A suction excavator or vacuum excavator is a construction vehicle that removes materials from a hole on land, or removes heavy debris on land.
Description
A suction excavator produces powerful suction through a wide pipe which is up to 30 centimetres (1Â ft) or so in diameter. The suction inlet air speed may be up to 100 metres per second (220Â mph). Its construction is somewhat like a vacuum truck (gully emptier) but with a wider suction hose and a more powerful suction.
The suction nozzle may have two handles for the operator to hold; those handles may be on a collar which can be rotated to uncover suction-release openings (with grilles over) to release the suction to make the suction nozzle drop anything which it has picked up and is too big to go up the tube.
The end of the tube may be toothed. This helps to cut earth when used for excavating; but when it is used to suck up loose debris and litter, some types of debris items may snag on the teeth. The earth to be sucked out may be loosened first with a compressed-air lance, or a powerful water jet.
Excavating with a suction excavator may called "vacuum excavation", or "hydro excavation" if a water jet is used. Vacuum excavation (also known as suction excavation) is considered a best practice for safely finding and seeing underground utilities, reducing by more than half the chance of damaging buried utilities.
History of fan-based suction technology
The RSP GmbH have been making suction excavators and stationary suction units since 1993. Since 2000, RSP developed a new suction principle, the ESE Series. These vehicles work with the internationally patented suction principle which guarantees the highest degree of gravity separation, lowest contamination of the filters and thus consistently high suction performance.
Since 1998, the MTS Mobile Tiefbau Saugsysteme GmbH is making another type of suction excavator. It is said to have a new designed air flow principle, and thus a considerably improved suction performance.
(Gully emptiers and the old type of suction street cleaner vehicle that could only pick up loose debris have been around for much longer.)
Design and operation
RSP GmbH - Reschwitzer Saugbagger Produktions GmbH
The RSP GmbH produced since 1993 (History) suction superstructures mounted onto two, three and four-axle vehicles, stationary suction units as well as custom-made machines.
The suction unit is roughly rectangular-block-shaped, about 2.5 metres wide and 3.6 metres high, and is usually mounted and used on the back of a truck, which must have power takeoffs to run the suction unit's air impeller and hydraulics. When it is emptying its load out, the spoil tank lid (with the hose connection) hinges off to the right, then the spoil tank (with the filters) tips about 90° over to the left to tip its load out.
Possible applications include:
- Replacement of pipes and fittings
- Renovation and new installation of gas-, water-, heating pipes, cables and disposal lines
- Exploratory excavations
- Railway trackside maintenance and repair
- Use of ground displacement rockets
- Clearing away environmental damage
- Replacement of contaminated soil around the roots of trees
- Removal of material in demolition projects
- Removal of gravel from flat roofs
- Cleaning blocked street gutters & gullies
- Operations involving the use of horizontal boring units
- Leaf removal
- Application for special operations
Suction excavators eliminate the need for costly and time-consuming manual labour. Buried pipe systems do not suffer damage. Output is up to sixteen times of that achieved by conventional excavation.
In the ESE 32/7:
- The suction pipe's internal diameter is 25Â cm (9.8Â in)
- The fan produces a maximum pressure reduction of about 30,000 pascals = about 0.3 atmosphere or 4.5 pounds/square inch. Across a circular suction opening 9.8Â inches diameter that would give an entry air speed of about 400Â mph and a maximum suction power of about 340 pounds = about 3 hundredweight. It can suck up objects up to 25Â cm or 9.8Â inches across of weight up to 30 kilograms = 66 pounds.
- It is described as able to suck up "earth, stones, vegetable waste, sand, mud, water, pebbles, rubble, asbestos, railway-type ballast".
- Its suction pipe has a detachable extension nozzle narrowing from 10Â inches to 4Â inches internal diameter, with handles on a rotatable panel to open or close side vents to let the operator let it drop overlarge objects which it has picked up.
- Its expected spoil extraction rates are roughly, in cubic metres per hour:
MTS Mobile Tiefbau Saugsysteme GmbH
MTS GmbH in Germersheim, Germany is making since 1998 these types of suction excavators:
With the MEGA-VAC the suction power across a 9.84-inch-wide hose entry would be about half a ton.
The MTS suction excavators are said to have a much easier air routing that leads to a more open spoil-hold design and much better suction performance.
