AcornVac Introduction to Vacuum Sewage and Plumbing Systems

AcornVac Introduction to Vacuum Sewage and Plumbing Systems
Introduction to
Vacuum Sewage and Plumbing Systems
by AcornVac, Inc.
What is a Vacuum Plumbing System?
Vacuum Plumbing Systems are simply a viable alternative to underground piping that uses
the combined energies of vacuum pressure and gravity for the collection and disposal of
waste through a piping network that can be routed above grade. Hundreds of vacuum
drainage systems are in operation around the world and are accepted by most code
authorities. Also, Vacuum Systems are included as a viable drainage solution in the latest
edition of the IPC and IAPMO.
What are the advantages of vacuum drainage?
Vacuum drainage systems offer a number of benefits to a variety of types of installation:
All types of construction:
• Vacuum toilets use only ½ gallon of water per flush to efficiently and effectively rinse
down and refill the toilet bowl. This provides a significant savings in water supply
and sewage disposal costs.
Vacuum plumbing systems use smaller diameter piping (PVC, copper or stainless)
and smaller diameter fittings, and are self venting thereby eliminating vent stacks
and reducing material and labor costs.
The drainage piping network servicing a vacuum plumbing system can be installed
vertically or horizontally, providing flexibility in layout and building design, as well as
providing solutions for renovation project piping.
Vacuum plumbing systems accommodate an open architectural environment by
eliminating the need to provide vent and waste stacks.
Vacuum drainage systems allow existing buildings with limited drainage to be
developed when traditional underground piping upgrades are cost prohibitive
because of structural limitations (post tension slab foundations), restrictive site
issues (bedrock, inappropriate inverts, historical building categorization), or
embedded contaminants in the floor (asbestos).
Prisons and Correctional Facilities:
Direct connection of two toilets into the same waste stack is eliminated, thereby
preventing prisoners from communicating or passing contraband between cells.
The operational dynamics of a vacuum plumbing system result in fewer in line
blockages, reducing maintenance cost and disruption. When toilet blockages do
occur, they are easily located and abusers can be readily identified.
In a shake-down, sections or pods can be isolated from the piping network, thereby
preventing prisoners from flushing their toilets and disposing of contraband or
creating disruption.
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Introduction to
Vacuum Sewage and Plumbing Systems
by AcornVac, Inc.
Vacuum drainage systems eliminate the need for costly underground drainage
piping in the sales area.
Vacuum drainage systems work in concert with the new "open" architectural store
environment where electrical and refrigeration services are brought to display cases
from overhead. Drainage can now follow these services, allowing for
unprecedented flexibility in store layout.
Vacuum drainage systems are completely adaptable to last minute merchandising
New construction projects can be completed faster, saving construction costs and
allowing a facility to be brought online in a more timely fashion. Often, projects can
be completed during inclimate weather because the facility can be closed before the
weather conditions prohibit construction.
Vacuum drainage systems create a cleaner environment and reduce health hazards
associated with gravity drains.
Vacuum drainage systems allow existing buildings with limited drainage to be
developed for supermarket use when traditional trenching and underground piping
upgrades are cost prohibitive because of site conditions – post tension slab,
bedrock, asbestos, high water tables, etc.
Because trenching is eliminated, store remodel activities are less expensive, safer,
more sanitary, and take less time.
Vacuum drainage equipment can be capitalized and taken with the owner if the
facility is abandoned.
How does it Work?
A Vacuum Drainage System consists of three or four basic components, 1) a vacuum
generating station, 2) a piping network that allows for transport of waste from its’ point of
origin – ex. toilet, wash basin, mop sink, shower, refrigerated food case, air condenser, etc.
to the vacuum generating station, and 3) vacuum interface components that isolate the
vacuum piping network from atmospheric pressure at the point of origin and allow
condensate to be removed, 4) purpose made toilets, designed to rinse and re-fill on ½
gallon of water.
Vacuum Generating Station
Referred to as the "Vac Center", the vacuum generating station includes vacuum
pumps to create a constant vacuum pressure within the piping network, and storage
tanks that collect and discharge the waste into the facilities' sewer main through a code
compliant air gap.
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Introduction to
Vacuum Sewage and Plumbing Systems
by AcornVac, Inc.
Operation of the pumps, collection tanks, historical data recording, and alarm reporting
is fully automated by controls provided with the Vac Center. The vacuum pumps run
only on demand, and full redundancy is always provided.
Piping Network
The piping network for a vacuum waste system is maintained under continuous vacuum
and is generally fabricated out of PVC, Copper, or other smooth bore, non-porous
material. The network consists of “risers” or “droppers” which transport the collected
waste vertically from the point of origin to horizontal mains and branches leading to the
Vac Center. The mains and branches are sloped at a rate of 1/8" per foot toward the
Vac Center and thus, for the most part, waste travels by gravity to the Vac Center, just
as is it does in traditional underground drainage piping.
A major benefit of this technology to the designer, installer, and user, compared to
traditional gravity-only drainage is the ability of the vacuum piping to be routed around
obstacles, and to allow slope recovery if the slope from the point of collection to the Vac
Center cannot be maintained at the1/8" per foot recommendation. This is done by
creating traps in the running branches and mains which are cleared by differential
pressures that exist between the point of origin and the Vac Center during a waste
extraction cycle.
