Hose clamp
Encyclopedia
A hose clamp or hose clip is a device used to attach and seal a hose
onto a fitting such as a barb or nipple.
in the USA) into which a screw
thread pattern has been cut or pressed. One end of the band contains a captive screw. The clamp is put around the hose or tube to be connected, with the loose end being fed into a narrow space between the band and the captive screw. When the screw is turned, it acts as a worm drive
pulling the threads of the band, causing the band to tighten around the hose (or when screwed the opposite direction, to loosen). Screw clamps are normally used for hoses 1/2 in diameter and up, with other clamps used for smaller hoses.
Pairs of screw clamps on a short rubber unit form a "no-hub band," often used for attaching sections of domestic wastewater piping, or used for other pipes as a flexible coupler (to fix alignment difficulties or to prevent pipe breakage due to relative movement of sections) or an emergency repair.
They can also be used in a similar way, as a simple means for the transmission of small amounts of power
. A short length of hose is clipped between two shafts
where vibration
or variations in alignment may be taken up by the flexibility of the hose. This technique is well adapted to use for mock-ups in a development laboratory.
This type of clamp was invented in 1921 by ex Royal Navy
Commander, Lumley Robinson, who founded L. Robinson & Co (Gillingham) Ltd., a business in Gillingham, Kent
. The company owns the trademark for Jubilee Clip
.
A similar type of clamp to the screw band, also with a solid screw and an interesting history, described here: Marman clamp
.
, cut so that one side has a narrow protrusion centered on the end, and the other side a pair of narrow protrusions on either side. The ends of these protrusions are then bent outwards, and the strip rolled to form a ring, with the protruding tabs intermeshing. To use the clamp, the exposed tabs are pressed towards each other (typically using pliers
), increasing the diameter of the ring, and the clamp is slid onto the hose, past the portion that will go onto the barb. The hose is then fit onto the barb, the clamp expanded again, slid onto the portion of the hose over the barb, then released, compressing the hose onto the barb. Clamps of this design are rarely used for high pressures or large hoses, as they would require unwieldy amounts of steel to generate enough clamping force, and be impossible to work with using just hand tools. They are commonly used on automotive cooling system hoses several inches in diameter, for example on most water-cooled Volkswagen automobiles.
Spring clamps are particularly suited for confined or otherwise awkward places where other clip types would require tightening tools applied from narrow and possibly inaccessible angles. This has made them particularly popular for applications such as automotive engine bays and for securing barb connections in PC water-cooling.
Another type of spring clamp, typically only used on vacuum hoses, is just a piece of spring steel wire bent into a loop, with the ends curled to provide handles. These are used similar to standard spring clamps, but are just pinched by hand, and provide very little clamping force. Rather than attempting to seal a hose into a barb, they just place a slight pressure on the hose, helping to keep it from sliding off the barb.
, typically steel, first bent into a tight U, then formed into a ring shape with one end overlapping the other, and finally the ends bent outwards and cut. A captive nut is attached to one end, and a captive screw to the other. When the screw is tightened, the overlapped ends of the wire are pushed apart, tightening the wire loop around the hose. For an explanation of why this design is used, see the section on sealing the connection.
) into which one or more “ears” or closing elements have been formed. The clamp is placed over the end of the hose or tube to be connected and when each ear is closed at the base of the ear with a special pincer tool, it permanently deforms, pulling the band, and causing the band to tighten around the hose. The size of clamp should be chosen such that the ear(s) are almost completely closed on installation.
Other features of this style of clamp include: narrow band widths, intended to provide a concentrated compression of the hose or tube; and tamper resistance, due to the permanent deformation of the clamp’s “ear”. If closure of the clamp “ear(s)” is performed to manufacturer's recommendations, which generally provide for constant jaw force, the sealing effect is not unduly sensitive to component tolerance variations.
Some such clamps feature dimples intended to provide a spring effect when the diameter of the hose or tube contracts or expands due to thermal or mechanical effects.