Saugmaster
Saugmaster is a RSP ESE model; it can suck 8Â m3/s of air, and its suction tube is 23Â cm (9.1Â in) wide inside.
History of vacuum-pump-based suction technology
Pacific Tek
Pacific Tek was founded in 1993 and went into the valve exerciser and vacuum excavator industry. Pacific Tek founders have created innovations, such as the Angled Vacuum Excavator Tank (1997) and 180° Swivel Mount Valve Operator (1999).
Ditch Witch
The USA firm Ditch Witch makes 4 models of suction excavators: FX20, FX25, FX30, FX60; the number is its approximate horsepower. It is mounted on a semitrailer. It has its own engine (petrol for FX20, the others diesel). Its spoil tank is cylindrical with somewhat rounded ends. Its suction hose is 3Â inches diameter inside (but the FX60 can take 4-inch-diameter suction hose). Its spoil tank can be supplied various sizes.
Airex
Airex GB Ltd in the UK make two current models of vacuum excavator: AX-68 and AX-180. Both systems are mounted on the back of rigid 7.5-ton trucks, designed for use in inner-city streets. The smaller design of these trucks gives less impact on their surroundings. The AX-68 uses a 4-inch hose but the AX-180 uses an 8-inch hose which can remove a tonne of earth in six minutes.
Ring-O-Matic
Ring-O-Matic Inc, in the U.S. makes several models of gasoline and diesel vacuum excavation units. They offer both trailer mounted and skid mounted models. Spoils tanks range in size from 150 gallon up to 2000 gallon tanks.
Vac-Tron Equipment, LLC
Vac-Tron Equipment, LLC in the U.S. makes more than 50 models of hydroexcavation and dry excavation gasoline and diesel vacuum excavators.
Cappellotto
Cappelotto makes various powered cleansing equipment including CAPGEO (a model of suction excavator). Its arm is said to reach 7 meters and to swivel 250 degrees.
(They also make CAPBORA, which is specifically for sucking up loose material.) Cappelotto was founded in 1953 and is based at Gaiarine in the province of Treviso in Italy.
The Cappellotto products are also distributed to 40 countries in the world, with KOR Equipment Solutions being the distributor for Australia and New Zealand
Uses
Suction excavators are useful to remove earth from around existing buried services or tree roots with much less risk of damaging them than using a conventional excavator with a metal bucket.
This type of excavation is held to be a safe and efficient form of excavation. However it is totally unsuitable for archaeological excavation. Using a powerful vacuum and high pressure water, precise holes, trenches and tunnels can be cut to the required size and proportion. Because compressed air or water is used to loosen the earth, the risk of damaging underground utilities is less and contractors can safely find and expose them. Often excavation reveals unknown utilities, saving lives, money and time.
It is also referred to as "daylighting", as the underground utilities are exposed to daylight during the process.
This type of excavating is quickly becoming recognized as a best practice when working in areas with underground utility congestion and frozen ground. Hydro excavation lessens the risk of damaging utilities, which may often be inaccurately mapped and located and marked on the surface.
A suction excavator is useful in bulk excavation in confined areas, where its suction hose can reach in over or through barriers, e.g. digging a swimming pool in a courtyard.
It can be used on railways (perhaps mounted on a railroad car base) to suck old track ballast off the track when re-ballasting the track.
It can be used as a very heavy-duty vacuum cleaner to pick up miscellaneous debris, e, g, rubble, or big accumulations of fallen leaves or litter.
It can suck up liquids, e.g. water from a hollow. In case of opting for air vacuum excavation, the Positive Displacement Blower should be properly checked because it can move great volumes of air and a malfunctioning can cause a serious accident. When digging on rocky soils, it is better to opt for water instead.
The National Grid Gas Plc (UK) has ordered 10 suction excavators.
As at July 2009 in England the North West Gas Alliance has 3 German-made suction excavators.
Vacuum excavation hire providers Pier (UK) work with utility and civil engineering companies throughout the UK to provide safer no-dig excavation. Projects include relocating underground utility lines to accommodate wider road lanes and filter lanes, and street works to provide essential maintenance of street lighting.
Force One Ltd specialist image library shows various uses of the new excavation technology including bridge refurbishment, clearing culverts, clearance of holding tanks, extension hose excavation, substations. rail excavations, airports, filter beds, lighthouse, and many more applications. Vacuum/suction excavators can excavate up to 140m horizontally and up to 20m depth depending on the type of material being excavated.