Vacuum Interface Components
At the heart of a vacuum drainage system are the vacuum interface components that
allow waste to be efficiently collected and transported to the Vac Center. These
components include a normally closed vacuum interface valve (Extraction Valve) which
separates the vacuum in the piping network from atmospheric pressure surrounding the
fixture, and a control device (Controller) which assists in opening the vacuum interface
valve in the presence of a pneumatically generated signal to remove waste from the
plumbing fixture. In the case of gray water these components also include a temporary
collection vessel (Accumulator) which is directly connected to the outlet of the plumbing
fixture other than toilets.
When a pneumatic signal is generated at the Controller, it uses vacuum from the
system to open the Extraction Valve, exposing the Accumulator and its contents to the
vacuum pressure. The difference between the vacuum pressure in the piping network
and surrounding atmospheric pressure causes air to enter the Accumulator, mixing with
the waste, and transporting the resultant emulsion into the piping network. The
extraction cycle lasts approximately 2.0 to 2.5 seconds.
With the AcornVac system, the Controller, which determines if waste is present and
opens the Extraction Valve, is designed to operate only if sufficient vacuum pressure
exists to completely remove the accumulated waste.
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Introduction to
Vacuum Plumbing Systems
by AcornVac, Inc.
Frequently Asked Questions
Q: What happens if the vacuum piping network develops a leak?
A: Since the piping is maintained under a continuous vacuum, any leaks that might
develop will draw air INTO the pipes, preventing waste exfiltration.
Accepting that problems can occasionally develop with any mechanical system, the
Acorn Vac Center is equipped with several alarm features that help alert
maintenance personnel of any leaks that might develop in the vacuum piping
For small leaks that lead to frequent pump cycling, an alarm will be
generated indicating "Too Many Vacuum Pump Starts per Hour".
For moderate leaks that might keep a pump running continuously, an
alarm will be generated indicating that the "Vacuum Pumps have run too
Should a major leak occur which causes the vacuum pressure to drop
below minimum safe levels, the Vac Center will generate a "Low Vacuum
Pressure" alarm.
Since the vacuum piping network exists in the overhead structure, finding and
correcting vacuum system leaks is easily accomplished. By comparison, leaking
pipes in an underground system may go undetected for years, possibly
contaminating the surrounding area or water table.
Q: What about a catastrophic piping failure, say pipe breakage due to an earthquake?
A: Unlike underground piping, a catastrophic piping failure, regardless of the cause, will
be immediately identified and easily repaired.
Q: Since the system uses electrically operated vacuum pumps, what happens if power
A: Most facilities add the Vac Center to their standby power generating system. In fact,
Acorn Vac offers a number of control features and hardware options to
accommodate the unique needs of standby generator power sources.
If the facility does not have a generator, or chooses not to add the Vac Center to the
standby power source, the drainage system is simply not available until normal
power is restored.
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Introduction to
Vacuum Plumbing Systems
by AcornVac, Inc.
Frequently Asked Questions
Q: Can the AcornVac system accept large water flows associated with multiple use
scenarios, such as large office buildings or prisons?
A: Yes. Proper engineering ensures that the system is sized for such events.
Q What happens when unusually large debris gets into the system?
A: Debris typically found to inhibit the performance of gravity drainage systems typically
has little detrimental effect on the performance of the vacuum drainage system. In
fact, items that would typically block a gravity drainage system will pass directly
through the vacuum piping network to the Vac Center collection tanks due to the fact
that they are assisted in their movement by atmospheric pressures entering the
system in the course of normal operations. Vacuum drainage systems virtually
eliminate clogged piping.
Q: Are spare parts available or should the facility carry spare parts themselves?
A: All parts are supplied by AcornVac and are available for immediate shipment.
However, a local factory certified maintenance contractor will stock a quantity of
repair parts for emergency purposes.
Q: How fail-safe is our system? Is there any redundancy built-in?
A: The AcornVac system is designed to provide complete redundancy on all primary
Vac Center components. This includes dual collection tanks and multiple pumps to
ensure that the system can continue to operate so long as electrical power is
When the Vac Center is operating on an emergency power generator, it is designed
to switch the pump control strategy to a method that is most compatible with this
power source. For those facilities with generators that have marginal capability for
starting induction motor loads such as a vacuum pump, we offer electronic motor
starters which minimize the inrush current of a pump as it is being brought on-line.
Q: What are the recommended maintenance requirements?
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Introduction to
Vacuum Plumbing Systems
by AcornVac, Inc.
Frequently Asked Questions
A: The primary service requirements would be at the Vac Center. The vacuum pumps
are equipped with a small cartridge filter that we recommend be changed every
twelve months. The pumps also have a cooling coil that should be cleaned once a
The AcornVac vacuum interface components have been tested to well over three
million cycles without failure. These components have no regular required preventive
maintenance. Should a problem occur with either a Controller or an Extraction
Valve, the component is designed to be easily removed and replaced.
Q: In a supermarket, is the system odor free?
A: Yes. Any gasses or odors which might exist in the Vac Center collection tanks are
discharged when the tank is drained, and any gasses or odors that might exist in the
piping network are contained therein by the normally closed Extraction Valve and
removed by the condensate extraction process.
Q: Can the vacuum lift piping or risers be higher than 22’?
A: Yes; however, the system must be engineered considering all load factors including
anticipated activity and peak loads as well as diversity requirements. Call the
AcornVac Engineering Department for design assistance.
Q: Where are the controller, valves, check valves, etc. made?
A: All vacuum parts are made in the USA.
Q: Does the vacuum system need vents (roof penetrations)?
A: No, the vacuum system does not need vent stacks. Air removed from the piping
network by the vacuum pumps becomes the vent for the system.
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