion. As water is expanded, it is contained in the bladder to prevent tank corrosion and water logging potentials. The pressure controlling air cushion is pre-charged at the factory and can be adjusted in the field to meet critical system requirements. This design and operation of this style of expansion tank allows the designer or specifying engineer to reduce tank sizes up to 80%.