Vacuum Lifting Glossary
Vacuum lifting is an important technology in various industries for handling heavy and awkward loads. It involves using suction to lift and move objects, rather than traditional lifting methods that rely on brute force. Vacuum lifting has many benefits, including increased safety, efficiency, and productivity.
One of the main advantages of vacuum lifting is its ability to handle heavy and bulky loads without risking injury to workers. This is especially important in construction, manufacturing, and logistics industries, where heavy lifting is a regular part of the job. Vacuum lifting also allows for more precise and controlled movements, reducing the risk of damage to the load or surrounding objects.
In addition, vacuum lifting can be more efficient than traditional lifting methods, as it requires less workforce and can be done more quickly. Overall, vacuum lifting is an important technology that benefits a wide range of industries.
In this vacuum lifting glossary, we will briefly explain terminology related to vacuum technology and vacuum systems.
In the context of vacuum systems, abrasion resistance refers to the ability of suction cups to withstand stress, particularly friction. The shape of suction cups and their material properties contribute to their abrasion resistance.
Absolute pressure is a vacuum pressure measured relative to a perfect vacuum (0 torr, PSI or bar), irrespective of the ambient air pressure.
Ambient pressure (atmospheric pressure)
The ambient or atmospheric pressure is the reference point of any vacuum pressure, which is, by definition, significantly lower. Hydrostatic pressure, as measured in units of mercury by a barometer, is affected by weather and altitude. The standard atmospheric pressure at sea level is 14.7 PSI, 760 Torr/mmHg (29.92 inHg) or 1,013 millibars. However, the actual ambient pressure will influence the maximum vacuum value that can be achieved.
An articulating crane is a type of crane whose arm articulates in the center, allowing rapid back-and-forth movement of the load. It is often referred to as a knuckle arm.
Atm is the unit used for describing any multiple of the standard atmospheric pressure at sea level.
Bar is a metric unit of pressure equal to 100,000 Pascals (100 kPa), derived from the Greek word baros, meaning weight or burden. In a vacuum system, mbar (millibar, one-thousandth of a bar) is the more common subunit.
Bernoulli’s principle states that the speed of a fluid (or gas) determines the amount of pressure it can exert. When air accelerates out of a suction cup, the static pressure falls, and a vacuum is produced.
The Bourdon-tube gauge is the most commonly used pressure gauge since the 19th century. It is a mechanical gauge that includes a Bourdon tube in the shape of an arc. Pressure bends the arc relative to the ambient pressure, actuating an attached dial via a set of gears and springs.
The bridge is the part of a crane consisting of girders, trucks, end ties, and a drive mechanism that carries the trolley or trolleys.
A check valve is a valve that only allows flow in one direction. It is often implemented as a security measure in different parts of a vacuum system.
Centralized vacuum system
A centralized vacuum system uses a central vacuum source to generate vacuum for two or more suction cups.
Compression ratio refers to the ratio between the outlet and the inlet pressure of a gas in a vacuum pump.
Control pressure range
The control pressure range is the range between the lowest required and the highest permissible control pressures for a vacuum system to operate correctly.
A crane girder is a metal beam on which the crab or hoist head of a travelling overhead crane runs.
The crane trolley is the unit that travels on the bridge rails and carries the hoisting mechanism.
Cycle time in vacuum handling and other workflows involving repetitive processes refers to the time taken to complete one cycle.
Decentralized vacuum system
In a decentralized vacuum system, vacuum is generated directly at each individual suction cup, as opposed to using a centralized vacuum source for several suction cups.
Dry vacuum pump
A dry vacuum pump is a vacuum pump that does not use oil or any other fluid in the pumping chamber when creating a vacuum.
Double girder crane
A double girder crane has two bridge girders, and the hoist trolley travels on rails, usually attached to the tops of the crane girder.
Evacuation time is the duration required to achieve a desired level of vacuum by removing a specific volume of gas from a particular space.
Flow rate refers to the amount of gas that passes through a vacuum system within a given period of time. It can be measured in terms of volume flow, such as cubic feet per minute (CFM).
Flow resistance is the frictional resistance that occurs within a vacuum system and impacts the pressure and rate of gas flow.
The friction coefficient is the ratio between the force of friction that acts between two objects and the force that holds them together.
A gantry crane is a type of overhead crane that uses two or more legs running on rails or another type of runway to support the bridge.
Gauge pressure is the pressure measured relative to the ambient atmospheric pressure, with the unit of measurement typically expressed as pounds per square inch gauge (PSIG).
Holding force is the force exerted by a suction cup to grip a workpiece, which is determined by the negative pressure (vacuum) and the effective suction area of the cup.
