By Murray Corporation on Dec 9, 2020 8:36:00 AM
Often, we get asked by customers, “what is the PSI or Pressure rating on your hose clamps?” Our answer: “Well, who cares?”
Actually, we do care, but is this information really important and can you get an accurate measurement that is useful for customers? The fact of the matter is that it depends on many variables.
If you have a hose that does not always have a good connection with the fitting, then the pressure rating will be affected, regardless of the type and quality of the hose clamp you install on the connection. All parts have tolerances, within a range. If you get a batch of fittings that are on the low end of the tolerance range, meaning they are smaller or more narrow, and you get a batch of hoses that are on the high end of the tolerance range, meaning they are slightly larger in diameter, then they won’t mate as well together. The fitting is slightly smaller and the hose is slightly larger than nominal. The fit between the hose and the fitting will be looser. A good clamp will generate band load in all directions, but if there is a certain amount of slack already, no clamp will overcome this poor fit and you could be prone to leaks no matter which clamp you install.
If you install a clamp on a hose material that is very “sticky”, the clamp band may experience added friction as you apply installation torque on a screw type clamp, or installation force on a pinch style clamp. The band material may stretch, or may compress the hose, and not actually slide around and evenly distribute the band load in a 360-degree fashion around the hose. Lubrication may help. (Read our Tech Tip on screw lubrication for worm drive clamps – Click HERE) Likewise if you have a hose that is very rigid, you may generate limited band load and hose compression. The clamp may be performing as intended but it may not be feasible to compress the hose sufficiently and may limit the pressure that can pass through the connection. A hose that can be compressed much more, and that is far less rigid, may not translate enough band load to prevent leaks. In either case, the amount of pressure that can be passed through the hose is independent of the hose clamp.
Is the pressure constant or pulsing? Is thermal cycling taking place where the connection is expanding and contracting due to large variations in temperature within the hose due to application temperature changes? Changes in outside environmental conditions, such as hot and cold, humidity or dryness in the environment outside of the hose can play a factor. Installation torque/force used to install the clamp and speed of installation also impact the quality of the connection. All of these and other variables can impact the amount of pressure that can pass through a given connection.
We understand why you want to know about a pressure rating for a clamp, but the best solution is to simulate the conditions of the application and test the connection to see if it meets your requirements. For some projects we may be able to help with testing where it’s appropriate. Please reach out to your Murray Clamps Sales Contact to find out more.