If you are wondering what is the best way you can test the integrity of the piston seal in the double-acting hydraulic cylinders, then there is an easy bench-test to help you do this. However, it includes the intensification of pressure in the hydraulic cylinder. This doesn’t necessarily mean to be unsafe unless you have a better understanding of what does this concept really mean, but if you don’t understand it well enough then you surely have reasons to worry regarding the safety. Here we’ll be discussing the threats of intensification in a double-acting hydraulic cylinder.
Force in a hydraulic cylinder is denoted by the product of pressure and area (F = p x A). In a double-acting cylinder, the effective area is not even on both sides, as a result, the force produced by the piston and rod sides of the hydraulic cylinder is unequal as well. It means that if the effective area of the rod side is half what it is for the piston side, it will produce the force accordingly meaning the force will be half of the piston side for a similar amount of pressure applied on both of them.
The transposed version of the equation F = p x A is p = F/A which means the pressure is equal to the force divided by the area. If the cylinder’s rod side is supposed to resist the force developed by the cylinder’s piston side, with only half of its area, then the amount of the pressure has to be doubled. For example, if the piston side is applied a pressure of 3,000 PSI, a 6,000 PSI pressure will be needed on the cylinder’s rod side to produce an equal amount of force. This is how pressure intensification occurs in double-acting cylinders. Important to take note that pressurizing a cylinder that is rated at 3,000 PSI, to 6,000 PSI, can bring some really devastating consequences.
In case, the pressure is applied at the piston side of the double acting hydraulic cylinder and simultaneously the fluid is restricted to escape from the rod side, the pressure will be intensified in the rod side until the forces are balanced or the hydraulic cylinder catastrophically fails.
One particular incident that one of our members experienced could be described somewhat like the following:
He said that his boss had tried to press out a pin at a day when the ambient temperature was minus 36 degrees and cylinder temperature was minus 10 degrees. He added that his boss had then turned on the pump and had moved the lever only to had found the gland of the cylinder that was 7.5’’ in size and had an operating pressure of 2,500PSI, had blown out.
From this narration, it should have easily understood that the cylinder’s gland blew out because of pressure intensification. This happened due to the blockage between the cylinder’s rod side and tank that resulted due to the cold conditions. Actually, the air temperature had fallen below the hydraulic oil’s port temperature, as a result, the oil couldn’t flow.
This should draw the line for the potential danger of pressure intensification in double-acting cylinders. And if you fail to consider its implications, it may prove to be a costly mistake.