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It Is Necessary to Abrogate All the International Basic Standards of Seals
Xu Changxiang,
Zhang Xiaozhong,
Chen Youjun
Issue:
Volume 5, Issue 4-1, July 2016
Pages:
1-12
Received:
22 June 2016
Accepted:
25 June 2016
Published:
24 August 2016
Abstract: According to definitions in the international standard JCGM 200, physical quantities, divided into base quantity and derived quantity, are a property of a phenomenon, body, or substance, where the property has a magnitude that can be expressed as a number and a reference (a measurement unit); a base quantity cannot be expressed in terms of the others, and a derived quantity can be defined in terms of the base quantities of its system; and these base and derived quantities are related to each other by some laws and their equations. In the International System of Quantities, tightness or leak resistance is a derived quantity defined by a sealing or leaking law, which is the product of pressure p and time t expended on leaking a unit cubage of fluid through the sealing joints of a pressure vessel or system at a constant pressure, but by no means the reciprocal of “leakage rate” fabricated by the international standards. Various fluid circuits in pipes, on objects and in joints differ only in their fluid (leak) resistance and reactance, and it is impossible to know how to identify and control a fluid circuit before knowing these physical quantities. All the international basic standards of seals should be abrogated as soon as possible because they were so enacted before knowing what the leak resistance (tightness) and the qualified seal are and how to design, install and inspect a seal that it is impossible to count on them providing any effective control of leakage for a pressure vessel or system.
Abstract: According to definitions in the international standard JCGM 200, physical quantities, divided into base quantity and derived quantity, are a property of a phenomenon, body, or substance, where the property has a magnitude that can be expressed as a number and a reference (a measurement unit); a base quantity cannot be expressed in terms of the othe...
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New Explanations of Common Applications and Demonstrations of Changes in Pressure with Velocity of a Fluid Current
Xu Changxiang,
Zhang Xiaozhong,
Chen Youjun
Issue:
Volume 5, Issue 4-1, July 2016
Pages:
13-21
Received:
22 June 2016
Accepted:
25 June 2016
Published:
24 August 2016
Abstract: Movements are relative. The rapid flowing of a fluid through a wall-bulged passage of pipes at a certain pressure can be regarded as a movement of the bulged wall relative to a static fluid in a certainly pressurized pipe. The axial movement of a cylindrical object in the atmosphere and the water whose free inherent pressure is not influenced can be regarded not only as the object's movement in a certainly pressurized pipe but also as the rapid flowing of a fluid in a certainly pressurized pipe past a static object, because the free inherent pressure (region) is a radial wall and an axial certain pressure of a pipe. Actually, any fluid that flows past an object or a pipe wall at a certain pressure will have a part of its pressure energy converted into its kinetic energy by an axial positive resistance or positive fluid reactance from their windward, and have a part of its kinetic energy converted back into its pressure energy by an axial negative resistance or negative fluid reactance from their leeward, attempting to cause it to flow rapidly past an obstacle met by it without consumption of energy; or any flow of fluids obeys the same mechanism of changes in pressure with velocity and has the same pressure and velocity fields as a flow in a pipe; or it is undoubted that all the common applications and demonstrations of changes in pressure with velocity should have had a uniform scientific explanation.
Abstract: Movements are relative. The rapid flowing of a fluid through a wall-bulged passage of pipes at a certain pressure can be regarded as a movement of the bulged wall relative to a static fluid in a certainly pressurized pipe. The axial movement of a cylindrical object in the atmosphere and the water whose free inherent pressure is not influenced can b...
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Pressure Energy, Resistance and Reactance in Fluid Leak & Flow
Xu Changxiang,
Zhang Xiaozhong,
Chen Youjun
Issue:
Volume 5, Issue 4-1, July 2016
Pages:
22-30
Received:
22 June 2016
Accepted:
25 June 2016
Published:
24 August 2016
Abstract: The fluid current in a fluid circuit, corresponding to the electrical current in an electrical circuit, is determined by a fluid pressure corresponding to electrical pressure (voltage), and a fluid impedance corresponding to electrical impedance, and directly proportional to the fluid pressure and inversely proportional to the fluid impedance between two ends of the fluid circuit. The fluid impedance is the algebraic sum of the fluid resistance and the fluid reactance between the two ends. Fluid resistance is a physical quantity for measuring the peripheral resistance of a fluid current; fluid reactance, a physical quantity for measuring the front resistance of a fluid current; and leak resistance, a physical quantity for measuring the tightness of a seal. The three quantities have an identical measuring unit, indicating the sustained fluid pressure needed for a unit of fluid currents, or for a unit cubage of fluids for a unit of time, to flow through a fluid resistance, a fluid reactance or a leak resistance, and so (the current) x (the resistance) = (the pressure energy consumed by the resistance), (the current) x (the reactance) = (the pressure energy converted into the kinetic energy by the reactance), (the current) x (the leak resistance) = (the pressure energy consumed by the leak resistance), and (the current) x (the resistance + the reactance) = (the general pressure needed for a fluid current to flow through a fluid circuit). A leak path of seals, almost with kinetic energy negligible, can be considered a typical fluid circuit without any fluid reactance. Reactance of piping is from its each bore-changing passage or port. Reactance from reducing passages or ports is positive, and reactance from enlarging passages or ports is negative. A fluid current flowing past a moving object is equivalent to the one flowing in a pipe's wall-bulged passage whose corresponding right inclusion body has the same axis, generatrix and volume as the object's has. The fluid currents flowing over and under a wing are equivalent to the ones flowing in two parallel contiguous pipe lengths that are placed one under the other and use the length of the wing chord plane as the circumference of their cylindrical inlet and outlet walls, and use the upper and lower average curve surfaces of the wing separately as their upper and lower curve walls. The lift of the wing is from the inner pressure difference of the two pipe lengths.
