Kink Resistance Under Flow – Short and Long Term

Determine the kink resistance of a single lumen catheter or medical tubing for short term (< 1h) or long term (> 1h) use.  Kink is defined when the bending causes a decrease in flow by more than 50 %.

Test Procedure

Different devices have different visco-elastic properties and expected exposure times. Therefore,  the test method for short term use (< 1 h) or long term use (> 1 h) should be chosen as appropriate.
For short term testing:
The flow through a straight device is measured, this will serve as a reference for when the flow has decreased by 50%. An appropriately sized kink tool is mounted to the tensile tester and the sample is placed into the grooves such that it forms an arch between the two plates. The plates will be lowered at a fixed speed and the corresponding flow will be measured. Testing is stopped once the flow is reduced by 50% and the corresponding plate distance is measured.
For Long term testing:
Perform a short term test to obtain approximate measure of kink length. Form samples  into a loop of the appropriate size and pass heated fluid through the system for the desired amount of time. Upon completion of testing check for 50% reduction in flow when using a constant pressure system. Then increase or decrease the tubing length until 50% of the samples have kinked.

Equipment

  • Kink test tool sized for the test device (short or long term)
  • Tensile tester (short term)
  • Constant Pressure System (long term)
  • Calibrated Calipers
  • Calibrated Flow meter
  • Data acquisition system
  • Temperature controlled test chamber
  • Calibrated Thermometer

Measured Parameters

Short term: Corrected mean value of plate distance with 50 % of full flow

Long term: Kink length  at which 50 % of the samples have kinked

Scope

Any single lumen catheter  or medical tubing

Service Levels

Applicable Standards

  • BS EN 13868:2002
    Catheters. Test methods for kinking of single lumen catheters and medical tubing

Related Tests

OLE/QV


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