A stepless type of ear clamp was invented by Hans Oetiker in Horgen, Switzerland, which eliminates steps or gaps on the inner circumference of the clamp. This is said to provide uniform compression and a 360° seal.
Such stepless clamps are claimed to be well suited to applications involving thin-walled hoses, supposedly with higher retained loads. This suggests they should be considered for difficult to seal applications such as molded plastics or other less malleable materials, commonly used in the automotive industry.
s (where a nylon or soft metal ferrule is compressed onto the hose by the tightening of the fitting), push-fit fittings (where the hose is inserted inside of a compression sleeve, designed such that force against the hose causes the sleeve to tighten), swage fittings/crimp fittings (where a stiff collar is compressed onto the hose), clamp fittings (where two blocks are tightened onto the sides of the hose, often found on garden hose
s), and a multitude of others. However, these devices are not typically referred to as hose clamps.
Hose clamps are frequently used for things other than their intended use, and are often used as a more permanent version of duct tape
wherever a tightening band around something would be useful. The screw band type in particular is very strong, and is used for non-plumbing purposes far more than the other types. These clamps can be found doing everything from mounting signs to holding together emergency (or otherwise) home repairs.
Another handy attribute: worm-drive hose clamps can be daisy-chained or "siamesed" to make a long clamp, if you have several, shorter than the job requires.
Some things seen assembled with hose clamps include the tail boom on a GMP Cricket model helicopter
, a homemade gas scooter
, makeshift pipe hangers, mounts for rooftop TV and shortwave
antennas, and virtually every imaginable automobile
body component.
To ensure a good seal, the barb must be smooth and free of nicks, scratches, or contamination. Stuck hoses should never be removed by slitting them, as this can leave a scratch on the barb which will cause a leak.
The other goal of a hose clamp is to provide mechanical attachment, to keep the hose from coming off the barb. To do this, they are typically placed behind a raised part of the barb, such that if the clamp does not slide on the hose, the clamp would have to expand to fit over the raised part, thus preventing the hose from being removed.
Hose (tubing)
A hose is a hollow tube designed to carry fluids from one location to another. Hoses are also sometimes called pipes , or more generally tubing...
onto a fitting such as a barb or nipple.
Screw/band (Worm Gear) clamps
Screw clamps consist of a band (usually stainless steelStainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
in the USA) into which a screw
Screw
A screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or an object that has the...
thread pattern has been cut or pressed. One end of the band contains a captive screw. The clamp is put around the hose or tube to be connected, with the loose end being fed into a narrow space between the band and the captive screw. When the screw is turned, it acts as a worm drive
Worm drive
A worm drive is a gear arrangement in which a worm meshes with a worm gear...
pulling the threads of the band, causing the band to tighten around the hose (or when screwed the opposite direction, to loosen). Screw clamps are normally used for hoses 1/2 in diameter and up, with other clamps used for smaller hoses.
Pairs of screw clamps on a short rubber unit form a "no-hub band," often used for attaching sections of domestic wastewater piping, or used for other pipes as a flexible coupler (to fix alignment difficulties or to prevent pipe breakage due to relative movement of sections) or an emergency repair.
They can also be used in a similar way, as a simple means for the transmission of small amounts of power
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...
. A short length of hose is clipped between two shafts
Driveshaft
A drive shaft, driveshaft, driving shaft, propeller shaft, or Cardan shaft is a mechanical component for transmitting torque and rotation, usually used to connect other components of a drive train that cannot be connected directly because of distance or the need to allow for relative movement...
where vibration
Oscillation
Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...
or variations in alignment may be taken up by the flexibility of the hose. This technique is well adapted to use for mock-ups in a development laboratory.
This type of clamp was invented in 1921 by ex Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
Commander, Lumley Robinson, who founded L. Robinson & Co (Gillingham) Ltd., a business in Gillingham, Kent
Gillingham, Kent
Gillingham is a town in the unitary authority of Medway in South East England. It is part of the ceremonial county of Kent. The town includes the settlements of Brompton, Hempstead, Rainham, Rainham Mark and Twydall....
