AIRVAC Vacuum liquid conveyance and collection systems consist of three basic components:

A. AIRVAC Vacuum Interface Valve Package - collection basin, vacuum interface valve, and pneumatic controller/sensor unit.

B. AIRVAC Piping Network - liquid transport mains, branches, and service laterals.

C. AIRVAC Vacuum Station - vacuum collection tank, vacuum pumps, liquid pumps, electrical panel, and control devices.

The collection process begins when fluid enters the valve package collection basin (sump). As the liquid level in the basin rises, air pressure increases against the pneumatic sensor. At a preset level, the sensor actuates the controller. The controller then opens the interface valve.

The open interface valve allows fluid collected in the basin to be evacuated into the piping network. Since the collection tank and piping network are maintained at 1/2 atmosphere (or less) of pressure, atmospheric pressure in the basin literally pushes the collected fluid into the piping network.

The lower pressure in the piping network and collection tank is maintained by vacuum pumps at the vacuum station. These vacuum pumps remove the air admitted with the fluid.

The vacuum mains empty into the collection tank at the station. Level sensors in the collection tank activate the liquid discharge pumps. The liquid pumps then transport the collected fluid to treatment facilities and/or holding tanks.

AIRVAC introduced the very successful model AV3 vacuum interface valve in 1970. This 3”, solids-handling valve is the key component in a system designed specifically to collect domestic sewage. The many patented features of the interface valve package applied in conjunction with AIRVAC proprietary piping design quickly established AIRVAC as the standard by which other vacuum conveyance technologies are measured.

At the same time that AIRVAC engineers were refining criteria for municipal vacuum collection systems, regulatory agencies around the world were examining the many sources of environmental pollution. Regulations developed by these agencies included increasingly stringent criteria for the handling and transport of industrial process fluids and waste.

As more and more entities implemented strict enforcement of these regulations, it became apparent that many industries had a need for a secure, user-friendly fluid transport system to satisfy these regulations without seriously disrupting production. This led many plant managers and designers to consider alternative technologies that might provide cost-effective liquid conveyance schemes.

In response to the needs of industrial users, AIRVAC research and development engineers have developed a family of specialized chemical and heat resistant liquid handling valves. Additionally, proven AIRVAC piping design standards have been adapted for use in Overhead Vacuum System (OVS) piping networks as documented in AIRVAC's OVS Design Manual.

AIRVAC OVS liquid conveyance schemes are often a cost effective means of resolving environmental, health, and safety issues related to the transport of process fluids and industrial wastewater.

What System Designers Want

• A system that accommodates conveyance of differing types of wastes in isolated flow streams allowing the user to comply with local codes while minimizing the cost of mandated pretreatment.
  
  
• A system that allows all piping to be located above ground and accessible, making buried liquid transport lines unnecessary.
  
  
• A system that requires minimal excavation inside operating facilities to reduce construction related dust and to avoid disturbing contaminated soils.
  
  
• A system that easily accommodates relocation and addition of collection points without extensive service interruptions.
  
  
• A system that utilizes a common power source to transport multiple fluid streams while maintaining "cross contamination free" flow paths. (As an example, the ideal system would allow the user to recycle air conditioning condensate to a cooling tower while sending non-contaminated wastewater to a sewer and contaminated wastewater to a pretreatment station or holding tank.)
  
  
• A system that includes factory validated and tested automatic controls complete with provisions to interface with both the process controls and the building automation system.
  
  
• A system that allows the user to comply with environmental and safety regulations without disrupting production.
  
  

Disadvantages of Buried Liquid Transport Piping

• Pipe or joint failures result in leaks that are difficult to isolate and which may allow undetected leakage to the environment.
  
  
• The piping network is subject to damage caused by seasonal ground movement, above grade traffic, and accidents during construction.
  
  
• The fluids being transported can collect in under-ground pockets and lie stagnant for extended periods, allowing bacteria growth.
  
  
• To maintain proper grade (or to intercept an existing sewer) gravity transport lines often require burial depths of eight feet or more.
  
  
• Many fluids may be transported underground only in double containment piping networks equipped with costly and complex leak monitoring systems.
  
  
• Repairs and modifications to system usually result in significant dust generation because the work often involves removal of concrete floors and excavation inside finished spaces.
  
  

Advantages of AIRVAC OVS Piping

• OVS technology provides lift capability of 23' allowing the piping network to be installed above floors, along walls, or across ceilings, while spaces remain in service.
  
  
• Since the piping network does not have to withstand the pressure of burial or traffic loads, the primary factor that needs be considered when selecting material for the piping network is chemical compatibility with the fluid being transported.
  
  
• Moderate pipe sizes (1.25" to 6") and minimal required pipe slope requirements (0.2%) simplify placement of the piping network in the building (above ceilings, on walls, around equipment, etc.).
  
  
• Pipe accessibility facilitates future process modifications since disassembly and reconfiguration are not hindered by the necessity to cut floors, work in a wet excavation, remove contaminated soil, replace excavated soil with engineered fill, and patch the floor.
  
  
• Individual AIRVAC vacuum interface valves can be serviced or repaired without interrupting service at any other input point.
  
  
• Water costs and wastewater treatment costs are minimized when OVS technology is utilized to provide segregated collection routes for fluids requiring different levels of treatment.
  
  
• Fluid is transported in the OVS piping network at velocities of 15-18 feet per second. This characteristic virtually eliminates the conditions that promote bacteria growth.