Abstract: The fluid current in a fluid circuit, corresponding to the electrical current in an electrical circuit, is determined by a fluid pressure corresponding to electrical pressure (voltage), and a fluid impedance corresponding to electrical impedance, and directly proportional to the fluid pressure and inversely proportional to the fluid impedance betwe...
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Definition, Quantifying and Gauging of Tightness
Issue:
Volume 5, Issue 4-1, July 2016
Pages:
31-34
Received:
22 June 2016
Accepted:
25 June 2016
Published:
24 August 2016
Abstract: A leakage for fluid in a pressure vessel to flow through its sealing joint to the atmosphere is just like a leakage for electric charges in a capacitor to flow through its insulator to the ground, and hence there is a sealing law for pressure vessels that is completely similar to Ohm's law, stating the leakage current IL flowing through a sealing joint of pressure vessels is directly proportional to the pressure difference p between its two ends and inversely proportional to its leak resistance RL, or IL = p/RL. Thus it can be known according to the sealing law that the tightness or leak resistance (RL = p/IL = pt/C) is the product of pressure p and time t expended on leaking a unit cubage of fluid through sealing joints under a fixed pressure p and can be gauged according to the sealing theorem RL = p(p – 0.5Δp)Δt/(ΔpC), and the greater the value of p/Δp, the shorter the time required to observe, or the closer to being done at a constant pressure and temperature the test, and the more accurate the test result, where p is the test pressure, Δt is the time expended on the pressure decay from p to (p – Δp), C is the test fluid cubage.
Abstract: A leakage for fluid in a pressure vessel to flow through its sealing joint to the atmosphere is just like a leakage for electric charges in a capacitor to flow through its insulator to the ground, and hence there is a sealing law for pressure vessels that is completely similar to Ohm's law, stating the leakage current IL flowing through a sealing j...
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Xu's Designs and Parameters for Sealing Elements
Issue:
Volume 5, Issue 4-1, July 2016
Pages:
35-42
Received:
22 June 2016
Accepted:
25 June 2016
Published:
24 August 2016
Abstract: Any leak-free achievement needs a sealing surface that has microcosmic irregularities fully complementary to a surface to be sealed and that can be qualified only by compressive working or installing in position. ASME Code mistakes the working stress needed to result in a qualified gasket in installation for the stress needed to enable a qualified gasket to function well or maintain its leak-free connection, and only considers the influence of the sealing material's strength but never its elasticity on sealing. Undoubtedly, ASME Code's leak-free Maintenance Factor m and Minimum Necessary Sealing Stress y of gaskets are both wrong in values. Similarly, neither is the gasket parameters system substituted for the gasket factors m and y by PVRC and EN 13555. Actually, the stronger the strength and the elasticity of a sealing contact layer, the more difficult for its sealing element to create or maintain a fully deformed contact; whereas the stronger the strength and the elasticity of a contact layer substrate, the easier for its sealing element to create or maintain a fully deformed contact; i.e. the index used to measure the difficulty for a sealing element to create or maintain a leak-free connection is its sealing difficulty factor m1 = its contact's elastic modulus Ec/its substrate's elastic modulus Es; so it is the most difficult for a rubber element to create or maintain a leak-free connection because its m1 ≡ 1, the easiest for a grease coating because its m1 = 0, and easier for the other sealing elements than for a rubber element because their m1 can be made smaller than 1 (or m1 < 1) by designing and coating.
Abstract: Any leak-free achievement needs a sealing surface that has microcosmic irregularities fully complementary to a surface to be sealed and that can be qualified only by compressive working or installing in position. ASME Code mistakes the working stress needed to result in a qualified gasket in installation for the stress needed to enable a qualified ...
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Xu's Sealing Theory and Rectangular & O-Shaped Ring Seals
Issue:
Volume 5, Issue 4-1, July 2016
Pages:
43-58
Received:
22 June 2016
Accepted:
25 June 2016
Published:
24 August 2016
Abstract: The difficulty for a sealing element to create and maintain a leak-free joint is determined by its sealing difficulty factor m1, m1 = elastic modulus Ec of its sealing contact layer/elastic modulus Es of its sealing contact layer substrate. Therefore, theoretically the contact layer of a sealing element shall be soft & inelastic and assembled up to its fully yielded deformation to provide a contact layer with a lower value of active elastic modulus Ec, and the contact layer substrate shall be strong & elastic and assembled up to its fully elastic deformation to provide a contact layer substrate with a higher value of active elastic modulus Es. It is the most difficult for a rubber sealing element to create a leak-free joint because its Ec ≡Es, and it is far easier for a metal sealing element than for a rubber sealing element because the metal sealing element can be designed and coated to ensure that assembling can cause its Ec < Es.
Abstract: The difficulty for a sealing element to create and maintain a leak-free joint is determined by its sealing difficulty factor m1, m1 = elastic modulus Ec of its sealing contact layer/elastic modulus Es of its sealing contact layer substrate. Therefore, theoretically the contact layer of a sealing element shall be soft & inelastic and assembled up to...
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