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A suction excavator or vacuum excavator is a construction vehicle that removes earth from a hole on land, or removes heavy debris on land, from various places, by powerful suction through a wide suction pipe which is up to a foot or so diameter. The suction inlet air speed may be up to 100 metres/second (224 mph).
The suction nozzle may have two handles for a man to hold it by; 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 use 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.
Its construction is somewhat like a gully emptier but with a wider suction hose and a more powerful suction.
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 locating and witnessing underground utilities, reducing the chance of utility strikes by more than half.
RSP Gmbh have been making suction excavators and stationary suction units since 1993, but gully emptiers and the old type of suction street cleaner vehicle that could only pick up loose debris have been around for much longer.
Since 1998, the MTS Mobile Tiefbau Saugsysteme GmbH is making a new type of suction excavator. It is said to have a new designed air flow principle, and thus a considerably improved suction performance.
RSP Gmbh in Germany make or made these models:
| model | length | fan capacity |
suction negative pressure |
maximum suction depth |
maximum suction span |
spoil tank volume |
specifications of carrying truck | info link | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| power | axles | wheelbase | weight | ||||||||
| ESE 18/7 | 7 m | 6.94 – 8.88 m³/s | 0.1 - 0.17 bar | 15 m | 70 m | 4 cu.m. | 280 hp | ≥ 2 | 4.2 m = 13 ft 10 in | 18 tonnes | [2] |
| ESE 19/5 | 8 m | 5 - 6.94 m³/s | 0.1 - 0.17 bar | 11 m | 50 m | 5 cu.m. | 310 hp | ≥ 2 | 4.5 m = 14 ft 10 in | 19 tonnes | [3] |
| ESE 26/7 | 8.8 m | 5 - 6.94 m³/s | 0.1 - 0.17 bar | 11 m | 50 m | 7 cu.m. | 310 hp | ≥ 3 | 4.2 m = 13 ft 10 in | 28 tonnes | [4] |
| ESE 32/7 | 9.8 m | 8.8888 m³/s | 0.3 bar | 16 m | 100 m | 7 cu.m. | 400 hp | ≥ 4 | 4.2 m = 13 ft 10 in | 32 tonnes | [5] |
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.
In the ESE 32/7:
| material | cu.m./hour | time for 1 cu.m. |
|---|---|---|
| heavy soil with buried cables and pipes | 1.6666 | 36 mins |
| dry heavy soil | 2.5 | 24 mins |
| wet heavy soil or clay | 3 | 20 mins |
| moderately heavy soil with buried cables and pipes | 4 | 15 mins |
| muddy soil, gravel, crushed rock | 6 | 10 mins |
| sandy soil | 10 | 6 mins |
| water | 30 | 2 mins |
| heavy soil with buried cables and pipes excavated by hand |
0.25 | 4 hours |
MTS GmbH in Germersheim, Germany is making since 1998[2] these types of suction excavators:
| Model | Fan | Air movement | Suction pressure | Spoil capacity | Max. suction depth | Max. suction distance | Suction hose diameter | Info link | Notes |
|---|---|---|---|---|---|---|---|---|---|
| Suction Box SBO | 1-2m³ | 125-200mm = 4.932 - 7.87 inches | [6] | Can be carried by excavators etc. In 22, 32, 42 kW versions. | |||||
| MINI-VAC | Single turbine | 6,944 m³/sec | 0.1974 bar | 1,5-2m³ | 5m | 25m | 200mm = 7.87 inches | [7] | buildup on 7.5 ton truck, compact for difficult-to-reach sites |
| DINO 2-5 | Single or double turbine |
6.944 – 10 m³/sec | 0.335 bar | 4m³ - 12m³ | 20m+ | 100m+ | 250mm= 9.84 inches | [8] | with telescopic boom or hydraulic boom |
| MEGA-VAC | Quadruple turbine | 10 m³/sec | 0.493 bar | 9m³ | 30m+ | 200m | 250mm = 9.84 inches | [9] | big for big jobs |
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 make a model similar to the ESE 32/7; it can suck 8 cu.m./second of air, and its suction tube is 9 inches = 23 cm wide inside.
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 3 inches diameter inside (but the FX60 can take 4-inch-diameter suction hose). Its spoil tank can be supplied various sizes.
Airex GB Ltd [10] 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 removing a tonne of earth in six minutes.
Ring-O-Matic, Inc [3] in the U.S. makes several different 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 [11] in the U.S. makes more than 50 models of hydro excavation and dry excavation gasoline and diesel vacuum excavators. They offer trailer mounted and skid mounted options, and gasoline and diesel models. Spoil tanks come in various sizes and configurations. Low profile increases maneuverability and can be towed by as small as a half-ton pickup truck.
Cappelotto[12] 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 (in Italian), 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.
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 scoop.
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[4] 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.
The National Grid (UK) (UK electricity suppliers) has ordered 10 suction excavators.[13]
As at July 2009 in England the North West Gas Alliance [14] has 3 German-made suction excavators.
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 http://www.vactruck.co.uk/gallery.html. There is little known fact about the diversity of the use of vacuum/suction excvators, for example - they are capable of excavating up to 140m horizontally and up to 20m depth depending on the type of material being excavated.
Suction excavator jobs in Italy described in RSP Gmbh's publicity include:
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.[5]
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."[6]
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 http://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.
When conventional locating is unworkable due to high densities of buried utilities, potholing can be used to verify the route of each buried line within the excavation zone. In some cases, the contractor may elect to perform the entire excavation using vacuum methods.
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.
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