. The company owns the trademark for Jubilee Clip
Jubilee Clip
A Jubilee Clip is a circular metal band or strip combined with a worm gear fixed to one end. It is designed to hold a soft, pliable hose onto a rigid circular pipe of smaller diameter....
.
A similar type of clamp to the screw band, also with a solid screw and an interesting history, described here: Marman clamp
Marman clamp
A Marman clamp is a type of heavy-duty band clamp; it allows two flat cylindrical interfaces to be simply clamped together with a ring clamp. Also sometimes known as a "Marman ring"....
.
Spring clamps
Spring clamps are typically made from a strip of spring steelSpring steel
Spring steel is a low alloy, medium carbon steel or high carbon steel with a very high yield strength. This allows objects made of spring steel to return to their original shape despite significant bending or twisting.-Grades:...
, cut so that one side has a narrow protrusion centered on the end, and the other side a pair of narrow protrusions on either side. The ends of these protrusions are then bent outwards, and the strip rolled to form a ring, with the protruding tabs intermeshing. To use the clamp, the exposed tabs are pressed towards each other (typically using pliers
Pliers
Pliers are a hand tool used to hold objects firmly, for bending, or physical compression. Generally, pliers consist of a pair of metal first-class levers joined at a fulcrum positioned closer to one end of the levers, creating short jaws on one side of the fulcrum, and longer handles on the other...
), increasing the diameter of the ring, and the clamp is slid onto the hose, past the portion that will go onto the barb. The hose is then fit onto the barb, the clamp expanded again, slid onto the portion of the hose over the barb, then released, compressing the hose onto the barb. Clamps of this design are rarely used for high pressures or large hoses, as they would require unwieldy amounts of steel to generate enough clamping force, and be impossible to work with using just hand tools. They are commonly used on automotive cooling system hoses several inches in diameter, for example on most water-cooled Volkswagen automobiles.
Spring clamps are particularly suited for confined or otherwise awkward places where other clip types would require tightening tools applied from narrow and possibly inaccessible angles. This has made them particularly popular for applications such as automotive engine bays and for securing barb connections in PC water-cooling.
Another type of spring clamp, typically only used on vacuum hoses, is just a piece of spring steel wire bent into a loop, with the ends curled to provide handles. These are used similar to standard spring clamps, but are just pinched by hand, and provide very little clamping force. Rather than attempting to seal a hose into a barb, they just place a slight pressure on the hose, helping to keep it from sliding off the barb.
Wire clamps
Wire clamps consist of a piece of heavy wireWire
A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...
, typically steel, first bent into a tight U, then formed into a ring shape with one end overlapping the other, and finally the ends bent outwards and cut. A captive nut is attached to one end, and a captive screw to the other. When the screw is tightened, the overlapped ends of the wire are pushed apart, tightening the wire loop around the hose. For an explanation of why this design is used, see the section on sealing the connection.
Ear Clamps
Ear Clamps consist of a band (usually stainless steelStainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
) into which one or more “ears” or closing elements have been formed. The clamp is placed over the end of the hose or tube to be connected and when each ear is closed at the base of the ear with a special pincer tool, it permanently deforms, pulling the band, and causing the band to tighten around the hose. The size of clamp should be chosen such that the ear(s) are almost completely closed on installation.
Other features of this style of clamp include: narrow band widths, intended to provide a concentrated compression of the hose or tube; and tamper resistance, due to the permanent deformation of the clamp’s “ear”. If closure of the clamp “ear(s)” is performed to manufacturer's recommendations, which generally provide for constant jaw force, the sealing effect is not unduly sensitive to component tolerance variations.
Some such clamps feature dimples intended to provide a spring effect when the diameter of the hose or tube contracts or expands due to thermal or mechanical effects.
A stepless type of ear clamp was invented by Hans Oetiker in Horgen, Switzerland, which eliminates steps or gaps on the inner circumference of the clamp. This is said to provide uniform compression and a 360° seal.
Such stepless clamps are claimed to be well suited to applications involving thin-walled hoses, supposedly with higher retained loads. This suggests they should be considered for difficult to seal applications such as molded plastics or other less malleable materials, commonly used in the automotive industry.
