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In a vault article, I described the danger associated with the intensification of push in a double-acting hydraulic cylinder. In this article, ns will explain how to usage the intensification impact to test the verity of the piston seal in a double-acting cylinder. But before attempting this check procedure, that is absolutely necessary that the danger linked with push intensification in a hydraulic cylinder is completely understood. Therefore, review this post FIRST!The conventional way of trial and error the integrity of the piston seal in a double-acting cylinder is to pressurize the cylinder at the finish of stroke and also measure any kind of leakage past the seal. This is typically referred to together the "end-of-stroke bypass test". The major limitation the the end-of-stroke bypass test, is the it generally doesn"t disclose ballooning of the cylinder tube resulted in by hoop anxiety as a result of under-designed cylinder wall surface thickness or palliation of wall surface thickness through too much honing. The ideal means to test for ballooning of the cylinder tube is to command a piston-seal bypass test, mid-stroke. The major difficulty with law this is that the force emerged by the cylinder needs to be mechanically resisted, i m sorry in the case of big diameter, high-pressure cylinders is impractical.However a mid-stroke bypass test can be conducted hydrostatically utilizing the intensification effect. The vital circuit is displayed in figure 1 below.
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Figure 1. Hydraulic cylinder test circuit.Test procedureThe procedure because that conducting the test is as follows:Secure the cylinder with its organization ports up.Fill both political parties of the cylinder v clean hydraulic fluid through its service ports.Connect round valves (1) and also (2), gauges (3) and also (4), relief valve (5) and also directional control valve (6) as displayed in number 1.With ball valves (1) and also (2) open, stroke the cylinder making use of the directional control valve (6) multiple times to eliminate all remaining air indigenous both political parties of the cylinder - take care not come "diesel" the cylinder.Position the piston stick mid-stroke and also close round valve (2).With the convey on the relief valve (5) donate out, straight flow to the rod side of the cylinder.Increase the setting of relief valve (5) until the cylinder"s rated press is viewed on gauge (3).Close round valve (1) and also center directional control valve (6). Note: the is assumed the the hydraulic power unit provided to command the test has actually its very own over-pressure defense - not displayed in figure 1. Document the respective press readings ~ above gauges (3) and (4) and also monitor any change over time. If the ratio of reliable area in between the piston and rod next of the cylinder is 2:1, climate if the rod next of the cylinder has actually been pressurized come 3,000 PSI, gauge (2) ~ above the piston side have to read 1,500 PSI. If the differential pressure across the piston is not maintained, this suggests a trouble with the piston seal or tube.Safety is paramountUnder no scenarios should circulation be directed to the piston next of the cylinder with ball valve (1) closed. Failure of the cylinder and/or an individual injury could result. As soon as conducting this or any other hydrostatic (pressure) test, always wear appropriate personal-protection equipment. associated articles:

Thermal expansion and also pressure intensification in hydraulic cylindersStoring hydraulic cylinders - safelyProactive maintenance for hydraulic cylinders

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