JCS recently carried out a number of laboratory assessments on a sample of constant tension hose clamps as well as its manufactured clamps to compare how the different designs perform.
During tightening of a constant tension clamp, which differs in design to the hi-grip and hi-torque worm drive clamps manufactured by JCS, the Belleville washers compress to act like a spring. When the rubber relaxes the spring action pulls the band through the housing, making the clamp smaller to compensate for shrinkage in the rubber hose.
However JCS believes the basic engineering principles underpinning this design are flawed as the spring may struggle to modulate the amount of pressure a clamp exerts over time, under a range of extreme environmental conditions, resulting in a leak. After testing six constant tension hose clamps of different sizes, made by a US based clamp manufacturer, JCS found that the constant tension ability of the clamps is quite limited and the capacity of the springs to compress can be a liability. On most tests, under identical conditions, JCS’ conventional HTM clamp substantially out-performed the Belleville design.
JCS ran a number of tests recording at intervals the grip of each clamp on a calibrated test rig to measure the clamping force. These included a 24-hour rubber cold flow test, and a five hour heat test with temperatures of 125°C Both types of clamp were then tested on a hydraulic pressure tester after the cold flow and heat cycle.
In addition, a salt spray corrosion-resistance test was performed, where the clamps were bombarded with salt water. While the JCS clamps remained unaffected, rust was found forming on the constant tension screw in less than 24 hours.
JCS considers there to be no substitute for clamps that are made to the highest quality and strength combined with innovations such as its ‘straight line’ housing, which ensures that every thread of the screw is fully engaged with the band to provide more torque.
Having spent a decade in the fastener industry experiencing every facet – from steel mills, fastener manufacturers, wholesalers, distributors, as well as machinery builders and plating + coating companies, Claire has developed an in-depth knowledge of all things fasteners.
Alongside visiting numerous companies, exhibitions and conferences around the world, Claire has also interviewed high profile figures – focusing on key topics impacting the sector and making sure readers stay up to date with the latest developments within the industry.