Other methods
Many other methods can be used to attach hoses or tubing, such as compression fittingCompression fitting
Compression fittings are used in plumbing and electrical conduit systems to join two tubes or thin-walled pipes together. In instances where two pipes made of dissimilar materials are to be joined , the fittings will also be made of one or more compatible materials appropriate for the connection...
s (where a nylon or soft metal ferrule is compressed onto the hose by the tightening of the fitting), push-fit fittings (where the hose is inserted inside of a compression sleeve, designed such that force against the hose causes the sleeve to tighten), swage fittings/crimp fittings (where a stiff collar is compressed onto the hose), clamp fittings (where two blocks are tightened onto the sides of the hose, often found on garden hose
Garden hose
A garden hose is a flexible tube used to carry water. There are a number of common attachments available for the end of the hose, such as sprayers and sprinklers...
s), and a multitude of others. However, these devices are not typically referred to as hose clamps.
Uses and applications
Hose clamps are typically limited to moderate pressures, such as those found in automotive and home applications. At high pressures, especially with large hose sizes, the clamp would have to be unwieldy to be able to withstand the forces expanding it without allowing the hose to slide off the barb or a leak to form. For these high pressure applications, compression fittings, thick crimp fittings, or other designs are normally used.Hose clamps are frequently used for things other than their intended use, and are often used as a more permanent version of duct tape
Duct tape
Duct tape, or duck tape, is cloth- or scrim-backed pressure sensitive tape often sealed with polyethylene. It is very similar to gaffer tape but differs in that gaffer tape was designed to be cleanly removed, while duct tape was not. It has a standard width of and is generally silver or black...
wherever a tightening band around something would be useful. The screw band type in particular is very strong, and is used for non-plumbing purposes far more than the other types. These clamps can be found doing everything from mounting signs to holding together emergency (or otherwise) home repairs.
Another handy attribute: worm-drive hose clamps can be daisy-chained or "siamesed" to make a long clamp, if you have several, shorter than the job requires.
Some things seen assembled with hose clamps include the tail boom on a GMP Cricket model helicopter
Radio-controlled helicopter
Radio-controlled helicopters are model aircraft which are distinct from RC airplanes because of the differences in construction, aerodynamics, and flight training...
, a homemade gas scooter
Kick scooter
A kick scooter or push scooter, originally scooter, is a human-powered vehicle with a handlebar, deck and wheels that is propelled by a rider pushing off the ground. The most common scooters today have two hard small wheels, are made primarily of aluminium and fold for convenience...
, makeshift pipe hangers, mounts for rooftop TV and shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...
antennas, and virtually every imaginable automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
body component.
Sealing and mechanical strength
One of the fundamental goals of most hose clamps is to ensure a tight seal between the hose and the barb, preventing the working fluid from escaping. To this goal, they are designed to provide even pressure on all sides, with no gaps. An example of this would be wire clamps. An obvious design would seem to be simply having a wire around the hose, one end attached to a nut, and the other end to the screw, and when tightened, pulling the ends of the wire towards each other. However, this will leave a gap where no pressure is applied (underneath the screw), and cause a leak. To combat this, the more complicated and weaker design of having the ends overlap and then be pushed apart from each other is used, as this ensures pressure around the entire circumference of the hose.To ensure a good seal, the barb must be smooth and free of nicks, scratches, or contamination. Stuck hoses should never be removed by slitting them, as this can leave a scratch on the barb which will cause a leak.
The other goal of a hose clamp is to provide mechanical attachment, to keep the hose from coming off the barb. To do this, they are typically placed behind a raised part of the barb, such that if the clamp does not slide on the hose, the clamp would have to expand to fit over the raised part, thus preventing the hose from being removed.
External links
- Hose Clamp Tightens Like Belt To Keep Hose Leak Proof August 1944 column with photo showing new worm gear hose clamp -- i.e. at bottom of page
- Timeline for Oetiker 1942-2007 (inventor of ear clamp