Specific jobs
Suction excavator jobs in Italy described in RSP Gmbh's publicity include:
- In the old center of Venice:
- Cleaning deep silt (accumulated over nearly 40 years) out of the Rio Terà San Polo, which was formerly a narrow open canal, but is now a roofed sewer under a busy street. The excavator sucked through a long hose. Access damage to its roof and the street above was limited to four manhole-sized holes, which afterwards were fitted with manhole covers for future access. This avoided a long smelly traffic-obstruction-causing manual job.
- Cleaning 1.6 meters deep silt out of the Rio Terà San Leonardo (a roofed sewer, 230 m long, 6 to 13 m wide): similarly.
- The south loggia of the Palazzo della Ragione in Padua: Sucking out a big accumulation of rubble and dust and bird droppings. The space is roofed by medieval vaulting through which only one small access hole was allowed. A 150-meter-long suction hose was used. (In the accompanying photographs the rubble seems to be largely plaster removed from the walls.)
- In Siena: removing about 150Â m3 of rubble left by building restoration works, which had been dumped in old tunnels cut in tuff.
Vacuum excavation
Vacuum excavation is excavating by high-powered vacuum suction machines. This process significantly reduces the risk of loss of property and injury to workers associated with contacting or cutting underground utilities, as often happens if backhoe, auger, hand digging, or other mechanical methods are used.
Portable vacuum excavation equipment such as suction excavators can quickly dig small deep precisely-controlled holes to uncover buried utilities. Soft excavation technology can dig around buried pipe or cable without the risk of damage inherent with backhoes, excavators, or other mechanical tools.
Typically, vacuum excavation loosens the soil with a blunt-nosed high pressure air lance or water source and immediately vacuums away loosened material. Air and water, when used appropriately, are far less likely than sharp-edged tools to damage underground structures.
Depending on the machine used and soil conditions, a 12-inch-square 5-foot-deep pothole can be completed in 20 minutes or less. Most models are capable of digging deeper, but utility potholes seldom need to be more than six feet deep.
Vacuum excavation is best used in conjunction with conventional underground (one-call) locating services. Because of a preponderance of overlapping buried utility lines, locating devices often incompletely identify all the buried utilities on a site or cannot completely or accurately mark a site.
According to New Mexico One Call 811: Aligning Change, Locating with Potholing, "One-call paint marks and flags are the first step in making the process of locating underground utilities safer, the use of vacuum excavation technology adds an additional margin of safety."
Potholing (which here means exposing buried utilities and seeing them to find where and how deep they are) using vacuum excavation, has made it safer to locate underground utilities.
When conventional locating is unworkable due to high densities of buried utilities, potholing can also be used to verify the route of each buried line within the excavation zone. In some cases, the contractor may choose to perform the entire excavation using vacuum excavation.
Today, according to "In the Pipeline" in an article on enewsbuilder.net, "As vacuum excavation technology and techniques for locating underground utilities has become both readily available and affordable, it’s already considered by many municipalities as a Best Practice." Many governmental entities and municipalities no longer allow the use of backhoes for the physical locating of underground utilities, citing the risk of damaging the utility or utilities. Many have implemented policies mandating the use of vacuum excavation.
To prevent utility strikes, the use of underground locating services has become the norm, and in most places, is required by law. However, the practice of underground location, while very useful, has its limitations. Locators have been known to incompletely identify all buried utilities or be unable to completely or accurately mark a site because of a preponderance of overlapping buried utility lines.
For these reasons, vacuum excavation techniques can be an effective way to locate, with virtually 100% accuracy, all underground structures in an excavation zone. Vacuum excavation is also typically more cost effective than hand digging.
Through aggressive educational efforts about the safety of vacuum excavation, vacuum excavation is now being mandated in many states and municipalities, and efforts are underway to achieve universal acceptance of vacuum excavation as the preferred technology.
See also
- Dredging
- Gully emptier
- Some street sweeper vehicles include a suction hose that the operator can control, but with less powerful suction and only able to pick up light loose litter and leaves.
- Sometimes, "suction excavator" is used to mean a floating suction dredger for dredging underwater
- Suction (medicine)
References