High vacuum is a range of vacuum pressures between 10-3 and 10-6 Torr.
Inches of mercury
Inches of mercury is a common scale used to measure vacuum pressure, typically designated as “Hg.
The inner volume refers to the volume of gas that must be removed during the suction process, and it affects the evacuation time.
Inlet pressure in a vacuum system refers to the total pressure at the vacuum pump’s inlet.
An isolation valve is used to seal off a vacuum system from the vacuum pump when it is turned off.
A jib crane is a type of crane with a horizontal arm, known as the jib or boom, that extends from the crane to support a movable hoist fixed to a wall or pillar mounted on the floor.
Low vacuum, also called rough vacuum or coarse vacuum, describes any vacuum pressure level below atmospheric pressure down to 25 Torr. Vacuum lifting systems often operate within this range.
A leak detector is an instrument used to identify leaks in a vacuum system.
A McLeod gauge is a vacuum gauge that uses mercury to measure the pressure within a vacuum system.
Mean free path
Mean free path refers to the average distance that a gas molecule can travel before colliding with another gas molecule. This distance is dependent on the gas density and molecule size.
Medium vacuum is a vacuum pressure range between 25 to 1×10-3 Torr.
Micron is a unit of measurement equal to one millionth of a meter, and it is also a unit of pressure that corresponds to one thousandth of a Torr (millitorr). In vacuum lifting systems, “micron” is more commonly used to refer to the density of a filter and define the size of particles that can be removed, e.g., 10 microns. For comparison, a HEPA filter used in a vacuum cleaner may have a density of 0.3 micron.
Millimeter of mercury
A millimeter of mercury is a common unit used to measure vacuum pressure, typically designated as “mmHg.”
A monorail crane is a simpler alternative to a conventional overhead crane, often used to move materials or products within a restricted area. Monorails may follow a straight line through a room or have curved beam designs for greater flexibility.
Negative pressure refers to a pressure level below that of the surrounding environment. Any significant negative pressure is considered to be a vacuum.
Nominal flow describes the maximum gas flow that can pass through a tube of a specific diameter.
Normal force refers to the force acting perpendicularly to a surface, as opposed to the shear force, which acts tangentially to a surface.
An overhead crane, also known as an overhead traveling crane, is a piece of equipment used for lifting and moving heavy goods from one location to another. It consists of a movable bridge carrying a movable or fixed hoisting mechanism that travels on an overhead fixed runway structure. Each overhead crane is carefully designed and engineered for a specific purpose or application.
Over-braced jib crane
An over-braced jib crane has a tension member from the top of the pillar to a point about two-thirds of the way down the jib arm. This allows the hoist to get as close as possible to the supporting structure, giving the maximum effective travel.
Overpressure resistance indicates the maximum pressure that a specific part of a vacuum system can withstand.
In a mixture of gases, such as air, partial pressure refers to the pressure exerted by an individual gas, such as nitrogen or oxygen.
The Pirani gauge is a thermal conductivity gauge used for measuring pressures in vacuum systems.
Pressure refers to the force that a gas exerts per area unit.
Pressure differential expresses the difference between the pressure on a component’s inlet side and the pressure on its discharge side.
Pumping speed refers to the volume of gas that a vacuum pump can remove from a system per unit of time.
Reference pressure is a specific pressure referred to by a sensor to determine the pressure in a system.
Relative pressure is the pressure value in relation to the prevailing ambient pressure, as opposed to absolute pressure.
Safe Working Load (SWL)
Safe Working Load refers to the maximum safe force that a piece of lifting equipment or lifting device can exert to lift, suspend, or lower a given mass without fear of breaking.
Shear force refers to the force acting tangentially to a surface, as opposed to normal force, which acts perpendicularly to a surface.
Single girder crane
A single girder crane has only one bridge girder, and the hoist trolley operates or travels on the lower flange of the bridge girder.
Suction rate (or suction force) is a value that indicates the volume that a vacuum generator can evacuate per unit of time.
Underbraced jib crane
Under-braced jib cranes are ideal for use in facilities with low ceilings or areas where there is an overhead obstruction. Supporting the jib arm from underneath, as opposed to from above, reduces the overall height of the crane.
Vacuum refers to a pressure level that is significantly lower compared to atmospheric pressure.
A vacuum system refers to the complete set of components that make up a specific vacuum lifting solution.
Ventilation time refers to the time it takes to dissipate the vacuum from a system.
Working Load Limit (WLL)
Working Load Limit refers to the maximum working load designed by the manufacturer. This load represents a force that is much less than that required to make the lifting equipment fail or yield.
Working radius refers to the radius of the area where tooling is suspended in the crane and can be reached.